Monday, November 16, 2009

Risk Assessment and Screening for Sexually Transmitted Infections, HIV, and Hepatitis Virus Among Long-Distance Truck Drivers in New Mexico, 2004-2006

Abstract (Summary)

We examined sexually transmitted infection (STI), HIV, and hepatitis virus prevalence and risk behaviors among truck drivers. We asked participants about their risk behaviors, and we screened them for STIs, HIV, and hepatitis infections. We used logistic regression to identify factors associated with outcomes. Of the 652 enrolled participants, 21% reported sex with sex workers or casual partners in the prior year. Driving solo (odds ratio [OR]=15.04; 95% confidence interval [CI]=1.92, 117.53; P=.01), history of injection drug use (IDU; OR=2.69; 95% CI=1.19, 6.12; P=.02), and history of an STI (OR=2.47; 95% CI=1.19, 5.09; P=.01) were independently associated with high-risk sexual behaviors. Fourteen percent of participants reported drug use in the previous year, and 11% reported having ever injected drugs. Participants tested positive as follows: 54 for HCV antibodies (8.5%), 66 for hepatitis B anticore (anti-HBc) antibodies (10.4%), 8 for chlamydia (1.3%), 1 for gonorrhea (0.2%), 1 for syphilis (0.2%), and 1 for HIV (0.2%). History of injecting drugs (OR=26.91; 95% CI=11.61, 62.39; P<.01) and history of anti-HBc antibodies (OR=7.89; 95% CI=3.16, 19.68; P<.01) were associated with HCV infection. Our results suggest a need for hepatitis C screening and STI risk-reduction interventions in this population.

Copyright American Public Health Association Nov 2009

[Headnote]
Objectives. We examined sexually transmitted infection (STI), HIV, and hepatitis virus prevalence and risk behaviors among truck drivers.
Methods. We asked participants about their risk behaviors, and we screened them for STIs, HIV, and hepatitis infections. We used logistic regression to identify factors associated with outcomes.
Results. Of the 652 enrolled participants, 21% reported sex with sex workers or casual partners in the prior year. Driving solo (odds ratio [OR]=15.04; 95% confidence interval [CI]=1.92, 117.53; P=.01), history of injection drug use (IDU; OR=2.69; 95% CI=1.19, 6.12; P=.02), and history of an STI (OR=2.47; 95% CI=1.19, 5.09; P=.01) were independently associated with high-risk sexual behaviors. Fourteen percent of participants reported drug use in the previous year, and 11% reported having ever injected drugs. Participants tested positive as follows: 54 for HCV antibodies (8.5%), 66 for hepatitis B anticore (anti-HBc) antibodies (10.4%), 8 for chlamydia (1.3%), 1 for gonorrhea (0.2%), 1 for syphilis (0.2%), and 1 for HIV (0.2%). History of injecting drugs (OR=26.91; 95% CI=11.61, 62.39; P<.01) and history of anti-HBc antibodies (OR=7.89; 95% CI=3.16, 19.68; P<.01) were associated with HCV infection.
Conclusions. Our results suggest a need for hepatitis C screening and STI risk-reduction interventions in this population. (Am J Public Health. 2009;99: 2063-2068. doi:10.2105/AJPH.2008.145383)

Studies in Africa, Southeast Asia, Eastern Europe, and South America have linked long-distance truck drivers and commercial sex workers with the dissemination of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV) infection. 1-15 Evidence suggests that the spread of HIV throughout central Africa was facilitated by truck traffic along the Kinshasa-Mombasa highway. 1,2 High rates of STIs and HIV have been observed among long-distance truck drivers in India and Bangladesh, where truck drivers are implicated in the spread of STIs and HIV into rural areas and areas surrounding international border crossings.7-11 Results from studies in Eastern Europe suggest risky behavior and increased syphilis rates among truck drivers.12,13 Additionally, studies among truck drivers in Brazil show low levels of perceived risk of infection despite high rates of syphilis and high levels of risky behaviors, e.g., unprotected sex with multiple partners, including commercial sex workers, and high levels of drug use.14,15

Little is known about the roles that longdistance truck drivers and sex workers at truck stops might play in spreading STIs or HIV in the United States. An ecological study in North Carolina examining reported syphilis cases during an outbreak found that the counties along interstate highways had higher syphilis rates than other counties in the state.16 The authors theorized that truck drivers and sex workers might have played a role in this finding, but there were no data to support this. A 1995 ethnographic study in Florida examining STI risk behaviors of truck drivers found low levels of perceived STI or HIV risk but high levels of risky behaviors.17 However, no laboratory studies were conducted; therefore, there are no data estimating the prevalence of STIs among long-distance truck drivers in the United States.

To examine the environments in which STIs, HIV, and hepatitis virus are transmitted, and to assess the prevalence of STIs, HIV infection, and hepatitis virus infection and risk behaviors among truck drivers, we conducted a risk assessment and screening for STIs, HIV, and hepatitis among truck drivers traveling through New Mexico.

METHODS

From December 2004 through March 2006, we used mobile clinic vans to conduct this study at a large trucking terminal in Albuquerque, New Mexico, and at 10 truck stops on interstate highways elsewhere in the state. The 10 truck stops ranged in size from small (parking capacity approximately 50) to very large (more than 400 parking places). Nine truck stops had 24-hour restaurants, 4 had private security patrolling the lots, and 2 were located on Indian reservations and associated with casinos. Seven truck stops were on Interstate 40, running east-west through New Mexico; the rest were located in the southern part of the state on Interstate 25, Interstate 10, and at the intersection of interstates 285 and 360.

Truck driverswere recruited via citizens' band radio and leaflets distributed at trucking venues. Any long-distance truck driver aged 21 years or older who had a valid commercial driver's license, who traveled interstate, and who did not return home nightly was eligible for the study. Participants provided verbal informed consent and completed a face-to-face interview conducted by a study team member. STI and hepatitis screening was conducted after the interview. Interviews lasted 15 to 30 minutes, and each participant was reimbursed $35 cash.

The structured interview form collected demographics, driving history (e.g., years working as a driver), sexual behavior (e.g., condom use, STI history), and drug and alcohol use. All interviews were conducted anonymously, with no identifying or locating information collected, and all interview forms were coded with unique numbers.

STI, HIV, and Hepatitis Screening

Blood and urine samples were collected from study participants at the conclusion of the interview. We used a nucleic acid amplification test (Aptima Combo 2, Gen-Probe Inc, San Diego, CA) to test urine samples for chlamydia and gonorrhea. Blood serum samples were tested for syphilis,HIV, hepatitis B virusmarkers, andHCV markers. Syphilis antibodieswere assayed using a rapid plasma reagin (RPR) assay (Wampole Impact Syphilis RPR Card Test, Inverness Medical ProfessionalDiagnostics,Waltham,MA); positive RPR tests were confirmed using a Treponema pallidum particle agglutination (TPPA) assay (Serodia-TP-PA, Fujirebio Diagnostics, Malvern, PA). HIV antibodies were assayed using an HIV enzyme immunoassay (EIA) (Vironostika HIV- 1Microelisa System, bioMe'rieux, Marcy l'Etoile, France); positive EIA results were confirmed using an HIV-1Western blot assay (Genetic Systems HIV-1Western Blot, Bio-Rad Laboratories, Hercules, CA). Hepatitis B surface antigen (HBsAg) was assayed using the Genetic Systems HBsAg 3.0 test (Bio-Rad Laboratories), and total antihepatitis B core antibodies (anti-HBc) were assayed using the ETI-AB-COREK PLUS assay (DiaSorin, Saluggia, Italy). HCV antibodies were assayed using the ORTHO HCV version 3.0 ELISA test (Ortho Clinical Diagnostics, Rochester, NY). Positive test results for total HCV antibody were reported with a signal-to-cutoff ratio. A signal-to-cutoff ratio of at least 3.8 is predictive of a true positive test result more than 95% of the time.18

All laboratory testing was performed by the Scientific Laboratory Division of the New Mexico Department of Health. No specimens were tested for drugs or alcohol.

Data Analysis

No identifying information was collected; thus, it was possible that drivers volunteered more than once. To identify potential duplicates, data were examined to identify drivers reporting the same response for age, gender, race, ethnicity, marital status, number of years driving, and home state. No potential duplicates were identified in this manner.

Truck drivers were classified by type of driver: company drivers (union and nonunion), lease drivers, and owners/operators. Company drivers are employees of union and nonunion shops; all loads, driving schedules, and routes are arranged for them by the company. For union employees, the driving schedule is usually a set route. For nonunion employees, the driving schedules and routes are highly variable and often are modified while the driver is on the road. Lease drivers own their own truck and lease it to 1 or more companies. These drivers have some flexibility in their driving schedules and routes, and they usually have their loads arranged for them by the company to which they lease their truck. Owner/operator drivers are completely independent; these drivers own their own trucks, arrange their own loads, and determine their own driving schedule and routes.

We used EpiInfo version 6 (Centers for Disease Control and Prevention, Atlanta, GA) and Intercooled Stata version 9 (StataCorp LP, College Station, TX) to conduct data analyses and all logistic regressions (descriptive, univariate, stratified, and multivariate). Numeric variables were analyzed as continuous variables. Age and number of years driving were also examined as categorical variables: age was divided into10- year age groups, and years driving was divided into groups of less than1year,1to5 years,6to10 years, and more than 10 years. For multivariate logistic regression analyses examining risk factors independently associated with having sex with a sex worker, drug use, and positive laboratory test results, all variables found by univariate analyses to be significantly associated with the outcomeat P£.05were included in analyses.

RESULTS

This study was conducted 2 to 3 times per month from December 2004 through March 2006 at the trucking terminal or a truck stop. A total of 652 drivers enrolled. Demographic characteristics are shown in Table 1. Most drivers resided in 44 of the contiguous 48 US states, with a few living in Canada. Thirty-nine (6%) had been driving for less than 1 year, and half of the drivers had been driving for more than 10 years (mean=13 years; range=1-48 years). Drivers reported being away from home a mean of 288 nights per year (range=60- 365 nights). However, the time away from home was not evenly distributed throughout the year. Some drivers (<10%)>

A number of differences were found when driver characteristics were examined by gender. Female drivers were significantly more likely than male drivers to have attended or completed college (odds ratio [OR]=2.79; 95% confidence interval [CI]=1.58, 4.93; P<.01) and to always drive as part of a team (OR=5.76; 95% CI=10.55, 19.45; P<.01). Of drivers always driving as part of a team, female drivers were significantly more likely to drive with their spouse or steady partner than male drivers were (OR=8.99; 95% CI=3.43, 24.16; P<.01). Female drivers also reported significantly fewer years driving than male drivers (mean 7.4 years for women vs 14.0 years for men; P<.01) and a lower mean annual income than men ($50000 vs $61000).

Of the 652 drivers in this study, 5% were union employees, 71% were nonunion employees, 19% were lease drivers, and 5% were owner/operators. Union drivers reported almost always being home on weekends and spent significantly less time away from home than any of the other 3 types of drivers (mean=219 nights away from home per year vs 291, 296, and 278 nights away from home per year for nonunion drivers, lease drivers, and owner/operators, respectively; P<.01). Union drivers were also significantly more likely to always drive as part of a team (45% vs 20%, 14%, and 3% respectively), to have health insurance (100% vs 73%, 51%, and 57% respectively), and to have paid sick leave (100%vs 21%, 5%, and 0%; P<.01 for all analyses).

Regarding health status, 31% of drivers reported their current health as fair or poor, with obesity, poor diet, and lack of exercise being common concerns. Health insurance coverage was reported by 67% of drivers, but only 19% had paid sick leave. For unionized drivers, health insurance was a benefit provided with employment. Most nonunion company drivers could purchase insurance through the company for which they worked; however, many said the cost was prohibitive. The high cost of insurance was also the main reason given by lease drivers and owner/operators for not purchasing health insurance coverage. Even though two thirds of the drivers had health insurance, they reported great difficulty accessing care and locating providers. As a result, drivers reported continuing to drive when ill (unless extremely ill) and using overthe- counter medications to alleviate symptoms

Alcohol Use, Drug Use, and Sexual Risk Behaviors

Twenty-five percent of drivers reported no alcohol consumption in the previous year, and 33% reported rarely drinking alcohol. Only 270 (41.4%) reported drinking 1 or more drinks per week (range=1-60 drinks/week). Binge drinking ([double dagger]5 drinks at 1 sitting) in the previous year was reported by 47% of drivers. Among these, 21% reported binge drinking at least 10 times in the previous year (mean=10; range=1-360).

The mean number of reported lifetime sexual partners was 48 (median=15; range=1 to>1000), and 3% of male drivers reported ever having sex with a man. Previous STI treatment was reported by 132 drivers (gonorrhea 12%, chlamydia 5%, herpes 2%, syphilis 1%, and human papillomavirus 1%).

Having sex with a sex worker in the previous 5 years was reported by 74 male drivers (13% of male drivers) and ranged from 1 time to more than 100 times. Forty-eight male drivers also reported having sex with a sex worker in the previous year (range=1-30 times). Sex with a casual partner (e.g., pick-up at bars, Internet contacts, another driver, truck stop employees) was reported by10 female and126 male drivers (21% of all drivers) for the previous 5 years and by 7 female and 73 male drivers (12% of all drivers) for the previous year. Among drivers reporting sex with a sex worker, 46% stated they used condoms less than half of the time, and 32% reported never having used condoms. Similar levels of condom use was reported for sex with a casual partner. Half the drivers reported that they had not used a condom the last time they had sex with a sex worker or casual partner. There were no statistically significant differences in reported condom use for drivers who reported having a spouse or steady partner.

In multivariate logistic regression, only being a solo driver (OR=15.04; 95% CI=1.92, 117.53; P=.01), having a history of current or prior injection drug use (IDU; OR=2.69; 95% CI=1.19, 6.12; P=.02), and having a history of an STI (OR=2.47: 95% CI=1.19, 5.09; P=.01) remained independently associated with having sex with a sex worker in the previous year (Table 2). Having a current partner (OR=0.44; 95% CI=0.22, 0.89; P=.02) and increasing number of years driving (OR=0.95; 95% CI=0.92, 0.99; P=.01) remained independently associated with a decreased likelihood of having sex with a sex worker in the previous year.

Drivers were asked about their use of ecstasy, heroin, crack cocaine, powder cocaine, methamphetamines, and marijuana in the previous 1 and 5 years. Overall, 195 (30%) reported any drug use in the previous 5 years and 93 (14%) in the previous year. However, 25% of the 652 drivers had been driving less than 5 years and 6% for less than 1 year. Thus, analysis of reported drug use among working drivers included only those working during the entire time period being analyzed, i.e., 486 drivers working at least 5 years and 613 drivers working at least 1 year.

For the 486 drivers working at least 5 years, 126 (26%) reported any drug use during those 5 years, and 65 (14%) reported drug use in the previous 1 year. This significant decrease in reported drug use (P<.01 for marijuana and methamphetamine; P=.03 for powder cocaine) was reported to be a direct result of required random drug testing20 and the consequences of a positive test result, i.e., loss of job. For the 613 drivers working at least 1 year, 85 (14%) reported any drug use during that year (Table 3). Of drivers reporting any drug use in the previous year, 34 reported using marijuana at least monthly and 19 weekly, 17 used methamphetamines at least monthly and14 weekly, 7 used cocaine at least monthly, and 7 used crack at least monthly. A history of IDU was reported by 70 (11%) of all 652 drivers, and IDU in the previous year was reported by 9 (1%) drivers. Of the 9 drivers reporting recent IDU, 3 reported usingmultiple drugs, 4 injected heroin, 4 injected cocaine, and 4 injected methamphetamines.

Univariate and multivariate logistic regression analyses were used to identify risk factors associated with reported drug use in the previous year. Only consuming at least 1 drink per week in the previous year (OR=2.44; 95% CI=1.26, 4.71; P=.01) remained independently associated with increased likelihood of using drugs, and only having health insurance (OR=0.59; 95% CI=0.35, 0.99; P=.05) remained independently associated with a decreased risk of drug use (Table 2).

STI and Hepatitis Screening Test Results

Urine specimens were obtained from 631 (96.8%) drivers and were tested for chlamydia and gonorrhea. Blood specimens were obtained from 636 (97.5%) drivers and were tested for HIV, syphilis, and hepatitis B and C. One male driver had a positive test for gonorrhea, and 8 drivers (4 men, 4 women) had positive test results for chlamydia (Table 4). One man with a history of IDU had positive test results for HIV (ELISA and Western blot). One man with a history of prior treatment of syphilis had a reactive test for syphilis (RPR 1:4 and TPPA positive). Three male drivers were HBsAg positive, and 66 others (10.4%; 5 women and 61 men) had remote resolved hepatitis B virus infection, i.e., a positive serum anti- HBc antibody test with a negative HBsAg test.

A total of 54 drivers (8.5%; 4 women and 50 men) had a positive test result for HCV antibodies by EIA. The anti-HCV signal-tocutoff ratio for all but 1 of these drivers was greater than 4.2, indicating a high likelihood that the EIA results were true positive results.18 Of these 54 drivers, 36 (66.7%) reported prior or current IDU (2 of these 36 drivers also reported receiving blood transfusions prior to 1990, and 1 other had worked as an emergency medical technician); 2 reported blood transfusions prior to 1990; 1 worked as a dialysis nurse; 1 had a spouse with HCV; and for 14 there was no risk identified in the interview. Five already knew they had HCV, and 1 had undergone treatment for HCV. Of the 54 drivers positive for HCV, 28 (52%) reported having health insurance, 43 (80%) reported drinking alcohol in the previous year, 27 (50%) reported at least 1 episode of binge drinking in the previous year, and 11 (20%) reported binge drinking more than 10 times in the previous year. In multivariate analyses comparing drivers with positive HCV test results to those with negative results, history of IDU (OR=26.91; 95% CI=11.61, 62.39; P<.01) and having a positive anti-HBc antibody test (OR=7.89; 95% CI=3.16, 19.68; P<.01) were highly associated with positive HCV test results (Table 2).

DISCUSSION

Similar to results from studies of truck drivers in developing countries and in Florida, drivers in this study reported engaging in risky behaviors associated with STIs.1-15,17 However, STI prevalence was low. Multiple factors may contribute to this finding. First, rates of STIs in the United States among the general population are lower than in developing countries, particularly for countries with high rates of HIV infection. Second, sexual contact with commercial sex workers was reported by a small minority of study participants. Additionally, half of the study participants reported using a condom during their last sexual encounter. Finally, the sample was a voluntary, convenience sample; it is possible that those with STIs choose not to volunteer.

An interesting finding was the high prevalence of HCV infection. The rate in this sample, 8.5%, was higher than the highest rate (4.3% in people aged 40-49 years) reported in the third National Health and Nutrition Examination Survey (1988-1994).21Two thirds of the HCVantibody- positive truck drivers reported previous or current IDU as a risk behavior likely related to HCV infection. Most participants who were HCV positive were unaware of their infection. This finding is significant because drivers also reported ongoing alcohol consumption, including binge drinking. Alcohol consumption is a strong independent risk factor for the progression of HCV-associated liver disease that potentially can be modified through patient education and behavior change.22,23

We found that14%of drivers reported using an illicit drug during the previous year, with marijuana use reported more than twice as often as methamphetamine or cocaine use. Although no drug or alcohol testing was included in this study, the self-reported drug use among study participants was similar to the results of voluntary drug testing in Oregon in April 2007, when 10% of drivers tested positive for controlled substances.24 The Oregon study lent some validity to the self-reported drug use of drivers in the current study. Although most drivers in the current study reported occasional drug use, some reported regular use, including IDU. This presents a potentially grave safety issue if any drivers are under the influence while driving.

Access to health care was repeatedly cited as a major concern for the truck drivers, a finding that has been previously documented.25 Even though most drivers had health insurance, they reported barriers to use. Their jobs necessitate mobility and routines that impede scheduling medical or dental appointments. Efforts such as establishing networks of medical or dental facilities with flexible hours at locations near trucking venues may provide improved access to health services for this population.

This study has several limitations. The sample was a convenience sample of drivers traveling across New Mexico who volunteered to participate. Therefore, the results may not be representative of all US truck drivers. No information was available for drivers who did not volunteer. Behaviors of these drivers may be different from those who volunteered; drivers engaging in risky behaviors may have chosen not to participate. The demographic breakdown of drivers in this study was very similar to that estimated by the Department of Labor and the American Trucking Association. In 2000, the American Trucking Association estimated that 80% of truckers were White, 9.7% Hispanic, 11.7% African American, 25.7% did not complete high school, 59% were aged 35 to 54 years, and 4.6% were women.26 The Department of Labor estimates that up to 12% of drivers are women.27 However, there may be significant differences in risk factors or STI prevalence between drivers traveling through New Mexico and those traveling the East Coast or between cities with high rates of STIs or HIV.

Additionally, the study design included a face-to-face interview, and data were selfreported. Therefore, social desirability may have caused under- or overreporting of risky behaviors, and drivers may have been reluctant to report use of alcohol or illegal drugs.

Despite these limitations, this study contributes to the literature on STIs and HIV among US truck drivers by providing information on drivers' current health needs and opportunities for intervention among them. Prevalence of STIs and HIV was low, but drivers reported risky behaviors. Our results suggest that drivers may benefit from HIV, STI, and hepatitis prevention interventions embedded within comprehensive wellness programs that are convenient and easily integrated into the mobile environment of the trucking industry. Additional studies including different US trucker populations and more rigorous study designs should be conducted to confirm these results and provide more data to inform the development of STI and HIV intervention and wellness programs for the study population.

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[Author Affiliation]
Sarah Valway, DMD, MPH, Steven Jenison, MD, Nick Keller, BS, Jaime Vega-Hernandez, and Donna Hubbard McCree, PhD, MPH, RPh

[Author Affiliation]
About the Authors
Sarah Valway, Steven Jenison, Nick Keller, and Jaime Vega-Hernandez are with the Public Health Division, New Mexico Department of Health, Santa Fe. Donna Hubbard- McCree is with the National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA.
Correspondence should be sent to Sarah Valway, DMD, MPH, New Mexico Department of Health, Infectious Diseases Bureau, 1190 South Saint Francis Drive, Santa Fe, NM 87502 (e-mail: s.valway@att.net). Reprints can be ordered at http://www.ajph.org by clicking the ''Reprints/ Eprints'' link.
This article was accepted February 17, 2009.
Contributors
All the authors conceptualized the study design and developed and tested questionnaires prior to implementation. N. Keller led the recruitment of truck drivers. S. Valway, S. Jenison, N. Keller, and J. Vega-Hernandez conducted interviews with study participants and oversaw specimen collection. S. Valway led data management, article writing, and analyses. S. Jenison, N. Keller, J. Vega-Hernandez, and D. Hubbard McCree made significant contributions to data management, article writing, and analyses. S. Jenison and D. Hubbard McCree provided overall supervision of the study.
Acknowledgments
This research was funded by cooperative agreement from the Centers for Disease Control and Prevention through the Association for Prevention Teaching and Research (U36/CCU300860).
The authors appreciate the assistance of the truck drivers who participated in this study. Without their assistance, the study could not have been completed.We also acknowledge the many staff of the New Mexico STD Program, whose assistance with this study was vital to its success.
Human Participant Protection
The study was approved by the institutional review boards of the Centers for Disease Control and Prevention and the New Mexico Department of Health.

References

Indexing (document details)

Subjects:Human immunodeficiency virus--HIV, Trucking industry, Truck drivers, Wellness programs, Studies, Risk factors, Hepatitis, Health services, Health care access, Flexible hours, Ethnicity, Drug testing, Data analysis, Alcohol use
Author(s):Sarah Valway, Steven Jenison, Nick Keller, Jaime Vega-Hernandez, Donna Hubbard McCree
Author Affiliation:Sarah Valway, DMD, MPH, Steven Jenison, MD, Nick Keller, BS, Jaime Vega-Hernandez, and Donna Hubbard McCree, PhD, MPH, RPh

About the Authors
Sarah Valway, Steven Jenison, Nick Keller, and Jaime Vega-Hernandez are with the Public Health Division, New Mexico Department of Health, Santa Fe. Donna Hubbard- McCree is with the National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA.
Correspondence should be sent to Sarah Valway, DMD, MPH, New Mexico Department of Health, Infectious Diseases Bureau, 1190 South Saint Francis Drive, Santa Fe, NM 87502 (e-mail: s.valway@att.net). Reprints can be ordered at http://www.ajph.org by clicking the ''Reprints/ Eprints'' link.
This article was accepted February 17, 2009.
Contributors
All the authors conceptualized the study design and developed and tested questionnaires prior to implementation. N. Keller led the recruitment of truck drivers. S. Valway, S. Jenison, N. Keller, and J. Vega-Hernandez conducted interviews with study participants and oversaw specimen collection. S. Valway led data management, article writing, and analyses. S. Jenison, N. Keller, J. Vega-Hernandez, and D. Hubbard McCree made significant contributions to data management, article writing, and analyses. S. Jenison and D. Hubbard McCree provided overall supervision of the study.
Acknowledgments
This research was funded by cooperative agreement from the Centers for Disease Control and Prevention through the Association for Prevention Teaching and Research (U36/CCU300860).
The authors appreciate the assistance of the truck drivers who participated in this study. Without their assistance, the study could not have been completed.We also acknowledge the many staff of the New Mexico STD Program, whose assistance with this study was vital to its success.
Human Participant Protection
The study was approved by the institutional review boards of the Centers for Disease Control and Prevention and the New Mexico Department of Health.
Document types:Feature
Document features:Tables, References
Section:RESEARCH AND PRACTICE
Publication title:American Journal of Public Health. Washington: Nov 2009. Vol. 99, Iss. 11; pg. 2063, 6 pgs
Source type:Periodical
ISSN:00900036
ProQuest document ID:1897707891
Text Word Count4757
Document URL:http://proquest.umi.com/pqdweb?did=1897707891&sid=1&Fmt=3&clientId=45625&RQT=309&VName=PQD

Candidiasis Genetics; Researchers at University of Kansas

Candidiasis Genetics; Researchers at University of Kansas have published new data on candidiasi genetics

Abstract (Summary)

Drosophila cuticular hydrocarbons (CHCs) can function as pheromones and consequently affect mate recognition. In a previous study of the two major CHCs in females that affect mating discrimination between Drosophila simulans and D. sechellia, quantitative trait loci (QTL) were identified on the X and third chromosome, and a few candidate genes were potentially implicated. Here we specifically test candidate genes for CHC biosynthesis and determine the genetic architecture of four additional CHCs that differ in abundance between D. simulans and D. sechellia females. The same QTL, and new ones, were found for additional CHCs. By examining all these CHCs and exploring their covariance, we were able to ascribe putative function to the major QTL. Although desaturases have received considerable attention for their role in CHC biosynthesis, evidence here implies that elongases may be just as important.

(c)Copyright 2009, Health & Medicine Week via NewsRx.com

2009 NOV 9 - ( NewsRx.com) -- A new study, 'Identification of quantitative trait loci function through analysis of multiple cuticular hydrocarbons differing between Drosophila simulans and Drosophila sechellia females,' is now available (see also Candidiasis Genetics). "The genetics of sexual isolation, behavioral differences between species that prevent mating, is understood poorly. Pheromonal differences between species can influence sexual isolation in many animals and in some cases a single locus can cause large functional changes in pheromonal mating signals," investigators in the United States report.

"Drosophila cuticular hydrocarbons (CHCs) can function as pheromones and consequently affect mate recognition. In a previous study of the two major CHCs in females that affect mating discrimination between Drosophila simulans and D. sechellia, quantitative trait loci (QTL) were identified on the X and third chromosome, and a few candidate genes were potentially implicated. Here we specifically test candidate genes for CHC biosynthesis and determine the genetic architecture of four additional CHCs that differ in abundance between D. simulans and D. sechellia females. The same QTL, and new ones, were found for additional CHCs. By examining all these CHCs and exploring their covariance, we were able to ascribe putative function to the major QTL. Although desaturases have received considerable attention for their role in CHC biosynthesis, evidence here implies that elongases may be just as important. Sex determination genes do not seem to have a role in this species difference although D. sechellia is sexually dimorphic in CHCs, whereas D. simulans is not," wrote J.M. Gleason and colleagues, University of Kansas.

The researchers concluded: "Epistatic interactions, only detected for CHCs limited to D. sechellia, imply that complex interactions among loci may also be having a role in these compounds that affect mating isolation."

Gleason and colleagues published their study in Heredity (Identification of quantitative trait loci function through analysis of multiple cuticular hydrocarbons differing between Drosophila simulans and Drosophila sechellia females. Heredity, 2009;103(5):416-24).

For additional information, contact J.M. Gleason, University of Kansas, Dept. of Ecology and Evolutionary Biology, Lawrence, KS USA..

The publisher of the journal Heredity can be contacted at: Nature Publishing Group, 345 Park Avenue South, New York, NY 10010-1707, USA.

Keywords: United States, Lawrence, Candidiasis Genetics, Behavior, Vaginal Candidiasis.

This article was prepared by Health & Medicine Week editors from staff and other reports. Copyright 2009, Health & Medicine Week via NewsRx.com.

Indexing (document details)

Author(s):Anonymous
Document types:Expanded Reporting
Publication title:Health & Medicine Week. Atlanta: Nov 9, 2009. pg. 837
Source type:Periodical
ISSN:15316459
ProQuest document ID:1892898141
Text Word Count392
Document URL:http://proquest.umi.com/pqdweb?did=1892898141&sid=2&Fmt=3&clientId=45625&RQT=309&VName=PQD

Sunday, November 8, 2009

Data mining of tuberculosis patient data using multiple correspondence analysis

Data mining of tuberculosis patient data using multiple correspondence analysis
T W RENNIE, W ROBERTS. Epidemiology and Infection. Cambridge: Dec 2009. Vol. 137, Iss. 12; pg. 1699, 6 pgs
Copyright © Cambridge University Press 2009

(ProQuest: ... denotes non-US-ASCII text omitted.)

Tuberculosis

INTRODUCTION

There has been a rise in tuberculosis (TB) notifications in the UK since 1987 [1]. However, excluding TB in London, rates of TB in the UK are relatively low and stable. In the context of North East (NE) London, high rates of TB are observed in some primary care trust areas (PCTs) whilst in others rates are relatively low [2]. This demonstrates the complexity of TB epidemiology in the UK and London and is suggestive of a range of factors that give rise to high rates of TB in specific geographical areas.

As TB is a notifiable disease specialist TB healthcare professionals report demographic and clinical variables of patients who are notified to public health authorities. The Enhanced Tuberculosis Surveillance (ETS) system was introduced in 1999 to aid notification [3]. These collected data show the different demographic and clinical profiles of patients observed in NE London and may account for variations in TB rates. This is a valuable health information source, for example, in identifying commissioning priorities for different PCTs. This requires appropriate statistical support and effective communication to decision makers [4, 5]. However, analysis of large amounts of data with a large proportion of categorical/nominal data (e.g. gender, ethnicity, etc.) that can display multiple associations may prove to be difficult to interpret if bivariate comparisons are made. Factor analysis and principal components analysis (PCA) are inappropriate methods of analysis for these data which include a mix of continuous and categorical data. Multiple correspondence analysis (MCA) is an analytical method that allows analysis of multiple categorical variables [6]. The usefulness of this method lies in its reduction of large quantities of data and inclusion of any number of categorical variables although it does not provide a statistical assessment of association. We demonstrate the use of MCA as a tool for performing epidemiological 'mapping' of TB patient variables. This may prove to be useful in identifying commissioning priorities in NE London.

METHOD

MCA

Greenacre [7] describes correspondence analysis (CA) in its simplest form as a two-way cross-tabulation summarizing the distribution of frequencies to display a data 'map' in two-dimensional space. MCA is the multivariable extension of CA that allows explanation of relationships between two or more variables [8]. By including more than two variables in this type of analysis the complexity is increased; relationships between variables are described in terms of the variance of data. As this technique involves categorical variables the variance of the data, specific to each variable category, can be plotted in dimensional space; the variance for each category can be 'averaged' to one point in space (the centroid). This results in two graphical outputs - object plots which show the spread of category data variance, and variable plots which can display joint category plots. The latter is useful in that entered variables may then be described by the proximity of variable categories to other categories' points, their inertia (degree of variance), and whether they lie along particular dimensions in common with other category points. This technique differs from PCA in that it permits analysis of multiple categorical variables [9]. However, continuous data, such as age, may be categorized and entered for analysis. For a full description of the use of MCA see Greenacre [6].

Analytical strategy

Data from the ETS dataset for NE London between the years 2002 and 2007 were selected and entered for analysis; this included data for seven PCTs. Denotified TB cases, where initial TB diagnosis was later changed, were excluded ( n =441). Data were entered into a data-frame in SPSS (version 14.0; SPSS Inc., USA) for analyses. After categorizing continuous data (patient age), data were entered for MCA using the 'optimal scaling' option in SPSS. A two-dimensional graphical output plot of data displaying variable categories was selected (variable plot - joint category plot function in SPSS).

RESULTS

Data for 4947 TB patients between the years 2002 and 2007 were entered for analysis. In this cohort of patients, male gender was slightly more common and the three most common ethnicities were Black African, Indian Asian, and Pakistani Asian; only 18·3% of patients were born in the UK (Table 1). A minority of patients (11·7%) had their consumption of treatment supervised by directly observed treatment (DOT) and over a third of patients were hospitalized. For three variables in particular (Table 1: employment, sputum smear test, bacterial resistance) there were large amounts of missing data. However, for data available, 46·4% of patients tested had a positive sputum smear result ( n =2269) and 18·3% of patients exhibited TB strains of any bacterial resistance to first-line TB medicines ( n =1673).

Table 1.

Demographic and clinical TB patient data, 2002-2006

DOT, Directly observed treatment.

Percentages calculated from n =4947 unless other sample size quoted due to missing data.

* Employment excluding children, retired, housewives, asylum seekers or any ambiguity regarding current employment.

[dagger]

'Any resistance' refers to resistance to any of isoniazid, rifampicin, streptomycin, ethambutol, pyrazinamide.

MCA was used to analyse these data in three ways: data were entered for analysis in their entirety, data were analysed by PCT, and data were analysed by year.

Complete dataset analysis

When all of the data were analysed together the joint category plot was complex and difficult to interpret reliably (Fig. 1 a ). However, PCT6 associated with 'Bangladeshi' ethnicity as an outlying group. This finding demonstrated the known higher prevalence of Bangladeshi TB patients in this PCT [10]. However, this strong association dominated the output. Therefore, to investigate associations between other variables without the dominating effect of ethnicity on PCT6, ethnicity was excluded and the analysis repeated (Fig. 1 b ). This suggested that both PCT6 and DOT ('Yes') categories were outliers from the dataset.

Fig. 1.

Multiple correspondence analysis graphical output of TB variable categories. ( a ) All variables, all years. ( b ) All variables, all years except ethnicity.

Analysis by PCT

MCA was repeated by analysing by each separate PCT. Figure 2 a displays an example of the output for PCT2 and is suggestive of an association between two groups of variable categories: Group 1: DOT ('Yes'), previous diagnosis ('Yes'), UK born ('Yes') and age >75 years. Group 2: hospital admission ('Yes'), positive sputum smear result ('Pos'), drug resistance ('Res') and pulmonary TB ('Yes'). The output for PCT7 is suggestive of a division between recent and earlier years of notification (Fig. 2 b ). More recent years (2004-2007) appear to group with more positive variable categories such as patients not being admitted to hospital ('No'), no previous diagnosis ('No') and no DOT ('No'). Earlier years (2002-2003) appear to associate with less positive variable categories such as previous TB diagnosis ('Yes'), DOT ('Yes'), and positive sputum smear result ('Pos').

Fig. 2.

Multiple correspondence analysis graphical output of TB variable categories by primary care trust (PCT). ( a ) PCT2; ( b ) PCT7.

Analysis by year

Finally, MCA was repeated by analysing by year. For example, Figure 3 a displays data from 2002 with a possible association between PCT2 and PCT3 with the variable categories DOT ('Yes') and UK born ('Yes'). However, in 2007 this specific grouping was not observed although PCT2 appeared to associate with DOT ('Yes'), previous TB diagnosis ('Yes'), UK born ('Yes') and resistance ('Res') suggesting a complex case-load for this PCT (Fig. 3 b ).

Fig. 3.

Multiple correspondence analysis graphical output of TB variable categories by year. ( a ) 2002; ( b ) 2007.

DISCUSSION

A commissioning framework report published by the Department of Health and informed by the governmental White Paper 'Our health, our care, our say: a new direction for community services' [4] highlighted the need for understanding the requirements of both populations and individuals as well as more effective sharing and use of information [5]. Data reported by healthcare systems is used to inform decisions concerning the commissioning of health services. Although these processes tend to be quite blunt, nevertheless, health commissioning would be ill-informed without the use of such data sources. It is pertinent to identify local trends in data to best focus healthcare resources and commission services appropriately. MCA is a well reported technique for the reduction of data and has previously been utilized in a wide range of different disciplines, e.g. analysis of wealth indices [9], more informative analyses of data for cardiac implantable devices [11], and investigations into subjective well-being, poverty and ethnicity [12]. This technique has previously been advocated for its use in the analysis of large datasets of categorical data, identifying themes according to data variance, and for scaling methods.

The current study used MCA to epidemiologically 'map' data that related to TB patients in NE London between 2002 and 2007. This identified a number of trends between data variables, differences between PCTs, and changes over time. For example, there appeared to be an association between patients that were born in the UK, patients that received DOT, and patients that were admitted to hospital. There may also be links between these variable categories and resistance to anti-tuberculous drugs and higher age group (>75 years). These associations are rational in that, within the TB population in London where most patients were born outside the UK, UK-born patients who contract TB are more likely to be older due to reactivation of disease rather than primary infection, and older patients are more likely to be admitted to hospital. MCA output for one PCT (PCT7) appeared to suggest recent improvement in that more positive variable categories, such as no hospital admission, associated closer to recent year categories (2004-2007) whereas less positive categories, such as previous TB diagnosis, associated closer to earlier year categories (2002-2003).

When analysed by year a similar grouping of more negative variable categories with two PCTs in particular (PCT2 and PCT3) was observed in 2002, and a similar grouping again observed for one of these PCTs (PCT2) in 2007. This suggests that cohorts of patients located within these PCTs had a greater burden of patients with complex needs in terms of provision of DOT and managing drug resistance, and that this issue had probably been resolved over time for PCT3. This clearly has resource implications. Treating patients with drug resistance, for example, has been estimated to be ten times the cost of treating a patient with drug-sensitive forms of TB [13]. Therefore, year-by-year analyses of this kind may inform where priorities lie. The various associations can be validated with further investigation to identify whether there are indeed greater priorities for certain PCTs in relation to specific patient groups and this, in turn, can inform commissioning priorities.

With such a large dataset where small associations are more likely to achieve statistical significance, MCA provides meaningful analyses that account for interactions between variables in the dataset as a whole. Another benefit of MCA is that it allows analysis of numerous variables of a categorical nature - the only continuous variable in the current study was patient age which was categorized for analysis. Analysis of a wider set of more descriptive variables in the current study, focusing on other aspects of patient complexity, for example, would better inform TB priorities for each PCT. However, to our knowledge, this is the first instance of an analysis of this type being performed with the explicit aim of identifying commissioning priorities. In addition, we believe this to be the first reporting of a TB dataset in this way.

A number of variables had large amounts of missing data. For example, sputum smear results and results for drug sensitivities were available for less than half of the cohort. This may relate to such results only having been recorded by TB services when they were deemed of clinical importance, such as resistance to a particular drug (recording only where tests had been performed and results obtained). However, it implies that these variables, in particular, were not reliably reported. Better recording of data would help to ensure that analyses were more reliable. Interestingly, MCA is a method used to explore patterns of missing data by categorizing missing data and including it in analyses, e.g. see Greenacre [7]. This technique could have been applied for the current dataset to assess whether missing data for specific variables differed from data that were better reported. Although this was beyond the aim of our study we are currently assessing data from the ETS dataset to better understand what the missing data might represent and, therefore, clarify reasons for non-reporting of data. In the current study only two-dimensional analyses were carried out to simplify the interpretation of results. In reality, the association between variables may be multidimensional and reveal further relationships between variable categories. However, for the purposes of using MCA as a commissioning tool multidimensional analyses are unlikely to be of significant added benefit.

In conclusion, we present an analytical technique that allows analysis of multiple datasets that can contain different data types. This tool can be used as an epidemiological method to inform commissioning priorities in healthcare such as TB service provision. Whilst users should be aware of the limitations, MCA is an efficient technique that effectively produces a data map displaying association. This may be of particular use where large amounts of heterogenous data are available.

ACKNOWLEDGMENTS

Our thanks to the continued efforts of TB Services in North East London without whose help this work could not have been conducted.

DECLARATION OF INTEREST

T.W.R. and W.R. are both employed on a full-time basis by the National Health Service.

[Reference]
REFERENCES
1. Health Protection Agency. (www.hpa.org.uk). Accessed 19 January 2009.
2. North East London TB Network. Annual report of demographic and epidemiological trends of TB in North East London. London, 2007.
3. BP Van. Data mining of tuberculosis patient data using multiple correspondence analysis Communicable Disease and Public Health 1998; 1: 219-220.
4. Department of Health. Our health, our care, our say: a new direction for community services. London: Department of Health, 2006.
5. Department of Health. Commissioning framework for health and well-being. London: Department of Health, 2007.
6. M Greenacre. Correspondence Analysis in Practice, 2nd edn. London: Taylor and Francis, 2007.
7. M Greenacre. Data mining of tuberculosis patient data using multiple correspondence analysis. Gaceta Sanitaria 2002; 16: 160-170.
8. E Kaciak, J Louviere. Data mining of tuberculosis patient data using multiple correspondence analysis. Journal of Marketing Research 1990; 27: 455-465.
9. LD Howe, JR Hargreaves, SR Huttly. Data mining of tuberculosis patient data using multiple correspondence analysis. Emerging Themes in Epidemiology 2008; 5: 3.
10. Directorate of Public Health. Tower Hamlets Public Health Report. Tower Hamlets Primary Care Trust, 2007.
11. M Gu├ęguin, Data mining of tuberculosis patient data using multiple correspondence analysis. Conference Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society 2007; 1: 3848-3851.
12. DF Neff. Data mining of tuberculosis patient data using multiple correspondence analysis. Social Indicators Research 2007; 80: 313-341.
13. VL White, J Moore-Gillon. Data mining of tuberculosis patient data using multiple correspondence analysis. Thorax 2000; 55: 962-963.

[Author Affiliation]
North East London Tuberculosis Commissioning Unit, Newham Primary Care Trust, London, UK

Indexing (document details)

Author(s):T W RENNIE, W ROBERTS
Author Affiliation:North East London Tuberculosis Commissioning Unit, Newham Primary Care Trust, London, UK
Document types:Feature
Publication title:Epidemiology and Infection. Cambridge: Dec 2009. Vol. 137, Iss. 12; pg. 1699, 6 pgs
Source type:Periodical
ISSN:09502688
ProQuest document ID:1894220731
Text Word Count2479
DOI:10.1017/S0950268809002787
Document URL:http://proquest.umi.com/pqdweb?did=1894220731&sid=2&Fmt=3&clientId=45625&RQT=309&VName=PQD