Driver's license and voter registration lists as population-based sampling frames for rural African Americans

Collecting behavioral evidence from a highly mobile and seasonal population: A protocol for a survey on quad bike injuries

BACKGROUND

Quad bikes are popular recreational, four-wheeled bikes in the Middle East. Injury prevention programs targeting quad bike crashes in the United Arab Emirates (UAE) need evidence about the risk factors and behaviours associated with these crashes in the target population. This is a protocol for a study aiming to investigate quad bike rider behaviours and to assess the risk factors associated with related injuries in the UAE.

METHODS

This is a cross-sectional observational study aiming to describe a seasonal sport in a desert environment. With an estimated sample size of 451, the survey will follow a three-stage, location-based sampling strategy using the line-transect method. A sampling frame of desert locations with high injury incidences was developed, using Dubai ambulance injury records. Further expansion of the sampling frame was participatory, involving police, enthusiasts, emergency responders and gas station employees. The data collection will be limited to the winter months in fifteen high-injury desert locations across three major Emirates in the UAE. Trained researchers will observe the riders directly in the desert to note their riding habits, followed by a researcher-administered interview on riding and injury history. The interviews will be administered in Arabic and English using Qualtrics software on handheld tablets with offline and online entry mode. In addition, paper-based entry with the same format will be used as a contingency in busy quad bike locations.

CONCLUSION

The objective of this study protocol is to develop a comprehensive survey that will furnish substantial evidence for the formulation of effective injury prevention strategies. To enhance the credibility of the recorded riding behaviors, field observations will be employed. The uniqueness of this study lies in its innovative sampling strategy, custom-tailored to accommodate the highly mobile and transient population of desert bikers in the UAE.

Strategies for recruiting representative samples of Asian Americans for a population-based case-control study

BACKGROUND

Data are limited on effective methods for recruiting persons, especially from ethnically diverse populations, into population-based studies. The goal of this study was to evaluate the variation among and representativeness of controls identified using multiple methods for a population-based case-control study of breast cancer among Asian Americans, Native Hawaiians and Pacific Islanders (AANHPIs) in the San Francisco Bay Area.

METHODS

We used a unique combination of targeted recruitment strategies, including address-based sampling, community-based methods, and internet-based and media-based approaches for recruiting controls, frequency matched on age and ethnicity to a population-based sample of cases. To characterise the participating controls, we compared the distribution of sociodemographic characteristics and cancer risk factors between recruitment sources using χ(2) tests. To ensure that the controls we recruited were representative of the underlying at-risk population, we compared characteristics of the controls, by ethnicity and in aggregate, to data from the California Health Interview Survey (CHIS), and adjusted the relative mix of recruitment strategies throughout the study as needed to achieve representativeness.

RESULTS

As expected, controls (n=483) recruited by any single method were not representative. However, when aggregated across methods, controls were largely representative of the underlying source population, as characterised by CHIS, with regard to the characteristics under study, including nativity, education, marital status and body mass index.

CONCLUSIONS

A multimode approach using targeted recruitment strategies is an effective and feasible alternative to using a single recruitment method in identifying a representative, diverse control sample for population-based studies.

Selection bias in population-based cancer case-control studies due to incomplete sampling frame coverage

BACKGROUND

Increasing numbers of individuals are choosing to opt out of population-based sampling frames due to privacy concerns. This is especially a problem in the selection of controls for case-control studies, as the cases often arise from relatively complete population-based registries, whereas control selection requires a sampling frame. If opt out is also related to risk factors, bias can arise.

METHODS

We linked breast cancer cases who reported having a valid driver's license from the 2004-2008 Wisconsin women's health study (N = 2,988) with a master list of licensed drivers from the Wisconsin Department of Transportation (WDOT). This master list excludes Wisconsin drivers that requested their information not be sold by the state. Multivariate-adjusted selection probability ratios (SPR) were calculated to estimate potential bias when using this driver's license sampling frame to select controls.

RESULTS

A total of 962 cases (32%) had opted out of the WDOT sampling frame. Cases age <40 (SPR = 0.90), income either unreported (SPR = 0.89) or greater than $50,000 (SPR = 0.94), lower parity (SPR = 0.96 per one-child decrease), and hormone use (SPR = 0.93) were significantly less likely to be covered by the WDOT sampling frame (α = 0.05 level).

CONCLUSIONS

Our results indicate the potential for selection bias due to differential opt out between various demographic and behavioral subgroups of controls. As selection bias may differ by exposure and study base, the assessment of potential bias needs to be ongoing.

IMPACT

SPRs can be used to predict the direction of bias when cases and controls stem from different sampling frames in population-based case-control studies.

Availability of driver's license master lists for use in government-sponsored public health research

Although the percentage of US drivers with valid driver's licenses varies from state to state, it has historically been high enough to constitute a useful sampling frame for many public health purposes. Over the past decade, states have had to restrict access to this information to comply with the Driver's Privacy Protection Act (18 U.S.C. 2721-2725). In 2009 and 2010, the authors conducted a survey of all 50 states on the availability of master lists of licensed drivers to be used to contact citizens of each state for research purposes. A hypothetical situation requiring driver's license data was sent to each state's responsible government agency for review. In addition, the authors collected data on opt-out mechanisms available to drivers, costs to researchers, and additional state privacy policies pertaining to driver's license files. A total of 42 states (84%) responded; 16 (32%) states allowed access to data, 4 (8%) states were unable to respond to the hypothetical situation, and 22 (44%) states denied access to data. A total of 74,697,574 records were available from the 16 states providing driver's license data. Although the Driver's Privacy Protection Act has restricted access to data on licensed drivers, these data are still an available resource in many states.

Sexual mixing patterns and heterosexual HIV transmission among African Americans in the southeastern United States

OBJECTIVES

Heterosexually transmitted HIV infection rates are disproportionately high among African Americans. HIV transmission is influenced by sexual network characteristics, including sexual partnership mixing patterns among subpopulations with different prevalences of infection.

STUDY DESIGN

We conducted a cross-sectional analysis of previously collected data from a North Carolina population-based case-control study. Respondents were heterosexual black men and women who either had recently reported heterosexually transmitted HIV infection (cases) or were randomly selected from the general population (controls).

METHODS

Respondents reported their own and their 3 most recent sex partners' education and involvement in illicit drug use, concurrent sex partners, and incarceration. We examined sexual mixing patterns by comparing the characteristics and behaviors of respondents reported for themselves with those they reported for their partners. We estimated Newman assortativity coefficient (-1.0 to 1.0) as an aggregate quantitative assessment of mixing patterns.

RESULTS

Across the 4 strata (male and female cases, male and female controls), mixing was assortative (0.31-0.45) with respect to illicit drug use and minimally assortative with respect to having concurrent partners (0.14-0.22). Mixing patterns for incarceration were assortative for men (0.18 and 0.41) but not women (0.07 and 0.08). Mixing with respect to education was assortative primarily for male controls (0.33).

CONCLUSIONS

These sexual partnership patterns, driven in part by the social and economic context of life for African Americans, likely contribute to the heterosexually transmitted HIV epidemic.

Timing and duration of incarceration and high-risk sexual partnerships among African Americans in North Carolina

PURPOSE

Incarceration may contribute to HIV transmission by disrupting stable partnerships and promoting high-risk partnerships. We investigated incarceration and high-risk partnerships among African Americans in North Carolina.

METHODS

We conducted a weighted analysis using the North Carolina Rural Health Project (N = 320), a population-based case-control study of HIV among African Americans. We measured associations between timing and duration of incarceration and high-risk partnerships (multiple partnerships or sex trade for money or drugs).

RESULTS

Duration of incarceration appeared to be more important than how long ago incarceration occurred. After adjustment for sociodemographic indicators, high-risk partnerships were associated with short-term (<1 month) incarceration of the respondent versus no respondent incarceration (men: adjusted prevalence ratio (aPR) 1.9, 95% confidence interval (95% CI) 1.2-2.8; women: aPR 3.1, 95% CI 1.2-8.3). High-risk partnerships also were associated with incarceration of a partner versus no partner incarceration (men: aPR 1.8, 95% CI 1.1-3.0; women: aPR 2.0, 95% CI 1.1-3.8). Among men, associations remained when adjusting for substance use. Among women, adjustment for substance use weakened estimates due to the strong correlation between substance use and incarceration.

CONCLUSIONS

HIV-prevention programs targeting currently and formerly incarcerated individuals and their partners may decrease HIV in African American communities with high incarceration rates.

Heterosexually transmitted HIV infection among African Americans in North Carolina

CONTEXT

Rates of heterosexually transmitted HIV infection among African Americans in the southeastern United States greatly exceed those for whites.

OBJECTIVE

Determine risk factors for heterosexually transmitted HIV infection among African Americans.

METHODS

Population-based case-control study of black men and women, aged 18-61 years, reported to the North Carolina state health department with a recent diagnosis of heterosexually transmitted HIV infection and age- and gender-matched controls randomly selected from the state driver's license file. A lower-risk stratum of respondents was created to identify transmission risks among people who denied high-risk behaviors.

RESULTS

Most case subjects reported annual household income < $16,000, history of sexually transmitted diseases, and high-risk behaviors, including crack cocaine use and sex partners who injected drugs or used crack cocaine. However, 27% of case subjects (and 69% of control subjects) denied high-risk sexual partners or behavior. Risk factors for HIV infection in this subset of participants were less than high school education (adjusted odds ratio [OR] 5.0; 95% CI: 2.2, 11.1), recent concern about having enough food for themselves or their family (OR 3.7; 1.5, 8.9), and having a sexual partner who was not monogamous during the relationship with the respondent (OR 2.9; 1.3, 6.4).

CONCLUSION

Although most heterosexually transmitted HIV infection among African Americans in the South is associated with established high-risk characteristics, poverty may be an underlying determinant of these behaviors and a contributor to infection risk even in people who do not have high-risk behaviors.

Methods and strategies to recruit African Americans into cancer prevention surveillance studies

OBJECTIVE

Recruitment of African Americans into health research studies is a major challenge. This report describes a study of different methods and strategies to recruit African Americans into a population-based assessment of cancer behavioral risk factors.

METHODS

African Americans ages 18 to 70 years in North Carolina (n = 5,000) were randomly selected from the Department of Motor Vehicle rosters and assigned at random to one of five different recruitment strategies based on variations of approach letters (generic versus culturally sensitive) and inclusion, exclusion, or promise of a small incentive. Prospective participants were sent an 11-page questionnaire by mail but could complete it by telephone or Internet as well as by mail.

RESULTS

The overall response rate was 17.5% (747 completed surveys of 4,276 delivered): 655, 84, and 8 by mail, Internet, and telephone, respectively. Among eligible respondents, response was significantly higher for incentive-based than nonincentive strategies; 23.9% for the generic letter plus incentive compared with 15.8% for the generic letter only (P < 0.001). The culturally sensitive letter had little effect on participation (15.8% for both the generic and culturally sensitive letters). The mean age of eligible respondents was 43.9 years, 41% were male, 37% were college graduates, and 75% were overweight/obese. There were no differences in respondent characteristics by assigned recruitment strategy.

CONCLUSIONS

Incentive-based strategies yielded the highest survey responses, whereas a culturally sensitive letter did not appreciably increase participation among African Americans in North Carolina. This study adds to what is known about culturally sensitive recruitment strategies for African Americans and challenges their usefulness in survey-based studies.

Public Health Surveillance of Low-Frequency Populations

Public health agencies often require data that address the needs of special populations, such as minority groups. Sources of surveillance data often contain insufficient numbers of subjects to fully inform health agencies. In this review, we address the problems of and potential approaches for situations with insufficient surveillance data. We use the examples of race and ethnic minority groups throughout our discussion. However, many of the broad issues are applicable to other special groups with low frequency or who are especially hard to reach. Our recommendations are based, in part, on a symposium held in Missouri with the collaboration of state health agency, community, and academic research participants. We review problems in using existing data and collecting new data, especially from nonprobability samples. We also describe fieldwork issues for reaching and collecting information from special populations. Decisions among methods and solutions may require seeking additional resources for surveillance.

Occupational exposure to crystalline silica and risk of systemic lupus erythematosus: a population-based, case-control study in the southeastern United States

OBJECTIVE

Crystalline silica may act as an immune adjuvant to increase inflammation and antibody production, and findings of occupational cohort studies suggest that silica exposure may be a risk factor for systemic lupus erythematosus (SLE). We undertook this population-based study to examine the association between occupational silica exposure and SLE in the southeastern US.

METHODS

SLE patients (n = 265; diagnosed between January 1, 1995 and July 31, 1999) were recruited from 4 university rheumatology practices and 30 community-based rheumatologists in 60 contiguous counties. Controls (n = 355), frequency-matched to patients by age, sex, and state of residence, were randomly selected from driver's license registries. The mean age of the patients at diagnosis was 39 years; 91% were women and 60% were African American. Detailed occupational and farming histories were collected by in-person interviews. Silica exposure was determined through blinded assessment of job histories by 3 industrial hygienists, and potential medium- or high-level exposures were confirmed through followup telephone interviews. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression.

RESULTS

More patients (19%) than controls (8%) had a history of medium- or high-level silica exposure from farming or trades. We observed an association between silica and SLE (medium exposure OR 2.1 [95% CI 1.1-4.0], high exposure OR 4.6 [95% CI 1.4-15.4]) that was seen in separate analyses by sex, race, and at different levels of education.

CONCLUSION

These results suggest that crystalline silica exposure may promote the development of SLE in some individuals. Additional research is recommended in other populations, using study designs that minimize potential selection bias and maximize the quality of exposure assessment.