Genetic association analysis under complex survey sampling: the Hispanic Community Health Study/Study of Latinos.

The cohort design allows investigators to explore the genetic basis of a variety of diseases and traits in a single study while avoiding major weaknesses of the case-control design. Most cohort studies employ multistage cluster sampling with unequal probabilities to conveniently select participants with desired characteristics, and participants from different clusters might be genetically related. Analysis that ignores the complex sampling design can yield biased estimation of the genetic association and inflation of the type I error.

Local Dependence in Latent Class Analysis of Rare and Sensitive Events.

For survey methodologists, latent class analysis (LCA) is a powerful tool for assessing the measurement error in survey questions, evaluating survey methods, and estimating the bias in estimates of population prevalence. LCA can be used when gold standard measurements are not available and applied to essentially any set of indicators that meet certain criteria for identifiability. LCA offers quality inference, provided the key threat to model validity-namely, local dependence-can be appropriately addressed either in the study design or in the model-building process.

Research priorities for FCTC Articles 20, 21, and 22: surveillance/evaluation and information exchange.

Introduction: Framework Convention on Tobacco Control (FCTC) Articles 20, 21, and 22 call for strong monitoring and reporting of tobacco use and factors influencing use and disease (Articles 20 and 21) and for collaboration among the Parties and relevant organizations to share resources, knowledge, and expertise on all relevant tobacco control strategies (Article 22).

Methods: This paper provides background information and discusses research strategies that would strengthen these efforts and better inform the parties. By necessity, Articles 20 and 21 are discussed separately from Article 22, although 1 example that relates to both 20/21 and 22 is discussed at the end.

Sample design and cohort selection in the Hispanic Community Health Study/Study of Latinos.

Purpose: The Hispanic Community Health Study (HCHS)/Study of Latinos (SOL) is a multicenter, community-based cohort study of Hispanic/Latino adults in the United States. A diverse participant sample is required that is both representative of the target population and likely to remain engaged throughout follow-up. The choice of sample design, its rationale, and benefits and challenges of design decisions are described in this study.

Prevalence of hip symptoms and radiographic and symptomatic hip osteoarthritis in African Americans and Caucasians: the Johnston County Osteoarthritis Project.

Objective: To report contemporary estimates of the prevalence of hip-related osteoarthritis (OA) outcomes in African Americans and Caucasians aged>or=45 years.

Methods: Weighted prevalence estimates and their corresponding 95% confidence intervals for hip symptoms, radiographic hip OA, symptomatic hip OA, and severe radiographic hip OA were calculated using SUDAAN for age, race, and sex subgroups among 3068 participants (33% African Americans, 38% men) in the baseline examination (1991-97) of The Johnston County Osteoarthritis Project, a population-based study of OA in North Carolina. Radiographic hip OA was defined as Kellgren-Lawrence radiographic grade>or=2, moderate/severe radiographic hip OA as grades 3 and 4, and symptomatic hip OA as hip symptoms in a hip with radiographic OA.

The rising prevalence of chronic low back pain.

Background: National or state-level estimates on trends in the prevalence of chronic low back pain (LBP) are lacking. The objective of this study was to determine whether the prevalence of chronic LBP and the demographic, health-related, and health care-seeking characteristics of individuals with the condition have changed over the last 14 years.

Methods: A cross-sectional, telephone survey of a representative sample of North Carolina households was conducted in 1992 and repeated in 2006.

Lifetime risk of symptomatic knee osteoarthritis.

Objective: To estimate the lifetime risk of symptomatic knee osteoarthritis (OA), overall and stratified by sex, race, education, history of knee injury, and body mass index (BMI).

Methods: The lifetime risk of symptomatic OA in at least 1 knee was estimated from logistic regression models with generalized estimating equations among 3,068 participants of the Johnston County Osteoarthritis Project, a longitudinal study of black and white women and men age >or=45 years living in rural North Carolina. Radiographic, sociodemographic, and symptomatic knee data measured at baseline (1990-1997) and first followup (1999-2003) were analyzed.

Prevalence of low sexual desire and hypoactive sexual desire disorder in a nationally representative sample of US women.

Background: We sought to estimate the prevalence of low sexual desire and hypoactive sexual desire disorder (HSDD) in US women, focusing on their menopausal status.

Methods: We performed a cross-sectional study. From a probability sample of households, 2207 US women aged 30 to 70 years and in stable relationships (>or=3 months) were interviewed by telephone.

Disproportionate sampling for population subgroups in telephone surveys.

Population studies often seek to examine phenomena in important population subgroups or to compare results among these and other subgroups. When subgroups of interest comprise a relatively small percentage of the population and acceptable subgroup member lists are not available to serve as sampling frames, it may be prohibitively expensive even by telephone to screen through a sample of the entire population. This paper considers some statistical effects of estimation from a class of two-stratum telephone sample designs where part of the frame with a higher subgroup concentration is disproportionately sampled compared to the rest of the frame.

Prevalence of knee symptoms and radiographic and symptomatic knee osteoarthritis in African Americans and Caucasians: the Johnston County Osteoarthritis Project.

Objective: To report contemporary estimates of the prevalence of knee-related osteoarthritis (OA) outcomes in African Americans and Caucasians aged > or = 45 years.

Methods: Weighted prevalence estimates for knee symptoms, radiographic knee OA, symptomatic knee OA, and severe radiographic knee OA were calculated for age, ethnic, and sex subgroups, in 3018 participants (33% African Americans, 38% men) in the baseline examination (1991-97) of The Johnston County Osteoarthritis Project, a population-based study of OA in North Carolina. Radiographic knee OA was defined as Kellgren-Lawrence radiographic grade > or = 2, severe radiographic knee OA as grades 3 and 4, and symptomatic knee OA as knee symptoms in a knee with radiographic OA.

Incidence and risk factors for concussion in high school athletes, North Carolina, 1996-1999.

A prospective cohort study was used to quantify risk factors for sports concussions. Analysis was based on a stratified cluster sample of North Carolina high school athletes followed during 1996-1999. Clustering was by school and sport, and the sample included 15,802 athletes with 1-8 seasons of follow-up per athlete.

Oral cancer knowledge and examination experiences among North Carolina adults.

Objective: This study assesses knowledge of oral cancer risk factors, clinical signs, and oral cancer examination experience among North Carolina adults.

Methods: A statewide random digit dial, computer-assisted telephone interview was conducted in 2002. Data from 1,096 respondents, with a response rate of 62 percent, were poststratified to 2000 census data by sex, race, and age group to produce population-based estimates.

Development and testing of interview questions to determine last menstrual period in Mexican immigrant populations.

The last menstrual period is used to estimate gestational age. This paper examines sources of measurement error related to the recall of last menstrual period among Mexican immigrant women living in the United States. Qualitative analyses (focus groups and cognitive interviews) suggest that last menstrual period recall does not seem to be a large source of measurement error in the calculation of gestational age and the impact of this type of error on the misclassification of preterm births appears to be minimal.

Sampling minority groups in health surveys.

Sampling racial and ethnic minority groups in population-based health studies presents the statistical designer with a variety of notable challenges, many of which can be traced to the manner in which the sampling frame maps into the set of group members. A brief review of sampling approaches aimed at race/ethnic groups is followed by findings on two particularly important statistical issues one may face when sampling minorities: the implications of the geographic diffusion of minorities within sampled area clusters, and the relative utility of different forms of space and time sampling to deal with sometimes dramatic change over time in the linkage between entries on a sampling frame and members of relatively mobile minority groups. Simulated findings from practical illustrations involving the sampling of Hispanics are presented to address each issue.