Meena Khare

Prevalence and ethnic differences in gallbladder disease in the United States

BACKGROUND & AIMS Gallbladder disease is one of the most common conditions in the United States, but its true prevalence is unknown. A national population-based survey was performed to determine the age, sex, and ethnic distribution of gallbladder disease in the United States. METHODS The third National Health and Nutrition Examination Survey (NHANES III) conducted gallbladder ultrasonography among a representative U.S. sample of more than 14, 000 persons. The diagnosis of gallbladder disease by detection of gallstones or cholecystectomy was made with excellent reproducibility. RESULTS An estimated 6.3 million men and 14.2 million women aged 20-74 years had gallbladder disease. Age-standardized prevalence was similar for non-Hispanic white (8. 6%) and Mexican American (8.9%) men, and both were higher than non-Hispanic black men (5.3%). These relationships persisted with multivariate adjustment. Among women, age-adjusted prevalence was highest for Mexican Americans (26.7%) followed by non-Hispanic whites (16.6%) and non-Hispanic blacks (13.9%). Among women, multivariate adjustment reduced the risk of gallbladder disease for both Mexican Americans and non-Hispanic blacks compared with non-Hispanic whites. CONCLUSIONS More than 20 million persons have gallbladder disease in the United States. Ethnic differences in gallbladder disease prevalence differed according to sex and were only partly explained by known risk factors.

Overview of the sampling design and statistical methods used in the National Immunization Survey22

Abstract: The National Immunization Survey (NIS) is a large federally funded survey designed to estimate vaccination coverage rates for children residing in the United States aged 19 to 35 months. In 1999, over 8 million telephone call attempts were made to obtain provider-reported vaccination histories on 22,521 children in the age range of interest.

Update on the seroepidemiology of human immunodeficiency virus in the United States household population : NHANES III, 1988-1994

To update the estimate of seroprevalence of HIV from the third National Health and Nutrition Examination Survey (NHANES III), data from the second phase of the survey were combined with previously published data to produce a more precise estimate. The testing was performed anonymously on 11,203 individuals 18-59 years of age examined from 1988 to 1994. Fifty-nine individuals were HIV positive, for an overall prevalence of 0.32%. The number of individuals living in households with HIV infection based on this estimate was 461,000, with a 95% confidence interval of 290,000-733,000. Analysis of nonresponse demonstrated that white and black men 40-59 years of age were least likely to participate in the survey. A sensitivity analysis demonstrated that this nonresponse may have biased the NHANES III estimate downward by 190,000 persons. Data from the second phase of the survey were used to analyze the association between drug use and HIV infection. Black women who used cocaine were 12 times more likely to be HIV positive compared with all tested black women (6.5% vs. 0.55%). This survey provides an estimate of HIV prevalence for individuals who reside in households but excludes some persons who are at higher risk for HIV infection, including prisoners and the homeless not residing in shelters.

Food intake patterns and gallbladder disease in Mexican Americans

OBJECTIVE Results of previous studies on diet and gallbladder disease (GBD), defined as having gallstones or having had surgery for gallstones, have been inconsistent. This research examined patterns of food intake in Mexican Americans and their associations with GBD. DESIGN Cross-sectional. SUBJECTS The study population included 4641 Mexican Americans aged 20-74 years who participated in the 1988-94 third National Health and Nutrition Examination Survey (NHANES III). GBD was diagnosed by ultrasound. Food intake patterns were identified by principal components analysis based on food frequency questionnaire responses. Component scores representing the level of intake of each pattern were categorized into quartiles, and prevalence odds ratios (POR) were estimated relative to the lowest quartile along with 95% confidence intervals (CI). RESULTS There were four distinct patterns in women (vegetable, high calorie, traditional, fruit) and three in men (vegetable, high calorie, traditional). After age adjustment, none were associated with GBD in women. However, men in the third (POR = 0.42, 95%CI 0.21-0.85) and fourth (POR = 0.53, 95%CI 0.28-1.01) quartiles of the traditional intake pattern were half as likely to have GBD as those in the lowest quartile. CONCLUSIONS These findings add to a growing literature suggesting dietary intake patterns can provide potentially useful and relevant information on diet-disease associations. Nevertheless, methods to do so require further development and validation.

Quantifying bias in a health survey: modeling total survey error in the national immunization survey.

Random-digit-dial telephone surveys are experiencing both declining response rates and increasing under-coverage due to the prevalence of households that substitute a wireless telephone for their residential landline telephone. These changes increase the potential for bias in survey estimates and heighten the need for survey researchers to evaluate the sources and magnitudes of potential bias. We apply a Monte Carlo simulation-based approach to assess bias in the NIS, a land-line telephone survey of 19-35 month-old children used to obtain national vaccination coverage estimates. We develop a model describing the survey stages at which component nonsampling error may be introduced due to nonresponse and under-coverage. We use that model and components of error estimated in special studies to quantify the extent to which noncoverage and nonresponse may bias the vaccination coverage estimates obtained from the NIS and present a distribution of the total survey error. Results indicated that the total error followed a normal distribution with mean of 1.72 per cent(95 per cent CI: 1.71, 1.74 per cent) and final adjusted survey weights corrected for this error. Although small, the largest contributor to error in terms of magnitude was nonresponse of immunization providers. The total error was most sensitive to declines in coverage due to cell phone only households. These results indicate that, while response rates and coverage may be declining, total survey error is quite small. Since response rates have historically been used to proxy for total survey error, the finding that these rates do not accurately reflect bias is important for evaluation of survey data. Published in 2011 by John Wiley & Sons, Ltd.