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Studies designed to evaluate HIV and STD prevention interventions often involve random assignment of groups such as neighborhoods or communities to study conditions (e.g., to intervention or control). Investigators who design group-randomized trials (GRTs) must take the expected intraclass correlation coefficient (ICC) into account in sample size estimation to have adequate power; however, few published ICC estimates exist for outcome variables related to HIV and STD prevention. The Prevention Options for Women Equal Rights (POWER) study was a GRT designed to evaluate a campaign to increase awareness and use of condoms among young African American and Hispanic women. The authors used precampaign and postcampaign data from the POWER study to estimate ICCs (unadjusted and adjusted for covariates) for a variety of sexual behavior and other variables. To illustrate the impact of ICCs on power, the authors present sample-size calculations and demonstrate how ICCs of differing magnitude will affect estimates of required sample size. (Contains 4 tables.)

Objectives. The United Nations High Commissioner on Refugees (UNHCR) and United-Nations Children's Fund (UNICEF) policy encourages foster care during refugee emergencies. We examined evidence to support this policy using data from the 1994 Rwandan refugee crisis. Methods. The association of weight gain and acute illness with family status (foster children vs children living with their biological families) was examined using latent growth curve and repeated measures logistic regression analysis. Results. Weight gain for all children averaged 0.40 kg/month and was associated with child's age but not with family status, child's or caregiver's sex, caregiver's marital status, possession of blankets or plastic sheeting, severe ma nutrition, month of enrollment, or acute illness. Illness was not more common among foster children than among children living with their biological families. Conclusions. This analysis supports the UNHCR/UNICEF recommendation of fostering for unaccompanied children during an acute refugee crisis.

This study assessed hypotheses that measures of power and control over male condom (MC) use would predict use of the female condom (FC) among women with main partners from two public STD clinics (n = 616). The women (mean age 24 years, 87% African American) were enrolled in an intervention study to promote barrier contraceptive use and were interviewed at baseline and at 6 monthly follow-up visits. Seven baseline predictor variables were assessed: her having requested MC use, his having objected, her having wanted a MC used but not asking, percentage of MC use, perceived control over MC use, anticipated consequences of refusing unprotected sex, and physical violence. In the first Poisson regression analysis, none of the hypothesized predictors was significantly associated with FC use during follow up. In the second regression analysis, which assessed the influence of the hypothesized set of predictors on follow-up FC use in situations when MCs were not used, we found two effects. Either no or inconsistent MC use before study entry was associated with less subsequent FC use; women who reported, at study entry, having more control over MC use were more likely to use FCs during follow up. We found no evidence of adoption of the FC by women in relationships marked by history of conflict over the MC, circumstances in which alternatives are most needed. On the contrary, we found that women with a history of control and consistent use of MCs were the most likely users of FCs when MCs were not used. KEYWORDS. Female condoms, gender

Objectives. This paper provides misclassification rates for current cigarette smokers who report themselves as nonsmokers. Such rates are important in determining smoker misclassification bias in the estimation of relative risks in passive smoking studies. Methods. True smoking status, either occasional or regular, was determined for individual current smokers in 3 existing studies of nonsmokers by inspecting the cotinine levels of body fluids. The new data, combined with an approximately equal amount in the 1992 Environmental Protection Agency (EPA) report on passive smoking and lung cancer, yielded misclassification rates that not only had lower standard errors but also were stratified by sex and US minority/majority status. Results. The misclassification rates for the important category of female smokers misclassified as never smokers were, respectively, 0.8%, 6.0%, 2.8%, and 15.3% for majority regular, majority occasional, US minority regular, and US minority occasional smokers. Misclassification rates for males were mostly somewhat higher. Conclusions. The new information supports EPA's conclusion that smoker misclassification bias is small. Also, investigators axe advised to pay attention to minority/majority status of cohorts when correcting for smoker misclassification bias. (Am J Public Health. 1998;88:1503-1509)

Background. Alzheimer's disease has been thought to have familial and sporadic forms, and several genetic defects have been identified that chiefly explain early-onset familial cases. In this study, our purpose was to detect all cases of dementia in an established twin registry and to estimate total extent of genetic contribution to liability to Alzheimer's disease. Methods. At the first stage, members of the registry were screened for dementia, using in-person or telephone mental status testing. At the second stage, those who screened positively and their partners were referred for clinical work-ups, including neuropsychological assessment, physician examination, laboratory tests, and neuroimaging. Clinical diagnoses were assigned at a multidisciplinary consensus conference. Probandwise concordance rates were examined by zygosity, and structural modeling was applied to the data to estimate genetic and environmental influences, using both single- and multiple-threshold models. Results. Sixty-five pairs were identified in which one or both was demented. The probandwise concordance rate for Alzheimer's disease among monozygotic pairs was 67%; the corresponding figure for dizygotic pairs was 22%. Heritability of liability to Alzheimer's disease was estimated to be .74; to any dementia, .43. The other variance is attributable to environmental influences. Conclusions. Findings indicate a substantial genetic effect for these predominantly late-onset Alzheimer's disease cases. At the same time, structural modeling results and large intra-pair differences in age of onset suggest that environmental factors are also important in determining whether and when an individual may develop dementia.

An interview with 1204 Hispanics and 536 non-Hispanic white over the telephone reveals their alcohol expectancies and the role of acculturation. The Hispanics have a greater emotional and behavioral impairment, emotional fluidity and social extroversion after consuming alcoholic beverages than the non-Hispanic whites. This is the reason for the increasing number of alcohol abuse among Hispanics. However, the expectations of the more acculturated Hispanics are similar to the non-Hispanic Whites.