Power calculations for detecting interaction in stratified 2x2 tables

Given several 2x2 contingency tables, the first step in epidemiologic research is to test for homogeneity of odds ratios across these tables. A second problem of equal interest, but often overlooked, is to evaluate the power of detection of interaction if it is present. We address the latter issue in the context of 2x2 contingency tables. For the 2x2x2 case, given the marginal totals and the odds ratios for the respective two tables, we provide a closed form power formula for the rejection of the null hypothesis of homogeneity of the odds ratios. For several 2x2 tables, we provide a resampling approach to assessing the power for detecting interaction, if present.Woolfs test Breslow-Day test Mantel-Haenszel test Logit model Polish migrant study

Correlates of readiness to receive Chlamydia screening among 2 populations of youths

OBJECTIVES: To assess young people\u27s preferences for Chlamydia testing venues and methods, attitudes about testing, sex differences among these variables, and their predictive associations with young people\u27s readiness for screening. DESIGN: Survey. SETTING: National Job Training site and Department of Youth Services site. PARTICIPANTS: One hundred fifty male and 150 female youths from the National Job Training site and 150 male youths from the Department of Youth Services site. MAIN OUTCOME MEASURE: Modifiable predictors of stage of readiness for Chlamydia screening. RESULTS: Modifiable variables associated with increasing readiness for Chlamydia screening included the following: (1) among males in the Department of Youth Services group, perceived likelihood of ever having a Chlamydia infection; (2) among males from the National Job Training site, lack of condom use as a risk factor for Chlamydia infection and perception of untreated Chlamydia infection as dangerous; and (3) among females from the National Job Training site, belief that a partner could have a Chlamydia infection and fewer perceived social consequences of Chlamydia testing. CONCLUSION: Interventions targeted at sex-specific modifiable variables may help reduce undiagnosed Chlamydia infection among sexually active youth

Improving transition from pediatric to adult cystic fibrosis care: lessons from a national survey of current practices

OBJECTIVES: More than 500,000 adolescents with special health care needs age into adulthood each year in the United States, and there is growing recognition of the need for support of their transition to adult-oriented health care. Because of improved survival, cystic fibrosis has experienced this increasing transition need, and cystic fibrosis policy leaders responded by mandating the transition of adults with cystic fibrosis to adult-focused cystic fibrosis care programs by 2000. The primary objective of this study was to characterize in detail recent transition practices at US cystic fibrosis programs, to identify areas for improvement and to serve as a model for other diseases. A secondary objective of this study was to develop and validate a survey for formal assessment of transition practices. METHODS: A 105-question survey on key aspects of transition was administered to cystic fibrosis care team members from all 195 US Cystic Fibrosis Care programs. Rates of adherence to recommended components of transition care were measured. RESULTS: A total of 448 surveys were obtained from 170 (87%) of 195 cystic fibrosis programs. Although transfer of care occurs at a median age of 19 years, initial discussion of transition does not occur until a median age of 17 years, limiting time to foster self-care skills. Only half of programs consistently perform a transition readiness assessment, 28% of centers offer visits focused on transition, and CONCLUSIONS: There is significant variability in transition support provided to young adults with cystic fibrosis, but there are simple steps that may lead to more consistent delivery of transition services. Methods of assessment and lessons learned from transitioning young adults at US cystic fibrosis programs may serve to improve transition for individuals with other childhood diseases