Age-related changes relevant to health in women: Design, recruitment, and retention strategies for the Longitudinal Assessment of Women (LAW) study

Objectives: The primary aim was to assess the age-related changes that occur in older women. This paper describes the study rationale and methods, recruitment, and retention strategies. Methods: The Longitudinal Assessment of Women (LAW) Study was a longitudinal, observational, and multidisciplinary evaluation of a population-based cohort of urban-living women, aged between 40 and 80 years at recruitment and randomly invited from a district in Brisbane (a city in Australia) via the electoral roll. Five hundred eleven women were recruited and stratified into four age groups (40-49, 50-59, 60-69, 70-79 years) and were assessed on three or four occasions each year, using interviews and diagnostic instruments (echocardiography, applination tonometry, dual-energy x-ray absorptiometry [DEXA]) Retention strategies included flexibility, accessibility, personalized attention, and feedback. Results: From a sample frame of 1598 names, there were 1082 respondents, of whom 511 (47%) were successfully recruited from those eligible to participate. Recruitment was quickest for the oldest age group, 70-79 years, and slowest for the age group 40-49 years; all age groups achieved their required quota. A scheduling program was developed to minimize the number of visits and maximize the use of allocated time. The largest dropout was seen in year 1 of the study, with very few thereafter. Of the 9 deaths, cancer was the cause in 7. The retention rate after 5 years was 95.5%. Conclusions: The design of the present study, with careful attention to coordination and a personal approach, facilitated the completion of a 5-year study, enabling a collection of a set of wide-ranging data from almost all the women recruited. The information thus collected will form the basis of cross-linking analysis of the risk factors associated with health problems in aging women.