Recruitment of healthy adults into a study of overnight sleep monitoring in the home: experience of the Sleep Heart Health Study

Abstract

The Sleep Heart Health Study (SHHS) is a prospective cohort study using participants from several ongoing cardiovascular and respiratory disease research projects to investigate the relationship between sleep-disordered breathing and cardiovascular disease. This study design required unusual and different recruiting techniques to meet the study's enrollment goal of between 6000 and 6600 participants. Individuals were recruited to undergo an overnight home polysomnogram, completion of several questionnaires, and collection of a small amount of physical examination data. This article describes the methods used to recruit these participants and how these procedures influenced the final participation rate and the representativeness of SHHS to its parent cohorts. Of 30,773 people eligible for recruitment into SHHS, attempts were made to enroll 11,145 (36%). Of those contacted, 6441 ultimately agreed to participate (58%). Recruitment rates (38 to 91%) varied among sites. SHHS participants were slightly younger (63.0 vs. 65.0 years, p < 0.001), had more years of education (14.1 vs. 13.7, p < 0.001), more likely to snore (34% vs. 23%, p < 0.001), had higher Epworth sleepiness scores (7.7 vs. 6.5, p < 0.001), slightly higher higher systolic and diastolic blood pressures (127.6/73.9 vs. 127.2/72.1, p < 0.001 for diastolic only), and a slightly higher body mass index (BMI) (28.5 vs. 27.5, p < 0.001). We conclude that it is feasible to recruit existing participants from one large-scale epidemiologic study into another with a high degree of success. However, the characteristics of the new cohort may vary in several respects from their original cohorts and therefore interpretation of study results will have to consider these differences.