The Ste-Justine Adolescent Idiopathic Scoliosis Cohort Study. Part I: Description of the study.

Objectives: This study determined the impact of adolescent idiopathic scoliosis (AIS) on health and well being in adulthood by comparing AIS subjects, more than 10 years after referral, to non-AIS subjects according to perceived health status, physical activity, fitness, reproductive health, respiratory condition, and back and neck pain. This paper describes the cohort, the design of the study, and response rates.
Study Design: The study was designed as a comparative retrospective cohort study. A total of 2,092 patients referred for AIS to Ste-Justine Hospital, Montreal, Quebec, between 1960 and 1979 were identified. A population-based control group was selected in 1989-90 by randomly telephoning persons in Quebec. The control group was approximately frequency-matched to the AIS cohort according to age group and broad geographic region of current residence.
Methods: Patients with adolescent idiopathic scoliosis were traced, and a self-administered questionnaire was sent by post in 1989 to subjects whose addresses were found. Identical questionnaires were sent to subjects in the control group.
Results: Seventy-one percent of the cohort (1,476 subjects) returned questionnaires in 1989. Subjects who did not respond to the questionnaires were similar to those who did complete the questionnaires on a number of key factors, except that lower response rates were observed for subjects with scoliotic curves under 20 degrees. The control group consisted of 1,755 subjects (55% response rate). It was similar to the general Quebec population and to the AIS cohort on a number of important sociodemographic factors.
Conclusion: Comparisons on health outcomes between the two study groups should not be affected by differential patterns of selection or response.