At Baseline, 21,241 participants were enrolled in the Tracking cohort and 30,097 participants in the Comprehensive cohort for a total of 51,338 CLSA participants.

The 30-minute Maintaining Contact Questionnaire (MCQ) interviews with additional health-related questions were completed approximately 18 months after the initial Baseline data collection. A total of 19,052 Tracking participants and 28,789 Comprehensive participants completed the MCQ. The indicator variable ADM_COMPLETE_MCQ is included in the dataset to indicate those participants who completed the MCQ.