Supplementary Material for: Trajectories of instrumental activities of daily living and their predictors among older men and women in Hong Kong: a 14-year prospective study

Introduction
This study aimed to identify the different patterns of trajectories in Instrumental Activities of Daily Living (IADL) in older men and women, respectively, and to examine the factors associated with the different trajectories.

Methods
We included 2,088 participants with an average age of 70.8 years at baseline from the MrOS and MsOS Hong Kong cohort study (men: 1,074; women: 1,014) and followed up the participants for over 14 years. The group-based trajectory models were used to identify IADL trajectories. Binary logistic regression and multinominal logistic regression models were used to identify factors associated with different trajectories.

Results
Two distinct trajectories were identified for men including ‘slow decliners’ (92.6% of men) and ‘rapid decliners’ (7.4%), while three distinct trajectories were identified for women including ‘slow decliners’ (43.5% of women), ‘intermediate decliners’ (48.2%), and ‘rapid decliners’ (8.3%). Being overweight or obese and slow walking speed were common predictors of more rapid IADL declining trajectories in both men and women. Particularly, having stroke, weak grip strength, and higher level of PM2.5 were associated with the higher risk of being rapid decliners in men, and having osteoporosis and poor self-rated health were associated with more rapid IADL declining trajectories in women.

Conclusion
Sex differences were observed in the IADL declining trajectories. Several risk factors were found that could possibly be useful in identifying and preventing disability in an earlier stage.