Disparities in overall survival by varying duration of disability in activities of daily living in older people: A population-based cohort from Chinese Longitudinal Healthy Longevity Survey (CLHLS).

OBJECTIVES: To investigate the association between duration of disability in activity of daily living (ADL) and overall survival in older individuals.

DESIGN: A prospective cohort study.

SETTING: Community-based data from Chinese Longitudinal Healthy Longevity Survey.

PARTICIPANTS: In total, 13,560 participants without ADL disability and 2772 participants with ADL disability at baseline were included.

MEASUREMENTS: ADL disability was assessed using Katz index scale, which included six essential ADLs: dressing, bathing, transferring, toileting, continence, and eating. Dependence of each item was scored on a scale of 1, the maximum total score was 6. At baseline, duration of ADL disability was defined as the maximum duration among the six items. The study outcome was overall survival. Accelerated failure time models were constructed to investigate the association between duration of ADL disability and overall survival. Subgroup analyses by sex, age, and multimorbidites, as well as sensitive analyses were conducted.

RESULTS: During 81,868.7 person-years follow-up, 11,092 deaths were recorded. Overall, ADL disability was associated with lower overall survival compared to non-ADL disability. With duration of ADL disability extending, the overall survival strikingly dropped in the first 12 months, reaching its lowest point with adjusted time ratio (TR) at 0.66 (95%CI: 0.61-0.72, p < 0.001), then moderately grew until the 60th month, finally stayed constant thereafter. Participants with ADL scores of 1-3 had higher survival compared to those with scores of 4-6, and both groups followed a similar trend of varied survival to the whole cohort. Moreover, subgroup analyses and sensitivity analyses showed the robustness of these findings.

CONCLUSIONS: Our findings first address a golden time window for the older individuals with ADL disability. More attention should be given to them, especially in the first 12 months since diagnosis, to reduce mortality and extend the lifespan.