Longitudinal association between depressive symptoms and disability burden among older persons.

BACKGROUND: Although depressive symptoms in older persons are common, their association with disability burden is not well understood. The authors evaluated the association between level of depressive symptoms and severity of subsequent disability over time and determined whether this relationship differed by sex.
METHODS: Participants included 754 community-living persons aged 70 years or older who underwent monthly assessments of disability in four essential activities of daily living for up to 117 months. Disability was categorized each month as none, mild, and severe. Depressive symptoms, assessed every 18 months, were categorized as low (referent group), moderate, and high. Multinomial logit models invoking Generalized Estimating Equation were used to calculate odds ratios and 95% confidence intervals.
RESULTS: Moderate (odds ratio = 1.30; 95% confidence interval: 1.18-1.43) and high (odds ratio = 1.68; 95% confidence interval: 1.50-1.88) depressive symptoms were associated with mild disability, whereas only high depressive symptoms were associated with severe disability (odds ratio = 2.05; 95% confidence interval: 1.76-2.39). Depressive symptoms were associated with disability burden in both men and women, with modest differences by sex; men had an increased likelihood of experiencing severe disability at both moderate and high levels of depressive symptoms, whereas only high depressive symptoms were associated with severe disability in women.
CONCLUSIONS: Levels of depressive symptoms below the threshold for subsyndromal depression are associated with increased disability burden in older persons. Identifying and treating varying levels of depressive symptoms in older persons may ultimately help to reduce the burden of disability in this population.