Depression and drug utilization in an elderly population.

OBJECTIVE

To verify whether depression, defined as a 15-item Geriatric Depression Scale (GDS) > 6, is associated with greater drug utilization by elderly patients.

POPULATION: 2568 patients enrolled in the Gruppo Italiano di Farmacovigilanza nell'Anziano (GIFA) study.

MAIN OUTCOME MEASURE: Polypharmacy, ie, the daily use of at least 3 drugs, excluding antidepressant and anxiolytic agents, in the month prior to admission.

METHOD: Home therapy data were collected according to a validated procedure. Correlates of polypharmacy were assessed by logistic regression analysis in the whole population and in subgroups for which indexes of disease severity were available.

RESULTS

GDS > 6 was found to be positively correlated with polypharmacy (odds ratio 1.22; 95% confidence interval 1.01-1.48) as were older age, comorbidity, hypertension, diabetes mellitus, congestive heart failure, and renal failure. Negative correlates of polypharmacy were smoking habit and alcohol consumption, and GDS > 6 was negatively associated with the use of analgesic (11.8% vs 15.6%, p = 0.012). In the subgroups with congestive heart failure and chronic renal failure, GDS > 6 was strictly associated with greater disease severity, but did not correlate with polypharmacy in multivariable models including indexes of disease severity.

CONCLUSIONS

Depressed mood is associated with polypharmacy in the broad elderly population. However, when indexes of disease severity were considered, the association was lost, indicating that depression is a marker of the burden of disease and does not increase drug consumption per se.