[Disability as a barrier to drug adherence in polypathological patients: role of main carer]

To determine which social and individual factors may predict adherence to medication in patients with more than two chronic symptomatic diseases (polypathological patients) under polypharmacy.

Cross-sectional observational study. In a primary care area assigned to our teaching hospital 265 patients with multiple chronic diseases and polypharmacy were recruited over a 6 month period. 84 patients with uncompleted data or died before finishing our study were excluded. An structured interview performed by a investigator different from responsible physicians was used. Drug adherence was assessed by a subjective method.

Disability measured by Barthel index was was the main predictor of drug adherence. Patients without carer support and Barthel Index lower than 100 showed the poorer drug adherence. In the later group number of drugs also affected adherence. However, in patients with carer available, medication adherence was better, mostly in more disabled ones, and unaffected by other factors.

In patients with multiple chronic diseases, social support by a carer may allow disabled patients to overcome the barrier of disability leading to a better drug adherence, even than non-disabled ones. These findings may help to design future prospective studies on medication adherence performed in this peculiar frail population.