Prevalence of adherence to treatment in homebound elderly people in primary health care: a descriptive, cross-sectional, multicentre study

Abstract

Background: Adherence to the therapeutic plan is one of the most important health issues in terms of treatment efficacy, healthcare costs and patient safety. Unfortunately, homebound elderly patients are especially vulnerable to nonadherence because they have higher morbidity rates combined with cognitive and social problems that hinder their correct use of drugs. The level of therapeutic adherence in homebound elderly people has not been adequately studied.

Objective: To estimate the prevalence of therapeutic adherence, using the Morisky-Green test, in homebound elderly patients taking polypharmacy (defined as use of four or more drugs), and to study the factors associated with adherence.

Methods: This was a descriptive, cross-sectional, multicentre study. A total of 327 patients were selected by random start systematic sampling from the total number of homebound patients taking four or more drugs in Healthcare Area 4 of the Madrid Autonomous Region, Spain. Through an in-home survey of patients and their caregivers, information was gathered on sociodemographic data, co-morbidities, number of hospital admissions, responsibility for purchasing and preparation of the medication, level of cognitive impairment (Pfeiffer questionnaire), functional dependence in activities of daily living (Katz Index), knowledge of the disease (Batalla test), adherence to treatment (Morisky-Green test), visual and auditory perception, and caregiver burden (Zarit interview).

Results: Of the homebound patients, 65.7% (95% CI 60.6, 70.9) had good adherence to treatment. The variables most negatively associated with therapeutic adherence, after adjustment for age, sex, number of drugs, knowledge of the disease, and cognitive function, were a large caregiver burden (odds ratio [OR] 3.09; 95% CI 1.75, 5.48) and impaired hearing (OR 2.00; 95% CI 1.17, 3.40). There was also a trend toward a positive association between nonadherence and patients aged <85 years (OR 1.57; 95% CI 0.93, 2.65) and patients who had nine or more drug prescriptions (OR 1.59; 95% CI 0.96, 2.65).

Conclusions: Poor therapeutic adherence in homebound elderly patients receiving polypharmacy is a serious problem affecting one of every three individuals concerned, and is directly related to caregiver burden, regardless of age, sex, cognitive status or number of drugs administered.