Background Only 50–75% of patients are adherent to medications prescribed for the management of chronic illnesses. Adherence is influenced by several factors. We need to develop a means of assessing adherence and the factors that influence it.

Purpose To determine the medication regimen adherence in polymedicated chronic patients aged ≥65 years, and secondly, to analyse the causes of non-adherence.

Material and methods Observational prospective study. We included patients aged ≥65 years, with ≥3 chronic diseases and polymedicated (≥5 drugs) who had been hospitalised between February and April 2015. The variables collected were: demographics, number of drugs, medication regimen adherence and causes of non-adherence. Adherence was determined by the Morisky Scale, 4 point score, where higher scores reflect greater adherence. Patients were considered adherent if they scored 4. The causes of non-adherence were evaluated by the ARMS Scale. This is a 12 item scale which includes two subscales. One subscale assesses a patient’s ability to correctly self-administer the prescribed regimen and the other assesses a patient’s ability to refill medications on schedule. The data were obtained directly from the patients.

Results 72 patients were included (36 (50%) male, 79 ± 5 years old). The mean number of drugs was 12 ± 6. 25 (35%) patients were considered non-adherent. Scores obtained from the Morisky Scale were: 9 (13%) patients 2 points, 16 (22%) 3 points and 47 (65%) 4 points. The median number of reasons for non-adherence was 3 (IQR 2–4). The causes related to medication self-administration were: 18 (72%) patients forgot to take the medicine, 8 (32%) decided not to take it, 8 (32%) did not take the medicine when they felt better, 6 (24%) changed the dose and 2 (8%) did not take the medicine when they felt sick. The causes of non-adherence related to the patient’s ability to refill medications were: 8 (32%) patients forgot to get the prescriptions filled, 5 (20%) ran out of medicine and 2 (8%) did not refill the medicines because they were expensive.

Conclusion There is a high prevalence of non-adherence in polymedicated chronic patients. There are too many different reasons why patients are non-adherent. Personal development strategies are required to improve medication adherence.

No conflict of interest.