Background Poor adherence to medical treatment represents a major issue in elderly population. It compromises the effectiveness of treatment making this a critical issue in population health.

Purpose The aims were to assess if the SMAQ questionnaire (SQ) is a reliable adherence measurement tool, to identify predictor factors of non-adherence and to investigate the relation between adherence and hospital readmissions in a cohort of patients.

Material and methods We recruited patients aged >65 years, receiving polypharmacy (more than 4 drugs), in the trauma ward, from 1 April 2014 to 31 August 2015. Adherence was assessed with the SQ and a clinical interview (CI). A patient was considered adherent (AP) if adherence was verified both in the SQ and CI, and non-adherent (N-AP) as follows: SQ non-adherent patient (S-N-AP) when non-adherence was detected only in the SQ and CI non-adherent patient (CI-N-AP) if non-adherence was not detected in the SQ but was detected in the CI. Demographic, clinical variables and hospital readmissions over 3 months were collected. Statistical analysis was performed with the SPSS program: χ² test for qualitative, ANOVA test for quantitative variables.

Results 245 patientst were enrolled. 213 (86.9%) completed the survey (SQ and CI). Mean age was 80.23 years (range 65–95). 25.3% were male and 61.6% female. The majority of diagnoses were hip (51.4%) and knee lesions (19.6%). 26.5% lived without caregiving. The main comorbidities were arterial hypertension (79.3%), 34.7% diabetes and 29.1% dislipidemia. 180 patients (84.5%) were AP and 33 (15.5%) were N-AP: 11 (5.2%) were S-N-AP and 22 (10.3%) were CI-N-AP. There were no factors significantly associated with medication adherence (sex, number of chronic drugs or comorbidities). Hospital readmissions were higher in N-AP (15.2% vs 7.8%) but the difference was not statistically significant.

Conclusion Non-adherence is a real problem for older patients receiving polypharmacy. Interventions to target patient adherence should take this into account. No clear indicators of non-adherence were identified. Future researchers should consider other possible factors. The SQ alone, without other adherence measurements, is not an appropriate tool for this group of patients due to the fact that it failed to detect CI-N-AP, which represented 66.7% of N-AP.

No conflict of interest.