Background The quality of studies assessing the effectiveness of interventions aimed at improving adherence in patients with multiple chronic conditions is variable so it is difficult to know if they reach valid conclusions.

Purpose To describe the quality of systematic reviews studying the effectiveness of interventions to improve medicines adherence in polypathological patients or similar.

Materials and methods The risk of bias was assessed using the AMSTAR checklist. This scale provides an 11-item tool mainly to perform a qualitative analysis of systematic reviews (SR). SR published from 1967 to 2012 were explored if they described controlled clinical trials aimed at improving adherence to self-administered medicines in polypathological patients, those taking multiple prescribed medicines or patients sharing similar chronic conditions to those with several illnesses. Databases: MEDLINE, EMBASE and the Cochrane Library. The search strategy varied across databases but generally included terms for adherence (compliance, persistence, adherence, dropouts), study population (polypharmacy, chronic disease, multiple chronic conditions, frail elderly, polypathological) and study design (meta-analysis, SR).

Results Of the 9 SR, 6 (67%) considered at least 70% of the 11 items. All the SR had an a priori design, a duplicate study selection, data extraction and a comprehensive literature search. Additionally, all of them described the characteristics of the studies included and the potential.

Conclusions The risk of bias in SR studying interventions to improve adherence in polypathological patients or similar is low to moderate. However, the assessment of publication bias and taking into account the quality of the included studies in formulating conclusions would be a clear improvement.

No conflict of interest.