A bitter pill to swallow? Impact of affective temperaments on treatment adherence: a systematic review and meta-analysis

BACKGROUND: Predominant affective temperament may affect adherence to prescribed pharmacotherapeutic interventions, warranting systematic review and meta-analysis. METHODS: The Scopus, Web of Science, PubMed, and OVID MedLine databases were inquired since inception up to 31st of March 2022 for records of any study design documenting quantitative evidence about affective temperaments as measured by the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego (TEMPS-A) questionnaire and treatment adherence measured by the means of major rating scales on the matter. People with low vs. high levels of treatment adherence, matched for otherwise clinically relevant variables, were deemed as cases and controls, respectively, using standardized mean differences (SMDs) in pertinent scores under random-effects meta-analysis. RESULTS: Nine studies encompassing 1138 subjects pointed towards significantly higher cyclothymic (SMD = −0.872; CI: [−1.51 to −0.24]; p = 0.007), irritable (SMD = −0.773; CI: [−1.17 to −0.37]; p < 0.001) and depressive (SMD = −0.758; CI: [−1.38 to −0.14]; p = 0.017) TEMPS-A scores both for psychiatric and nonpsychiatric samples with poorer adherence. LIMITATIONS: Intrinsic limitations of the present report include the heterogeneity of the operational definitions documented across different primary studies, which nonetheless reported on the sole medication-treatment adherence, thus limiting the generalizability of the present findings based on a handful of comparisons. CONCLUSIONS: Though further primary studies need to systematically account for different clinical and psychosocial moderators across different clinical populations and operational definitions, cyclothymic, depressive, and irritable temperament scores may nonetheless predict treatment adherence and, thus, overall treatment outcomes.