The aims of the study were to investigate the prevalence of hospital visits associated with medication-related problems (MRPs, i.e., adverse drug events [ADEs], adverse drug reactions [ADRs], nonadherence [NA] to medication, and medication error) and to identify the medications involved in hospital visits associated with MRPs in outpatient departments (OPDs).
A prospective observational study was carried out in OPD of 11 hospitals in the lower northern region of Thailand. Patients visiting OPDs were screened for suspected MRPs by clinical pharmacists using medical record review supplemented by patient interview. Three experts evaluated suspected MRPs using the following 3 criteria: causality, severity, and preventability.
Of the 3069 patients who visited the OPDs during the study period, 113 (3.7%) were deemed to have causal MRPs. Nearly half of the causal MRPs (n = 49, 43.4%) were preventable. The following 4 types of causal MRPs were identified: ADEs (n = 112, 3.7%), ADRs (n = 65, 2.1%), NA to medications (n = 48, 1.6%), and medication errors (n = 1, 0.03%). In nonelective patients (n = 764), 35 patients (4.6%) were judged to have causal MRPs. Of the nonelective patients who experienced causal MRPs, 25 (71.4%) were preventable. The medications commonly associated with ADEs and NA to medication were those targeting the cardiovascular system (especially enalapril, amlodipine, and hydrochlorothiazide), whereas the medications involving ADRs involved the cardiovascular and endocrine systems (especially, enalapril, amlodipine, and metformin).
Outpatient department visits associated with MRPs, particularly in nonelective patients, were preventable. Effective strategies are needed for reducing visits to hospital OPD associated with preventable MRPs.