Frequency, types and severity of medication use-related problems among medical outpatients in Nigeria

To determine the frequency, types and severity of medications use-related problems among medical outpatients in a tertiary care setting in southwestern Nigeria.

Medical outpatient clinics of a 900-bed Teaching Hospital located in Ibadan, Southwestern Nigeria.

A prospective cross-sectional medication use review was conducted by ten pharmacists for 400 randomly selected medical outpatients over a 4 week period at a 900-bed premier teaching hospital located in Ibadan, Nigeria. Severity assessment of medication use-related problems was done by 3 independent assessors with a modified severity index.

Frequency, types and severity of medication use-related problems identified through pharmacist-initiated medication use review.

Of the 400 randomly selected patients, 324 (81.0%) consented and were interviewed. One hundred and sixty-three (50.3%) of the cohort were males and 161 (49.7%) were females; with mean ages 51.5 ± 17.6 and 52.1 ± 17.4 years respectively. Median no. of drugs prescribed per patient per day was 4 (Minimum-Maximum, 1-7). About 27.5% were self medicating with orthodox (prescription-only and over-the-counter) and/or herbal medicines; and only 14.6% claimed disclosure to their physicians. The proportion of patients self medicating with orthodox medicines was significantly higher (P < 0.0001). Two hundred and twenty-six medication use-related problems were identified from 58.6% of patients, but the highest number (5) was identified among 2.6% of patients. The frequency of medication use-related problems appear strongly related to the number of medicines prescribed (r = 0.71, P = 0.006). The majority of medication use-related problems were ranked as potentially harmful [Inter-rater reliability coefficient: Gwet AC1: 0.7214 (P ≤ 0.001)]. Non-adherence (43.8%), problems associated with self medication (39.3%) and adverse drug reactions (15.6%) were the most frequent. Unauthorized drug holidays (46.5%) and stoppage of prescribed prescription-only medications for local herbs (29.3%) were the major consequences of non-adherence. Potentially harmful drug-disease interactions were the most frequent medication use-related problems arising from self medication (40.4%).

Potentially harmful medication use-related problems are frequently encountered among medical outpatients in Nigeria. The institutionalization of medication use review and the devolution of this task to pharmacists may prove beneficial in optimizing outcomes of medication use in Nigeria.