Pharmaco-epidemiologic study of the prescription of contraindicated drugs in a primary care setting of a university: a retrospective review of drug prescription

BACKGROUND: The prescription of contraindicated drugs is a preventable medication error, which can cause morbidity and mortality. Recent data on the factors associated with drug contraindications (DCIs) is limited world-wide, especially in Malaysia.

AIMS: The objectives of this study are 1) to quantify the prevalence of DCIs in a primary care setting at a Malaysian University; 2) to identify patient characteristics associated with increased DCI episodes, and 3) to identify associated factors for these DCIs.

METHODS: We retrospectively collected data from 1 academic year using computerized databases at the Universiti Sains Malaysia (USM) from patients of USM's primary care. Descriptive and comparative statistics were used to characterize DCIs.

RESULTS: There were 1,317 DCIs during the study period. These were observed in a cohort of 923 patients, out of a total of 17,288 patients, representing 5,339 DCIs per 100,000 patients, or 5.3% of all patients over a 1-year period. Of the 923 exposed patients, 745 (80.7%) were exposed to 1 DCI event, 92 (10%) to 2 DCI events, 35 (3.8%) to 3 DCI events, 18 (2%) to 4 DCI events, and 33 patients (3.6%) were exposed to 5 or more DCI events. The average age of the exposed patients was 30.7 ± 15 y, and 51.5% were male. Multivariate logistic regression analysis revealed that being male (OR = 1.3; 95% CI = 1.1 - 1.5; p < 0.001), being a member of the staff (OR = 3; 95% CI = 2.5 - 3.7; p < 0.001), having 4 or more prescribers (OR = 2.8; 95% CI = 2.2 - 3.6; p < 0.001), and having 4 or more longterm therapeutic groups (OR = 2.3; 95%CI = 1.7 - 3.1; p < 0.001), were significantly associated with increased chance of exposure to DCIs.

DISCUSSION AND CONCLUSIONS: This is the first study in Malaysia that presents data on the prevalence of DCIs. The prescription of contraindicated drugs was found to be frequent in this primary care setting. Exposure to DCI events was associated with specific socio-demographic and health status factors. Further research is needed to evaluate the relationship between health outcomes and the exposure to DCIs.