DISCUSSION
Polypharmacy is common in patients with cardiovascular disease13, increasing risk of DDIs8 that worsen treatment outcomes 18. DDI screening tools embedded within EMR can assist with DDI identification and management, however, DDIs are still highly prevalent 14. The objective of the current study was to evaluate the prevalence of DDIs in the CVICU at MM and to compare it to the prevalence in an ICU in KTH, Pakistan. Our study confirmed a high prevalence of DDIs in MM (58%), but a significantly lower prevalence than KTH (95%, p< 0.01).
Estimates of DDI prevalence worldwide varies from 38% to 71%, depending on the study setting, population and tools employed to evaluate DDIs 8, 19, 20. At MM 1.57 DDIs per patient were present, which is lower than the DDIs per patient at KTH (3.09) or reported from an ICU in Serbia (~6). The lower prevalence of DDI at MM likely reflects the effectiveness of DDI screening by the EMR, as there is no computerized DDI screening system at KTH or Serbia 21.
Polypharmacy and longer ICU stay increased risk of DDIs in MM (both,p < 0.01), while in KTH only polypharmacy increased DDI risk (p < 0.01). Polypharmacy and length of stay have been previously reported to increase DDI risk in various studies conducted in the US and worldwide 22-25. Gender and age have also been reported to be associated with DDIs22-25 but were not associated with DDIs in MM or KTH (p > 0.05). Prior reports of association may have been due to analyzing cohorts from mixed treatment units with mixed disease states, which could introduce issues with confounding.
Of the total clinically relevant DDI observed in MM CVICU patients, only 21% (14/66) were undetected by the MM EMR. In comparison, 100% of clinically relevant DDIs are undetected at KTH due to the lack of any DDI screening system. Recent studies highlighted the effectiveness of EMR based DDI detection tools and pharmacists in reducing medication errors and DDIs 26-28. Thus implementation of an EMR based DDI screening tool and pharmacist screening could help prevent DDIs at KTH. At MM, a subset of clinically relevant DDIs were not detected by the EMR. Of the 8 DDI pairs that were not detected, 2 pairs resulted in 57% of observed DDIs. The DDI of tacrolimus and omeprazole is important in transplant patients as omeprazole may increase tacrolimus concentrations leading to increased risk of hepatotoxicity and nephrotoxicity 29, 30. EMR DDI detection systems could be further improved by enhancing information display and contextualization, and providing DDI management recommendations that are tailored to the individual provider and unit 31.
Strengths of the study include a large sample size, inclusion of all concurrently administered drugs and use of multiple tools to analyze clinical relevance of DDIs. However, several limitations should be considered. This study was conducted in a single unit of a single tertiary care hospital, limiting the generalizability of these findings. Additionally, the retrospective study design precludes meaningful analyses of the number of DDIs that were detected and appropriately managed.