The authors of this research note that the simple application of guideline recommendations in people who have co-morbidities may result in polypharmacy and a potential for interaction (drug and disease). The purpose of their study was to quantify how often the drugs recommended by three NICE clinical guidelines (heart failure, type 2 diabetes, and depression) have either drug-drug or drug-disease interactions in the presence of nine other commonly comorbid conditions and the drugs recommended for their treatment in the relevant NICE guidelines.
For each of the three NICE guidelines, the BNF was searched to identify drug-disease warnings for the recommended drugs, taking into account the other 11 conditions. The BNF was also used to identify potentially serious interactions between drugs recommended by each of the three index guidelines and drugs recommended by any of the 12 guidelines.
The authors found overall that drug-disease interactions were not common, with the exception of those related to chronic kidney disease, which occurred with type 2 diabetes in particular. Potentially serious drug-drug interactions were however common. For type 2 diabetes, the most common category was cardiovascular related harm, whereas it was bleeding events for the depression and heart failure guidelines. The authors note that a limited number of the identified drug-drug interactions were highlighted in the guidelines for the index condition.
The authors suggest that their findings may be conservative, as they only studied a selection of clinical guidelines as exemplar case studies and they excluded recommendations regarding treatment for acute conditions. They do however acknowledge that there are other guidelines available that discuss potential drug interactions in more detail (e.g. the NICE guideline on the treatment of depression in people with a chronic physical health problem).
They recommend that guideline developers need to more explicitly account for drug-disease and drug-drug interactions in people with multimorbidity and should use epidemiological evidence to identify when interactions are likely to be common and serious enough to require specific mention in a guideline. They also suggest that electronic based guidelines that allow interactive searching for specific conditions are a potential way forward to account for multimorbidity in guideline recommendations.