Prescription study finds potentially serious drug clashes

Blindly following recommendations for drug prescriptions in national clinical guidelines for conditions including diabetes, depression and heart failure will often result in potentially serious drug interactions, according to a new study.

The research, led by Professor Bruce Guthrie at the University of Dundee in collaboration with the Universities of Aberdeen, Manchester and Professor Stewart Mercer at Glasgow, examined National Institute of Health and Care Excellence (NICE) guidelines for potential clashes between recommended drugs for one condition and recommended drugs for other common conditions.

They found that following recommendations to prescribe drugs in twelve of the national clinical guidelines would result in several potentially serious drug interactions, where the drugs being prescribed could actually cause a negative effect through combination with other recommended treatments or because they were unsuitable if patients had another condition.

Potentially serious clashes between drugs prescribed for different conditions were ‘common’, said the researchers.

Examining the guidelines for type 2 diabetes, depression and heart failure and comparing them to each other and guidelines for another eleven conditions showed:

•  133 potentially serious drug-drug interactions for drugs recommended in the type 2 diabetes guidelines
•  89 for depression
•  111 for heart failure

Professor Guthrie said the findings showed clinical guidelines needed to take much greater account of patients suffering from more than one condition.

“Despite widespread multimorbidity, where patients have more than one condition, the clinical guidelines are largely written as though patients have a single condition and the cumulative impact of treatment recommendations from multiple guidelines is not really considered,” said Professor Guthrie.

“Clinical guidelines of course are not intended to be completely comprehensive guides to practice, in that clinicians are expected to use their judgement in deciding which treatments are appropriate in individual patients.

“However, it is potentially dangerous to have guidelines that do not take account of the effect of combinations of recommended treatments.

“We recommend that during the development of clinical guidelines the process should consider how to identify and more explicitly highlight the potential for interactions between recommended drugs and other conditions and other drugs that patients with the guideline condition are likely to have.

“The number of potentially serious combinations of drugs and diseases requires a better approach to multimorbidity to allow clinicians and patients to make informed decisions about drug treatments.”

Professor Stewart Mercer, who is the national lead for multimorbidity research in primary care and the Director of the Scottish School of Primary Care, said: “This important work led by Professor Guthrie adds to our understanding of the complexity of treating patients with multiple complex conditions, and reinforces the need for services and evidence to be built around and tailored to the needs of such patients.”

The results of the study have been published by the British Medical Journal.