Prospective observational study of adverse drug reactions to diclofenac in children.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Diclofenac is frequently used off-label in children for acute pain, but little information is available on diclofenac adverse drug reactions in this population. WHAT THIS STUDY ADDS • The common adverse drug reactions of diclofenac for acute pain in children are of a similar type to those seen in adults. • Serious adverse reactions occur in <0.8% of children and the incidence of diclofenac-induced bronchospasm in asthmatic children is <2.7%. AIM The aim of this study was to investigate the type of common (occurring in >1% of patients) adverse reactions caused by diclofenac when given to children for acute pain. METHODS A prospective observational study was undertaken on paediatric surgical patents aged ≤12 years at Great Ormond Street and University College London Hospitals. All adverse events were recorded, and causality assessment used to judge the likelihood of them being due to diclofenac. Prospective recruitment meant not all patients were prescribed diclofenac, allowing an analysis of utilization. Causality of all serious adverse events was reviewed by an expert panel. RESULTS Children prescribed diclofenac were significantly older, and stayed in hospital for shorter periods than those who were not. Diclofenac was not avoided in asthmatic patients. Data on 380 children showed they suffer similar types of nonserious adverse reactions to adults. The incidence (95% confidence interval) of rash was 0.8% (0.016, 2.3); minor central nervous system disturbance 0.5% (0.06, 1.9); rectal irritation with suppositories 0.3% (0.009, 1.9); and diarrhoea 0.3% (0.007, 1.5). No serious adverse event was judged to be caused by diclofenac, meaning the incidence of serious adverse reactions to diclofenac in children is <0.8%. CONCLUSION Children given diclofenac for acute pain appeared to suffer similar types of adverse reactions to adults; the incidence of serious adverse reaction is <0.8%.