Diclofenac for acute postoperative pain in children

Many children undergo various surgeries, which often lead to acute postoperative pain. This pain influences recovery and quality of life. Non-steroidal anti-inflammatory drugs (NSAIDs), specifically cyclo-oxygenase (COX) inhibitors such as diclofenac, can be used to treat pain and reduce inflammation. There is uncertainty regarding diclofenac's benefits and harms compared to placebo or other drugs for postoperative pain.

To assess the efficacy and safety of diclofenac (any dose) for acute postoperative pain management in children compared with placebo, other active comparators, or diclofenac administered by different routes (e.g. oral, rectal, etc.) or strategies (e.g. 'as needed' versus 'as scheduled').

We used standard, extensive Cochrane search methods. We searched CENTRAL, MEDLINE, and trial registries on 11 April 2022.

We included randomised controlled trials (RCTs) in children under 18 years of age undergoing surgery that compared diclofenac (delivered in any dose and route) to placebo or any active pharmacological intervention. We included RCTs comparing different administration routes of diclofenac and different strategies.

We used standard methodological procedures expected by Cochrane. Our primary outcomes were: pain relief (PR) reported by the child, defined as the proportion of children reporting 50% or better postoperative pain relief; pain intensity (PI) reported by the child; adverse events (AEs); and serious adverse events (SAEs). We presented results using risk ratios (RR), mean differences (MD), and standardised mean differences (SMD), with the associated confidence intervals (CI).

We included 32 RCTs with 2250 children. All surgeries were done using general anaesthesia. Most studies (27) included children above age three. Only two studies had an overall low risk of bias; 30 had an unclear or high risk of bias in one or several domains. Diclofenac versus placebo (three studies) None of the included studies reported on PR or PI. We are very uncertain about the benefits and harms of diclofenac versus placebo on nausea/vomiting (RR 0.83, 95% CI 0.38 to 1.80; 2 studies, 100 children) and any reported bleeding (RR 3.00, 95% CI 0.34 to 26.45; 2 studies, 100 children), both very low-certainty evidence. None of the included studies reported SAEs. Diclofenac versus opioids (seven studies) We are very uncertain if diclofenac reduces PI at 2 to 24 hours postoperatively compared to opioids (median pain intensity 0.3 (interquartile range (IQR) 0.0 to 2.5) for diclofenac versus median 0.7 (IQR 0.1 to 2.4) in the opioid group; 1 study, 50 children; very low-certainty evidence). None of the included studies reported on PR or PI for other time points. Diclofenac probably results in less nausea/vomiting compared to opioids (41.0% in opioids, 31.0% in diclofenac; RR 0.75, 95% CI 0.58 to 0.96; 7 studies, 463 participants), and probably increases any reported bleeding (5.4% in opioids, 16.5% in diclofenac; RR 3.06, 95% CI 1.31 to 7.13; 2 studies, 222 participants), both moderate-certainty evidence. None of the included studies reported SAEs. Diclofenac versus paracetamol (10 studies) None of the included studies assessed child-reported PR. Compared to paracetamol, we are very uncertain if diclofenac: reduces PI at 0 to 2 hours postoperatively (SMD -0.45, 95% CI -0.74 to -0.15; 2 studies, 180 children); reduces PI at 2 to 24 hours postoperatively (SMD -0.64, 95% CI -0.89 to -0.39; 3 studies, 300 children); reduces nausea/vomiting (RR 0.47, 95% CI 0.25 to 0.87; 5 studies, 348 children); reduces bleeding events (RR 0.57, 95% CI 0.12 to 2.62; 5 studies, 332 participants); or reduces SAEs (RR 0.50, 95% CI 0.05 to 5.22; 1 study, 60 children). The evidence certainty was very low for all outcomes. Diclofenac versus bupivacaine (five studies) None of the included studies reported on PR or PI. Compared to bupivacaine, we are very uncertain about the effect of diclofenac on nausea/vomiting (RR 1.28, 95% CI 0.58 to 2.78; 3 studies, 128 children) and SAEs (RR 4.52, 95% CI 0.23 to 88.38; 1 study, 38 children), both very low-certainty evidence. Diclofenac versus active pharmacological comparator (10 studies) We are very uncertain about the benefits and harms of diclofenac versus any other active pharmacological comparator (dexamethasone, pranoprofen, fluorometholone, oxybuprocaine, flurbiprofen, lignocaine), and for different routes and delivery of diclofenac, due to few and small studies, no reporting of key outcomes, and very low-certainty evidence for the reported outcomes. We are unable to draw any meaningful conclusions from the numerical results.

We remain uncertain about the efficacy of diclofenac compared to placebo, active comparators, or by different routes of administration, for postoperative pain management in children. This is largely due to authors not reporting on clinically important outcomes; unclear reporting of the trials; or poor trial conduct reducing our confidence in the results. We remain uncertain about diclofenac's safety compared to placebo or active comparators, except for the comparison of diclofenac with opioids: diclofenac probably results in less nausea and vomiting compared with opioids, but more bleeding events. For healthcare providers managing postoperative pain, diclofenac is a COX inhibitor option, along with other pharmacological and non-pharmacological approaches. Healthcare providers should weigh the benefits and risks based on what is known of their respective pharmacological effects, rather than known efficacy. For surgical interventions in which bleeding or nausea and vomiting are a concern postoperatively, the risks of adverse events using opioids or diclofenac for managing pain should be considered.