Postoperative pain relief for children

Pain is commonly experienced after surgery. Children tend to rely on a parent or carer to give medication to help relieve the pain. Medication can either be given when the child complains of pain (as required), or 'around the clock' (fixed schedule, e.g. every four hours).

In July 2014, we found three studies (randomised controlled trials) of 246 children under the age of 16 years. All studies compared the two ways of giving medicine for pain relief after tonsillectomy (an operation to remove the tonsils). The studies were small, and generally of low quality.

One study showed that the children in the 'around the clock' group took more medication, but they did not have better pain relief. There were no differences in pain relief or side effects between the two groups. There was not enough evidence to be sure which method is better for a child's pain relief after surgery. More high quality, large studies are needed.

Authors' conclusions: 

There was limited evidence available to draw any conclusions about the efficacy of PRN versus ATC analgesic administration for the management of postoperative pain in children.

Read the full abstract...

Acute postoperative pain occurs as a result of tissue damage following surgery. Administering the appropriate analgesia to children is a complex process and it is unclear whether children's postoperative pain is more successfully treated by using 'as required' (when pain occurs) (termed 'pro re nata' or PRN) or fixed scheduled 'around the clock' (ATC) analgesic administration (irrespective of pain at the time of administration).


To assess the efficacy of as required versus fixed schedule analgesic administration for the management of postoperative pain in children under the age of 16 years.

Search strategy: 

On 2 July 2014, we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and CINAHL databases. We reviewed the bibliographies of all included studies and of reviews, and searched two clinical trial databases, and the World Health Organization (WHO) International Clinical Trials Registry Platform, to identify additional published or unpublished data.

Selection criteria: 

We included randomised controlled trials (RCTs) comparing PRN versus ATC analgesic administration for postoperative pain in children under the age of 16 years who had undergone any surgical procedure requiring postoperative pain relief, in any setting.

Data collection and analysis: 

Two review authors (AH, PW) independently extracted efficacy and adverse event data, examined issues of study quality, and assessed risk of bias as recommended in the Cochrane Handbook for Systematic Reviews of Interventions.

Main results: 

We included three RCTs (four reports) of 246 children aged under 16 years undergoing tonsillectomy. Children were given weight-appropriate doses of the study medication, either PRN or ATC, by a parent or carer at home for up to four days following surgery. We did not identify any studies assessing the management of postoperative pain in children in any other setting (i.e. as an inpatient). All studies included in this review were based on the use of paracetamol, and an opioid was added to paracetamol in two studies. Analgesics were administered either orally (tablet or elixir) or rectally (suppository). Reporting quality was poor and there were fewer than 50 children in each arm. Mean pain intensity scores decreased over time, as did medication use. However, children were still reporting pain at the final assessment, suggesting that no administration schedule provided adequate analgesia. There were no significant differences in pain intensity scores at any time point. The studies reported adverse events that may have been related to the study medication, such as nausea and vomiting, and constipation, but no statistically significant differences were noted between the groups. There were too few data from only three small studies and meta-analysis was not possible. One study reported that a higher amount of analgesics was consumed in the ATC group compared with the PRN group: it would have been helpful to show that the higher volume in the ATC group led to better analgesia but we were not able to demonstrate this.