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ANALGESIA FOR CHILDREN WITH ACUTE ABDOMINAL PAIN AND DIAGNOSTIC ACCURACY
A 9-year-old boy presents with severe right iliac fossa pain. You contact the surgical team who are currently in theatre and will not be able to attend for at least 20 min. You wonder if administering morphine to the boy will hinder or delay diagnosis.
Structured clinical question
In children with acute abdominal pain [patient] does analgesia before surgical consultation [intervention] affect surgical diagnostic accuracy [outcome]?
Search strategy and outcome
Medline and Embase were searched using the Dialog Datastar interface.
MEDLINE (1950–date) search terms: (abdominal ADJ pain OR acute ADJ abdomen) AND (analges$ OR pain ADJ relief) AND diagnosis AND LG = EN AND HUMAN = YES AND (CHILD# OR ADOLESCENT.DE. OR INFANT#)
EMBASE (1974–date) search terms: (abdominal ADJ pain OR acute ADJ abdomen) AND (analges$ OR pain ADJ relief) AND diagnosis AND LG = EN AND HUMAN = YES AND CHILD = YES
The BestBETs website was searched.
MEDLINE yielded 56 papers and EMBASE yielded 100 papers. BestBETs yielded 1 BET, but although the clinical scenario involved the assessment of a child, all of the evidence related to studies performed in adults.
After removal of duplicates, 134 abstracts were scanned. Four papers were found to be relevant to the three-part question (see table 2).
Classic teaching in general surgery has suggested that administration of analgesia in children with acute abdominal pain should be deferred until after a definitive surgical treatment plan has been formulated. Theoretically, analgesia may mask pain and lessen examination findings that would normally suggest a surgical cause for abdominal pain.
All but one of the studies found that opioid analgesia was effective at reducing pain scores in children with acute abdominal pain. Bailey et al4 state that morphine was not more effective than placebo in diminishing pain. This study suffers from being significantly underpowered regarding this outcome, but this does not fully explain the result, which appears to be due to a high placebo response compared to the other studies rather than a lack of response to morphine. The reasons for such a high response are likely to be complex and beyond the scope of this commentary.
The studies identified all report that administration of analgesia to children with acute abdominal pain did not significantly interfere with diagnosis. Diagnostic accuracy was defined in two studies as true surgical and true non-surgical diagnoses as a proportion of all results. One study detected no difference,3 while the other1 noted a difference when children were examined by one subgroup of doctors, although the confidence intervals are borderline, and the authors’ other measure of diagnostic accuracy (reduction in mean number of areas of abdominal tenderness) was unaffected by the administration of analgesia. One study2 used the doctors’ estimation of confidence in diagnosis as their measure of diagnostic accuracy. The remaining study4 used the time between arrival in the emergency department and the surgical decision. Other proxy measures of diagnostic accuracy, such as differences in time to operating theatre and perforation rates, where recorded, are also reported as being unaffected.
These results are in keeping with what is known in adult patients; a recent Cochrane review5 of this topic concluded that the use of opioid analgesics in patients with acute abdominal pain does not delay treatment decisions. None of the studies identified included children less than 5 years old. In infants and preschool children, acute abdomen is uncommon, examination findings may be non-specific and as a result diagnosis may be difficult. Generalising findings from older children to this age group may therefore be detrimental.
The clinical assessors were reported as blinded to whether the children had received analgesia or placebo. However, as the same assessor was responsible for examining the child before and after administration of the study drug, no mechanism existed to prevent bias introduced by the assessor remembering the previous clinical findings. Only in the study by Green et al2 were the children examined after administration of medication by another assessor (a paediatric surgeon) who was naive to the initial examination findings and whose confidence in diagnosis was the same for both the analgesia and the placebo groups.
The studies all suffer from being underpowered to detect true differences in diagnostic ability. Post-hoc power calculations performed on the papers by Green et al2 and Kokki et al3 indicate that in order to attain a power of 80% over 1000 patients would need to be recruited into each arm of a trial. This would be a significant undertaking and subjecting several thousand children in pain to placebo analgesia to identify a difference in diagnostic accuracy that may have little clinical impact is ethically suspect. Certainly, none of the studies above identified major morbidity or mortality as a result of early treatment with analgesia.
Since such a trial is therefore very unlikely to be performed, what remains is to make an informed decision based on the current evidence, and with the patient’s interests foremost. Taking these into account, children with acute abdominal pain should be treated promptly and adequately with analgesia unless future studies suggest evidence of harm.
Competing interests: None.
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