Seventeen studies (n=1,572) were included in the review: 16 of retrospective non-randomised design and one prospective non-randomised design. Quality scores ranged from 4 to 9 and 11 studies scored more than 6.
No significant difference was found between conservative treatment and acute appendectomy for the duration of intravenous antibiotics given to patients (four studies), duration of first hospitalisation (eight studies) and overall duration of hospitalisation (seven studies); significant statistical heterogeneity was found for all these analyses.
Significantly more complications were found with acute appendectomy than with conservative treatment (OR 0.24, 95% CI 0.13 to 0.44, I2=74.6%; 16 studies). Specifically, a significantly greater incidence of ileus/bowel obstruction (OR 0.35, 95% CI 0.17 to 0.71; eight studies), abdominal/pelvic abscess formation (OR 0.19, 95% CI 0.07 to 0.58; eight studies), re-operations (OR 0.17, 95% CI 0.04 to 0.75; four studies) and wound infection (OR 0.28, 95% CI 0.13 to 0.60; 10 studies) were found with acute appendectomy. No significant between-group differences were found for incidence of pneumonia, sepsis/diffuse peritonitis, deep venous thrombosis/pulmonary embolism, mortality, adhesions and fistula formation.
No significant between-group difference was found for ileus/bowel obstruction after sensitivity analyses (only paediatric patients, score of more than 6 on the Newcastle-Ottawa scale, studies published in or after 2001) were carried out or for re-operation (studies with >90 patients); otherwise, results were not significantly altered.
No evidence of publication bias was observed.