Eligible studies were of tonsillectomy and adenoidectomy in obese or non-obese patients less than 20 years old who had obstructive sleep apnoea/hypopnoea syndrome (confirmed by an abnormal preoperative polysomnographic data) and that reported both preoperative and postoperative polysomnogram.
Studies that included mostly patients with craniofacial syndromes, chromosome disorders or neuromuscular disorders were excluded.
Studies were either prospective trials or retrospective observational studies. All studies appeared to be uncontrolled as no details of control groups were provided. Mean patient age ranged from three to 9.3 years. The proportion of male patients reported in the studies ranged from 49% to 86%. Definition of success rate varied between studies: approximately half of studies used an apnoea-hypopnoea index <1 and half used an apnoea-hypopnoea index <5; one study used an apnoea-hypopnoea index <2. Mean preoperative apnoea-hypopnoea index ranged from 6.9 to 69.3. Outcome assessments points were stated by the review authors to have been inconsistent among the studies, but were reported in the studies. Nine studies were defined as having children with comorbidities; at least three quarters of children were obese or had severe obstructive sleep apnoea/ hypopnoea syndrome.
The main outcomes of interest were treatment success as defined per study and mean change in apnoea-hypopnoea index from preoperative to postoperative polysomnogram. Additional outcomes of interest were: treatment success defined as apnoea-hypopnoea index <1; treatment success defined as apnoea-hypopnoea index <5; mean change in apnoea-hypopnoea index from preoperative to postoperative polysomnogram for children without comorbidities; and mean change in apnoea-hypopnoea index from preoperative to postoperative polysomnogram for children with comorbidities.
Two reviewers independently performed study selection.