Design: Multicentre, single-blind randomised trial.

Allocation: Concealed (web-based randomisation)

Blinding: Study investigators (other than surgeons) were blinded. Families were not blinded.

Study question

Setting: Seven academic sleep centres in the USA.

Patients: Children 5–9 years with obstructive sleep apnoea syndrome (OSAS). Without recurrent tonsillitis, body mass index z-score >3 and medication for attention-deficit hyperactivity disorder.

Intervention: Tonsillectomy within 4 weeks or watchful waiting.

Outcomes: Change in attention and executive-function score caregiver and teacher rating of behaviour; symptoms of OSAS global quality of life; intellectual functioning and polysomnographic indices.

Follow-up period: 7 months.

Patient follow-up: 464 children randomised—226 assigned to early adenotonsillectomy and 227 to watchful waiting. Primary outcome analysis recorded in 194 assigned to early adenotonsillectomy and 203 to watchful waiting.

Main results

 Executive and attention scores improved in both groups, early …