Intranasal Treatments for Children With Sleep-Disordered Breathing: The MIST+ Randomized Clinical Trial

Importance: Symptoms of obstructive sleep apnea are common in childhood and associated with significant comorbidity. Surgical treatment with adenotonsillectomy is first-line treatment but medical treatments show potential to improve symptoms and reduce the need for surgery.

Objective: To determine the efficacy of 6 weeks of intranasal steroid (INS) compared with saline in children with obstructive sleep-disordered breathing (OSDB) with persistent symptoms after a 6-week intranasal saline run-in.

Design, setting, and participants: This was a double-blind, placebo-controlled, randomized clinical trial involving specialist clinic waitlists at 2 sites in Australia. Included were children aged 3 to 12 years. Study data were analyzed from January to June 2025.

Interventions: All children received once-daily intranasal saline for 6 weeks (run-in). Those with persisting symptoms (SDB score ≥-1) were randomized to either once-daily intranasal mometasone furoate, 50 µg, (INS) or continued saline for a further 6 weeks.

Main outcomes and measures: The primary outcome was symptom resolution (SDB score <-1). Secondary outcomes included behavior, quality of life, and parental perception of need for surgery. Analyses were adjusted for site and baseline measures.

Results: A total of 150 children (mean [SD] age, 6.2 [2.3] years; 93 male [62%]) were recruited. Of 139 children who completed the run-in phase, 41 (29.5%) had symptom resolution after saline run-in. Among 93 children randomized to intervention groups (47 INS; 46 saline), symptom resolution occurred in 35.6% (95% CI, 22.9%-50.6%) and 36.4% (95% CI, 23.5%-51.6%) of the INS and saline group, respectively, with no evidence for a clinically significant difference between groups (risk difference, -0.9%; 95% CI, -20.7% to 19.0%; P = .93). No group differences were found in secondary outcomes. Subgroup analysis did not reveal a group more or less likely to respond to medical treatment.

Conclusions and relevance: Results of this randomized clinical trial show that 6 weeks of intranasal saline resolved OSDB symptoms in nearly one-third of children. An additional 6-week course of INS or saline led to resolution in another one-third (total resolution around 50%), with no added benefit from INS. Intranasal saline is an effective short-term first-line treatment for OSDB before consideration of polysomnography or surgical intervention. Results suggest that saline should be recommended for 3 months before assessing the need for specialist referral.

Trial registration: ClinicalTrials.gov Identifier: NCT05382494.