Tonsillectomy Indication Based on AHI Score
Tonsillectomy is recommended for children with OSA when AHI is >1 event per hour in the presence of adenotonsillar hypertrophy, though the decision should not be based on AHI alone but must incorporate clinical symptoms, physical examination findings, and likelihood of benefit. 1
AHI Thresholds and OSA Severity Classification
The American Academy of Otolaryngology-Head and Neck Surgery defines abnormal polysomnography in children as:
- AHI >1 event/hour is considered abnormal 1
- Mild OSA: AHI 1-4.9 events/hour 1
- Moderate OSA: AHI 5-9.9 events/hour 1
- Severe OSA: AHI ≥10 events/hour 1
When Polysomnography Is Required vs. Optional
PSG is mandatory before tonsillectomy in these high-risk groups:
- Children <2 years of age 2, 3
- Obesity 4, 2, 3
- Down syndrome 2, 3
- Craniofacial abnormalities 2, 3
- Neuromuscular disorders 2, 3
- Sickle cell disease 2, 3
- Mucopolysaccharidoses 2, 3
PSG is not required in otherwise healthy children with strong clinical history of obstructive breathing, daytime symptoms, and grade 3-4 tonsillar hypertrophy on examination 1, 2, 3. In these straightforward cases, proceeding directly to surgery avoids unnecessary delay and cost 2.
Clinical Decision-Making Beyond AHI
The decision to recommend tonsillectomy must integrate multiple factors, not AHI alone: 1
- Clinical history: Witnessed apneas, snoring, mouth breathing, restless sleep 1
- Physical examination: Degree of tonsillar hypertrophy (Brodsky grade 3-4) 2
- Daytime symptoms: Behavioral problems, poor school performance, excessive sleepiness 1
- Quality of life impact: Measured by validated instruments like OSA-18 3
- Oxygen saturation: Levels <92% on PSG are concerning 1
Expected Outcomes by Patient Characteristics
Success rates vary significantly based on patient factors: 1
- Normal-weight, otherwise healthy children: 60-80% complete resolution of OSA 1, 2
- Obese children: Only 10-50% complete resolution 1, 2
- Children with severe baseline OSA (AHI ≥10): Lower cure rates, only 25% complete resolution in some studies 4, 3
- Overall success rate (AHI <2): Approximately 79% in the landmark CHAT trial 1
The mean AHI reduction in multicenter studies was from 18.2 to 6.4 events/hour, demonstrating significant improvement even when complete cure is not achieved 1.
Critical Pitfalls to Avoid
Do not rely solely on AHI cutoffs - the 2019 AAO-HNS guideline explicitly states there is "intentional vagueness" regarding diagnostic criteria because values may not correlate with surgical outcomes 1. A child with AHI of 2 and severe daytime impairment may benefit more than a child with AHI of 8 but minimal symptoms 1.
Do not assume surgery cures all cases - families must be counseled that OSA may persist or recur, particularly in obese children, those with severe baseline disease, or children <7 years old 1. Postoperative PSG should be considered in high-risk groups 3.
Do not delay surgery for PSG in straightforward cases - in healthy children with clear clinical OSA and large tonsils, requiring PSG adds unnecessary cost, delay, and risk of additional infections while awaiting the study 2, 3.