Neck Circumference Thresholds for OSA Risk
A neck circumference of ≥17 inches (43 cm) in men and ≥15.5 inches (39 cm) in women indicates high risk for obstructive sleep apnea, though these thresholds must be interpreted alongside other clinical risk factors rather than as standalone diagnostic criteria. 1
Sex-Specific Thresholds
The American Academy of Sleep Medicine establishes clear sex-based cutoffs for OSA risk assessment 1:
- Men: ≥17 inches (43 cm)
- Women: ≥15.5 inches (39 cm)
The American Society of Anesthesiologists uses a slightly lower threshold of ≥16 inches (41 cm) for women in perioperative settings 1. Recent research from multiple populations supports these ranges, with a 2021 Romanian study identifying 41 cm as an optimal cutoff for men (sensitivity 81%, specificity 52%) 2, and a 2008 study finding mean neck circumferences of 43 cm in men and 38 cm in women with sleep-disordered breathing 3.
Clinical Context: Not a Standalone Criterion
Neck circumference functions as a secondary criterion that becomes clinically significant only when combined with other risk factors 1. The American Academy of Sleep Medicine emphasizes that neck circumference alone does not diagnose OSA—it must be interpreted alongside 1:
- BMI ≥28-33 kg/m²
- Loud habitual snoring
- Witnessed apneas
- Daytime sleepiness
- Hypertension or other comorbidities
Population-Specific Considerations
A 2023 Colombian study revealed important ethnic variations, suggesting that Latin American populations may have different optimal cutoffs (36.5 cm for women, 41 cm for men) compared to North American and Asian populations 4. This highlights that the standard American thresholds may require adjustment for different ethnic groups 4.
For short-sleeping obese individuals, a 2014 study found that neck circumference ≥38 cm had 54% sensitivity and 70% specificity for predicting metabolic syndrome, with 58% sensitivity and 79% specificity for OSAS 5.
Integration with Physical Examination
The American Society of Anesthesiologists recommends evaluating neck circumference alongside 1:
- Modified Mallampati score (class 3-4 increases risk)
- Craniofacial abnormalities (retrognathia, micrognathia)
- Tonsillar hypertrophy
- Lateral peritonsillar narrowing
Research demonstrates that waist circumference actually correlates more strongly with sleep-disordered breathing severity than neck circumference (r=0.366-0.445 vs r=0.358-0.38), though both are superior to BMI alone 3.
Practical Clinical Algorithm
The American Academy of Sleep Medicine recommends this stepwise approach 1:
- Measure neck circumference at the level of the cricothyroid membrane
- Assess BMI category (particularly if ≥28 kg/m²)
- Evaluate for additional risk factors (snoring, witnessed apneas, sleepiness, hypertension)
- Refer patients with ≥2 risk factors for comprehensive sleep evaluation with polysomnography
Critical Pitfalls to Avoid
Never use neck circumference as a standalone diagnostic tool 1. The American Academy of Sleep Medicine explicitly warns against this practice, as it lacks sufficient sensitivity and specificity when used in isolation 1.
Do not assume normal neck circumference excludes OSA 1. The American Society of Anesthesiologists emphasizes that patients with craniofacial abnormalities or severe symptoms may have significant OSA despite normal neck measurements 1. In the 2008 study, only half of patients with AHI ≥5 were clinically obese, demonstrating that anthropometric measures miss a substantial proportion of OSA cases 3.
Recognize that neck circumference predicts CPAP response 2. A 2021 network medicine analysis found that neck circumference was the most significant qualitative indicator for apnea-hypopnea index improvement with CPAP therapy, with the 41 cm threshold classifying CPAP responses with 91% sensitivity and 86% specificity 2.