NoSAS Score: Clinical Guide

Overview

Screens adults for risk of clinically significant sleep-disordered breathing using neck circumference, obesity, snoring, age and sex.

Clinical Significance

A total of 8 or more is conventionally a positive screen for clinically significant sleep-disordered breathing. The score estimates risk and does not establish diagnosis or severity.

When to Use

• Use when the patient and clinical question match the population and purpose described.
• Use accurate current inputs and preserve the original score definitions.

How It Is Calculated

• NoSAS assigns 4 points for neck circumference >40 cm; 3 points for BMI 25 to <30 kg/m² or 5 points for BMI ≥30 kg/m²; 2 points for snoring; 4 points for age >55 years; and 2 points for male sex. Total range 0–17.

Interpretation

• A total of 8 or more is conventionally a positive screen for clinically significant sleep-disordered breathing. The score estimates risk and does not establish diagnosis or severity.

Worked Example

Enter a complete, clinically consistent set of values. MedicalC then applies the published method: NoSAS assigns 4 points for neck circumference >40 cm; 3 points for BMI 25 to 55 years; and 2 points for male sex. Total range 0–17.

Patient Considerations

• Derived and validated in adult population cohorts. Performance may differ in pregnancy, children, craniofacial syndromes, neuromuscular disease and highly selected sleep-clinic populations.

Limitations

• Do not use as a substitute for sleep study assessment. Screening sensitivity and specificity vary with population, sex distribution, ethnicity, referral setting and the apnoea-hypopnoea threshold used.
• Performance and calibration may differ outside the derivation and validation settings.
• The result supports but does not replace clinical assessment, investigation or local guidance.

Clinical Pearls

• NoSAS deliberately uses only five readily available variables, which can improve completion compared with longer questionnaires.
• Document component values as well as the final result.

Common Mistakes

• Using an incorrect threshold, unit or category definition.
• Applying the tool to a population for which it has not been validated.
• Treating the calculated category as a diagnosis or automatic treatment instruction.

Evidence Base

Marti-Soler H et al. The NoSAS score for screening of sleep-disordered breathing: a derivation and validation study. Lancet Respir Med. 2016;4:742–748.

References

1. Marti-Soler H et al. The NoSAS score for screening of sleep-disordered breathing: a derivation and validation study. Lancet Respir Med. 2016;4:742–748. — Primary or authoritative source supporting the implemented method.