New diagnostic model detects obstructive sleep apnoea in primary care

A combination of clinical judgment and portable monitor test outcomes can help diagnose obstructive sleep apnoea (OSA) in the primary care setting, a recent study has shown.

To develop a new diagnostic model for OSA, primary care practitioners were trained to recognize symptoms of sleep apnoea. Patients were also recruited based on the clinical need to investigate OSA. Symptom questionnaires, anthropomorphic measurements, digital facial photography, and a single-channel nasal flow monitor worn at home for three nights were used to assess patients.

The reference test used was the in-laboratory PSG. OSA was defined as apnoea-hypopnoea index (AHI) ≥10 events/h.

In the model development phase, 25 primary care practitioners examined a total of 315 patients with suspected OSA, of whom 57 percent had AHI ≥10 events/h and 22 percent had ≥30 events/h.

Published OSA questionnaires generated low to moderate prediction of OSA (area under the curve [AUC], 0.53–0.73). The nasal flow monitor alone produced high accuracy for the prediction of OSA (AUC, 0.87). Sensitivity and specificity were 0.87 and 0.77, respectively, at a threshold respiratory event index (REI) at 18 events/h.

In a model that added age, gender, symptoms, and body mass index to the nasal flow monitor, REI only modestly improved OSA prediction (AUC, 0.89), with similar AUC (0.88) confirmed in the validation population of 114 patients.

“Use of in-laboratory PSG to OSA is cost- and resource-intensive,” the authors said. “Questionnaires, physical measurements, and home monitors have been studied as potential simpler alternatives.”