Combination of oximetry and sleep questionnaires as screening tools for CPAP initiation in patients with obstructive...

Obstructive sleep apnea syndrome (OSA) is a cause of high morbidity and mortality so diagnosis and treatment is essential. Questionnaires and oximetry have been used for OSA screening.

To evaluate the clinical utility of different sleep questionnaires (Stop Bang (S-B), Berlin (BQ), Epworth Sleepiness Scale (ESS)) in deciding on treatment with Continuous Positive Airway Pressure (CPAP) and to examine whether the combination of the questionnaires alone or with oximetry improves their predictive value for CPAP initiation.

Patients visiting a Sleep Clinic were prospectively studied. They completed the questionnaires. Home oximetry and in laboratory polysomnography (PSG) were performed within 3-20 days. Patients received CPAP if they were symptomatic with AHI≥5 or had AHI>15.

204 patients were studied (77.5%males, mean age 51.8±13.8 years, BMI 32.8±6.2kg/m²). There was a good correlation between Oxygen Desaturation Index of oximetry (ODIox) and ODI of PSG (r=0.95, p<0.0001) and between ODIox and AHI (r=0.811, p<0.0001). ODIox≥15 presented sensitivity 89.3%, specificity 83.5%, PPV 87% NPV 86.4% for CPAP initiation. ESS had the best specificity (68.6%) and PPV (68.6%) and S-B had the highest sensitivity (98%) and NPV (80%) but the lowest specificity (11%) for CPAP initiation. The combination of different questionnaires or questionnaires with oximetry did not improve their predictive value for CPAP initiation.

Oximetry accurately predicted CPAP initiation. Questionnaires alone had limited value as screening tools for CPAP initiation; the combination of oximetry with questionnaires did not improve their predictive value.