Association between sodium bicarbonate and STOP-BANG questionnaire in OSA screening

Obstructive Sleep Apnea Syndrome (OSAS) is the most common sleep disorder and is prevalence increases in the overweight population. The STOP-BANG questionnaire is a validated diagnostic tool, in which a score ≥3 has a high sensitivity in OSAS detection but a relatively low specificity. The objective of this study is verify if the association between sodium bicarbonate and the STOP-BANG questionnaire increases the specificity, with minimal effect in sensitivity. Subjects included were overweight patients referred for a polygraphic sleep study, which had also an arterial blood gas analysis in the same time period. Anthropometric data, as well as the results of the STOP-BANG were collected. Of the 141 patients studied, the mean age was 51 years, 35.5% were male, with an average BMI of 39.7 kg/m 2 . According to the polysomnographic study, 60% of patients had OSAS and the mean AHI was 17.3/h. The analysis of STOP-BANG showed a 85% sensitivity and 43% specificity for an AHI>5/h, with an increased sensitivity to 90% for moderate/severe OSAS and 97% for severe OSAS. When adding the HCO3 − values to the analysis, the specificity was increased (98%), but with markedly decreased sensitivity (15%). With the two steps method analysis the results showed a sensitivity of 44% and a specificity of 91%. In assessing the ROC curves, it shows that the STOP-BANG has an area of 0.738. In association with HCO3 − values has an area of 0.772 and using the two steps method the area is 0.811. In conclusion, STOP-BANG questionnaire has an important value in the screening of OSAS. However, for a more effective ranking, the addiction of HCO3 − values in overweight patients who have intermediate degrees of the questionnaire is essential