BACKGROUND: Obstructive sleep apnea is a relatively common disease, with an estimated prevalence in the general population of between 0.3 percent and 4 percent. However, among high-risk groups the prevalence is 45 percent. The gold standard for diagnosing obstructive sleep apnea, nocturnal polysomnography is time consuming, expensive, and labor intensive.
OBJECTIVES: To develop a prediction rule for obstructive sleep apnea from clinical parameters of Filipino patients that can be used to identify either high-risk patients requiring full nocturnal polysomnography or low-risk patients in whom polysomnography could be avoided
STUDY DESIGN: Cross-sectional study of all patients with clinical suspicion of obstructive sleep apnea
SETTING: Sleep Disorders laboratory of the Neurophysiology Unit of St. Luke's Medical Center
STATISTICAL TEST: Multiple regression analysis which include 13 clinical variables (age, body mass index, neck size, sex, chief complaint affecting daily activities, too much sleep, too little sleep, daytime fatigue, daytime sleepiness, snoring, snoring affecting others, smoking and hypertension) were used to develop the clinical scoring system. A p value 0.05 was considered statistically significant.
PATIENTS: 344 Filipino patients who satisfied the clinical criteria for obstructive sleep apnea were included in the study. All patients underwent nocturnal polysomnography.
RESULTS: The within- laboratory prevalence of obstructive sleep apnea in our patients was 62 percent. Body mass index, snoring affecting others and daytime sleepiness were found to be significant predictors of obstructive sleep apnea (p0.05). A sleep apnea clinical score 8 was determined as the cut-off value to predict the presence of obstructive sleep apnea (sensitivity=71 percent, specificity=77 percent, likelihood ratio=3.09, posttest probability of 85 percent and overall accuracy of 73 percent).
CONCLUSION: In the diagnostic work-up of patients suspected of having obstructive sleep apnea, the clinical scoring system can help select and prioritize patients for nocturnal polysomnography.