Sites of obstruction in obstructive sleep apnea.

STUDY OBJECTIVE: The aim of this article was to identify the most common sites of obstruction in patients with obstructive sleep apnea (OSA) by a systematic review of published studies. DESIGN: The review was conducted by a MEDLINE search of the English literature published during the years 1980 to 2002. The inclusion criteria were experiments involving five or more adult subjects, total rather than partial obstruction or narrowing of the upper airway, and techniques that were performed on the subjects while they were asleep. CONCLUSION: Although there was considerable variability in the techniques and the results, the most common site of obstruction detected by these studies was at the level of the oropharynx, with extension to the laryngopharynx commonly observed.

Reliability and validity of two self-administered questionnaires for screening restless legs syndrome in population-based studies.

BACKGROUND: A reliable and valid questionnaire for screening restless legs syndrome (RLS) is essential for determining accurate estimates of disease frequency. In a 2002 NIH-sponsored workshop, experts suggested three mandatory questions for identifying RLS in epidemiologic studies. We evaluated the reliability and validity of this RLS-NIH questionnaire in a community-based sample and concurrently developed and evaluated the utility of an expanded screening questionnaire, the RLS-EXP. METHODS: The study was conducted at Kaiser Permanente of Northern California and the Stanford University Sleep Clinic. We evaluated test-retest reliability in a random sample of subjects with prior physician-assigned RLS (n=87), subjects with conditions frequently misclassified as RLS (n=31), and healthy subjects (n=9). Validity of both instruments was evaluated in a random sample of 32 subjects, and in-person examination by two RLS specialists was used as the gold standard. RESULTS: For the first three RLS-NIH questions, the kappa statistic for test-retest reliability ranged from 0.5 to 1.0, and sensitivity and specificity was 86% and 45%, respectively. For the subset of five questions on RLS-EXP that encompassed cardinal features for diagnosing RLS, kappas were 0.4-0.8, and sensitivity and specificity were 81% and 73%, respectively. CONCLUSIONS: Sensitivity of RLS-NIH is good; however, the specificity of the instrument is poor when examined in a sample that over-represents subjects with conditions that are commonly misclassified as RLS. Specificity can be improved by including separate questions on cardinal features, as used in the RLS-EXP, and by including a few questions that identify RLS mimics, thereby reducing false positives.