The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

SYSTEMATIC REVIEW OF THE LITERATURE REGARDING THE DIAGNOSIS OF SLEEP APNEA

I. Elaine Allen, PhD, Susan D. Ross, MD, FRCPC, Katherine J. Harrison, BA, Marion Kvasz, MD, MPH, Janet Connelly, BS, Iris Sheinhait, MA, Meta Works, Inc, Boston, MA

Objective: To establish the evidence base for the diagnosis of sleep apnea (SA). Diagnostic tests covered were all sleep monitoring devices, radiologic imaging, laboratory assays, and clinical signs and symptoms posited for use in screening or diagnosis of SA. The standard sleep lab polysomnogram (PSG) was the gold standard. The evidence base was derived using systematic review methods.

Methods: A literature search conducted back to 1980 using Medline and Current Contents, was supplemented by a manual review of the bibliographies of all accepted papers. The search cut-off date was November 1, 1997. Included diagnostic studies had to report the results of any test to establish or support a diagnosis of SA, in relation to a PSG-derived apnea index (AI), apnea-hypopnea index (AHI) or respiratory distress index (RDI). Studies included a minimum of 10 adult patients suspected of, or diagnosed with SA as determined by a standard PSG. Eligible languages were English, German, French, Spanish, or Italian. Papers reporting prevalence or clinical comorbidities of SA were also accepted. 147 studies met or exceeded minimum evidence scores. From these, data on study, patient, and test characteristics, and on outcomes were collected. Non-diagnostic studies reporting prevalence or clinical comorbidities were separately extracted. Study and patient-level covariates were summarized. Outcomes were analyzed using fixed effects models and using summary receiver operating characteristic curves (ROC) where data were available.

Results: In 71 analyzable studies (7,572 patients) the sensitivity and specificity of partial channel, and partial time PSGs appeared most promising as pre-screening tests, or replacements for, full PSG. Prediction models also achieved high sensitivity and specificity. Portable devices were very variable due to study and device heterogeneity. Radiology studies and studies of questionnaires, anthropomorphic signs, and ENT exams were too hetergeneous to be analyzed. Global clinical impressions and oximetry provided similar sensitivity and specificity but may be insufficient as substitutes for pre-selection for full PSG. Least accurate were flow volume loops. The review and analysis were limited by variability in PSG definitions of apnea and thresholds for diagnosis. SA prevalence studies were reviewed covering different patient populations (e.g. elderly, hypertensives). Few studies utilized PSG to diagnose SA and diagnosis was based upon unvalidated tests.

Conclusions: Progress has been made in establishing reasonable sensitivity and specificity of other tests. Standardization of terms and criteria would expedite development and enhance the utility of this literature in the future. When compared to the gold standard, no diagnostic achieved consistently high sensitivity and specificity.

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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