**Warning:**	The NCBI web site requires JavaScript to function. 	more...

An official website of the United States government

**The .gov means it's official.**							Federal government websites often end in .gov or .mil. Before							sharing sensitive information, make sure you're on a federal							government site.						

**The site is secure.**							The **https://** ensures that you are connecting to the							official website and that any information you provide is encrypted							and transmitted securely.						

Log in

#### Account

                          - Dashboard
                          - Publications
                          - Account settings
                          - Log out

Access keysNCBI HomepageMyNCBI HomepageMain ContentMain Navigation

# Bookshelf

## 

                -  Browse Titles 
                -  Advanced 
                -  Help 
                -  Disclaimer 

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

AHRQ Evidence Report Summaries. Rockville (MD): Agency for Healthcare Research and Quality (US); 1998-2005. 

                        - This publication is provided for historical reference only and the information may be out of date.

**This publication is provided for historical reference only and the information may be out of date.**

## AHRQ Evidence Report Summaries.

Show details

Agency for Healthcare Research and Quality (US)

                            - Contents

< PrevNext >

#  1Systematic Review of the Literature Regarding the Diagnosis of Sleep Apnea: Summary

SD Ross, IE Allen, KJ Harrison, M Kvasz, J Connelly, and IA Sheinhait.

Current as of December 1998.

## Overview

In this study, MetaWorks investigators have developed an evidence base via a systematic review of the literature pertinent to diagnostic testing and screening in sleep apnea in adult patients.Sleep apnea (SA) is a recently recognized disorder of sleep characterized by recurrent apneic and hypopneic episodes.

Apnea was typically defined as complete cessation of airflow, but in some studies, a >80 percent reduction in airflow was used.For defining hypopnea, most papers suggested a 50 percent or greater reduction in airflow was used, with or without a coincident O2desaturation of anywhere from 2 percent to 4 percent from some average SaO2 over a precedinginterval of time.

In view of its high prevalence and serious associated morbidity, SA has recentlybeen described as a major public health concern. A major problem in the field in 1998 isdiagnosis: who to test, how to test, and what are the implications of test results regarding the risk of serious clinical sequelae?

 Sleep apnea is a condition where the gold standard diagnostic method, overnight full-channelpolysomnography (PSG) in a sleep lab is intrusive and costly, and the interpretation can bedifficult. A standard PSG typically consists of electroencephalogram (EEG), submental (±tibialis)electromyogram (EMG), electrooculogram (EOG), respiratory airflow (usually by oronasal flowmonitors), respiratory effort (usually by plethysmography), and oxygen saturation (oximetry).Electrocardiography (ECG) and body position are also frequently monitored in formal sleepstudies and stated to be standard requirements of PSG by some groups.

 If, however, the estimated prevalence of sleep apnea at 2 percent to 4 percent of middle-agedadults is correct, the costs of full PSGs to diagnose all suspected cases would be prohibitive. The development of simpler and less costly alternatives for diagnostic testing would be highlydesirable as would simpler prescreening tests prior to full PSG.

Diagnostic approaches whichmight be viewed either as alternatives to PSGs or as screening tests to better select patients forPSG include:- Partial channel PSGs.
- Partial night or daytime PSGs.
- Portable sleep monitoring devices for use at home.
- Radiologic imaging of the head and neck for anatomic abnormalities predictive of sleep apnea, including cephalometry.
- Magnetic resonance imaging (MRI) and computed tomography (CT) scans.
- Anthropomorphic measurements, such as neck circumference. 
- Nasopharyngeal and laryngeal endoscopic measurements of both structure and function.
- Focused questionnaires. 
All such interventions were within the scope of this review, providedthey compared results against the gold standard diagnostic test, the standard PSG.

 Although the type of sleep evaluation study preferred (and reimbursed) varies widely amongphysicians, sleep centers, and managed care organizations, MetaWorks investigators haveavoided making specific recommendations in this review. MetaWorks investigators also did notreview technical considerations related to data acquisition, storage, retrieval, and analysis ofvarious devices, which were beyond the scope of this project. Rather, it is intended that thissynthesis of the best available evidence will serve as an information resource for localdecisionmakers and developers of guidelines/recommendations. It should also serve to highlightgaps in literature and areas ripe for future research.

## Reporting the Evidence

 The key questions that guided this review were:-  What diagnostic and screening tests are presently available?
-  What is the strength of the evidence in support of each?
-  What is the predictive value of these tests in different populations (which requiresestimating the prevalence of SA in different populations)?
-  What are the implications of certain PSG results in terms of serious clinical eventsoccurring as comorbidities in association with a diagnosis of SA?

## Methodology

 In general, MetaWorks investigators used systematic review methods derived from the evolvingscience of review research. The review followed a prospective protocol that was developed a priori and shared with the nominating partners on the project (Blue Cross/Blue Shield [BC/BS]of Massachusetts and the Sleep Disorders Centre of Metropolitan Toronto), a panel of technicalexperts (with representation from consumer groups and professional specialties: neurology,pulmonology, dentistry, otolaryngology, epidemiology, and nursing); and the Task Order Officersat AHCPR. The protocol outlined the methodsto be used for the literature search, study eligibility criteria, data elements for extraction, andmethodological strategies to minimize bias and maximize precision during the process of datacollection, extraction, and synthesis.

 The published literature was searched from 1980 to present. The search cutoff date wasNovember 1, 1997, and the retrieval cutoff date was January 30, 1998. The search started with abroad Medline search using the terms "sleep apnea syndrome" and "monitoring, physiologic,""sleep apnea syndrome" and "airway resistance," and "human." Also, MetaWorks investigatorssearched "sleep apnea syndromes," "sleep apnea syndrome," and "index." In addition, the 1997Current Contents CD-ROM was searched ("sleep apnea") to the same cutoff date. All citationsand abstracts were printed and screened at MetaWorks for any mention of diagnostic tests inadults with SA, for which full papers were obtained. The electronic searches noted above weresupplemented by a thorough search of the reference lists of all eligible studies and relevantreview articles.

To be included in the review, studies had to report results of any diagnostic testor intervention to establish or support a diagnosis of SA in adults, with at least 10 patients astotal sample size. Studies reported in the following Western European languages-English,German, French, Spanish, or Italian-were accepted.

 All eligible papers were scored on features pertinent to diagnostic test study design, execution,and reporting, with a range of possible scores from 0 to 44. Those falling in the lowest 20 percentof the distribution of actual scores were dropped from data extraction and analysis. Eachaccepted diagnostic study was extracted in duplicate by investigators with one extractor using ablinded copy of each study report, masked as to source of financial support, authors, and journal.The agreement between extractors was approximately 78 percent and differences were resolvedby consensus.

 Key data elements sought for extraction from each study included study level, patient level, andtest characteristics. Only clearly reported aggregate results were extracted from studies. Resultsthat were only given for individual patients, and results that would require extrapolations fromgraphs or derivations from figures or tables were not captured. For all tests, sensitivity,specificity, positive predictive value, negative predictive value, and correlation coefficients ofeach test relative to PSG AI or AHI (RDI) results were sought.

Apnea index (AI) is defined asthe number of apneic episodes/hour sleep, and apnea-hypopnea index (AHI) is the total apneasplus hypopneas during total time asleep, divided by the number of hours asleep. The respiratorydistress index (RDI) is the same as AHI.

 The main objective of the analysis was to evaluate the diagnostic accuracy of alternatives to fullPSG for the diagnosis of SA as compared to a full PSG (gold standard). Initially, weightedaverages using Mantel-Haenszel fixed effects models combining the comparative summarystatistics were calculated and summarized for groups based on diagnostic test category. Studyand patient-level covariates and study evidence scores were also summarized for each diagnostictest category. A summary receiver operating characteristic (ROC) curve was calculated for eachdiagnostic group where data were available. While differences among studies may be anargument against estimating one common sensitivity and specificity using fixed or randomeffects models, these factors can be described using the summary ROCs, which both display andsummarize the heterogeneity.

 A group of 22 peer reviewers drawn from consumer groups and professional organizations, alongwith our technical experts and partners, was assembled to review and provide suggestions to thedraft final report describing this project. Their feedback, as well as that from AHCPR, wasincorporated wherever possible within the original scope of the project.

##  Findings

###  All Studies: PSG

                          -  71 studies (7,572 patients), mean evidence score = 20.6 (range, 16 to 34). Level III to IVevidence overall (that is, primarily derived from case series and observational studies).
                          -  Variability in PSG definitions of apnea and hypopnea, and AI or AHI thresholds fordiagnosis, with or without presence of clinical signs and/or symptoms. 
                          -  Variability in components of "standard" PSG is evident, and requirement for all"standard" PSG channels not established in SA diagnosis. Night to night PSG reproducibility isnot well documented and may differ by SA diagnostic thresholds.

###  Partial Channel PSGs

                          -  3 studies of partial channel PSGs (213 patients), mean evidence score = 17.7 (range, 17 to19). 
                          -  Sensitivity ranged from 82 percent to 94 percent and specificity from 82 percent to 100percent. 
                          -  Sensitivity and specificity of partial channel PSGs appear promising as possibleprescreening tests or replacements for full PSG.

###  Portable Devices

                          -  25 studies of portable monitoring devices (1,631 patients), mean evidence score = 22.1(range, 16 to 34).
                          -  Portable device results were mostly from supervised sleep labs, not at home.
                          -  Reliability in unattended home use, equipment failure rates, night to night reproducibility,price, compliance, and safety are rarely reported. 
                          -  Sensitivity ranged from 32 percent to 100 percent and specificity from 33 percent to 100percent.
                          -  Studies of portable devices were variable due to study and device heterogeneity.

###  Oximetry

                          -  12 studies of oximetry alone (1,784 patients); mean evidence score = 20 (range, 16 to 32).
                          -  Mean sensitivity and mean specificity are 87.4 percent (range, 36 percent to 100 percent)and 64.9 percent (range, 23 percent to 99 percent), respectively.
                          -  Oximetry studies provided moderate sensitivity and specificity.

###  Partial Time PSGs

                          -  7 studies of partial time PSGs (505 patients), mean evidence score = 18.6 (range, 17 to20).
                          -  Mean sensitivity at AI/AHI threshold of 5 was 69.7 percent (range, 66 percent to 93percent), and at threshold of 10, 79.5 percent (range, 42 percent to 89 percent). Specificity atAI/AHI threshold of 5 was 87.4 percent (range, 50 percent to 100 percent) and at threshold of 10,86.7 percent (range, 57 percent to 100 percent).
                          -  Sensitivity and specificity of partial time PSGs appear promising as possible prescreeningtests or replacements for full PSG.

###  Radiologic

                          -  5 radiologic studies-1 MRI, 3 cephalometry, and 1 CT + cephalometry-notmeta-analyzable. 
                          -  Radiology studies could not be analyzed due to insufficient data.

###  Miscellaneous

                          -  17 clinical studies (too few studies each for anthropomorphic signs or ears/nose/throat[ENT] exams). Also, 1 chemical assay and 3 questionnaire studies not meta-analyzable.
                          -  4 studies of flow volume loops (595 patients), mean evidence score = 18.3 (range, 17 to20). When both FEF50/FIF50 (a measure of extrathoracic airway obstruction) and the sawtoothsign (indicative of pharyngeal fluttering during respirations) were analyzed together, the meansensitivity was 39.1 percent (range, 41 percent to 59 percent) and mean specificity was 60.5percent (range, 54 percent to 85 percent).
                          -  4 studies of global impressions of clinicians (1,139 patients), mean evidence score = 23(range, 19 to 28). Mean sensitivity = 58.9 percent (range, 52 percent to 79 percent), specificity =65.6 percent (range, 50 percent to 100 percent).
                          -  Several miscellaneous studies of questionnaires, anthropomorphic signs, and ENT examscould not be analyzed due to insufficient data.
                          -  Global clinical impressions provided moderate sensitivity and specificity; least accuratewere flow volume loops.

###  Prediction Equations

                          -  8 models (1,908 patients), mean evidence score = 21.5 (range, 17 to 30). Mean sensitivity= 66.5 percent (range, 61 percent to 98 percent) and mean specificity = 88.7 percent (range, 21percent to 100 percent).
                          -  Prediction models achieved high sensitivity and specificity.

###  Prevalence Studies

                          -  General populations: 11 prevalence studies (2,410 patients), mean prevalence of SA = 9.2percent (range, 0 to 33 percent).
                          -  Healthy elderly: 7 prevalence studies (469 patients), mean prevalence of SA = 34.6percent (range, 2 percent to 43 percent).
                          -  Coronary artery disease: 8 studies (461 patients), mean prevalence of SA = 54.9 percent(range, 50 percent to 100 percent).
                          -  Hypertension: 4 studies (166 patients), mean prevalence SA = 26.9 percent (range, 22percent to 30 percent).
                          -  Erectile dysfunction/impotence: 3 studies (1,138 men), mean prevalence of SA = 42.2percent (range, 11 percent to 44 percent).
                          -  Other special populations (stroke, end stage renal disease, congestive heart failure,Alzheimer's disease, depression, and healthy offspring of SA patients): too few studies tosummarize.
                          -  Caveat: Prevalence studies may be underrepresented in this set due to search strategy ofidentifying primarily diagnostic studies.
                          -  Caveat: Few prevalence studies here utilized gold standard PSG to diagnose SA, sodiagnosis based upon unvalidated tests. Such prevalence estimates are suspect.

###  Comorbidity Studies

 Conditions associated with SA:-  Hypertension: 24 studies (3,497 SA patients), mean proportion with hypertension = 42.0percent (range, 9 percent to 77 percent).
-  Coronary artery disease: 9 studies (1,086 SA patients), mean proportion with coronaryartery disease (manifest as angina or myocardial infarction [MI]) = 20.3 percent (range, 2 percentto 33 percent).
-  Ventricular arrhythmias: 5 studies (205 SA patients), mean proportion with ventriculararrhythmias (usually complex arrhythmias, during nocturnal monitoring) = 13.1 percent (range, 3percent to 47 percent).
-  Mortality: 5 studies (2,281 SA patients) with prolonged follow-up (5 to 13 years) reporteddeaths (all causes) in 6 percent to 11 percent of patients, mean = 7.0 percent.
-  Caveat: Studies with actual clinical consequences of certain AIs, with or without signsand symptoms, and with or without treatment, are not well represented in this set. Inclusion oftreatment studies might be useful. Clinical implications of SA diagnosis are unclear.

##  Future Research

 Future studies of diagnostic test strategies should address the many limitations of the literaturenoted above. The field could benefit from adoption of a common terminology and definitions forfundamental concepts such as apnea and hypopnea, and the relation between AI and AHI shouldbe established, in order to allow conversions and comparisons across studies. Researchers shouldseek to clarify what is the frequency of sleep apnea/hypopnea in general populations by genderand age. More naturalistic sleep studies (in the home) are still of interest, as MetaWorksinvestigators suspect much of the uncertainty about the nature of SA, its pathophysiology, therisk factors, and the clinical consequences, derive from the fact that the phenomenon of SA maybe altered by the fact of observing it via standard PSG. Long-term followup studies arerecommended to better document the findings of treated vs. untreated SA. Lastly, all sleepmonitoring systems which are proposed as prequalifiers or replacements for PSG must bevalidated in the setting in which they are intended to be used.

##  Availability of the Full Report

 The full evidence report from which this summary was taken was prepared for AHCPR by MetaWorks, Inc., Boston, MA, under contract No.290-97-0016. It is expected to be available by early 1999. At that time, print copies may beobtained free from the AHCPR Publications Clearinghouse by calling1-800-358-9295. Requesters should ask for Evidence Report/Technology Assessment No. 1,Systematic Review ofthe Literature Regarding the Diagnosis of Sleep Apnea (AHCPR Publication No. 99-E002).The Evidence Report will be available online at: http://www.ahcpr.gov/clinic/index.html#evidence.

AHCPR Pub No. 99-E001Current as of December 1998

**Internet Citation:**Systematic Review of the Literature Regarding the Diagnosis of Sleep Apnea. Summary, Evidence Report/Technology Assessment: Number 1, December 1998.Agency for Health Care Policy and Research, Rockville, MD.http://text.nlm.nih.gov/ftrs/directBrowse.pl?collect=epc&dbName=apnsum

                        - 
AHCPR Pub No. 99-E001

Copyright Notice

Bookshelf ID: NBK11925

Contents
< PrevNext >

Share

### Views

                    - PubReader
                    - Print View
                    - Cite this Page Ross SD, Allen IE, Harrison KJ, et al. Systematic Review of the Literature Regarding the Diagnosis of Sleep Apnea: Summary. 1998 Dec. In: AHRQ Evidence Report Summaries. Rockville (MD): Agency for Healthcare Research and Quality (US); 1998-2005.  1.

### In this Page

                    - Overview
                    - Reporting the Evidence
                    - Methodology
                    -  Findings
                    -  Future Research
                    -  Availability of the Full Report

### Other titles in this collection

                    - Health Services/Technology Assessment Text(HSTAT)

### Related publications

                    - Full Report

### Recent Activity

ClearTurn OffTurn On
                      - Systematic Review of the Literature Regarding the Diagnosis of Sleep Apnea: Summ... Systematic Review of the Literature Regarding the Diagnosis of Sleep Apnea: Summary - AHRQ Evidence Report Summaries 
                      - Ephedra and Ephedrine for Weight Loss and Athletic Performance Enhancement Ephedra and Ephedrine for Weight Loss and Athletic Performance Enhancement 
                      - Vaginal Birth After Cesarean (VBAC) Vaginal Birth After Cesarean (VBAC) 
                      - S-Adenosyl-L-Methionine for Treatment of Depression, Osteoarthritis, and Liver D... S-Adenosyl-L-Methionine for Treatment of Depression, Osteoarthritis, and Liver Disease 
                      - Management of Clinically Inapparent Adrenal Mass Management of Clinically Inapparent Adrenal Mass 

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on
See more...

TwitterFacebookLinkedInGitHubNCBI Insights Blog

Connect with NLM
                      - Twitter
                      - Facebook
                      - Youtube

National Library of Medicine8600 Rockville Pike							Bethesda, MD 20894

Web PoliciesFOIAHHS Vulnerability Disclosure

HelpAccessibilityCareers

-  NLM 
-  NIH 
-  HHS 
-  USA.gov