Sleep apnea in adults: How accurate is clinical prediction?

Evidence summary

OSAHS is marked by daytime somnolence, snoring, difficult-to-control hypertension, refractory arrhythmias, angina, or heart failure.¹ The syndrome is defined as an apnea-hypopnea index (AHI) of 5 or more events per hour during a sleep polysomnogram, accompanied by either excessive daytime sleepiness or 2 of the following: choking or gasping during sleep, recurrent awakenings from sleep, daytime fatigue, and impaired concentration.²

What questionnaires can tell you

The Epworth Sleepiness Scale rates the likelihood of dozing in 8 situations. Factor analysis of test-retest on 104 medical students and 150 patients with various sleep disorders showed that the scale was internally consistent but measured only daytime sleepiness.³

The Berlin Questionnaire assesses snoring, daytime sleepiness, history of hypertension, age, and body mass index (BMI). The questionnaire was evaluated in 744 adults presenting for unrelated problems at 5 primary care sites. Of 100 patients who underwent sleep studies, a finding of high risk on the Berlin Questionnaire predicted an AHI >5 with 86% sensitivity and 77% specificity, a positive likelihood ratio of 3.79.⁴

Mallampati scores, truncal obesity offer clues

Mallampati scoring grades visibility of the posterior pharynx when the patient opens his mouth and sticks out his tongue. Visibility is ranked on a scale of 1 to 4, with 1 representing the greatest visibility and 4 the least. Prospective multivariate assessment of Mallampati scores in adults referred to a sleep clinic yielded likelihood ratios of OSAHS for Mallampati grades 1 to 4 of 0.4, 0.7, 1.6, and 1.7, respectively.⁵

A cross-sectional study correlating OSAHS with truncal obesity in 192 patients referred to a sleep clinic found that the likelihood of OSAHS was 2.6 times greater if the waist-to-hip ratio was >1 in men and >0.85 in women.⁶

No single model is sufficient

A systematic review and meta-analysis of 249 studies of sleep apnea diagnosis from 1980 through November 1997 concluded that studies of focused questionnaires were too heterogeneous to be combined in a meta-analysis. Sensitivity and specificity were good for clinical prediction rules in general, but evidence was insufficient to justify adoption of any single model.⁷

A 2000 prospective study of 4 previously developed clinical prediction models for OSAHS in sleep center populations found sensitivities of 75% to 96% and specificities of 13% to 54% for identifying patients, using a criterion of AHI >9.⁸

A 2004 prospective evaluation examined a clinical decision rule on 837 patients referred for polysomnogram that used age, sex, BMI, snoring, and cessation of breathing during sleep to stratify patients into low-, moderate-, or high-risk groups. The study found OSAHS prevalences of 8%, 51%, and 82%, respectively.⁹

Recommendations

The Institute for Clinical Systems Improvement recommends polysomnography for patients with symptoms of OSAHS and 1 or more of the following: cardiovascular disease, hypertension, coronary artery disease, obesity, sleep complaint, type 2 diabetes mellitus, recurrent atrial fibrillation, and large neck circumference.¹⁰

The Canadian Thoracic Society states that clinical prediction formulas assess the pretest probability of sleep-disordered breathing and prioritize patients for evaluation, but are insufficient for diagnosis. The guidelines recommend that all patients with suspected sleep-disordered breathing complete an assessment of daytime sleepiness such as the Epworth Sleepiness Scale.¹¹

The American Academy of Sleep Medicine recommends no single clinical model to predict the severity of OSAHS. Polysomnography is indicated for diagnosis of any sleep-disordered breathing.¹²

Evidence summary

OSAHS is marked by daytime somnolence, snoring, difficult-to-control hypertension, refractory arrhythmias, angina, or heart failure.¹ The syndrome is defined as an apnea-hypopnea index (AHI) of 5 or more events per hour during a sleep polysomnogram, accompanied by either excessive daytime sleepiness or 2 of the following: choking or gasping during sleep, recurrent awakenings from sleep, daytime fatigue, and impaired concentration.²

What questionnaires can tell you

The Epworth Sleepiness Scale rates the likelihood of dozing in 8 situations. Factor analysis of test-retest on 104 medical students and 150 patients with various sleep disorders showed that the scale was internally consistent but measured only daytime sleepiness.³

The Berlin Questionnaire assesses snoring, daytime sleepiness, history of hypertension, age, and body mass index (BMI). The questionnaire was evaluated in 744 adults presenting for unrelated problems at 5 primary care sites. Of 100 patients who underwent sleep studies, a finding of high risk on the Berlin Questionnaire predicted an AHI >5 with 86% sensitivity and 77% specificity, a positive likelihood ratio of 3.79.⁴

Mallampati scores, truncal obesity offer clues

Mallampati scoring grades visibility of the posterior pharynx when the patient opens his mouth and sticks out his tongue. Visibility is ranked on a scale of 1 to 4, with 1 representing the greatest visibility and 4 the least. Prospective multivariate assessment of Mallampati scores in adults referred to a sleep clinic yielded likelihood ratios of OSAHS for Mallampati grades 1 to 4 of 0.4, 0.7, 1.6, and 1.7, respectively.⁵

A cross-sectional study correlating OSAHS with truncal obesity in 192 patients referred to a sleep clinic found that the likelihood of OSAHS was 2.6 times greater if the waist-to-hip ratio was >1 in men and >0.85 in women.⁶

No single model is sufficient

A systematic review and meta-analysis of 249 studies of sleep apnea diagnosis from 1980 through November 1997 concluded that studies of focused questionnaires were too heterogeneous to be combined in a meta-analysis. Sensitivity and specificity were good for clinical prediction rules in general, but evidence was insufficient to justify adoption of any single model.⁷

A 2000 prospective study of 4 previously developed clinical prediction models for OSAHS in sleep center populations found sensitivities of 75% to 96% and specificities of 13% to 54% for identifying patients, using a criterion of AHI >9.⁸

A 2004 prospective evaluation examined a clinical decision rule on 837 patients referred for polysomnogram that used age, sex, BMI, snoring, and cessation of breathing during sleep to stratify patients into low-, moderate-, or high-risk groups. The study found OSAHS prevalences of 8%, 51%, and 82%, respectively.⁹

Recommendations

The Institute for Clinical Systems Improvement recommends polysomnography for patients with symptoms of OSAHS and 1 or more of the following: cardiovascular disease, hypertension, coronary artery disease, obesity, sleep complaint, type 2 diabetes mellitus, recurrent atrial fibrillation, and large neck circumference.¹⁰

The Canadian Thoracic Society states that clinical prediction formulas assess the pretest probability of sleep-disordered breathing and prioritize patients for evaluation, but are insufficient for diagnosis. The guidelines recommend that all patients with suspected sleep-disordered breathing complete an assessment of daytime sleepiness such as the Epworth Sleepiness Scale.¹¹

The American Academy of Sleep Medicine recommends no single clinical model to predict the severity of OSAHS. Polysomnography is indicated for diagnosis of any sleep-disordered breathing.¹²

Evidence summary

OSAHS is marked by daytime somnolence, snoring, difficult-to-control hypertension, refractory arrhythmias, angina, or heart failure.¹ The syndrome is defined as an apnea-hypopnea index (AHI) of 5 or more events per hour during a sleep polysomnogram, accompanied by either excessive daytime sleepiness or 2 of the following: choking or gasping during sleep, recurrent awakenings from sleep, daytime fatigue, and impaired concentration.²

What questionnaires can tell you

The Epworth Sleepiness Scale rates the likelihood of dozing in 8 situations. Factor analysis of test-retest on 104 medical students and 150 patients with various sleep disorders showed that the scale was internally consistent but measured only daytime sleepiness.³

The Berlin Questionnaire assesses snoring, daytime sleepiness, history of hypertension, age, and body mass index (BMI). The questionnaire was evaluated in 744 adults presenting for unrelated problems at 5 primary care sites. Of 100 patients who underwent sleep studies, a finding of high risk on the Berlin Questionnaire predicted an AHI >5 with 86% sensitivity and 77% specificity, a positive likelihood ratio of 3.79.⁴

Mallampati scores, truncal obesity offer clues

Mallampati scoring grades visibility of the posterior pharynx when the patient opens his mouth and sticks out his tongue. Visibility is ranked on a scale of 1 to 4, with 1 representing the greatest visibility and 4 the least. Prospective multivariate assessment of Mallampati scores in adults referred to a sleep clinic yielded likelihood ratios of OSAHS for Mallampati grades 1 to 4 of 0.4, 0.7, 1.6, and 1.7, respectively.⁵

A cross-sectional study correlating OSAHS with truncal obesity in 192 patients referred to a sleep clinic found that the likelihood of OSAHS was 2.6 times greater if the waist-to-hip ratio was >1 in men and >0.85 in women.⁶

No single model is sufficient

A systematic review and meta-analysis of 249 studies of sleep apnea diagnosis from 1980 through November 1997 concluded that studies of focused questionnaires were too heterogeneous to be combined in a meta-analysis. Sensitivity and specificity were good for clinical prediction rules in general, but evidence was insufficient to justify adoption of any single model.⁷

A 2000 prospective study of 4 previously developed clinical prediction models for OSAHS in sleep center populations found sensitivities of 75% to 96% and specificities of 13% to 54% for identifying patients, using a criterion of AHI >9.⁸

A 2004 prospective evaluation examined a clinical decision rule on 837 patients referred for polysomnogram that used age, sex, BMI, snoring, and cessation of breathing during sleep to stratify patients into low-, moderate-, or high-risk groups. The study found OSAHS prevalences of 8%, 51%, and 82%, respectively.⁹

Recommendations

The Institute for Clinical Systems Improvement recommends polysomnography for patients with symptoms of OSAHS and 1 or more of the following: cardiovascular disease, hypertension, coronary artery disease, obesity, sleep complaint, type 2 diabetes mellitus, recurrent atrial fibrillation, and large neck circumference.¹⁰

The Canadian Thoracic Society states that clinical prediction formulas assess the pretest probability of sleep-disordered breathing and prioritize patients for evaluation, but are insufficient for diagnosis. The guidelines recommend that all patients with suspected sleep-disordered breathing complete an assessment of daytime sleepiness such as the Epworth Sleepiness Scale.¹¹

The American Academy of Sleep Medicine recommends no single clinical model to predict the severity of OSAHS. Polysomnography is indicated for diagnosis of any sleep-disordered breathing.¹²