Using the Berlin Questionnaire to Identify Patients at Risk for Sleep Apnea Syndrome

abstract & commentary

Synopsis: This study attempted to use a survey as a means of identifying patients with sleep apnea in the primary care setting. The survey addressed the presence and frequency of snoring behavior, waketime sleepiness or fatigue, and history of obesity and hypertension. Patients were classified as high risk for sleep apnea if two of these three findings were present. The survey was followed by a portable unattended sleep study in a subset of patients to measure respiratory disturbance index (RDI). Approximately 37% of the respondents were found to be in the high-risk category as defined by the survey. Risk grouping was useful in prediction of the RDI. Netzer et al conclude that the Berlin questionnaire is useful in identifying patients who are likely to have sleep apnea.

Source: Netzer NC, et al. Ann Intern Med 1999;131:485-491.

The obstructive sleep apnea-hypopnea syndrome is a common disorder found in 2-4% of the general population.1 This syndrome is characterized by excessive daytime sleepiness, disruptive snoring, repeated episodes of upper airway obstruction during sleep, and nocturnal hypoxemia. However, recognition of the syndrome by community physicians is low. Only 7% of women and 12% of men who had moderate to severe illness reported receiving a diagnosis of sleep apnea from a medical encounter in Wisconsin.2 Specialist intervention, physician education, or simply asking patients to report their symptoms has been found useful in identifying patients at risk.

The Berlin questionnaire consists of a series of questions selected from the literature that attempt to predict the presence of sleep disordered breathing. The questions focus on snoring, daytime sleepiness, blood pressure, and obesity. The patients were classified in high- and low-risk groups based on responses in three different categories. High risk was defined as persistent symptomatic snoring (> 3-4 times/wk) in category 1, in category 2 by persistent waketime sleepiness, drowsy driving, or both (> 3-4 times/wk) and in category 3, by a history of high blood pressure or a body mass index (BMI) more than 30 kg/m2. High risk of having sleep apnea was defined by being high risk in at least two different categories.

The survey was conducted at five primary care sites in Cleveland, Ohio. Each patient visiting these sites was given a questionnaire to complete. Of 1008 surveys, 744 (74%) were entered for analysis. A portable sleep study was completed for 100 patients and their RDI and oxygen saturation were recorded. A blinded independent researcher performed the scoring.

Approximately 52% reported snoring, of which 24.6% felt that their snoring was louder than normal speech. Forty-eight percent reported snoring at least 3-4 times per week and 55% said their snoring bothered others. Sixteen percent reported breathing pauses during sleep at least once per month. Thirty-four percent felt not rested after a full night’s sleep 3-4 times per week and 39% experienced waketime tiredness or fatigue 3-4 times per week. Nineteen percent said that they had fallen asleep while driving, of which 4% said they did it at least 3-4 times per week.

Approximately 44% of men and 33% of women were found to be at high risk. High-risk group patients were more likely to have a higher BMI, to be male, to have a history of high blood pressure, to have gained weight recently, to snore loudly, to have observed apneas, to be tired during waketime, and to fall asleep at the wheel. Approximately 13% of the respondents underwent a sleep study. The high-risk group had a mean respiratory disturbance index (RDI) of 21.1 ± 18.5, oxygen desaturation index of 19.4 ± 19.5, and lowest SaO2 of 82.6% ± 9.2%. The values in the low-risk group were RDI of 4.7 ± 7.7, oxygen desaturation index of 5.9 ± 7.6, and lowest SaO2 of 89.9% ± 5.9%. Eighty-six percent of the patients with an RDI of higher than 5 were identified using the survey. The patients at low risk had a higher likelihood of having an RDI of lower than 5. Qualification in only one symptom category did not predict RDI threshold as well as grouping did (85% vs 63-78%).

Comment by David Ost, MD

Despite being common, the majority of primary care physicians are unaware and have no easy means to diagnose the Apnea Hypopnea syndrome. The prevalence of this disorder is estimated to be as high as 2-4%.1 Stoohs and colleagues estimated that as many as 20% of the primary care patient population might have sleep disordered breathing.5 Because most patients with sleep disorders are referred to a tertiary care center for diagnosis and treatment, many patients remain undiagnosed because of lack of resources and infrastructure. The Walla Walla project attempted to educate physicians and the public in order to provide the necessary equipment and technical expertise necessary for sleep disorder diagnosis and treatment.3 Ball and colleagues found that in the vast majority of cases, sleep apnea remains undiagnosed. Community physicians were capable of discovering and caring for such patients when resources were provided. Haponik and colleagues also demonstrated that physicians uncommonly obtained sleep histories, while physicians trained in sleep were more likely to ask about sleep.4 They concluded that major changes in physician attitude and behaviors are essential in order to recognize sleep problems.

Netzer and colleagues used a survey and established its role reasonably well in the diagnosis of sleep apnea in this study. It has a high sensitivity of 86% in identifying patients with an RDI of higher than 5. The major advantage of this technique is that it identifies the high-risk patient without personal physician encounters or referring the patient to a tertiary care center. Due to ease and convenience of the technique, physicians and patients could participate in this process alike. However, despite the advantages of the test, Netzer et al cautioned that apart from its validation in different primary care settings, physician judgment is still needed to initiate a management system, to detect unusual cases, and to recognize causes for waketime sleepiness other than sleep apnea.

References

1. Young T, et al. N Engl J Med 1993;328:1230-1235.

2. Young T, et al. Sleep 1997;20:705-706.

3. Ball EM, et al. Arch Intern Med 1997;157:419-424.

4. Haponik, et al. J Gen Intern Med 1996;11:759-761.

5. Stoohs RA, et al. Sleep and Breathing 1997;2:11-22.

The prevalence of the Sleep Apnea-Hypopnea syndrome is estimated to be:

a. 1-2%.

b. 2-4%.

c. 4-6%.

d. 6-8%.