Awareness and knowledge of obstructive sleep apnea among the general population.

BACKGROUND: Obstructive sleep apnea (OSA) is an increasingly prevalent condition that remains largely undiagnosed. We aimed to assess the level of awareness and knowledge of OSA among the general population. METHODS: The Singapore Health 2 was a population-based study that comprised interview and health screening components. Out of 2720 subjects who completed the interview component, 2080 subjects gave consent for further health surveys. We contacted these subjects and conducted a structured telephone interview. RESULTS: We completed 1306 telephone interviews (response rate 62.8%). Two hundred and eighty-one (21.5%) respondents were aware of OSA, but only 170 (13.0%) respondents could define OSA correctly. A total of 77 (5.9%), 158 (12.1%), 150 (11.5%) and 110 (8.4%) respondents were able to correctly list at least one risk factor, symptom, health consequence and treatment options for OSA, respectively. The most common sources of information about OSA were traditional media such as newspapers (42.0%), internet (14.2%) or relatives and friends (14.6%). On multivariate analysis, respondents were more likely to define OSA correctly if they were older (≥61years), (odds ratio of 2.99, 95% Confidence Interval [CI]: 1.66-5.41), were Chinese as compared to Indians (odds ratio 2.63, 95% CI: 1.46-4.72), had higher levels of income (odds ratio 2.18, 95% CI 1.16-4.10) and post-secondary education (odds ratio 2.87, 95% CI: 1.28-6.45). CONCLUSION: Awareness and knowledge of OSA among the general population is currently poor. The effectiveness of ongoing health education campaigns to increase awareness should be monitored by examining temporal trends in public knowledge of sleep apnea.

Validation of NoSAS score for screening of sleep-disordered breathing in a multiethnic Asian population.

PURPOSE: The NoSAS score was developed to identify subjects at high risk of sleep-disordered breathing (SDB). We aimed to validate the NoSAS score in a multiethnic Asian cohort and compare its performance to the STOP-Bang and Berlin questionnaires. METHODS: A sample of 242 subjects selected from a population-based cohort in Singapore completed home-based sleep testing with an Embletta device (type 3 monitor). All subjects were given the STOP-Bang and Berlin questionnaires for self-administration prior to the sleep study. The NoSAS score was subsequently calculated based on available demographic data and Berlin questionnaire responses. RESULTS: The prevalence of severe SDB, defined as an apnea-hypopnea index cutoff of ≥30 events/h, was 10.7%. The number of subjects who were classified as high risk by the NoSAS score and STOP-Bang and Berlin questionnaires were 76 (31.4%), 89 (36.8%), and 79 (32.6%), respectively. The sensitivity, specificity, and negative and positive predictive values of the NoSAS score to predict severe SDB were 69.2, 73.1, 95.2, and 23.7%, respectively. The STOP-Bang and Berlin questionnaires performed similarly to the NoSAS score, with area under the curve (AUC) values of all three questionnaires clustered around 0.682-0.748. Compared to the STOP-Bang (94.8%) and Berlin questionnaires (96.3%), the NoSAS score (95.2%) had equally high negative predictive value in ruling out severe SDB. CONCLUSIONS: The NoSAS score performed similarly to the STOP-Bang and Berlin questionnaires in a multiethnic Asian cohort. All three questionnaires had high negative predictive values in ruling out severe SDB and may have utility as screening tools.

Using the Berlin Questionnaire to Predict Obstructive Sleep Apnea in the General Population.

STUDY OBJECTIVES: The Berlin questionnaire is a self-administered questionnaire that was developed to identify subjects with obstructive sleep apnea (OSA) in primary care settings. This study evaluated the performance of the questionnaire to predict OSA in the general population. METHODS: A sample of 242 subjects in a population-based cohort completed a home-based sleep study with an Embletta device (type 3 monitor). Subjects completed the Berlin questionnaire on the evening just prior to the sleep study. The sleep studies were manually scored according to the 2012 American Academy of Sleep Medicine (AASM) criteria. RESULTS: The prevalence of moderate-to-severe and severe OSA defined as apnea-hypopnea index (AHI) of ≥ 15 and ≥ 30 was 28.1% and 10.7%, respectively. Seventy-nine subjects (32.6%) were classified as high risk according to the Berlin questionnaire. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of the questionnaire to predict an AHI ≥ 15 was 58.8%, 77.6%, 82.9%, and 50.6%, respectively. The area under the receiving operator characteristic (ROC) curve for moderate-to-severe OSA was 0.682. When used to predict an AHI ≥ 30, the sensitivity of the questionnaire increased to 76.9% with a small drop in specificity to 72.7%. The corresponding NPV, PPV, and area under the ROC curve of the questionnaire to predict severe OSA were 96.3%, 25.3%, and 0.748, respectively. CONCLUSIONS: The Berlin questionnaire may have utility in the general population setting as a screening tool for OSA in view of its good sensitivity and high NPV in ruling out severe OSA.

Predicting obstructive sleep apnea using the STOP-Bang questionnaire in the general population.

OBJECTIVE: The STOP-Bang questionnaire was developed as a quick and simple screening tool for obstructive sleep apnea (OSA) in preoperative clinics. We aimed to evaluate the validity of the STOP-Bang questionnaire to predict moderate-to-severe and severe OSA in the general population. METHODS: A sample of 242 subjects selected from a population-based cohort in Singapore completed home-based sleep testing with a type 3 monitor. Subjects were asked to complete the STOP questionnaire while body mass index (BMI), age, neck circumference, and sex were recorded. A score of ≥3 on the questionnaire indicated high risk of OSA. RESULTS: A total of 68 subjects (28.1%) and 26 subjects (10.7%) had an apnea-hypopnea index (AHI) of ≥15 and ≥30 events per hour, respectively. Of the subjects, 89 (36.8%) were classified as high risk based on the questionnaire. The sensitivity of a STOP-Bang score of ≥3 was 66.2% to detect AHI ≥15 and 69.2% to detect AHI ≥30. The specificities were 74.7% and 67.1%, respectively. The negative predictive values were 85% for moderate-to-severe OSA and 94.8% for severe OSA. The corresponding positive predictive values were 50.6% and 20.2%, respectively. Using BMI cutoffs of 30 and 27.5 for Asians compared to the original cutoff of 35 did not improve the questionnaire performance significantly. CONCLUSION: The STOP-Bang questionnaire can be used as a screening tool in the general population in view of its moderate sensitivity and high negative predictive value for subjects with moderate-to-severe and severe OSA. The cutoff of BMI >35 can be used in Asians, as lower BMI cutoffs did not improve questionnaire performance.

Prevalence of sleep-disordered breathing in a multiethnic Asian population in Singapore: A community-based study.

BACKGROUND AND OBJECTIVE: Limited data exist on the prevalence variation in sleep-disordered breathing (SDB) across different Asian ethnicities. This population study aimed to estimate the prevalence of SDB in Singapore, a multiethnic nation, and to quantify the prevalence variation among Chinese, Malays and Indians. METHODS: The Singapore Health Study 2012 was a cross-sectional population study conducted on adults aged 21-79 years. Among 2329 participants who completed baseline examination, a sample of 242 subjects completed home-based sleep testing with an Embletta device (type 3 monitor). Moderate-to-severe SDB, defined as an apnoea-hypopnoea index (AHI) of ≥15 events/h, was used to estimate prevalence. RESULTS: The weighted estimates of the population prevalence of moderate-to-severe SDB and sleep apnoea syndrome were 30.5% and 18.1%, respectively. Of subjects with AHI ≥15, 91.0% were previously undiagnosed. Moderate-to-severe SDB prevalence varied across the Chinese (32.1%), Malays (33.8%) and Indians (16.5%). The mean body mass index (BMI) was lowest in Chinese (23.3 kg/m(2) ) and highest among Malays (26.0 kg/m(2) ) and Indians (25.4 kg/m(2) ). Compared with Chinese, Indians had lower odds of moderate-to-severe SDB after adjustment for age, sex and BMI (odds ratio 0.82, 95% CI: 0.70-0.96, P = 0.02). CONCLUSION: Sleep-disordered breathing is prevalent but mostly undiagnosed among Asians in Singapore. There was a lower prevalence of SDB among Indians compared with Chinese that remained after adjustment for age, sex and BMI. Strategies are needed to optimize diagnosis and recognize ethnic differences in SDB prevalence.

Risk factors for pandemic (H1N1) 2009 seroconversion among adults, Singapore, 2009.

A total of 828 community-dwelling adults were studied during the course of the pandemic (H1N1) 2009 outbreak in Singapore during June-September 2009. Baseline blood samples were obtained before the outbreak, and 2 additional samples were obtained during follow-up. Seroconversion was defined as a >4-fold increase in antibody titers to pandemic (H1N1) 2009, determined by using hemagglutination inhibition. Men were more likely than women to seroconvert (mean adjusted hazards ratio [HR] 2.23, mean 95% confidence interval [CI] 1.26-3.93); Malays were more likely than Chinese to seroconvert (HR 2.67, 95% CI 1.04-6.91). Travel outside Singapore during the study period was associated with seroconversion (HR 1.76, 95% CI 1.11-2.78) as was use of public transport (HR 1.81, 95% CI 1.05-3.09). High baseline antibody titers were associated with reduced seroconversion. This study suggests possible areas for intervention to reduce transmission during future influenza outbreaks.

2009 influenza A(H1N1) seroconversion rates and risk factors among distinct adult cohorts in Singapore.

CONTEXT: Singapore experienced a single epidemic wave of 2009 influenza A(H1N1) with epidemic activity starting in late June 2009 and peaking in early August before subsiding within a month. OBJECTIVE: To compare the risk and factors associated with H1N1 seroconversion in different adult cohorts. DESIGN, SETTING, AND PARTICIPANTS: A study with serial serological samples from 4 distinct cohorts: general population (n = 838), military personnel (n = 1213), staff from an acute care hospital (n = 558), and staff as well as residents from long-term care facilities (n = 300) from June 22, 2009, to October 15, 2009. Hemagglutination inhibition results of serum samples taken before, during, and after the epidemic and data from symptom questionnaires are presented. MAIN OUTCOME MEASURES: A 4-fold or greater increase in titer between any of the 3 serological samples was defined as evidence of H1N1 seroconversion. RESULTS: Baseline titers of 40 or more were observed in 22 members (2.6%; 95% confidence interval [CI], 1.7%-3.9%) of the community, 114 military personnel (9.4%; 95% CI, 7.9%-11.2%), 37 hospital staff (6.6%; 95% CI, 4.8%-9.0%), and 20 participants from long-term care facilities (6.7%; 95% CI, 4.4%-10.1%). In participants with 1 or more follow-up serum samples, 312 military personnel (29.4%; 95% CI, 26.8%-32.2%) seroconverted compared with 98 community members (13.5%; 95% CI, 11.2%-16.2%), 35 hospital staff (6.5%; 95% CI, 4.7%-8.9%), and only 3 long-term care participants (1.2%; 95% CI, 0.4%-3.5%). Increased frequency of seroconversion was observed for community participants from households in which 1 other member seroconverted (adjusted odds ratio [OR], 3.32; 95% CI, 1.50-7.33), whereas older age was associated with reduced odds of seroconversion (adjusted OR, 0.77 per 10 years; 95% CI, 0.64-0.93). Higher baseline titers were associated with decreased frequency of seroconversion in community (adjusted OR for every doubling of baseline titer, 0.48; 95% CI, 0.27-0.85), military (adjusted OR, 0.71; 95% CI, 0.61-0.81), and hospital staff cohorts (adjusted OR, 0.50; 95% CI, 0.26-0.93). CONCLUSION: Following the June-September 2009 wave of 2009 influenza A(H1N1), 13% of the community participants seroconverted, and most of the adult population likely remained susceptible.