Table 2 Summary of the community studies with instrumental sleep and/or full PSG assessment

Ip et al. [20]; 2001

China/Hong-Kong

Cross-Sectional study using sleep questionnaire and PSG

n-784 (153 underwent PSG) Males-100% Mean age-41.2 years Mean BMI-23.9 kg/m²

23% had snoring. 41.8% were diagnosed with OSA by PSG. Estimated OSA and OSAS prevalence was 8.8% and 4.1%

Older age, higher BMI, snoring and time taken to fall asleep

6 points: single area study, no funding information.

Ip et al. [21]; 2004

China/Hong-Kong

Cross-Sectional study using sleep questionnaire and PSG

n-884 (105 underwent PSG) Females-100% Mean age-41.6 years Mean BMI-22.4 kg/m²

15% had snoring. AHI ≥ 5, AHI ≥ 10 and AHI ≥ 15 were present among 30%, 15% and 10% respectively. Estimated prevalence of OSA and OSAS was 3.7% and 2.1% respectively

Older age and higher BMI

5 points: single area study, no discussion of potential limitations and no funding information.

Hui et al. [22]; 2006

China/Hong-Kong

Cross-Sectional study using sleep questionnaire, 4 channel home sleep monitoring and PSG

n-1,477 (211 undergone 4 channel home sleep study and 25 have been assessed by PSG) Males-65.74% Mean age-45.3 years Mean BMI- 24.9 kg/m²

EDS was present in 60.9%, falling asleep in 24%, snoring in 23.9% and witnessed apnea in 3.7%. RDI ≥ 5 was present in 83.9% and RDI ≥ 15 was present in 17.5%. It was estimated that OSA and OSAS was present in 8.4% and 4.4% respectively

Higher BMI, neck circumference and snoring

6 points: single area study, no funding information.

He et al. [23]; 2010

China

Cross-Sectional study using PSG

n-2,297 Males-86.24% Mean age-46 years Mean BMI- 27.64 kg/m²

88.81% were diagnosed with OSA and 51.28% were diagnosed with severe OSA

Systolic and diastolic blood pressure

6 points: no discussion of the potential limitations and no funding information.

Chen et al. [24]; 2011

China

Cross-Sectional study using PSG

n-1,035 Males-83.67% Mean age-45 years Mean BMI- 26.2 kg/m² in mild OSAS, 27.5 kg/m² for moderate and 28.8 kg/m² for severe OSAS

75.9% had OSAS and 37.7% had AHI > 40.

ESS score correlated with ODI, AHI and BMI. ODI was associated with ESS score.

6 points: Single area study and no discussion of the potential limitations.

Tanigawa et al. [25]; 2004

Japan

Cross-Sectional study using pulse oximetry monitoring

n-1,424 Males-100% mean age-58.6 years Mean BMI-24 kg/m²

31.46% and 9% had ODI of 5–15 and ODI > 15 respectively

Arterial hypertension, BMI, smoking and older age

4 points: single area study, PSG was not used, no discussion of the potential limitations and no funding information.

Cui et al. [26]; 2006

Japan

Cross-Sectional study using pulse oximetry monitoring

n-1,313 Males-96% Mean age- for 3% ODI of 5–14 was 47 years and 47.3 years for 3% ODI > 15Mean BMI- 3% ODI of 5–14 was 25.6 kg/m² and 28.5 kg/m² for 3% ODI > 15

Subjects aged 40–69 have SDB prevalence of 8.5% compared to 4% among aged 20-39

age ≥ 40 years, higher BMI, ESS > 11 and arterial hypertension

6 points: PSG was not used, no funding information.

Okabayashi et al. [27]; 2007

Japan

Cross-Sectional study using home pulse oximetry and then PSG study among Japanese workers

n-368 underwent home pulse oximetry and 153 were screened with PSG Males-100% Mean age-45.7 years Mean BMI-25.8 kg/m²

313 patients out of 368 (85%) had ODI ≥ 5 events. 149 out of 153 (97.3%) had OSA

7 points: no funding information.

Asaoka et al. [28]; 2010

Japan

Cross-Sectional study using 3 channel home sleep monitoring in patients with positive ESS and/or snoring, witnessed apneas, BMI ≥ 25 kg/m² and concomitant arterial hypertension

n-370 undergone home sleep study; 129 participants undergone PSG study Males-100% Mean age-44.5 years Mean BMI-24.3 kg/m²

OSA was present among 3.7%

5 points: single area study, PSG was not used, no funding information

Sharma et al. [29]; 2006

India

Cross-Sectional study using sleep questionnaire and PSG

n-2,150 Males-52.8% Mean age-43.9 years for snorers Mean BMI- 27 kg/m²

151 subjects (77 snorers and 74 nonsnorers) undergone PSG

25.16% subjects were found to have OSA and 7.28% subjects were found to have OSAS (among who underwent PSG). It was estimated that 13.74% and 3.57% of the population should have OSA and OSAS respectively

Male gender, older age, snoring, higher BMI and greater waist to hip ratio

6 points: single area study, no funding information.

Reddy et al. [30]; 2009

India

Cross-Sectional study using sleep questionnaire and PSG

n-2,505 Males-50.4% Mean age-41 years Mean BMI-24.3 kg/m² 360 subjects (287 snorers and 73 nonsnorers) undergone PSG

26.94% subjects had OSA and 12.2% subjects had OSAS (among who underwent PSG).

Male gender, BMI ≥ 25 kg/m² and abdominal obesity

7 points: single area strudy.

Kim et al. [31]; 2004

Korea

Cross-Sectional study using home sleep study or PSG

n- 457 Males- 67.6% Mean age-49.1 years for males with snoring and 54.3 years for females with snoring Mean BMI-26.5 kg/m² for males with snoring and 26.6 kg/m² for females with snoring

OSA and was found in 42% men and 20% women and OSAS was present in 4.5% men and 3.2% women

Male gender, higher BMI and hypertension

7 points: single area study.

Yusoff et al. [32]; 2010

Malaysia

Cross-Sectional study using PSG

n-279 Males-100% Mean age-43.8 years Mean BMI- 29.4 kg/m² for patients with OSA

44.3% had AHI ≥ 5 and 6.6% had xAHI ≥ 30.

Older age, greater BMI and neck circumference, snoring and hypertension

7 points: no discussion of the potential limitations.

Puvanendran et al. [33]; 1999

Singapore

Cross-Sectional study using PSG

n-106 male: female ratio 9:1 No data on mean age and mean BMI are provided

87.5% had OSA and 72% had OSAS. It was calculated that 15.7% of the Singaporean population may have OSA.

6 points: no discussion of the potential limitations and no funding information.