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Table 1 Characteristics of study participants (non-obese men) grouped by respiratory disturbance index (RDI)

From: Association between physical activity and sleep-disordered breathing in male Japanese workers: a cross-sectional study

  Sleep disordered breathing P a
Cases Controls
(RDI ≥15) (RDI <15)
n 46 125  
RDI [events/h], mean (SD) 24.8 (8.8) 8.4 (3.8) <0.001
Age [years], mean (SD) 45.4 (7.9) 36.9 (10.0) <0.001
Body weight [kg], mean (SD) 75.0 (8.1) 67.8 (8.5) <0.001
Body mass index [kg/m2], mean (SD) 25.1 (2.2) 22.9 (2.5) <0.001
Adult weight gain [kg], mean (SD) 11.4 (5.8) 5.2 (6.6) <0.001
Physical activity [MET-h/week], median (25%, 75%) 12.6 (6.2, 28.6) 18.1 (8.0, 67.5) 0.095
Overtime hours [h/month], median (25%, 75%) 13.5 (1, 30) 20 (10, 40) 0.19
Sleep duration [h/day], mean (SD) 5.9 (0.9) 6.2 (0.9) 0.055
Pittsburgh Sleep Quality Index (PSQI) score, mean (SD) 5.8 (2.3) 5.3 (2.2) 0.25
Current smoker, n (%) 16 (35) 58 (46) 1.00
Regular drinker, n (%) 37 (80) 83 (67) 0.040
Marital status (cohabiting after marriage), n (%) 30 (65) 60 (48) 0.058
Education (university or higher), n (%) 34 (74) 72 (58) 0.075
Work type, n (%)    0.008
 Specialized or technical 5 (11) 28 (23)  
 Managerial 20 (43) 24 (20)  
 Clerical 0 (0) 5 (4.1)  
 Marketing and sales 19 (41) 45 (37)  
 Service 1 (2.2) 15 (12)  
 Production or labor services 1 (2.2) 2 (1.6)  
 Other 0 (0) 4 (3.3)  
Night shift worker, n (%) 6 (13) 43 (35) 0.007
History of hypertension, n (%) 10 (22) 11 (9.2) 0.035
History of type 2 diabetes, n (%) 4 (9.1) 3 (2.6) 0.089
History of cardiovascular disease, n (%) 4 (9.1) 5 (4.2) 0.25
  1. The number of participants varied across variables as a result of missing information
  2. aWilcoxon rank-sum test was used for continuous variables, and Fisher’s exact probability test was used for categorical variables