Table 3.
Subgroup analysis of the association between sleep variability (per hour) and incident cardiovascular disease
| Sleep duration SD | Sleep onset timing SD | |||
|---|---|---|---|---|
| HR (95% CI)1 | p for interaction2 | HR (95% CI)1 | p for interaction2 | |
| Age | 0.63 | 0.96 | ||
| <70 years | 1.50 (0.99, 2.27) | 1.17 (0.96, 1.42) | ||
| ≥70 years | 1.34 (0.97, 1.87) | 1.19 (1.04, 1.36) | ||
| Sex | 0.57 | 0.44 | ||
| Male | 1.54 (1.11, 2.14) | 1.25 (1.09, 1.44) | ||
| Female | 1.40 (0.90, 2.19) | 1.17 (0.96, 1.42) | ||
| Race/ethnicity | 0.43 | 0.61 | ||
| White | 0.91 (0.57, 1.46) | 1.04 (0.84, 1.29) | ||
| African American | 1.66 (0.93, 2.95) | 1.34 (1.05, 1.71) | ||
| Hispanic | 2.19 (1.35, 3.57) | 1.38 (1.13, 1.69) | ||
| Chinese | 2.41 (0.77, 7.59) | 1.55 (0.96, 2.51) | ||
| Average sleep duration | 0.92 | 0.76 | ||
| <7 hours | 1.46 (0.99, 2.15) | 1.22 (1.04, 1.42) | ||
| 7–8 hours | 1.40 (0.85, 2.33) | 1.30 (1.06, 1.59) | ||
| >8 hours | 1.16 (0.66, 2.04) | 1.03 (0.74, 1.45) | ||
| Work schedules | 0.84 | 0.76 | ||
| Day shift/do not work | 1.42 (1.08, 1.87) | 1.20 (1.07, 1.35) | ||
| Other shift | 1.66 (0.65, 4.21) | 1.43 (0.93, 2.20) | ||
1
Stratified by study site, and adjusted for age, sex, race/ethnicity, education, work schedules, smoking status, physical activity, depressive symptoms, BMI, diabetes status, systolic blood pressure, HDL cholesterol, total cholesterol, average sleep duration, insomnia symptom scores, chronotype, Epworth Sleepiness Scale and AHI
2
P for interaction was calculated by the likelihood ratio test comparing the models with versus without the cross-product interaction term(s)
AHI = Apnea-Hypopnea Index; BMI = body mass index; CI = confidence interval; HR = hazard ratio; SD = standard deviation