Table 2.
Adjusted Relative Risk of Clinical Depressiona According to Baseline Restless Legs Syndrome Status, Nurses' Health Study, 2002–2008
| No RLS |
RLS |
P Value | ||
|---|---|---|---|---|
| RR | 95% CI | |||
| No. of cases | 1,235 | 33 | ||
| Person-years of follow-up | 295,493 | 4,662 | ||
| Crude incidence (per 100,000 person-years) | 418 | 708 | ||
| Age-adjusted RR | 1 | 1.66 | 1.18, 2.35 | 0.004 |
| Multivariate RRb | 1 | 1.58 | 1.11, 2.23 | 0.01 |
| Multivariate RRc | 1 | 1.51 | 1.07, 2.14 | 0.02 |
| Multivariate RRd | 1 | 1.49 | 1.06, 2.10 | 0.02 |
Abbreviations: CI, confidence interval; RLS, restless legs syndrome; RR, relative risk.
aClinical depression was defined as reported regular use of antidepressant medication and physician-diagnosed depression.
bAdjusted for age (years), body mass index (weight (kg)/height (m)2; continuous), ethnicity (Caucasian or other), smoking status (never, past, or current smoker), marital status (married/in a partnership, widowed, or separated/divorced/single), solitary living status (yes/no; binary), regular involvement in a social or community group (yes/no; binary), menopausal status (premenopausal or postmenopausal), menopausal hormone use (never, past, or current user), alcohol intake (0, 0.1–4.9, 5.0–9.9, 10.0–14.9, or ≥15 g/day), and physical activity (quintiles).
cFurther adjusted for the presence of diabetes, arthritis, stroke, myocardial infarction, angina, cancer, hypertension, high cholesterol level, or Parkinson's disease (yes/no).
dFurther adjusted for use of iron-specific supplements, sleep duration (≤5, 6, 7, 8, or ≥9 hours per 24-hour period), and snoring frequency (every night, most nights, a few nights per week, occasionally, or almost never).