Table 1.

Baseline characteristics of participants (n = 3824) according to incident depressive symptoms (n = 618) over 4-year follow-up

	Depressive Symptoms
	Low (N = 3206)		High (N = 618)
Variable	n	%	n	%	OR	95% CI	P*
Age (years)
< 70	1056	32.94	169	27.35	1		< 0.0001
70-74	1132	35.30	193	31.23	1.07	0.85-1.33
75-79	760	23.71	188	30.42	1.55	1.23-1.94
≥ 80	258	8.05	68	11.00	1.65	1.21-2.25
Gender
Female vs Male	1691	52.74	442	71.52	2.25	1.86-2.72	< 0.0001
High level of education
Yes vs No	744	23.21	104	16.83	0.67	0.53-0.84	0.0005
Living alone
No vs Yes	2253	70.27	400	64.72	0.78	0.65-0.93	0.0062
Alcohol (g/day)
< 12	1931	60.23	419	67.80	1		< 0.0001
12-36	936	29.20	166	26.86	0.82	0.67-0.99
> 36	339	10.57	33	5.34	0.45	0.31-0.65
Coffee (cups per day)
> 2 vs ≤ 2	841	26.23	135	21.84	0.79	0.64-0.97	0.0222
Smoking status
Never	1841	57.41	396	64.08	1		0.0014
Past	1185	36.96	198	32.04	0.78	0.65-0.94
Current	180	5.61	24	3.88	0.62	0.40-0.96
Past major depression
Yes vs No	226	7.05	80	12.94	1.96	1.50-2.57	< 0.0001
Body mass index (kg/m2)
Normal (< 25)	1496	46.66	293	47.41	1		0.83
Overweight (25-29)	1324	41.30	242	39.16	0.93	0.78-1.12
Obese (≥ 30)	386	12.04	83	13.43	1.10	0.84-1.44
Number of chronic diseasesa
0	620	19.34	95	15.37	1		0.0016
1	1131	35.28	202	32.69	1.17	0.90-1.52
2 and more	1455	45.38	321	51.94	1.44	1.12-1.84
Disability
Yes vs No	126	3.93	45	7.28	1.92	1.35-2.73	0.0003
Prescribed sleep medication intake
Yes vs No	291	9.08	122	19.74	2.46	1.95-3.11	< 0.0001
Non-prescription treatments for sleepb
Yes vs No	32	1.00	14	2.27	2.30	1.22-4.33	0.0101

^aIncludes a chronic disease (cardiovascular disease, stroke, other heart problems, high blood pressure, high cholesterol, diabetes, thyroid problems).

^bIncludes homeopathic medication intake.

^*For variables with > 2 categories, the P-value of the test for trend is given.