Table 1.

Basic characteristics of the nested case-control study of depression

	Care Register for Health Care and Register of Primary Health Care visits
	Cases (N = 23,480)		Controls (N = 93,880)
	N	%	N	%
Marital status
Unmarried	17,664	75.2	70,639	75.2
Married	4285	18.2	19,526	20.8
Divorced	1442	6.1	3487	3.7
Widowed	46	0.2	122	0.1
Other	43	0.2	106	0.1
Socioeconomic group
Self-employed	650	2.8	2934	3.1
Upper-level employees	1561	6.6	9566	10.2
Lower-level employees	5804	24.7	29,295	31.2
Manual workers	3406	14.5	14,385	15.3
Students	6738	28.7	23,046	24.5
Pensioners	500	2.1	1297	1.4
Others	3227	13.7	7687	8.2
Unknown	1594	6.8	5670	6.0
Education
Upper secondary	12,071	51.4	45,454	48.4
Post-secondary non-tertiary	105	0.4	474	0.5
Short-cycle tertiary	286	1.2	1497	1.6
Bachelor	3082	13.1	16,502	17.6
Master	1150	4.9	7787	8.3
Doctoral	42	0.2	374	0.4
Missing (including, e.g., missing information on education other than of primary school level, school dropouts)	6744	28.7	21,792	23.2
Age group *
15–19 years	4296	18.3	17,168	18.3
20–24 years	6795	28.9	27,170	28.9
25–29 years	5125	21.8	20,495	21.8
30–34 years	3083	13.1	12,327	13.1
35–39 years	2052	8.7	8206	8.7
40–44 years	1338	5.7	5350	5.7
45–49 years	791	3.4	3164	3.4
Previous psychiatric hospitalizations
No	13,552	57.7	89,962	95.8
In the previous 6 months	9132	38.9	2080	2.2
6 to 24 months before	796	3.4	1838	2.0
Cancer in the previous 5 years	203	0.9	678	0.7
Chronic diseases at baseline
Hypothyroidism	197	0.8	599	0.6
Multiple sclerosis	65	0.3	195	0.2
Epilepsy	328	1.4	866	0.9
Severe psychiatric disorders	532	2.3	774	0.8
Connective tissue diseases	374	1.6	1165	1.2
Ulcerative cholitis or Chron’s disease	237	1.0	735	0.8
Diabetes mellitus	491	2.1	1142	1.2
Former HC use	11,129	47.4	47,229	50.3
Recent delivery
No	21,878	93.2	86,601	92.2
In the previous 6 months	315	1.3	1346	1.4
6 to 24 months before	1287	5.5	5933	6.3

^* Matched by age

HC hormonal contraception