Table 2.

Baseline characteristics of the study population in relation to work ability (n=16 460)

Characteristic	Good work ability n: 14 471 (88%)		Poor* work ability n: 1989 (12%)
	n	%	n	%
Female	8279	57	1252	63
Age mean (SD)	43.2	10.0	42.9	10.5
Age median (min–max)	44	18–60	44	18–60
Socioeconomic status
Unskilled/semiskilled workers	1498	11	406	22
Skilled workers	1401	10	248	13
Assistant non-manual workers	1932	14	244	13
Intermediate non-manual workers	4164	30	468	25
Employed/self-employed professionals	3501	25	333	18
Self-employed other than professionals	1283	9	169	9
Household composition
Living together with adult (with or without children)	11 628	81	1464	74
Living with children	805	5	147	7
Living alone	1990	14	369	19
Body mass index, kg/m2
<18.5	187	1	39	2
18.5–24.9	7978	56	1022	53
25.0–29.9	4628	33	600	31
≥30.0	1446	10	281	15
Daily smoking	1424	10	320	16
Physical activity†
None or low (less than 1 hour/week)	1989	14	445	23
Intermediate	8730	60	1149	58
High	3288	23	336	17
Very high (more than 5 hours/week)	424	3	47	2
Sedentary leisure time (TV, reading, etc)
<2 hours/day	9111	63	1038	53
2–3 hours/day	3740	26	578	29
More than 3 hours/day	1558	11	360	18
Sleep disturbances
No	10 478	73	914	47
Yes, mild	355	25	866	44
Yes, severe	237	2	169	9
Psychological Distress (GHQ12‡)
No (0–2)	12 250	85	1005	51
Mild (3–6)	1590	11	485	25
Severe (7–12)	602	4	493	25
Long-standing illness	8200	22	3837	54

Total numbers across rows differ due to internal missing values.

*WAI (Work Ability Index) items,¹¹ self-perceived physical and/or mental work ability in relation to job demands and defined as moderate, rather poor, poor.

†Defined as a combination of cycling/walking and other physical activity expressed as hours per week.

‡GHQ12, General Health Questionnaire–12 items.³⁸