Long-term sickness absence in a working population: development and validation of a risk prediction model in a large Dutch prospective cohort

Table 1 Baseline characteristics of participants in the development and validation cohort

	Level	Development cohort	Validation cohort
		n = 11,221	n = 5604	p-value
Female, (%)		4819 (42.9)	2753 (49.1)	< 0.001
Age, mean (SD)		53.9 (5.4)	50.2 (5.2)	< 0.001
Educational level^a, n(%)	Low	2924 (26.1)	1390 (24.8)	0.12
	Medium	4349 (38.8)	2253 (40.2)
	High	3948 (35.2)	1961 (35.0)
SF-12 physical health^b, mean (SD)		52.4 (7.0)	52.2 (7.4)	0.07
Physically fit^c, n(%)		4502 (40.4)	2535 (45.4)	< 0.001
Physical job load^d, mean (SD)		1.8 (0.9)	1.9 (0.9)	< 0.001
Knowledge and skills match the job, n(%)	Bad/mediocre	488 (4.4)	255 (4.6)	0.54
	Reasonable/good	10,687 (95.6)	5323 (95.4)	0.54
Major life events previous year, n(%)	0	5877 (52.4)	3239 (57.8)	< 0.001
	1	3577 (31.9)	1640 (29.3)
	≥2	1767 (15.7)	725 (12.9)
Work ability^e, mean (SD)		8.0 (1.4)	8.1 (1.4)	0.10
Sickness absence days previous year, mean (SD)		2.9 (5.1)	2.7 (4.9)	0.01
Employment status, n(%)	Employee	10,066 (89.7)	5056 (90.2)	0.30
	Self-employed	1155 (10.3)	548 (9.8)	0.30

SD = standard deviation, SF = Short Form Health Survey
^aLow: lower general secondary educational, preparatory secondary vocational education. Medium: intermediate vocational training, higher general secondary education, pre-university education. High: higher vocational education, university education
^bWeighted summary score (range 0–100) assessing physical health using 6 items of the 12-Item Short-Form Health Survey. Higher scores indicating better perceived health
^cIntensive physical exercise at least ≥3 days per week for ≥20 min
^dAverage of five items (range: 1 = never, 5 = always) from the Dutch Musculoskeletal Questionnaire [22]
^eMeasured with the first item of the Work Ability Index (WAI) [23]

ISSN: 1471-2458