Table 1.

Characteristics of newly qualified health care workers with and without previous episodes of LBP at baseline

Time at measurement	Variable		Cases without LBP (n = 1111)	%	Cases with previous LBP (n = 1566)	%
Baseline	Age
		< 20	68	6.1	91	5.8
		20-29	331	29.8	497	31.7
		30-39	309	27.8	437	27.9
		40-49	292	26.3	384	24.5
		>50	111	10	157	10
Baseline	Education
		Health care helper	741	66.7	972	62.1
		Health care assistant	370	33.3	594	37.9
Baseline	Foreign background
		Born in Denmark	962	86.6	1413	90.2
Baseline	Living status
		Living with partner	131	12	141	9.1
		Living with spouse/partner
			734	76	1058	75.2
Baseline	Children living at home
		No	504	45.7	754	48.6
		1 child	213	19.3	289	18.6
		2 children	257	23.3	351	22.6
		3 or more children	128	11.6	159	10.2
Baseline	Musculoskeletal disorder previous 12 months
		Low back	-	-	1349	88.2
		Upper back	230	20.8	584	37.8
		Neck	682	61.9	1052	67.5
		Shoulder	356	32.1	798	51.3
Follow-up	Days with low back pain previous 12 months
		No pain	586	53	331	21.3
		1-7 days	269	24.3	404	26
		8-30 days	162	14.6	444	28.5
		> 30 days	89	8	377	24.3
Follow-up	Body mass index
		< 18.5	19	3.2	27	2.8
		18.5-24.9	419	60	533	57.4
		25.0-29.9	188	27.3	270	27.7
		≥ 30	85	9.6	153	12.2
Follow-up	Smoking
		Current smoker	429	38.9	682	43.9
		Ex-smoker	227	20.6	333	21.4
		Never smoked	446	40.5	538	34.6
Follow-up	Leisure time physical activity
		Sedentary	77	7.1	137	8.9
		Light	570	52.4	778	50.5
		Moderate	377	34.7	540	35.1
		High	64	5.9	85	5.5

Note: Foreign background, living status and musculoskeletal disorder previous 12 months do not summarize to 100% as they were single items with the response categories yes/no