Table 1

Characteristics^* of the occupational groups

Characteristics	Construction workers	Floor- and bricklayers	Farmers	Healthcare assistants	Office workers
N	487 156	4381	217 055	496 478	912 228
Years of follow-up, mean (SD)	8.5 (3.3)	8.1 (3.6)	9.1(3.0)	9.2 (2.9)	9.0 (3.2)
Female, %	7.9	2.2	25.4	82.9	65.3
Age, median (IQR)	38 (27–52)	39 (25–52)	44 (32–59)	39 (28–51)	36 (25–51)
Low income^†, %	21.1	25.7	18.4	21.4	20.3
Low education^‡, %	47.1	37.1	58.4	38.6	28.8
Marital status: single, %	37.5	36.4	29.2	38.7	35.5
Employed more than 80% of the year, %	85.3	86.3	89.2	82.6	88.6
History of knee injury, %	3.3	3.5	1.9	2.5	2.4

↵* Characteristics at first year of follow-up, unless noted otherwise.
↵† Low income was defined as the lowest 25% income of the Danish population.
↵‡ Low education was defined as the highest completed education that is primary school.