Table 2 The mean number of sickness absence days (register data) at baseline and at follow-up as well as the mean and standard deviation (SD) for direct total costs

Availability of resource use data	Study group	Group size	Sick leave days per group						Direct total cost
			Baseline			Follow-up			Direct total cost
			% zero	Mean	SD	% zero	Mean	SD	% zero	Mean	SD
Data available	Control	138	36	16.9	37	25	23.7	45	4	1048.9	1368
Data available	Intervention	134	29	18.2	34	32	22.0	50	4	973.6	1628
Data missing	Control	54	31	17.4	29	19	45.8	67	4	1261.3	1183	*
Data missing	Intervention	58	21	15.4	29	29	13.1	25	3	813.0	746	*
All	Control	192	34	17.1	35	23	29.9	53	4	1108.6	1319	†
All	Intervention	192	27	17.4	32	31	19.3	44	4	925.1	1420	†

*Direct cost data are based on missing data imputation.
†Direct cost data are partly based on missing data imputation.
The results are presented by randomised groups among those subjects for whom the resource use questionnaire data were available, resource use data were missing, and for all subjects.