Table 5.

Results from the per-protocol and sensitivity analyses (RTW)

Analysis	Sample size		∆ Cost* (€) mean (95% CI)	∆ Effect* (days) mean (95% CI)	ICER €/day	Distribution CE plane
	IC	UC				NE† (%)	SE‡ (%)	SW§ (%)	NW¶ (%)
Per-protocol analysis	205	188	−359 (−866 to −11)	6.4** (−0.2 to 12.9)	−56	8	87	5	1
Complete-case analysis	154	150	−45 (−466 to 362)	11.6** (−5.4 to 19.3)	−4	45	55	0	0
Friction cost approach	227	206	−228 (−708 to 136)	4.1** (−2.6 to 10.8)	−56	15	69	10	6
Healthcare perspective	227	206	−61 (−361 to 218)	4.1** (−2.6 to 10.8)	−15	28	56	5	10

*Uncertainty estimated using bootstrapping and corrected for clustering by hospital and type of surgery.

†Refers to the north-east quadrant of the CE plane, indicating that the intervention care programme is more effective and more costly than usual care.

‡Refers to the south-east quadrant of the CE plane, indicating that the intervention care programme is more effective and less costly than usual care.

§Refers to the south-west quadrant of the CE plane, indicating that the intervention care programme is less effective and less costly than usual care.

¶Refers to the north-west quadrant of the CE plane, indicating that the intervention care programme is less effective and more costly than usual care.

**Note that a positive value indicates faster RTW in the intervention group compared with the control group.

CE, cost-effectiveness; IC, intervention care; ICER, incremental cost-effectiveness ratio; RTW, return to work; UC, usual care.