Effectiveness of hip or knee replacement surgery in terms of quality-adjusted life years and costs

Figures & data

Figure 1. The 15 dimensions of the 15D instrument before primary hip replacement and 12 months afterwards (*denotes significant improvement from baseline at the p < 0.05 level).

Table 1.  Health-related quality of life (HRQoL) and cost data. Values are percentages or means with standard deviations (SD) in parentheses

Variable	Primary THA (n = 96)	Revision THA (n = 24)	Primary TKA (n = 103)
Mean HRQoL at baseline	0.805 (0.084)	0.812 (0.086)	0.807 (0.093)
Mean HRQoL at 6 months	0.868 (0.092) ^a	0.841 (0.088) ^a	0.830 (0.109) ^a
Mean HRQoL at 12 months	0.858 (0.115) ^a	0.823 (0.097) ^b	0.841 (0.108) ^a
HRQoL improved at 12 months, %	78	71	63
Mean hospital costs at 12 months, €	8,737 (2,786)	11,239 (2,996)	8,047 (2,051)
Mean OALYs gained at 12 months	1.302 (2.621)	0.215 (0.831)	0.575 (1.228)
Mean QALYs gained at 12 months (discounted by 5%)	0.708 (1.334)	0.127 (0.543)	0.359 (0.744)
Cost per QALY, €	6,710	52,274	13,995

THA: total hip arthroplasty; TKA: total knee arthroplasty; QALY: quality-adjusted life year

^a significant improvement from baseline at the p < 0.001 level.

^b p = 0.4

Table 2.  Characteristics of the primary total hip arthroplasty (THA) and primary total knee arthroplasty (TKA) patients whose health-related quality of life (HRQoL) improved in a clinically significant manner (improvement ≥ 0.03 at 12 months) compared to those with little or negative change (HRQoL change < 0.03). Values are percentages or means with standard deviations (SD) in parentheses

Variable	Worse or clinically insignificant improvement (HRQoL change < 0.03)	Clinically significant improvement (HRQoL change ≥ 0.03)	P-value
Primary THA	n = 40	n = 56
Mean HRQoL at baseline	0.824 (0.086)	0.792 (0.081)	0.07
Mean age, years	65.9 (123)	61.3 (10.5)	0.07
Women, %	63	63	1.0
Mean hospital costs at 12 months, €	8,460 (2,901)	8,934 (2,711)	0.4
Mean waiting time, days	248 (197)	211 (172)	0.3
Primary TKA	n = 47	n = 56
Mean HRQoL at baseline	0.820 (0.102)	0.796 (0.085)	0.2
Mean age, years	70.2 (9.0)	68.3 (9.6)	0.3
Women, %	72	77	0.6
Mean hospital costs at 12 month, €	7,898 (1,735)	8,171 (2,292)	0.5
Mean waiting time, days	330 (172)	258 (184)	0.04

Figure 2. The 15 dimensions of the 15D instrument before revision hip replacement and 12 months afterwards (*denotes significant improvement from baseline at the p < 0.05 level).

Figure 3. The 15 dimensions of the 15D instrument before knee replacement surgery and 12 months afterwards (*denotes significant improvement from baseline at the p < 0.05 level).

Table 3.  Cost-utility analysis: base case and sensitivity analyses (SA) varying the discount rate between 1% and 5%, using median values, and using the upper and lower values of the 95% confidence interval (CI) for the mean differences in treatment effectiveness (improvement in health-related quality of life) and costs. See Table 1 for explanation of abbreviations

	Primary THA			Revision THA			Primary TKA
	Costs, €	QALY gain	Cost per QALY gained, €	Costs, €	QALY gain	Cost per QALY gained, €	Costs, €	QALY gain	Cost per QALY gained, €
Base case analysis using
mean values	8,737	1.302	6,710	11,239	0.215	52,274	8,047	0.575	13,995
median values	8,516	0.751	11,340	10,793	0.215	50,200	7,345	0.441	16,655
SA varying the discount rate for QALYs
discount rate 5%		0.708	12,340		0.127	88,496		0.359	22,415
discount rate 3%		0.882	9,906		0.154	72,981		0.426	18,890
discount rate 1%		1.132	7,718		0.192	58,536		0.517	15,565
SA varying treatment effectiveness (QALY gain)
upper 95% CI		1.833	4,767		0.566	19,857		0.815	9,874
lower 95% CI		0.771	11,332		−0.136	^a		0.335	24,021
SA varying treatment costs
upper 95% CI	9,301		7,144	12,504		58,158	8,448		14,692
lower 95% CI	8,172		6,276	9,973		46,386	7,646		13,297

^a Can not be established