Table 7.

Total knee replacement economic results

	Difference (intervention – control) a
	N	Mean	(95 % CI)	P value
MAIN ANALYSIS: NHS and personal social services (PSS) perspective
Mean QALY gain	316	0.009	(−0.030 to 0.049)	0.64
Mean NHS+PSS Cost difference	316	–£77	(£–451 to £296)	0.68
Incremental net monetary benefit – lambda £10,000	316	£171	(£–452 to £793)	0.59
Incremental net monetary benefit – lambda £20,000	316	£264	(£–710 to £1,238)	0.60
Incremental net monetary benefit – lambda £30,000	316	£357	(£–992 to £1,707)	0.60
SECONDARY ANALYSIS: NHS perspective only
Mean QALY gain	316	0.009	(−0.030 to 0.049)	0.64
Mean NHS cost difference	316	–£74	(£–414 to £266)	0.67
Incremental net monetary benefit – lambda £20,000	316	260	(£–690 to £1,210)	0.59
SENSITIVITY ANALYSIS: using macro-costed prescribed medications
Prescribed medications b	316	–£14	(£–21 to £ –6)
Mean QALY gain	316	0.009	(−0.030 to 0.049)	0.64
Mean NHS+PSS cost difference	316	–£121	(£–491 to £249)	0.52
Incremental net monetary benefit – lambda £20,000	316	£308	(£–665 to £1,281)	0.53
SENSITIVITY ANALYSIS: 50 % higher local inpatient costs
Initial inpatient stay b	316	–£258	(£164 to £353)
Mean QALY gain	316	0.008	(−0.032 to 0.047)	0.70
Mean NHS+PSS cost difference	316	–£2	(£–483 to £478)	0.99
Incremental net monetary benefit – lambda £20,000	316	£159	(£–882 to £1,200)	0.76
SENSITIVITY ANALYSIS: 50 % lower local inpatient costs
Initial inpatient stay b	316	£84	(£–66 to £234)
Mean QALY gain	316	0.006	(−0.034 to 0.045)	0.79
Mean NHS+PSS cost difference	316	–£143	(£–423 to £137)	0.32
Incremental net monetary benefit – lambda £20,000	316	£253	(£–674 to £1,180)	0.59

^a All results are adjusted for minimisation variables, and baseline utility for QALYs, M=20 multiple imputation sets, bootstrapped confidence intervals with 1000 replications, except results noted with ^b

^b Unadjusted estimates with imputed data using M=20 multiple imputation sets