Table 5.

Cost for a 1% improvement in mortality

				30-day cost			Nurse-adjusted 30-day cost
Patient group	N pairs	30-day mortality diff	P value	30-day cost diff (95% CI)	P value	Value estimate (95% CI)	30-day cost diff (95% CI)	P value	Value estimate (95% CI)
All general, orthopaedic and vascular surgery	62 715	−0.413%	<0.001	$317 ($172 to $461)	<0.001	$767 ($287 to $1248)	$840 ($694 to $987)	<0.001	$2035 ($1083 to $2986)
Risk quintile 1	12 762	0.039%	0.384	$20 (−$109 to $149)	0.762	Undefined	$229 ($97 to $363)	<0.001	Undefined
Risk quintile 2	12 567	−0.048%	0.423	$467 ($288 to $646)	<0.001	Undefined	$736 ($553 to $918)	<0.001	Undefined
Risk quintile 3	12 741	−0.141%	0.192	$515 ($269 to $761)	<0.001	Undefined	$960 ($712 to $1209)	<0.001	Undefined
Risk quintile 4	12 596	−0.484%	0.011	$212 (−$155 to $578)	0.257	$437 (−$426 to $1301)	$925 ($554 to $1296)	<0.001	$1910 ($159 to $3661)
Risk quintile 5	12 049	−1.486%	<0.001	$338 (−$273 to $949)	0.279	$227 (−$198 to $653)	$1407 ($784 to $2030)	<0.001	$947 ($290 to $1604)
All general surgery	15 390	−0.689%	0.003	$428 ($4 to $853)	0.048	$622 (−$127 to $1371)	$1300 ($869 to $1 732)	<0.001	$1887 ($510 to $3265)
All orthopaedic surgery	39 956	−0.328%	<0.001	$200 ($74 to $326)	0.002	$609 ($91 to $1127)	$579 ($450 to $708)	<0.001	$1766 ($726 to $2805)
All vascular surgery	7369	−0.299%	0.390	$716 ($137 to $1297)	0.015	Undefined	$1349 ($761 to $1935)	<0.001	Undefined

Note: The jackknife was used to estimate the SE of the value ratio and then applied to the point estimate of the value using the standard Wald interval (estimate ±1.96×SE). In cases where there was no significant difference in mortality, a value estimate is not produced and has been designated as ‘undefined’. diff, difference.