Table 2.

Comparisons of mean values of outcome variables by estimation method and treatment^*

Estimation method and treatment	Prostate cancer–specific death		All-cause death
	% died (95% CI)	Survival, mo (95% CI)	% died (95% CI)	Survival, mo (95% CI)
All patients (unweighted)	0.028	73.2	0.200	83.0
Observational (unweighted)
RP	0.025 (0.022 to 0.028)	75.0 (74.46 to 75.62)	0.177 (0.170 to 0.185)	85.1 (84.49 to 85.70)
CM	0.036 (0.030 to 0.041)	69.2 (68.38 to 70.05)	0.249 (0.237 to 0.263)	78.4 (77.57 to 79.33)
P for difference in means	<.001	<.001	<.001	<.001
PS reweighted (IPTW)
RP	0.026 (0.023 to 0.030)	75.2 (74.6 to 75.7)	0.185 (0.177 to 0.193)	85.1 (84.5 to 85.7)
CM	0.035 (0.029 to 0.040)	68.4 (67.6 to 69.2)	0.236 (0.223 to 0.248)	77.8 (76.9 to 78.7)
P for difference in means	<.001	<.001	<.001	<.001
PS reweighted (SMRW)
RP	0.030 (0.026 to 0.033)	75.4 (74.8 to 76.0)	0.203 (0.195 to 0.211)	85.2 (84.6 to 85.8)
CM	0.036 (0.030 to 0.041)	69.2 (68.4 to 70.0)	0.250 (0.237 to 0.263)	78.4 (77.6 to 79.3)
P for difference in means	<.001	<.001	<.001	<.001
Instrumental variable†
Less than median value of instrument	0.027 (0.023 to 0.031)	73.7 (73.05 to 74.41)	0.192 (0.183 to 0.201)	83.6 (82.94 to 84.35)
Median value of instrument or higher	0.030 (0.026 to 0.034)	72.7 (72.05 to 73.39)	0.208 (0.199 to 0.218)	82.4 (81.71 to 83.12)
P for difference in means	.351	.038	.012	.016
RCT (12 y of follow-up)‡
RP	0.131 (0.088 to 0.195)	NR	0.420 (0.350 to 0.505)	NR
CM	0.132 (0.089 to 0.196)	NR	0.393 (0.325 to 0.477)	NR
P for difference in means	NR		NR

^*A two-sided t test was used. CM = conservative management; IPTW = inverse probability of treatment weights; NR = not reported; PS = propensity score; RCT = randomized controlled trial; RP = radical prostatectomy; SMRW = standardized mortality ratio weights.

^†Lagged area treatment was the only instrument.

^‡Bill-Axelson et al. (29).