Table 2: Estimates of the effect of mastectomy relative to breast conserving surgery with radiation on 7-year survival by estimator and sample subsets1.

Estimator
Estimation Sample Mastectomy percentageLinear probability estimates2Instrumental variable estimates3
(1st5th quintile range)Mastectomy effect on 7-year survival (std. error)Instrument chow test [44] -valueOver
identification test -value
Mastectomy effect on 7-year survival (std. error)

Full sample28,67556.2 0.60
(37.9–68.6)(0.006)(0.029)
Trial status comparable4
 Yes5,00343.5 −0.001 50.43*0.570.05
(25.5–57.0)(0.010)(0.05)
 No23,67258.8 215.60*0.38
(40.4–71.1)(0.006)(0.03)
Stage
 Stage I17,90847.3 174.75*0.93 −0.02
(28.2–61.3)(0.006)(0.03)
 Stage IIa7,70067.2 63.02*1.28
(50.3–78.5)(0.011)(0.06)
  Stage IIb2,82780.2 23.81*2.03 −0.22
(66.4–88.7)(0.023)(0.13)
Age
 66–708,03750.9 −0.010 75.53*1.990.02
(33.5–64.3)(0.009)(0.05)
 71–758,40551.4 −0.016 81.82*0.15 −0.05
(31.4–64.1)(0.010)(0.05)
  76–806,61157.5 69.94*0.42 −0.11
(39.9–71.2)(0.012)(0.06)
  81+5,62269.2 37.15*1.06
(52.3–78.6)(0.015)(0.09)

1All models also specified all measured covariates listed in the variable definition section and are more fully described in Keating et al. [8].
2Average treatment effect on the treated (ATT). In this case, average effect of mastectomy on 7-year survival for those patients choosing mastectomy.
3Local average treatment effect (LATE). The average effect of mastectomy on 7-year survival for those patients whose mastectomy choice would have changed with local area mastectomy practice style.
4ESBC patients with low-risk tumors (stage ), little comorbid illness, and age ≤ 70.
.