. Author manuscript; available in PMC: 2020 Apr 1.

Published in final edited form as: Health Econ. 2019 Jan 29;28(4):517–528. doi: 10.1002/hec.3860

Table 4.

Exploring treatment mix effect

	Instrumental Variables (IV) Analysis
Dependent Variable	Estimate (Robust Standard Error)
*Dosage adjustment*
Log (Frequency of dosage-adjusted drug claims)	−0.06(0.03)^**
Log (Drug spending per dosage-adjusted claim)	0.23(0.04)^***
*Changes in drug composition among lung cancer patients*
Use of high-cost drugs	0.14(0.05)^***
*By practice size*	*Size <= 2*	*2 < Size <= 6*		*Size > 6*
Log(Chemotherapy drug spending per claim)	0.35(0.11)^***	0.27(0.08)^***		0.19(0.14)^†
*By type of acquiring hospitals*	*Teaching*	*Non-teaching*	*340B*	*Non-340B*
Log(Chemotherapy drug spending per claim)	0.27(0.07)^***	0.33(0.08)^***	0.32(0.07)^***	0.28(0.07)^***

Notes: Oncologist fixed effects are included; Covariates controlled for in all models are year dummies, patient demographic characteristics, chronic condition indicators, cancer type, metastasis indicator, and ZIP-level socio-economic variables; Standard errors account for clustering within practices; Spending measures are adjusted to 2013 dollars;

^†

p=0.1

p < 0.10,

^**

p < 0.05,

^***

p < 0.01.