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Does Higher Spending Improve Survival Outcomes for Myocardial Infarction? Examining the Cost‐Outcomes Relationship Using Time‐Varying Covariates
Author(s) -
Cohen Deborah,
Manuel Douglas G.,
Tugwell Peter,
Sanmartin Claudia,
Ramsay Tim
Publication year - 2015
Publication title -
health services research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 121
eISSN - 1475-6773
pISSN - 0017-9124
DOI - 10.1111/1475-6773.12286
Subject(s) - covariate , medicine , myocardial infarction , demography , econometrics , economics , sociology
Objectives Previous patient‐level acute myocardial infarction ( AMI ) research has found higher hospital spending to be associated with improved survival; however, survivor‐treatment selection bias traditionally has been overlooked. The purpose of this study was to examine the AMI cost‐outcome relationship, taking into account this form of bias. Data Sources Hospital Discharge Abstract data tracked costs for AMI hospitalizations. Ontario Vital Statistics data tracked patient mortality. Study Design A standard Cox survival model was compared to an extended Cox model using hospital costs as a time‐varying covariate to examine the impact of cost on 1‐year survival in a cohort of 30,939 first‐time AMI patients in Ontario, Canada, from 2007 to 2010. Principal Findings Higher patient‐level AMI spending decreased the hazard of dying (Standard Model: log‐cost hazard ratio: 0.513, 95 percent CI : 0.479–0.549; Extended Model: log‐cost hazard ratio: 0.700, 95 percent CI : 0.645–0.758); however, the protective effect was overestimated by 62 percent when survivor‐treatment bias was overlooked. In the extended model, a 10 percent increase in spending was associated with a 3.6 percent decrease in hazard of death. Conclusion The findings of this study suggest that if survivor‐treatment bias is overlooked, future research may materially overstate the protective effect of patient‐level spending on outcomes.