Moral Hazard and Less Invasive Medical Treatment for Coronary Artery Disease

To test whether less invasive medical technologies induce moral hazard at the individual level we study how changes in patient smoking and alcohol drinking behaviors are related to three common treatments for Coronary Artery Disease (CAD): medical management, Percutaneous Coronary Intervention (PCI), and Coronary Artery Bypass Graft (CABG).  In this paper, we test one hypothesis that may explain why CABG patients have relatively good long-term outcomes, despite a higher surgical complication rate.  Specifically, we expect that the more invasive nature of CABG surgery – a patient is in the hospital for a week, has a longer post-operative recovery period, and is left with a major scar and residual pain from the sternectomy long after the procedure – sends a stronger signal to the patient that he as a serious health problem.  As a result, we hypothesize that a patient who undergoes CABG rather than PCI is more likely to change his behavior in a way that promotes good health and a longer life: he is more likely to quit smoking, begin exercising, improve his diet, and avoid excessive alcohol intake.

We employ the Health and Retirement Survey linked to respondents’ Medicare claim files for this analysis.  We find that while having PCI does not have a statistically significant impact on quitting smoking or drinking, CABG does.  Neither procedure appears to have a statistically significant impact on changes in the quantity or frequency of alcohol consumption.  To be precise, those smokers who receive CABG are about 30 percentage points more likely to quit smoking by the wave following treatment.  Those who drink alcohol are about 7 percentage points more likely to quit drinking by the wave following treatment.

We then demonstrate that long term outcomes, such as mortality, appear to differ systematically with treatment invasiveness in a way that interacts with behavior change. We discuss the implications these findings have in the context of comparative effectiveness research.  Overall our results indicate that those who have more invasive treatment are more likely to quit smoking and quit drinking, that this impacts long term health outcomes, and together has implication for policy surrounding comparative effectiveness research, which to date has largely ignored the role of systematic differences in post- treatment patient behavior change.