Author: Ettner, Susan
Ongoing Project: Measuring the Structural Effect of Depression on Changes in Insurance Coverage
The goal of this research was to determine how the persistence of depression influences the rates of various types of health insurance coverage. Data came from the Partners in Care Study (PIC), a randomized controlled trial examining the effect of quality improvement (QI) programs involving medication or psychotherapy on the outcomes of initially depressed patients in seven managed care settings. Single-equation multivariate probit regressions were estimated to determine the association of depression burden days aggregated over the 6 to 24-month period post-baseline with the following dichotomous outcomes: continuous health insurance over 6 to 24 months; continuous private health insurance over 6 to 24 months; any public health insurance over 6 to 24 months; and more generous mental health care coverage at 24 months. To address the possibility of endogeneity bias in the relationship between depression and insurance, consistent estimates were derived from instrumental variables (IV) probit regressions and the endogeneity of depression burden days was tested. Evidence was found that depression burden days were exogenous to all of the health insurance outcomes except for more generous mental health care coverage. Based on the appropriate estimates (single-equation if exogenous, IV if endogenous), depression burden days appeared to increase the probability of having any public health insurance coverage and decrease the probability of having more generous mental health coverage. However, these effects were small in magnitude. Future analyses should examine the mediating factors in the relationship between depression and generosity of mental health coverage, e.g., diminished employment opportunities with large companies that offer more generous benefits.