Medication adherence leads to lower health care use and costs despite increased drug spending

Health Affairs

Volumn 30, Issue 1, 2011, Pages 91-99

  Roebuck, M Christopher ^a   Liberman, Joshua N ^a   Gemmill Toyama, Marin ^b   Brennan, Troyen A ^a  

^a CVS Caremark   (United States)

^b CENTERS FOR MEDICARE AND MEDICAID SERVICES   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

AGED; ARTICLE; CONGESTIVE HEART FAILURE; CONTROLLED STUDY; COST BENEFIT ANALYSIS; COST CONTROL; DIABETES MELLITUS; DYSLIPIDEMIA; EMERGENCY WARD; FEMALE; GOVERNMENT; HEALTH CARE COST; HEALTH CARE POLICY; HEALTH CARE UTILIZATION; HEALTH INSURANCE; HOSPITALIZATION; HUMAN; HYPERTENSION; MAJOR CLINICAL STUDY; MALE; META ANALYSIS; PATIENT COMPLIANCE; PHARMACY; VASCULAR DISEASE;

CHRONIC DISEASE; HEALTH EXPENDITURES; HEALTH SERVICES; HUMANS; INSURANCE CLAIM REVIEW; MEDICATION ADHERENCE; MODELS, ECONOMETRIC; PATIENT PROTECTION AND AFFORDABLE CARE ACT; PHARMACEUTICAL SERVICES; UNITED STATES;

EID: 79951624338     PISSN: 02782715     EISSN: 15445208     Source Type: Journal    
DOI: 10.1377/hlthaff.2009.1087     Document Type: Article

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21. To make our inferences robust in spite of heteroskedasticity-non-constant variances-across panels, serial correlations within panels, and cross-sectional dependence, we used the standard errors recommended by John Driscoll and Aart Kraay. Driscoll JC, Kraay AC. Consistent covariance matrix estimation with spatially dependent panel data. Rev Econ Stat. 1998;80(4):549-60.
22. See Appendix Section 2 (see Note 17) for a comparison of our linear fixed-effects models to pooled ordinary least-squares estimation. This exercise largely confirms the endogeneity of adherence and shows that prior studies probably overestimated the absolute value of the impact of adherence on health services use and cost.
23. Fixed-effects modeling does not allow for the control of confounders that vary over time. Thus, for example, if patients who become adherent simultaneously start exercising regularly (assuming that both of these behavioral changes reduce health services use and spending), the estimated impact of adherence would remain biased. Another drawback of the linear fixed-effects modeling approach is that it leaves open the possibility of reverse causality. That is, the reported relationships could indicate an impact of hospitalization on adherence. For example, a hospitalization may shock a patient into becoming adherent. We examined this possibility by estimating the impact of prior adherence on hospitalization and found no effect.
24. Bivariate relationships between adherence and health services use and spending are presented in Appendix Table A4 (see Note 17). The complete set of linear fixed-effects model results are provided in Appendix Tables A5-A10.
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28. Of course, there would certainly be some administrative fixed cost involved in implementing value-based insurance design, and lower copayments might have moral-hazard costs. That is, with low or no out-ofpocket spending required, patients might be induced to fill more prescriptions than necessary, possibly for consumption by other patients with higher copayments.