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Impact of Antidepressant Medication Adherence on Health Services Utilization and Cost


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Impact of Antidepressant Medication Adherence on Health Services Utilization and Cost

  1. 1. Impact of Antidepressant Medication on Health Services Utilization and Cost M. Christopher Roebuck Director, Health Economics Western Economic Association International 84 th Annual Conference June 30, 2009
  2. 2. Background and Objective <ul><li>National burden of depression estimated at $26.1 billion in 2000 1 </li></ul><ul><li>Per-patient costs declined from $4,100 in 1990 to $3,300 in 2000 1 </li></ul><ul><ul><li>Better diagnosis, more treatment options, and shift to primary care setting </li></ul></ul><ul><li>Could greater antidepressant medication use lead to even lower costs? </li></ul><ul><ul><li>Nearly ⅓ of antidepressant prescriptions are never filled (primary noncompliance) 2 </li></ul></ul><ul><ul><li>Nearly ½ of patients discontinue pharmacotherapy during the first month 3 </li></ul></ul><ul><li>Objective: To estimate the impact of use of and adherence to antidepressant medications on health services utilization and cost </li></ul><ul><ul><li>Greater use and adherence, by definition, should increase drug costs, and may also be associated with more physician visits and higher outpatient costs. </li></ul></ul><ul><ul><li>However, more costly inpatient hospital and emergency department visits may be lower resulting in lower total health care costs. </li></ul></ul>
  3. 3. Depression Clinical Practice Guidelines 4 <ul><li>Acute treatment phase </li></ul><ul><ul><li>Goal: Relieve symptoms, identify the right medication, optimize dose </li></ul></ul><ul><ul><li>Duration: 1-3 months </li></ul></ul><ul><li>Continuation of therapy phase </li></ul><ul><ul><li>Goal: Resolve depressive episode, prevent relapse </li></ul></ul><ul><ul><li>Duration: 4-9 months </li></ul></ul><ul><li>Long-term maintenance phase </li></ul><ul><ul><li>Goal: Prevent relapse </li></ul></ul><ul><ul><li>Duration: 3 months-5 years depending on # of lifetime episodes and comorbid anxiety </li></ul></ul>
  4. 4. Extant Literature * Mental health drug costs only -$376 $378 ≥ 90 days of continuous therapy Eaddy -$39 — MPR≥80% Cantrell $1,070 $86 * No gap of 15+ therapy days Thompson -$976 $1584 MPR≥70% White CDN $19 $219 ≥ 180 days of continuous therapy Tournier Annual Total Healthcare Costs Annual Pharmacy Costs Adherence Measure Primary Author
  5. 5. Data <ul><li>Integrated pharmacy and medical claims data from 9 PBM employer clients </li></ul><ul><li>Quarterly panel dataset of 9,208 individuals </li></ul><ul><li>With continuous eligibility throughout study period: 1/1/05–6/30/08 </li></ul><ul><li>Age≥18 </li></ul><ul><li>With depression diagnosis </li></ul><ul><ul><li>ICD9CM: 300.4x, 296.2x, 296.3x, 311.xx, 309.0x, 309.1x, 309.28 </li></ul></ul><ul><li>For each individual, included 4 consecutive quarters of data beginning with quarter of first depression diagnosis (in study period) prior to which at least 2 consecutive quarters of no depression diagnosis </li></ul><ul><ul><li>i.e., analyzing the first year of a new episode of depression </li></ul></ul>
  6. 6. Data <ul><li>Dependent Variables </li></ul><ul><li>Health Services Utilization: </li></ul><ul><ul><li>Quarterly Inpatient Hospital Days </li></ul></ul><ul><ul><li>Quarterly Emergency Department Visits </li></ul></ul><ul><ul><li>Quarterly Outpatient Hospital Visits </li></ul></ul><ul><ul><li>Quarterly Outpatient Physician Visits </li></ul></ul><ul><li>Health Services Costs: </li></ul><ul><ul><li>Quarterly Pharmacy Costs </li></ul></ul><ul><ul><li>Quarterly Medical Costs </li></ul></ul><ul><ul><li>Quarterly Total Healthcare Costs </li></ul></ul><ul><li>Independent Variables </li></ul><ul><ul><li>Optimally Adherent (0/1): Medication Possession Ratio (MPR)≥0.80 </li></ul></ul><ul><ul><li>Charlson Comorbidity Index </li></ul></ul><ul><ul><li>Vector of quarterly time dummies </li></ul></ul>
  7. 7. Methods <ul><li>To control for potential endogeneity of estimated fixed effects models to remove time-invariant, individual-level unobservables </li></ul><ul><ul><li>Hausman test rejected (p<0.01) in all cases </li></ul></ul><ul><li>Used conditional fixed effects Poisson models for 4 health services utilization measures </li></ul><ul><ul><li>Heteroskedasticity detected by modified Wald test (p<0.01) in all cases </li></ul></ul><ul><ul><li>Used robust standard errors </li></ul></ul><ul><li>Used linear fixed effects models for 3 health services cost measures </li></ul><ul><ul><li>Heteroskedasticity detected by modified Wald test (p<0.01) in all cases </li></ul></ul><ul><ul><li>Used robust standard errors </li></ul></ul><ul><ul><li>Note: as expected, costs data was highly skewed and kurtotic, thus still considering alternative specifications (e.g., gamma-log GLM models with fixed effects) </li></ul></ul>
  8. 8. Univariate Results 0.45 0.12 Quarterly Emergency Department Visits 9.77 1.79 Quarterly Inpatient Hospital Days 1.06 0.68 Charlson Index 0.19 0.04 Young Adult (Ages 18-24) 18.84 56.60 Male 0.48 0.34 Age 23,026 4,805 Quarterly Medical Costs 1,170 725 Quarterly Pharmacy Costs 2.68 2.34 Quarterly Outpatient Physician Visits 1.50 0.52 Quarterly Outpatient Hospital Visits 0.44 0.41 Medication Possession Ratio (MPR) 23,139 5,530 Quarterly Total Healthcare Costs 0.47 0.34 Optimally Adherent (MPR ≥ 0.80) S.D. Mean Variable
  9. 9. Bivariate Results: Health Services Utilization
  10. 10. Bivariate Results: Health Services Costs
  11. 11. Results: Fixed Effects Poisson Models of Health Services Utilization Quarterly Outpatient Physician Visits 1.06*** [0.10] <ul><ul><li>Optimally Adherent </li></ul></ul>1.16** [0.48] <ul><ul><li>Optimally Adherent </li></ul></ul>Quarterly Emergency Department Visits Quarterly Outpatient Hospital Visits 0.80** [-1.96] <ul><ul><li>Optimally Adherent </li></ul></ul>Quarterly Inpatient Hospital Days 1.07 [0.10] <ul><ul><li>Optimally Adherent </li></ul></ul>IRR [ME] <ul><li>Dependent Variable </li></ul><ul><ul><li>Independent Variable </li></ul></ul>
  12. 12. Results: Linear Fixed Effects Models of Health Services Costs -836** <ul><ul><li>Optimally Adherent </li></ul></ul>Quarterly Medical Costs Quarterly Total Healthcare Costs 190*** <ul><ul><li>Optimally Adherent </li></ul></ul>Quarterly Pharmacy Costs -646 (p=0.11) <ul><ul><li>Optimally Adherent </li></ul></ul>Coefficient <ul><li>Dependent Variable </li></ul><ul><ul><li>Independent Variable </li></ul></ul>
  13. 13. Conclusions <ul><li>Diagnosed patients adherent to antidepressant medication had fewer inpatient hospital days, but more emergency department & outpatient physician visits. </li></ul><ul><ul><li>Inpatient hospital days 20% lower among adherent patients </li></ul></ul><ul><ul><li>Emergency department visits 16% higher among adherent patients, but magnitude of visits relatively small </li></ul></ul><ul><ul><li>Outpatient physician visits 6% higher among adherent patients </li></ul></ul><ul><li>Overall, quarterly total healthcare costs $646 lower for the adherent (p=0.11) </li></ul><ul><ul><li>Highly skewed cost data should perhaps be more appropriately modeled using a log-transformation, gamma-log GLM, etc.; however with fixed effects. </li></ul></ul><ul><ul><li>Marginal effects presented are for the mean patient (arguably of interest to plan sponsor actuaries), but not necessarily applicable for the “average” individual. </li></ul></ul>
  14. 14. Policy Implications <ul><li>Programs and plan designs intended to increase antidepressant use and adherence for clinically diagnosed depression patients may be cost-saving for payers in terms of total healthcare costs, and may be particularly appealing to employers who might also realize productivity gains. </li></ul><ul><ul><li>Disease Management </li></ul></ul><ul><ul><li>Value-Based Insurance Design (i.e., reduced copays) </li></ul></ul><ul><li>Net economic benefits of antidepressants will likely increase with additional SSRIs scheduled to go generic. </li></ul><ul><li>Adherence to depression medications has been shown to be positively related to adherence to therapy for other conditions. 5 </li></ul>
  15. 15. Limitations <ul><li>Endogeneity still possible </li></ul><ul><ul><li>Reverse causality (e.g. no indexing) </li></ul></ul><ul><ul><li>Time-variant unobservables correlated with depression adherence and utilization/cost </li></ul></ul><ul><li>Unable to capture prescriptions dispensed within the hospital </li></ul>
  16. 16. Thank You! <ul><li>Comments and suggestions are welcomed . </li></ul><ul><ul><ul><li>M. Christopher Roebuck </li></ul></ul></ul><ul><ul><ul><li>CVS Caremark </li></ul></ul></ul><ul><ul><ul><li>Director, Health Economics </li></ul></ul></ul><ul><ul><ul><li>11311 McCormick Road, Suite 230 </li></ul></ul></ul><ul><ul><ul><li>Hunt Valley, MD 21031 </li></ul></ul></ul><ul><ul><ul><li>410-785-2136 </li></ul></ul></ul><ul><ul><ul><li>[email_address] </li></ul></ul></ul>
  17. 17. Sources <ul><li>1 Greenberg PE, Kessler RC, Birnbaum HG, et al. The economic burden of depression in the United States: how did it change between 1990 and 2000? J Clin Psychiat 2003; 64: 1465-1475. </li></ul><ul><li>2 Hutchins DS, Liberman JN, Popiel RG, et al. Uncovering noncompliance to prescribed drugs in several therapeutic classes [poster]. Academy of Managed Care Pharmacy 20th Annual Meeting and Showcase, April 18 2009, San Francisco. </li></ul><ul><li>3 Whooley MA, Simon GE. Managing depression in medical outpatients. NEJM 2000; 343: 1942-1950. </li></ul><ul><li>4 National Guideline Clearinghouse; . Accessed June 17, 2009. </li></ul><ul><li>5 Katon W, Cantrell CR, Sokol MC, et al. Impact of antidepressant drug adherence on comorbid medication use and resource utilization. Arch Intern Med 2005; 165: 2497-2503. </li></ul><ul><li>Literature review </li></ul><ul><li>Cantrell CR, Eaddy MT, Shah MB, et al. Methods for evaluating patient adherence to antidepressant therapy: a real-world comparison of adherence and economic outcomes. Med Care 2006; 44: 300-303. </li></ul><ul><li>Eaddy MT, Druss BG, Sarnes MW, et al. Relationship of total health care charges to selective serotonin reuptake inhibitor utilization patterns including the length of antidepressant therapy--results from a managed care administrative claims database. J Manag Care Pharm 2005; 11:145-150. </li></ul><ul><li>Thompson D, Buesching D, Gregor KJ, et al. Patterns of antidepressant use and their relation to costs of care. Am J Manag Care 1996; 2: 1239-1246. </li></ul><ul><li>Tournier M, Moride Y, Crott R, et al. Economic impact of non-persistence to antidepressant therapy in the Quebec community-dwelling elderly population. J Affect Disorders 2009 115: 160–166 </li></ul><ul><li>White TJ, Vanderplas A, Ory C, et al. Economic impact of patient adherence with antidepressant therapy within a managed care organization. Dis Manag Health Out 2003; 11: 817-822. </li></ul>