Cost-effectiveness of converting non- sedating antihistamines from prescription to over-the-counter status Michael B. Nichol, Ph.D. Patrick Sullivan, Ph.D. (cand.) Department of Pharmaceutical Economics and Policy School of Pharmacy University of Southern California

Study Purpose Determine the cost-effectiveness of converting non- sedating antihistamines from prescription to over-the- counter status Identify the key assumptions of a cost-effectiveness model Vary the assumptions to determine the sensitivity of the model

Cost-effectiveness Models Cost-effectiveness models can provide insight into the relative costs and effects of health care interventions Principal outcome is an incremental cost-effectiveness ratio (ICER) The numerator is the incremental change in cost from the index treatment to the new treatment The denominator is the incremental change in life years saved (LYS) or quality-adjusted life years (QALYs) In the U.S., health care innovations that have an incremental cost-effectiveness of $50K/QALY is commonly adopted

Cost-Effectiveness Model Structure Perspective: Societal Period: One year Cohort: Adult population in the U.S. Index comparison: Prescription loratidine Impact: Effects of sedation on motor vehicle accidents Output: Incremental cost per quality-adjusted life year

Cost-effectiveness Model Structure

Key Base Case Assumptions VariableBase Case Value Reference Annual risk of collision0.109 Redelmeier DA, Weinstein MC. Medical Decision Making. 1999; 19:1-8 Relative risk of collision if sedated 4 O'Hanlon JF, Ramaekers JG. Allergy Simpson H. Journal of Alcohol Drugs and Driving Vinson DC, Mabe N, Leonard LL, et al. Archives of Family Medicine Weiler JM, Bloomfield JR, Woodworth GG, et al. Annals of Internal Medicine Risk of fatality if collision Calculated from data on: ncsa/factprev.html#1997 Risk of injury if collision0.183 Calculated from data on: ncsa/factprev.html#1997

Key Base Case Assumptions VariableBase Case Value Reference Percent of patients treated by MD 12% Malone DC, et al. Allergy Clin Immunol Given MD visit, percent of market share of non-sedating 80% Assumption OTC market share of non- sedating after conversion 50% Assumption Percent drop in non-sedating after conversion.183 Kalish SC, Bohn RL, Avorn J. Medical Care Percent of year on antihistamines 33% Schering-Plough Briefing Paper

Base Case Results The Incremental Cost-Effectiveness Ratio (ICER) for the base case analysis is a savings of more than $62,000 per quality- adjusted life year Using the same base case values, an alternative estimate produced a savings of more than $98,000 per life year saved

ICER Sensitivity Analysis: Percent Drop in Non-sedating Price After OTC Conversion Percent Cost/QALY Base Case 66% Drop $50K/QALY breakeven point: 27.5% drop

ICER Sensitivity Analysis: Percent of Patients Treated by MD Percent Cost/QALY Base Case: 12% Treated by MD

ICER Sensitivity Analysis: Non-sedating Market Share, Given MD Visit Percent Cost/QALY Base Case: 80% Rx Market Share

ICER Sensitivity Analysis: Effect of Rate of Sedation from Sedating Antihistamines Rate of Sedation Cost/QALY Base Case: 17% Rate

Study Assumptions One of the primary assumptions is that the population requiring antihistamine treatment is static (zero-sum trade- offs in utilization between sedating and non-sedating medications) –The availability of non-sedating medications over-the- counter may change the demand for these products –A change in price is likely to change the demand for these products

Future Analyses Impact of inappropriate treatment with OTC: –Likelihood of inappropriately self-treating –Likelihood of significant difference in physician managed treatment –Likelihood that inappropriate treatment would result in increased costs and decreased QALYs Modeling effect of OTC availability on price and demand Refining incremental QALY improvements due to availability of non-sedating antihistamine Impact on workplace productivity

Conclusions The present cost-effectiveness model provides preliminary evidence that converting non-sedating antihistamines to over-the-counter status would be cost-saving to society, whether expressed in terms of quality-adjusted life years or simply life years saved Additional factors should be incorporated into a final model to refine the estimates