Background: As defined by the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, medication therapy management programs (MTMPs) must be designed to decrease adverse drug events and improve patient outcomes by promoting appropriate medication use. WellPoint Inc. contracted with the pharmacist-run University of Arizona College of Pharmacy Medication Management Center (UA MMC) to provide a pilot telephone-based MTMP to approximately 5,000 high-risk beneficiaries from among its nearly 2 million Medicare prescription drug plan (PDP) beneficiaries. Eligibility for the program was determined by a minimum of 2 of 6 chronic diseases (dyslipidemia, cardiovascular disease, depression, diabetes mellitus, congestive heart failure, and chronic obstructive pulmonary disease; at least 1 of the latter 2 diseases must be present), at least 3 Part-D covered medications, and greater than $4,000 per year in predicted drug spending. In addition to these criteria, WellPoint Inc. used the Johns Hopkins adjusted clinical groups (ACG) predictive model to identify the high-risk beneficiaries to be enrolled in the program. Medication therapy reviews were conducted for these patients. If any medication-related problems (MRPs) were identified, the patient's prescribers were contacted via a fax communication with recommendation(s) to resolve these MRPs. The UA MMC fax interventions were categorized as cost saving, guideline adherence, or safety concerns., Objectives: To (a) determine prescriber responses to pharmacist-initiated recommendations in an MTMP for the 3 intervention categories, (b) compare prescriber responses between intervention categories, and (c) compare prescriber response by prescriber type (primary care physician [PCP] vs. specialist) within each intervention category., Methods: A retrospective analysis of pharmacist-initiated interventions from August through December 2008 was performed using data collected from the UA MMC database. Data were collected on intervention category (cost saving, guideline adherence, or safety concerns), and responses of prescribers were recorded as either approval or decline (no response was considered decline). Prescriber specialty was identified from searching records of state medical boards. Logistic regression analyses with the robust variance option to adjust for correlation within prescribers were conducted to compare prescriber approval rates between and within intervention categories. Significance was assessed at alpha 0.05., Results: Of 4,967 Medicare Part D beneficiaries determined to be MTMP-eligible, 4,277 beneficiaries (86.1%) were available for assessment (400 declined, 186 disenrolled, and 104 were deceased). Pharmacists initiated 1,548 valid medication recommendations (i.e., recommendations were excluded for deceased patients, incorrect prescribers, and where prescriber specialty was not identified). These recommendations for 1,174 beneficiaries (27.5% of those available) were faxed to prescribers requesting approval. Mean (SD) age for beneficiaries having recommendations was 72.9 (9.4) years, and the majority (57.6%) was female. By category of recommendation, 58.3% (n=902) were guideline adherence, 33.3% (n=515) were cost saving, and 8.5% (n=131) were safety concerns. Prescriber approval rates were 47.2% overall (n =731/1,548), 41.4% (n=373/902) for guideline adherence, 58.3% (n=300/515) for cost savings, and 44.3% (n=58/131) for safety concerns; 817 recommendations were not approved by prescribers (n= 255 [16.5%] denials and 562 no response [36.3%]). Prescriber approval was significantly higher for cost-saving interventions compared with guideline adherence interventions (odds ratio [OR]=1.98, 95% CI=1.56-2.51, P< 0.001) and compared with safety interventions (OR=1.76, 95% CI=1.19, 2.59, P=0.004); there was no significant difference in the prescriber approval rates for the interventions for safety versus guideline adherence. The overall approval rate was higher for PCPs (49.8%, n=525/1,054) versus specialists (41.7%, n=206/494; OR=1.39, 95% CI=1.08-1.78, P=0.011) and for the category for guideline adherence interventions (44.0% for PCPs vs. 35.9% for specialists; OR =1.40, 95% CI=1.01-1.95, P=0.044), but not for the other 2 intervention categories., Conclusions: Prescriber approval rates for pharmacist recommendations for drug therapy changes for MTMP beneficiaries were approximately 47% overall and higher for recommendations that involved cost savings compared with recommendations for safety concerns or guideline adherence. Compared with specialists, PCPs had higher approval rates for pharmacist recommendations overall and for the intervention category guideline adherence., Competing Interests: The authors report no financial or other conflicts of interest.