OBJECTIVES: Using prescription claims data, the primary objective of this study was to evaluate whether utilization differed among various plan characteristics after controlling for covariates. The secondary objective was to examine the relationships among plan characteristics and cost of pharmaceuticals within various therapeutic categories. METHODOLOGY: Data were obtained from 1996 prescription claims information for the commercial population administered by a Rhode Island-based PBM. There were 29,211 subscribers representing 64,815 enrollees eligible during 1996. Six therapeutic categories were analyzed. Statistical analyses utilizing multiple regression and analysis-of-covariance were performed. RESULTS: Significant associations (p<0.001) were found between plan characteristics and cost of pharmaceuticals. Utilization differed (p<0.0001) among various plan characteristics such as co-payment, mode of payment, formulary status and pharmacy type after controlling for average wholesale price and days supply. CONCLUSIONS: Results obtained in this study may be helpful in understanding some of the factors associated with cost of pharmaceuticals. For example, the inverse relationship of pharmaceutical cost with eligible days may be helpful in budgeting program costs while the non-significant association of pharmaceutical cost with number of members eligible suggests a lack of importance of group size in negotiating pharmacy benefit contracts. Differences in utilization among various co-payment levels suggest the effectiveness of different co-payment levels in promoting use of generic products. Lower utilization found under capitation may be encouraging to those PBMs accepting a capitation method of reimbursement. Association of closed formularies with higher utilization indicates the importance of adjusting cost data for rebates before evaluating formulary strategies. Finally, differences in utilization between independent and chain pharmacies suggest the importance of careful provider contract negotiation. “OUTCOMES (QUALITY OF LIFE) RESEARCH METHODS ISSUES” POR 1 METHODLOGY FOR DEVELOPING AN INDEX SCORE FOR BOTHERSOMENESS OF ADVERSE EVENTS Becker LA1, Cramer JA2, Ashraf T1; 1Abbott Laboratories, Abbott Park, Il, USA; 2Yale University, New Haven, CT, USA Measures of adverse effect frequency and severity do not accurately depict patient’s tolerability to an illness and/or a treatment. The adverse effect frequency model is also a weak predictor for tolerability and compliance. Additional multi-dimensional variables are required to fully assess the impact on quality of life which can be used as explanatory variables to develop an index for bothersomeness to predict tolerability and hence compliance to therapy. OBJECTIVE: To develop a methodology for developing an index of bothersomeness. METHODS: Data on bothersomeness were collected on 50 patients participating in a randomized, placebo-controlled clinical trial. At baseline and final visits, patients completed a questionnaire designed to capture the frequency and bothersomeness of the impact of illness on seven domains of quality of life. Regression methods were used to test the response to bothersome scale for linearity. Additive and predictive models were used to convert the scale to a domain summary scores and hence a composite index for patient bothersomeness. Finally multivariate models (stepwise procedure) were used with clinical and demographic variables as predictor and composite index derived from additive and predictive methods as dependent variables to estimate observed variance and model fit. RESULTS: An index scores for bothersomeness was estimated using the additive and predictive methods using data collected over time on 50 patients participating in a clinical trial with the best model fit. CONCLUSION: The methodology used to calculate the bothersome index can be used in other disease and treatment modalities. The index scores may be used to better describe patient’s tolerability, therefore improving the communication between patient and physician when discussing the treatment or illness impact on patients’ quality of life.