OBJECTIVES Tamsulosin Ocas (oral controlled absorption system) is an improved formulation of tamsulosin modified release (MR) capsules, providing a smoother 24h plasma concentration profile, improved Cmax/C24h ratio, and independence from oral food intake [1]. The formulations are similarly effective, but tamsulosin Ocas is associated with a lower incidence of orthostatic hypotension and abnormal ejaculation [2,3]. Our objective was to determine if patients preferred tamsulosin Ocas over tamsulosin MR. METHODS Discrete Choice Analysis based on 12 hypothetical paired scenarios was used to compare patient preferences in 50 men aged ≥45 years with LUTS/BPH. Each scenario included convenience of administration with/without food, frequency of orthostatic hypotension, ejaculatory dysfunction, and out-of-pocket expenses; one mandatory pair tested for irrationality. Disease severity and health-related quality of life were assessed by IPSS and EuroQol EQ-5D. RESULTS 56% of the trial population had moderate and 26% had severe symptoms on IPSS scores; mean EQ-5D was 0.78. Five respondents with irrational responses were excluded. Respondents were significantly more likely to prefer tamsulosin Ocas over MR overall (OR 19.45; 95% CI 6.27, 60.39; p<0.001). Orthostatic hypotension was the most important factor driving this preference (OR 9.07; 95% CI 4.61, 17.82; p<0.001). On average, participants would have been willing to pay an extra 72.00GBP per month (range 32.40-144.40) for tamsulosin Ocas over MR; orthostatic hypotension contributed 76% to the choice for overall WTP. CONCLUSIONS There was a strong patient preference for tamsulosin Ocas over tamsulosin MR that was primarily driven by the orthostatic hypotension attribute. This preference equated to patients being willing to pay about 72GBP more per month for tamsulosin OCAS; the actual cost differential between the two formulations is 11.27GBP. REFERENCES: [1] Chapple CR, Chartier-Kastler E. BJU Int 2006;29Suppl.):S9-12.; [2] Chapple CR, et al. Eur Urol 2005;4(Suppl.):S33-44; [3] Michel MC, et al. Eur Urol 2005;4(Supp.):S53-60.