¡¡¡¡Latanoprost was slightly more effective compared to travoprost and bimatoprost in all three Scandinavian countries. Based on shortª²term clinical trials the comparative ocular hypotensive efficacy of these medicines remains controversial. Some investigators have indicated that travoprost and bimatoprost demonstrate a slight superiority in ocular hypotensive effect than latanoprost while others have suggested that all three prostaglandins have similar efficacy[2]. However, our model added into the evaluation of the prostaglandins several longª²term factors not easily evaluable in a shortª²term trial. The most important factor that could have influenced longª²term efficacy in our model was the greater reported persistency of latanoprost compared to bimatoprost or travoprost. This explanation was suggested in that the effectiveness of the patients in the timolol maleate arm (the treatment chosen for nonª²persistent patients on a prostaglandin) was less than those patients who maintained their original prostaglandin therapy.

¡¡¡¡Cost sensitivity testing for the costs up to 15 of the latanoprost bottle, blindness and visits added little to the results in each country. The sensitivity testing was instructive, however, in that if the unit cost of latanoprost was reduced 10%ª²15% to a level comparable to travoprost and bimatoprost in Denmark then it would have also dominated these two prostaglandins for effectiveness and cost as it did in Sweden and Norway. Consequently, sensitivity testing helped confirm the assessment that the greater persistency of latanoprost allows the maintenance of the original prostaglandin therapy with the associated potential longª²term cost savings. Sensitivity testing for latanoprost control rates, however, showed this medicine failed to dominate with even 5% less absolute control (16%ª²21% reduced relative control). This finding shows the importance of control rates in the longª²term outcomes provided by a glaucoma medicine.
This study suggests that latanoprost provides a costª²effective alternative to other available prostaglandin analogs in Scandinavia. Importantly, the findings of this study are based on results from the literature and do not represent data from actual patients. This study did not evaluate the longª²term clinical effectiveness and cost of the prostaglandin analogs in a prospective, randomized, doubleª²masked manner. In addition, the model in order to limit over complexity had to make assumptions, such as a stable oneª²year period between health states. Such assumptions limit the accuracy of the Markov model to real clinical settings. Further, more detailed utility weights related to the various degenerative stages of glaucoma are needed to help create a more accurate Markov model for this disease state. Such data would help eliminate the assumption made for a midª²point progressed stage for glaucomatous progression. Hopefully, future research will better evaluate the longª²term cost and effectiveness differences between latanoprost, bimatoprost and travoprost.

¡¡¡¡Acknowledgements: The authors thank to a grant from Pfizer, Inc., New York, NY.

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