Escalating medical costs have made it increasingly important to carry out economic evaluations of drug therapy. In the area of acid-related diseases, much of the current interest is focused on comparisons between omeprazole and H2 receptor antagonists. After having discussed the basic methodology used in these analyses, viz. the decision-tree analysis, this paper presents an extension of this methodology, the Markov chain approach, which is more appropriate for analyses of longer time periods. Thereafter, this methodology is used to analyze the cost-effectiveness of omeprazole in intermittent versus maintenance treatment of reflux esophagitis. The cost data are from Sweden and the time period studied is one year. It is found that maintenance treatment provides 63 more healthy days per year at an extra direct cost of SEK 40 per day. From a sensitivity analysis it is concluded that the cost-effectiveness of intermittent versus maintenance treatment is mainly determined by the probability of relapse when off treatment, the severity of the symptoms in the case of a relapse and the value to the patient of a healthy day, i.e. a day free from reflux esophagitis.
The clinical outcome and cost-effectiveness of episodic treatment of duodenal ulcer with omeprazole and ranitidine were evaluated over a 5-year period. The analysis was based on data from published clinical trials comparing healing rates obtained with omeprazole and with ranitidine, as well as on data from the literature on ulcer recurrence and other clinical events. Patients with an active duodenal ulcer were treated until healed or for a maximum of 24 weeks. Maintenance therapy was instituted in patients with ulcers that were very slow to heal and in patients with frequent relapses after cessation of treatment. Patients who experienced frequent relapses while receiving maintenance therapy, and those whose ulcer had not healed after 24 weeks of continuous treatment, were defined as candidates for surgery. A statistical model was set up and a random number generator used to generate a sequence of clinical events, month by month, over a 5-year period for each patient in a large cohort. Episodic treatment with omeprazole was shown to be more effective in avoiding maintenance treatment and surgery when compared with episodic treatment with ranitidine. Patients who received episodic treatment with omeprazole also spent more time in remission from disease. Using current Swedish cost data, it was found that episodic treatment with omeprazole was more cost-effective than episodic treatment with ranitidine.