Numbers of recurrences on each dose of ranitidine, and in smokers and non-smokers were compared using Fisher's exact test. Cumulative recurrence rates were calculated using the product limit life table method. Patients who were withdrawn from the study for reasons other than ulcer relapses were included in analysis up to the time of the last valid endoscopic examination. Differences were deemed statistically significant if p was less than 0.05 for a two tailed test.

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