The Kaplan and Meier and the Nelson estimate for the probability of ulcer recurrence 10 and 15 years after parietal cell vagotomy.

The use of a nonparametric estimate from incomplete observations is demonstrated on ulcer recurrence 10-15 years after parietal cell vagotomy in 339 patients with duodenal ulcer. The median period of observation was 108 months (range: 1-197 months). Proven recurrent ulcer developed in 62 patients. The life-table method as described by Kaplan and Meier and Nelson's modification are demonstrated. The calculated risk of recurrence after 10 years was 23% (+/- 3.8%) and after 15 years was 27% (+/- 4.3%). The rate of recurrence seemed to decline toward the end of the trial time.