Aetiological factors of peptic ulcer: perspectives of epidemiological observations this century.

There are five known environmental, causative factors for peptic ulcer, namely, non-steroidal anti-inflammatory drugs (NSAID), Helicobacter pylori infection, cigarette smoking, environmental stress and dietary habit. There have been six factual, epidemiological observations on peptic ulcer this century: the rise and fall of ulcer frequency in Western societies; geographical variations in ulcer rates; in sex ratios; in duodenal: gastric ulcer ratios; and in placebo healing rates; and seasonal variation in ulcer frequencies. This report examines each of these epidemiological observations to see if each of the environmental factors can explain the observations. The secular trends and the variation in ulcer rates can be related to all the environmental factors. The sex ratios can be explained on the basis of cigarette smoking and environmental stress, whereas the duodenal: gastric ulcer ratios may be ascribed to NSAID use. Placebo healing and seasonal occurrence of ulcer is probably more related to environmental stress. Helicobacter pylori infection alone cannot explain the sex ratios, the duodenal: gastric ulcer ratios, the placebo healing and the seasonal occurrence of ulcer. Cigarette smoking or NSAID use alone does not tally with the seasonal variation of ulcer frequencies. Environmental stress alone does not fit into the recent fall of ulcer rates in Western countries. This report supports the concept of heterogeneity in peptic ulceration.