ARE DUODENAL-ULCER SEASONAL FLUCTUATIONS PARALLELED BY SEASONAL-CHANGES IN 24-HOUR GASTRIC-ACIDITY AND HELICOBACTER-PYLORI INFECTION

The occurrence of duodenal ulcer is characterized by seasonal variatio n, for poorly understood reasons. No previous study has assessed wheth er 24-h intragastric acidity and Helicobacter pylori infection have si milar seasonal fluctuations in patients with this disorder. For this r eason, we evaluated retrospectively the circadian gastric pH in 319 ne w patients (226 men and 93 women, mean age 45.2 years) with endoscopic ally proven duodenal ulcer, who agreed to undergo this examination dur ing the years 1987-1992 in our center. The month-by-month occurrence o f the disease over the global 6-year period was assessed, and the mean pH values were calculated for each patient during three time interval s of interest: 24 h, daytime (08:00-19:59 h), and nighttime (20:00-07: 59 h). The mean pH values of these three time periods were then calcul ated month by month throughout the annual cycle. H. pylori infection w as sought by histology in 171 patients examined in the period from 199 0 to 1992. The percentage of H. pylori-positive duodenal ulcer patient s was then calculated for each season. The calendar fluctuation of duo denal ulcer occurrence showed an evident increase (p < 0.001) in fall (October-December) and in winter (January-March) compared with spring (April-June) and summer (July-September). Both 24-h and nighttime gast ric acidity showed no significant variation by month, whereas daytime gastric pH varied significantly (p < 0.05) with two evident decreases, meaning higher acidity, in April and August. H. pylori infection was detected in 152 of 171 patients (89%), and the percentage of H. pylori -positive duodenal ulcers did not differ from season to season. We con clude that there was no parallel circannual fluctuation of duodenal ul cer, gastric acidity, and H. pylori infection in the restricted sample of patients we studied. This reduces the apparent relevance of acid i n inducing ulcer seasonal fluctuation. Also, the responsibility of H. pylori in this phenomenon can be excluded until a reliable diagnostic method capable of distinguishing recent from old infection is found.