Time-dependent association between omeprazole and esomeprazole and hospitalization due to hyponatremia

PURPOSE: The aim of this study was to explore the time-course of hospitalization due to hyponatremia associated with omeprazole and esomeprazole. METHODS: In this register-based case–control study, we compared patients hospitalized with a main diagnosis of hyponatremia (n = 11,213) to matched controls (n = 44,801). We used multiple regression to investigate time-related associations between omeprazole and esomeprazole and hospitalization because of hyponatremia. RESULTS: The overall adjusted OR (aOR) between proton pump inhibitor (PPI) exposure, regardless of treatment duration and hospitalization with a main diagnosis of hyponatremia, was 1.23 (95% confidence interval CI 1.15–1.32). Exposure to PPIs was associated with a prompt increase in risk of hospitalization for hyponatremia from the first week (aOR 6.87; 95% CI 4.83–9.86). The risk then gradually declined, reaching an aOR of 1.64 (0.96–2.75) the fifth week. The aOR of ongoing PPI treatment was 1.10 (1.03–1.18). CONCLUSION: The present study shows a marked association between omeprazole and esomeprazole and hyponatremia related to recently initiated treatment. Consequently, newly initiated PPIs should be considered a potential culprit in any patient suffering from hyponatremia. However, if the patient has had this treatment for a longer time, the PPI should be considered a less likely cause.