Delirium is a frequent and severe condition, especially in old adults. Its occurrence is due to a drug in 30% of cases. In 2009, the French national health authority (Haute Autorité de Santé) mentioned proton pump inhibitors (PPIs) among the drugs causing delirium. Most reports of delirium associated with PPI use in the literature are due to severe hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion. However, a few case reports have described the occurrence of delirium PPI without hyponatremia related to PPI use. In 2016, a prospective observational study including 675 old adults found an association between PPI use and the occurrence of delirium.

Evidence linking delirium and PPI use is thus scarce. By using data from the pharmacovigilance database of the World Health Organization (WHO), the investigators aim to describe the characteristics of delirium reports in which PPI were suspected to be involved, and to evaluate the association between PPI use and delirium, and the impact of hyponatremia in this association by performing a disproportionality analysis.

Inclusion Criteria:

• PPI use
• Delirium mentioned in the safety report

The investigators describe the profile of patients who are reported in the WORLD HEALTH ORGANIZATION Vigibase pharmacovigilance database, as having experienced a delirium. In particular, the number of patients who use proton pomp inhibitors (PPIs), the number of patients who presented associated illnesses known to induce delirium, the number of patients who presented associated drug prescriptions known to induce delirium.