Objective: Corticosteroids can cause psychiatric symptoms known as corticosteroid-induced psychiatric disorders (CIPDs). Little is known regarding the relationship between intravenous pulse methylprednisolone (IVMP) and CIPDs. Therefore, we aimed to examine the relationship between corticosteroid use and CIPDs in this retrospective study. Methods: Patients who were prescribed corticosteroids during their hospitalization at a university hospital and referred to our consultation-liaison service were selected. Patients diagnosed with CIPDs according to the ICD-10 codes were included. The incidence rates were compared between patients receiving IVMP and those receiving any other corticosteroid treatment. The association between IVMP and CIPDs was examined by classifying patients with CIPD into three groups according to the use of IVMP and timing of CIPD onset. Results: Of the 14,585 patients who received corticosteroids, 85 were diagnosed with CIPDs, with an incidence rate of 0.6%. Among the 523 patients who received IVMP, the incidence rate of CIPDs was 6.1% (n = 32), which was significantly higher than that in patients receiving any other corticosteroid treatment. Among the patients with CIPDs, 12 (14.1%) developed CIPDs during IVMP, 19 (22.4%) developed CIPDs after IVMP, and 49 (57.6%) developed CIPDs without IVMP. There was no significant difference in the doses at the time of CIPD improvement among the three groups when we excluded one patient whose CIPD improved during IVMP. Conclusion: Patients receiving IVMP were more likely to develop CIPDs than those who did not receive IVMP. Furthermore, corticosteroid doses at the time of improvement of CIPDs were constant, regardless of IVMP use.
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