Objectives This study aimed to determine if the drug-induced lymphocyte stimulation test (DLST) for various oral mesalamines can diagnose mesalamine intolerance and predict the success of retreatment in patients with adverse events (AEs) due to the first oral 5-aminosalicylate (5-ASA). Methods Data from patients with ulcerative colitis who experienced AEs after administration of the first oral 5-ASA and underwent DLSTs for two or more types of mesalamine, including the first oral 5-ASA were retrospectively analyzed. Mesalamine intolerance was defined as AEs within 6 months of starting the first oral 5-ASA and the inability to take oral mesalamine. Clinical characteristics, symptoms, type of first oral 5-ASA, DLST results, and the efficacy of retreatment with oral mesalamine were compared. The DLST for the first oral 5-ASA (F-DLST), highest DLST among the different oral mesalamine types (H-DLST), and mean DLST (M-DLST) were analyzed. Results Twenty-eight patients (median age 39 years, 57.1% male) were eligible. Six patients were tolerant to oral mesalamine, and 22 patients were intolerant. Positive F-DLST (odds ratio [OR], 2.300; p = 0.002), positive M-DLST (OR, 2.667; p = 0.007) and an older age at diagnosis (median 24.5 vs. 41.5; p = 0.006) were associated with mesalamine intolerance. Fourteen of the 28 patients underwent retreatment with mesalamine. Higher F-DLST (median 88.0 vs. 174.0; p = 0.026), M-DLST (median 118.5 vs. 170.3; p = 0.040), and older age at diagnosis (median 24.5 vs. 39.0; p = 0.033) were associated with retreatment failure for oral mesalamines. Conclusions DLST for various oral mesalamines and an older age at diagnosis are useful for diagnosing mesalamine intolerance and predicting retreatment efficacy in patients with ulcerative colitis.

The authors have declared no competing interest.

The author(s) received no specific funding for this work.

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The Ethics Committee of Tokyo Medical University School of Medicine approved this study (approval number: T2021-0352), and the study was conducted in accordance with the tenets of the Declaration of Helsinki.

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