Safety of pyrazinamide in elderly patients with tuberculosis in Japan: A nationwide cohort study.

Background and objective: Pyrazinamide (PZA) is the standard first-line treatment for tuberculosis (TB); however, its safety in elderly patients has not been thoroughly investigated.

Methods: This retrospective study used data from the Japanese Diagnosis Procedure Combination inpatient database. We identified patients who were admitted for TB between July 2010 and March 2022. Patients were categorized into HRE (isoniazid, rifampicin and ethambutol) and HREZ (isoniazid, rifampicin, ethambutol and PZA) groups. Primary outcomes included in-hospital mortality and overall adverse events (characterized by a composite of hepatotoxicity, gout attack, allergic reactions and gastrointestinal intolerance). Secondary outcomes included the length of hospital stay, 90-day readmission and use of drugs related to the primary outcome adverse events. Data were analysed using propensity score matching; we also conducted a subgroup analysis for those aged ≥75 years.

Results: Among 19,930 eligible patients, 8924 received HRE and 11,006 received HREZ. Propensity score matching created 3578 matched pairs with a mean age of approximately 80 years. Compared with the HRE group, the HREZ group demonstrated a higher proportion of overall adverse events (3.1% vs. 4.7%; p < 0.001), allergic reactions (1.4% vs. 2.5%; p < 0.001) and antihistamine use (21.9% vs. 27.6%; p < 0.001). No significant differences were observed regarding in-hospital mortality, hepatotoxicity or length of hospital stay between the groups. Subgroup analysis for those aged ≥75 years showed consistent results.

Conclusion: Medical practitioners may consider adding PZA to an initial treatment regimen even in elderly patients with TB.