Analysis of Antipsychotic Dosage in Patients With Tardive Dyskinesia: A Case-Control Study Using the Claims Database of the Corporate Health Insurance Association.

Purpose: This study aimed to assess the association between antipsychotic doses and the risk of tardive dyskinesia (TD) in clinical practice using a Japanese claims database from 2010 to 2020.

Methods: The study population included patients 15 years or older with a diagnosis record of schizophrenia, depression, or bipolar disorder who were prescribed antipsychotics. Using a case-control design, we categorized patients newly diagnosed with TD as cases, with corresponding 1:10 matching in the control group. The primary endpoint was the relative risk of TD in the >median dose and ≤median dose groups, as determined using conditional logistic regression analysis adjusted for age.

Results: The analysis population included 58,452 patients, and the median daily antipsychotic dose was 75 mg/d of chlorpromazine equivalent (CPZE). Of these, 80 were identified as TD cases, and doses >75 mg/d were associated with a significantly increased risk of TD at the last prescription and the maximum dose, respectively, before the date of the first diagnosis of TD. Post-hoc analysis further showed a significant association between doses ≥300 mg/d and the risk of TD compared to doses ≤75 mg/d and doses >75 to <300 mg/d. Comparing ≥300 mg/d versus >75 to <300 mg/d, the odd ratios at the last prescription and maximum dose before the first diagnosis of TD were 3.40 and 3.50, respectively.

Conclusions: In the Japanese medical claims database of patients receiving relatively low doses of antipsychotics, doses >75 mg/d were associated with an increased risk of TD in a dose-dependent manner.