FRI481 Clinical Characteristics Of Neutropenic Patients Under Anti-thyroid Drug: A Retrospective Cohort Study In Taiwan

Disclosure: C. Tseng: None. C. Tseng: None. H. Chen: None. P. Chen: None. C. Huang: None. Background: Thionamide-induced agranulocytosis (TiA), is a rare adverse event with a reported incidence of around 0.1-1.75%. To reduce mortality, prompt recognition is critical but the differential diagnosis of TiA cases from non-TiA neutropenia can be challenging as other causes of neutropenia, such as concomitant chemotherapy, liver dysfunction or infection, may simultaneously exist. The present study aimed at investigating the possible factors associated with the development of TiA. Method: This is a retrospective cohort study of patients treated with anti-thyroid drugs (ATDs) in Taipei Veterans General Hospital from 2006-2018. Patients who developed a neutropenic event under treatment of ATDs were identified from the medical records. TiA was defined as (1) development of neutropenia under treatment or within 7 days of previous exposure to the same ATDs; (2) total recovery of neutropenia within one month after discontinuation of the culprit drug with absolute neutrophil count > 1500/μL; (3) exclusion of other causes for neutropenia. The incidence and risk factors for developing TiA were analyzed and compared to those with non-TiA neutropenia. Results: Among 6644 patients treated with ATDs, 66 (mean age, 53±15 years; 16.2% men) developed a neutropenic event and 20 were diagnosed with TiA (incidence: 0.3%). In univariate analysis, TiA was associated with shorter treatment duration, lesser cumulative ATD dosage, higher ATDs dosage, higher absolute neutrophil count and higher free T4 level at the time of the neutropenic event, compared to non-TiA neutropenia. After accounting for age, gender and time to neutropenia, ATDs dosage at the time of neutropenic event [odds ratio (OR) and 95% confident intervals (CIs): 635.47, 1.88-214562.36], free T4 level (OR and 95% CIs: 17.23, 1.02-290.58), and absolute neutrophil count (OR and 95% CIs: 1.00, 1.00-1.01) were still independently associated with TiA in multivariable logistic regression. Conclusions: TiA patients were more likely to have higher free T4 level, higher absolute neutrophil count at the time of neutropenic event and had received higher dosage of ATDs, compared to non-TiA cases. Presentation: Friday, June 16, 2023