A Retrospective Database Analysis of Healthcare Resource Utilization in Patients with Warm Autoimmune Hemolytic Anemia in the United States
Authors: Jackson Louis , Pesa Jacqueline , Choudhry Zia , Ferrante Shannon , Campbell Alicia K , Piatek Caroline 
Published: December 2024

Background: Warm autoimmune hemolytic anemia (wAIHA) is a rare, life-threatening autoimmune disorder that is caused by autoantibodies and associated with an increased risk of morbidity and mortality (Jäger et al. Blood 2019). Assessments of healthcare resource utilization and outcomes in real-world patients with wAIHA in the United States (US) have been limited (Murakhovskaya et al. Ann. Hematol. 2024).

Objective: The objectives of this analysis were to describe patient demographics, clinical characteristics, and healthcare resource utilization (HCRU) among wAIHA patients in the 12 months prior to initial diagnosis (baseline period), and to describe HCRU in the 12 months after diagnosis (follow-up period).

Methods: This was a retrospective study of data sourced from HealthVerity, which consisted of large, de-identified US closed medical and pharmacy insurance claims databases. Patients were required to have one of the following between January 2019 and June 2023: ≥1 claim with a diagnosis code for wAIHA (International Classification of Diseases, 10th Revision, Clinical Modification [ICD-10-CM]: D59.11) in the primary billing position on an inpatient visit, ≥2 claims ≥30 days apart with D59.11 in any position, or ≥1 claim with D59.11 and ≥1 claim with a diagnosis code for AIHA (D59.1x) ≥30 days prior. The date of the first diagnosis was defined as the diagnosis date. Included patients were aged ≥18 years on the diagnosis date and had ≥12 months continuous enrollment in the dataset before diagnosis. Patients were excluded if they had ≥2 claims with diagnosis codes for cold or mixed type AIHA (ICD-10-CM: D59.12 or D59.13) ≥30 days apart at any time during the study period. Outcomes were assessed separately for cohorts of patients with secondary wAIHA (defined as ≥1 claim during the baseline period with ≥1 additional claim ≥30 days apart at any time during the study period with diagnosis codes for select hematologic, lymphoproliferative, immune, or inflammatory disorders or infections) and primary wAIHA (those without the specified conditions).

Results: 1,309 patients were included in the study (763 primary and 546 secondary wAIHA). Mean (SD) age was 50.3 (18.4) years and 65.9% were female. In the secondary wAIHA cohort, the most common defining conditions included systemic lupus erythematosus (25.9%), solid tumors (19.0%), immune thrombocytopenia (18.3%), chronic lymphoid leukemia (13.3%), and rheumatoid arthritis (10.9%). Mean (standard deviation [SD]) baseline Quan Charlson Comorbidity Index score was 1.7 (2.1) and 3.5 (2.8) in the primary and secondary wAIHA cohorts, respectively. During the 12-month baseline period and during the 12-month follow up period, respectively, the primary wAIHA cohort experienced a mean (SD) of 8.7 (30.2) and 8.3 (30.0) inpatient hospitalization days, 2.0 (4.4) and 2.1 (5.4) emergency department (ED) visits, 0.2 (0.5) and 0.2 (0.6) urgent care (UC) visits, 8.6 (12.6) and 13.7 (16.4) hospital outpatient visits, 2.5 (4.2) and 3.5 (6.1) specialist office visits, 0.3 (2.7) and 0.5 (3.7) skilled nursing facility days, and 1.2 (3.6) and 1.4 (4.2) telehealth visits. The secondary wAIHA cohort experienced a mean (SD) of 10.4 (23.5) and 8.3 (20.9) inpatient hospitalization days, 2.4 (3.7) and 2.3 (3.9) ED visits, 0.2 (0.6) and 0.3 (0.9) UC visits, 13.4 (17.7) and 17.7 (19.6) hospital outpatient visits, 4.3 (13.4) and 4.4 (12.0) specialist office visits, 0.2 (2.8) and 0.6 (4.0) skilled nursing facility days, and 1.8 (4.3) and 2.1 (7.0) telehealth visits during the 12-month periods before and after diagnosis, respectively.

Conclusions: This retrospective database analysis is among the first to evaluate a representative real-world sample of US patients with wAIHA. HCRU remained high in both 12-month periods preceding and following the initial wAIHA diagnosis. These findings suggest that wAIHA is associated with a high disease burden, and that opportunities remain to achieve greater disease control after initial wAIHA diagnosis.