The Natural History of Cold Agglutinin Disease
Authors: Swiecicki Paul L , Hegerova Livia , Gertz Morie A 
Published: October 2019

Abstract
Abstract 5152

Introduction:
Cold agglutinin disease (CAD) is a rare and poorly understood disorder accounting for 15% of patients with autoimmune hemolytic anemia. Treatment has been largely controversial with few studies addressing safety and efficacy of various treatment regimens. This study reports a single institution's experience with cold agglutinin disease, defines the clinical features, prognosis and management.

Methods:
A retrospective analysis of Mayo Clinic medical records since 1960 was performed to identify all cases of CAD. Initial appraisal identified 89 patients after which an in depth review of clinical notes, laboratory evaluations, and treatment regimens was performed. Statistical analysis was performed via descriptive statistics and Kaplan-Meier survival.

Results:
The median age at onset of symptoms was 65 years (range: 40, 82), while the median age at diagnosis was 72 (42, 91). The most common sign at presentation was anemia (38. 4%). The most common symptom during the course of disease was similarly finger discoloration (43. 8%). Over half of patients had symptoms that were triggered by a cold environment (52. 8%) and a minority (22. 5%) had exacerbations precipitated by other factors. The median time from onset of symptoms to time of disease diagnosis was 37 months (0, 374). The majority of patients had an underlying hematologic disorder (48. 3%) of which the most common was monoclonal gammopathy of undetermined significance. At diagnosis the average hemoglobin was 10. 2 (6. 2, 17. 7) with positive coombs testing in 75% of patients. All patients had documented positive cold agglutinin titers.
Approximately 40% of patients received transfusions at some point during their disease course and 83% needed drug therapy at some point. The most common reason to initiate drug treatment was progressive anemia (44. 9%). In 15% of patients, CAD was able to be managed with watchful waiting. The median duration between initial symptoms to initiation of treatment was 60 months. 56. 2% and 33. 7% of patients required second and third line therapy respectively. Treatment characteristics and responses are displayed in Table 1. Rituximab showed the longest duration of response and had the lowest percentage of patients needing further treatment, while 4 out of 5 patients on prednisone required additional therapies.
Median survival in all patients with CAD was 127. 5 months and 76. 9% of patients were alive at 5-years after diagnosis (Figure 1).

Conclusions:
This is the largest study of patients with cold agglutinin disease to date. Symptoms were frequently ill-defined resulting in delay of diagnosis. Although drug therapy was frequently indicated, many patients were successfully observed. New treatment agents including Rituximab demonstrate promising response rates compared to traditional regimens, especially in patients with underlying hematologic abnormalities. These results support consideration of CAD as part of the differential diagnosis in the setting of new onset anemia and re-enforces the importance of evaluation for underlying B Cell abnormality in this patient population.

Disclosures:
Off Label Use: Rituximab, Cyclophosphomide, Chlorambucil, and Prednisone will be discussed as therapy modalatities for the treatment of cold agglutinin hemolytic anemia.