There might be a significant association between high grades of direct antiglobulin test (DAT) results and the severity of anemia, hemolysis, and jaundice in patients with autoimmune hemolytic anemia (AIHA), both warm and cold types such as cold agglutinin disease (CAD), according to a study published in the Asian Journal of Medical Sciences.
The researchers conducted a cross-sectional study on a sample of 50 AIHA patients between March 1, 2012, and August 31, 2013. Most participants belonged to the 31- to 40-year age group and there was a significant female predilection.
A large number of patients (56%) suffered secondary AIHA, and the most frequently reported underlying condition was systemic lupus erythematosus.
The researchers performed several immunohematological tests such as polyspecific and monospecific DAT, immunoglobulin (Ig) G subtyping, and thermal amplitude, as well as biochemical tests measuring hemoglobin, percentage of reticulocytes, total serum bilirubin, and serum lactate dehydrogenase. The values of these parameters were then analyzed using the Statistical Package for the Social Sciences (SPSS) version 17.
Read more about CAD diagnosis
According to the results, a large number of participants (46%) were grade 4 DAT positive. Higher grades of DAT positivity were associated with higher degrees of anemia, hemolysis, and hyperbilirubinemia.
“This finding may help in utilizing DAT as a simple diagnostic tool as well as a predictor for severity and also for monitoring treatment,” Sasikala and colleagues noted. “DAT is considered to be the hallmark in the diagnosis of AIHA and a very simple, quick, and inexpensive test.”
In 52% of analyzed samples, the researchers identified the presence of IgG autoantibodies, with IgG1 being the predominant subclass. The presence of C3d alone was detected in 18% of participants, while C3d and IgG together were found in 30% of patients.
About 48% of the participants developed the warm-type AIHA, 20% had the cold form of the disease, and 32% suffered from mixed-type AIHA. The majority of study participants (80%) were treated with only steroids, while a small number of them (16%) also received immunosuppressant therapy. Regardless of that, 4% of patients underwent splenectomy.
Read more about CAD therapies
“Majority of our study population had a warm type of AIHA and the warm type responded to steroids dramatically. IgG3 was more commonly associated with severe hemolysis and poor response to the treatment. Patients may have more hemolysis when their red cells are coated with more than one Ig class and subclass compared to a single class or subclass,” the study authors added.
AIHA, an immunological disease marked by symptoms of anemia and hemolysis, is caused by the development of autoantibodies directed toward the self-antigens on the surface of red blood cells.
Sasikala AP, Shahulhameed SP, Vilambil S, Chakrapani UK. Role of direct antiglobulin test in assessing the severity of extravascular hemolysis in autoimmune hemolytic anemia – analysis from a cross-sectional study. Asian J Med Sci. Published online March 1, 2023. doi:10.3126/ajms.v14i3.49833.