Prophylactic Antibiotics Versus Immunoglobulin Replacement in Specific Antibody Deficiency

To compare treatment outcomes in patients with specific antibody deficiency (SAD) who were treated with immunoglobulin replacement therapy (IGRT) and/or prophylactic antibiotics (PA).

This study included 65 patients with SAD (mean age 18, range 2–71 years old) who were treated with IGRT and/or PA at two tertiary care centers in the United States.

This was a retrospective chart review that evaluated clinical characteristics, laboratory findings, treatment patterns and clinical outcomes of patients with SAD who were treated with IGRT and/or PA. All patients were followed for a minimum of 1 year. Crude rate of infection within 1 year of treatment initiation was the primary outcome.

Among all SAD patients, the median number of infections per year was 5. The most commonly reported infections included sinusitis (65%), pneumonia (39%), otitis media (32%), and upper respiratory infections (23%). The majority of SAD patients were of the moderate phenotype (55%), while 23% had memory phenotype, 17% had severe, and 5% had mild. Almost half (45%) of patients were treated with IGRT, while 11% received PA, 11% received both PA and IGRT, 23% failed PA then switched to IGRT, and 11% did not receive treatment. There was no significant difference in infection rate in those treated with PA versus IGRT after 1 year of therapy. SAD phenotype was not predictive of infection rates within 1 year of treatment. Sixty percent of memory SAD patients failed PA and were switched to IGRT. Low baseline IgG level and presence of autoimmunity were predictors of persistent infection after 1 year of treatment.

IGRT and PA were equally effective as the first line preventative therapy in reducing infections in SAD patients. Patients who fail PA later benefited from IGRT.

SAD is a common primary immunodeficiency that classically presents with recurrent sinopulmonary infections. Treatment options for SAD includes PA and IGRT. This study found that IGRT and PA were equally effective in preventing infections in patients with SAD. SAD phenotype was not predictive of rates of infections within 1 year of treatment, and the decision to treat with PA versus IGRT was not dependent on the SAD phenotype. Patients who initially failed treatment with PA had a decrease in infections after switching to IGRT. Interestingly, a higher proportion of patients with memory SAD (60%) failed PA and were switched to IGRT. Baseline IgG level and presence of autoimmunity (most commonly thyroiditis in this cohort) were found to significantly impact the prediction of persistent infection. This study is limited by its small sample size, especially within SAD groups, making it challenging to identify significant differences.