Comparing the number of antibiotic treated infections of primary and secondary immunodeficiency disease patients on immunoglobulin replacement therapy-preliminary findings in an Australian cohort

Abstract

Background: Immunoglobulin replacement therapy (IRT) in the form of intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg) is used to prevent recurrent severe infections seen in patients with primary immunodeficiency (PID) or secondary immunodeficiency disease (SID). While hypogammaglobulinaemia in PID is due to a genetic inability to produce functional Immunoglobulin G (IgG), hypogammaglobulinaemia in SID is secondary to malignancy or drug therapies. Aims: To compare the number of antibiotic treated infections for Australian adult SID vs PID patients over consecutive years of IVIg then SCIg treatment. Methods: This was a non-interventional retrospective study on a cohort of 14 PID and 13 SID patients treated at the Sunshine Coast Hospital and Health Service (SCHHS). Data was collected from medical charts at SCHHS and from patient's treating General Practitioners over their last year of IVIg and first year of SCIg treatment. IVIg was administered every 4 weeks and SCIg administered weekly with one quarter of the IVIg dose. Results: The total number of infections that required antibiotic treatment for the PID cohort over the year of IVIg was 31 infections, and for the year of SCIg treatment period were 25 infections. For the SID cohort there were 24 infections while on IVIg and 29 infections while on SCIg. Upper Respiratory Tract Infections (URTI) were the most frequent infection in both groups. For the PID cohort there were 15 episodes of URTI while on IVIg and 16 while on SCIg. Interestingly, for the SID cohort there were 8 episodes of URTI while on IVIg and 17 while on SCIg. The number of hospitalisations due to infection for PID patients were 4 on IVIg and 2 on SCIg, and for the SID patients 3 on IVIg and 1 on SCIg. Serum IgG trough levels were not available for all patients. Mean serum IgG levels for PID cohort while on IVIg was 8.8 g/l (n = 13) and 9.2 g/l while on SCIg (n = 9). In the SID cohort (n = 12) the mean serum IgG level was 7.1 g/l on IVIg and 8.2 g/l while on SCIg. Summary/Conclusions: There was a decrease in number of infections for the PID cohort when they switched from IVIg to SCIg. In contrast, there was an increase in number of infections when the SID cohort switch to SCIg. However, the significance of this finding is limited by the small sample size. Presently, there is very little published data on SID patients using SCIg, as most reports consist of a larger PID cohort combined with a small SID cohort. The results of this study, raises the question of whether clinical efficacy of switching SID patients from IVIg to SCIg can be based on findings from combined PID/SID cohorts. Therefore, a study of a larger cohort over a longer period is currently underway to confirm if SID patients do experience more infections while on SCIg, and to determine whether that is due to progression of underlying secondary disease or the different IRT treatment i.e. SCIg.L616917201 <br />