Prevalence of Hypogammaglobulinemia in Adult Invasive Pneumococcal Disease

Abstract

Background: Patients with humoral immune deficiency are susceptible to invasive pneumococcal disease (IPD). This study estimates the prevalence of underlying hypogammaglobulinemia in admitted IPD cases and examines whether IPD cases had received preventative treatment.

Methods: All adult IPD cases (Streptococcus pneumoniae in blood or cerebrospinal fluid) admitted to The Ottawa Hospital (TOH) from January 2013 to December 2015 were identified through the Eastern Ontario Regional Laboratory. Documented clinical demographics, S. pneumoniae serotype, serum immunoglobulins measured previously or in convalescence, and vaccination status of the cases were collected retrospectively for descriptive analyses.

Results: There were 134 IPD in 133 patients (47.4% male; mean age 63, standard deviation [SD] = 15.6 years) during a 3-year observation period. All-cause mortality rate was 22.6% over a mean follow-up time of 362, SD = 345 days. Fifty-seven patients (42.9%) had serum immunoglobulin levels measured. Eighteen were either found to have hypogammaglobulinemia in convalescence (8/18) or previously known to have hypogammaglobulinemia (10/18). None of the known hypogammaglobulinemic patients had received antibiotic prophylaxis and/or immunoglobulin replacement therapy within 4 months prior to IPD. The high and low estimates of prevalence of hypogammaglobulinemia were 31.6% (of all measured) and 13.5% (of all cases). Among 18 patients with hematological malignancies in our cohort, 13 had hypogammaglobulinemia. Many isolates were vaccine serotypes; however, only 8 had documented previous pneumococcal vaccination.

Conclusions: IPD has high mortality, and hypogammaglobulinemia was present in at least 13.5% of IPD cases. Secondary hypogammaglobulinemia is especially common in cases with hematological malignancy and IPD.

Keywords: Invasive pneumococcal disease; hypogammaglobulinemia; pneumococcal serotypes; pneumococcal vaccination; prevalence.