Serious infections in systemic lupus erythematosus with a focus on pneumococcal infections

Background: Infections are important denominators of morbidity and mortality in patients
with systemic lupus erythematosus (SLE). Pneumococcus pneumoniae has been identified as a
relatively frequent cause of serious infections in SLE and vaccination against this pathogen is
possible. We analysed the incidence of serious infections in a cohort of SLE patients, focussing
on Streptococcus pneumoniae. Methods: We retrospectively screened the medical records of all
SLE patients who were regularly seen in the outpatient clinic of our department between
January 2010 and December 2012. We registered all infections that necessitated admission
to the hospital (serious infection) and compared relevant clinical and laboratory parameters
and immunomodulating/immunosuppressive treatment in patients with and without serious
infections. Results: In the total cohort of 260 patients, there were 132 episodes of serious
infection in 70 patients, with a median follow-up per patient of 11.4 years (range 0 to 50.2
years). S. pneumoniae accounted for 11/132 (8.3%) serious infection episodes and eight of
11 episodes were invasive. With a follow-up of 3970.6 years for the total cohort, this leads
to an incidence of 201/100.000 patient-years. In the multivariate analysis neither clinical parameters
nor use of immunosuppressive drugs correlated with occurrence of serious
infections. Conclusions: Compared to the incidence of invasive pneumococcal infections in
the Dutch population (15.6/100.000 patient years), the incidence in SLE patients is 13 times
higher. This, in combination with the absence of a relation to use of immunosuppressive drugs,
is a strong argument to recommend vaccination against S. pneumoniae in all SLE
patients.