Pneumocystis jirovecii pneumonia in systemic autoimmune rheumatic disease: A case-control study.
Pneumocystis jirovecii pneumonia (PJP) is an opportunistic fungal infection that affects the immunocompromised. Patients with systemic autoimmune rheumatic disease are increasingly recognised as an at-risk clinical population with a high mortality. This case-control study examined differences in the characteristics and peripheral blood parameters between patients with systemic autoimmune rheumatic disease who developed PJP and gender, age and disease-matched controls.



Historical data collected between 2002 and 2013 at the Royal Melbourne Hospital, Australia were reviewed. Cases were defined by having a systemic autoimmune rheumatic disease and a diagnosis of PJP (either a positive toluidine blue O stain or P. jirovecii PCR, with a concurrent respiratory illness that was clinically consistent with PJP). Controls were matched for age, gender and disease in a 4:1 ratio. Peripheral blood results were retrieved from an in-house pathology database. Clinical information including glucocorticoid exposure, PJP prophylaxis, comorbidities and month of admission were retrieved from medical notes.



After adjustment for corticosteroid exposure and C-reactive protein, lymphocyte count on admission (0.4 vs. 1.3; p = 0.04) and at nadir (0.2 vs. 0.8 × 109/L; p = 0.05) was significantly lower in cases than in controls. Cases (n = 11) were more frequently Caucasian rather than non-Caucasian (81.8% vs. 65.9%; p = 0.04). In addition, cases more commonly presented in autumn (March to May) than in other seasons (OR = 7.3; 95% CI: 1.4-38.7; p = 0.02).



These data demonstrate that patients with systemic autoimmune rheumatic disease who develop PJP have significantly greater lymphopenia than age, gender and disease-matched controls, independent of corticosteroid exposure, as well as a potential ethnicity and seasonal predilection to PJP. This may help to inform prophylactic guidelines for PJP in these patients.
Department of Rheumatology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.
Susan
S
Tadros
Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Alfred Hospital, Monash University, Melbourne, Victoria, Australia.
Andrew J
AJ
Teichtahl
Department of Rheumatology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.
Sabina
S
Ciciriello
Department of Rheumatology, The Royal Melbourne Hospital, Parkville, Victoria, Australia; Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville 3050, Victoria, Australia; University of Melbourne, Department of Medical Biology, Parkville, Victoria, Australia. Electronic address: ian.wicks@mh.org.au.
Ian P
IP
Wicks
D000368:Aged; D001327:Autoimmune Diseases / Q000150:complications* / Q000276:immunology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D008297:Male; D008875:Middle Aged; D009894:Opportunistic Infections / Q000150:complications* / Q000276:immunology; D045363:Pneumocystis carinii / Q000302:isolation & purification*; D011020:Pneumonia, Pneumocystis / Q000150:complications* / Q000276:immunology; D012189:Retrospective Studies; D012216:Rheumatic Diseases / Q000150:complications* / Q000276:immunology
Immunocompromised; Lymphocyte; Pneumocystis jirovecii; Systemic autoimmune rheumatic