Background/Purpose: Leukopenia is a common manifestation of SLE. Addition of immunosuppressive therapy is of concern, in that it could worsen leukopenia; increase the risk of infection, or both. The aim of this study was to analyze the effect of mycophenolate on the white blood cell count and the rate of infection in SLE patients.

Methods: Three hundred patents within the Hopkins Lupus Cohort who were on mycophenolate mofetil were included in the study. SLE patients served as their own control (before and after mycophenolate mofetil). The white blood cell count and rate of infection were compared on the day mycophenolate was started with the white blood cell count and rate of infection at the next visit. Statistical analysis was performed using the paired t-test.

Results:

At the time of the analysis, three hundred patients in the cohort were taking mycophenolate mofetil. The study population included 43% Caucasians, 47% African-Americans and 10% other ethnicities. There was a slight but not statistically significant increase in the white blood cell count (6.65±3.34 vs. 7.02±3.28, P= 0.075), after starting mycophenolate. Patients with a baseline white blood cell count less than 3,000/mm³ did have a statistically significant increase in the white blood cell count after starting mycophenolate mofetil (2.49±0.46 vs. 4.83±2.66, P= 0.0007). In the multivariate model for factors associated with the white blood count, mycophenolate use was not statistically significant (Table 1). We also found a statistically significant increase in the rate of bacterial infection (but not viral infection) after starting mycophenolate mofetil (5% vs. 9%, P= 0.032, Table 2).

Table 1. Factors Associated with the White Blood Cell Count Adjusted for Ethnicity and Prednisone dose.

 

Variable	Effect on white blood cell Count	p-value
Ethnicity
African-American vs. Caucasian	-0.91±0.33	0.0049
Other ethnicity vs. Caucasian	-0.52±0.51	0.31
Prednisone (per mg/d)	0.07±0.01	<0.0001
Mycophenolate mofetil (before vs. after)	0.20±0.18	0.28

Table 2. Frequency of Infection Before and During the Use of Mycophenolate mofetil.

           

Variable	Before mycophenolate mofetil (%)	After mycophenolate mofetil (%)	Adjusted p-value*
Infection (viral or bacterial)	14	18	0.087
Viral infection	10	10	0.17
Bacterial infection	5	9	0.032

* p-value adjusted for prednisone dose.

Conclusion: Leukopenia does not worsen with mycophenolate. However, mycophenolate does increase the rate of bacterial (but not viral) infection.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effect-of-mycophenolate-on-the-white-blood-cell-count-and-the-frequency-of-infection-in-systemic-lupus-erythematosus/