Lymphopenia as an Independent Marker of Disease Activity in Children with Systemic Lupus Erythematosus.

Background

Lymphopenia is associated with disease activity in adult patients with systemic lupus erythematosus (SLE), but no similar studies exist among children. Furthermore, lymphopenia has only been used as a parameter of disease activity in the SLE disease activity index (SLEDAI), but not as an independent marker.

Objectives

This study aimed to ascertain lymphopenia as an independent marker related to disease activity in children with SLE.

Methods

This was a retrospective cohort study on patients newly diagnosed with SLE. The data were collected from January 2009 to March 2017, including clinical manifestations, complete blood counts, anti-dsDNA, and Mexican-SLEDAI (MEX-SLEDAI) scores. Statistical analysis was performed using the Chi-square test, Student's t-test, and ROC curve analysis.

Results

A total of 103 patients, aged from 12 to 18 years, participated in the study. Of these, 58 patients (56.3%) exhibited lymphopenia. The most commonly observed clinical manifestations in the lymphopenia group included nephritis (72.4%), hypertension (24.1%), and leukopenia (36.2%), with p < 0.05. Furthermore, neuropsychiatric SLE was found exclusively in the lymphopenia group. A negative correlation was observed between lymphocyte counts and anti-dsDNA levels (r = -0.24), as well as between lymphocyte counts and the MEX-SLEDAI score (r = -0.63, with p < 0.05). The receiver operating characteristic (ROC) curve indicated that a lymphocyte count with a cut-off point of ≤1738/mm3 is significant for predicting anti-dsDNA reactivity.

Conclusions

Lymphopenia is significantly correlated with higher anti-dsDNA levels and increased disease activity, potentially serving as an independent marker of disease activity in children with SLE. However, further research is needed.