Risk factors for damage in childhood-onset systemic lupus erythematosus in Asians: a case control study

Abstract

Background: Accumulated damage is an important prognostic factor in systemic lupus erythematous. However, the pattern of disease damage and its risk factors have not been well studied in childhood-onset systemic lupus erythematosus (cSLE) in Asia. The objectives are to evaluate the pattern of damage and to identify the risk factors for accumulated damage in an Asian group of cSLE.

Methods: A retrospective chart review was conducted on a group of 59 patients with cSLE. Patient demographics and clinical variables were first collected at diagnosis. Over the course of their disease, clinical variables considered as risk factors for damage were also collected. Damage was measured using the Systemic Lupus International Collaborating Clinics/ American College of Rheumatology Damage Index (SDI) for each patient at their last encounter. Based on their SDI scores, patients were then dichotomized to two groups: a group with presence of disease damage (SDI ≥1) and a group with absence of disease damage (SDI score = 0). Clinical variables including age at diagnosis, gender, ethnicity, disease duration, disease manifestations, laboratory values at diagnosis, disease activity at diagnosis and last encounter, major organ involvement, number of lupus flares, major infection, and intensity of immunosuppressive medications were compared between the two groups. Growth failure and estimated glomerular filtration rate (eGFR) were also analysed as secondary outcomes.

Results: After a median disease duration and follow up of 7.8 years, 39 patients (66.1%) had no disease damage while 20 patients (33.9%) had acquired disease damage. Disease damage most frequently occurred in the ocular (15.3%), neuropsychiatric (11.9%) and musculoskeletal (11.9%) domains. The most frequent forms of damage were cataracts (11.9%), and avascular necrosis (unilateral and bilateral combined 10.2%). After controlling for other variables, presence of neuropsychiatric manifestations remained the only statistically significant risk factor for damage. The rate of growth failure in our group of patients was 16%. Patients who experienced growth failure were significantly younger at disease diagnosis. The median age of diagnosis was 10 for those who experienced growth failure, whereas the median age of diagnosis was 13 for those who did not experience growth failure. Despite a high rate of renal involvement in the group (79.7%), renal damage was only seen in 3.2% of the patients. 91.5% of the studied group had normal eGFR of ≥90 ml/min/1.73m² at their last follow up.

Conclusion: This group of patients had a low rate of damage accrual, with one of the lowest rates in renal damage when compared to other cohorts reported. The presence of neuropsychiatric manifestations was identified as the most significant risk factor for disease damage, while the most frequent forms of damage were cataracts and avascular necrosis, which were both related to prolonged steroid use. Despite the limitations of this study, it highlights the need for larger prospective studies to understand the relationship between childhood-onset SLE and its resulting damage.

Keywords: Damage index; Outcome; Paediatrics; Systemic lupus erythematosus.

Fig. 1

Flowchart of patients included in this study

Fig. 2

Heat map showing frequency of disease damage in different domains across different studies. In the heat map shown, each column represents a separate study. Each row across represents an organ system/domain. Each figure in the cell represents the percentage of patients with that organ damage in that study. The color of each cell reflects its percentage, with reference to the gradient legend on the right. Among our group of patients, 15.3% had ocular damage, 11.9% had neuropsychiatric damage, 11.9% had musculoskeletal damage, 5.1% had skin damage, 3.4% had renal damage and 3.4% had cardiovascular damage. Percentage of renal damage is among the lowest across the studies