Objectives To study the effect of renal damage on extra-renal organ damage and mortality in patients with SLE.
Methods Patients who fulfilled ≥4 ACR criteria for SLE between 1995 and 2011 were longitudinally followed. Organ damage in 12 systems was assessed by the ACR SLICC damage scores (SDI). The cumulative rate of survival was studied by Kaplan-Meier's plot. For those who died during the disease course, data were censored at the time of death. For those who were lost follow-up, data were censored at the time of last clinic visits. Comparison of extra-renal organ damage and survival rate was made between patients with and without renal damage during the course of SLE.
Results 756 SLE patients were studied (696 women, 92%). All were ethnic Chinese. The mean age of onset of SLE was 32.7±13.6 years and the mean follow-up time of the entire cohort of patients was 9.4±7.4 years. 76 (10%) patients died during the course of illness and 34 (4.5%) patients were lost to follow-up. 26 (3.4%) patients developed end stage renal failure (ESRF). The main contributing causes of death in those 76 patients were: infection (49%), cardiovascular events (12%), cerebrovascular events (13%), cancer (11%), suicide (3%) and others (13%). Overall, renal damage occurred in 84 (11%) patients (64% with impaired glomerular filtration rate; 6% persistently heavy proteinuria; 30% ESRF). Compared with patients without renal damage (renal SDI=0), those with renal damage had significantly higher incidence of damage in the eyes, central nervous system, pulmonary system, cardiovascular system, musculoskeletal system, gonads and the endocrine system (P<0.001 in all). The corresponding mean SDI scores in these systems were also significantly higher in patients with renal damage than those without. The cumulative survival rates of our patients were 94% at 5 years, 90% at 10 years and 86% at 15 years. Patients with renal damage had significantly higher mortality than those without (log rank test; p<0.001). The age and sex adjusted hazard ratio for mortality in patients with renal damage relative to those without renal damage was 3.55 (95% CI 2.22-5.66; <0.001).
Conclusions In patients with SLE, renal damage significantly and adversely affects survival. The presence of renal damage significantly increases the incidence of extra-renal organ damage, particularly in the cardiovascular, pulmonary, neuropsychiatric, ophthalmological, musculoskeletal, gonadal and endocrine systems.
Disclosure of Interest : None declared