Seasonal variation of lupus nephritis in a cohort of Egyptian patients

Introduction Systemic lupus erythematosus is an autoimmune multisystem disease; renal affection is one of its most common manifestations. The effect of environmental factors on lupus nephritis flares is not fully understood. Methods This is a retrospective study that included 200 patients with lupus nephritis flares. All patients had confirmed diagnosis of lupus nephritis on histopathological examination. Lupus nephritis flares were defined by either (1) nephritic flare: defined as increased proteinuria or serum creatinine concentration; abnormal urinary sediment or a reduction in creatinine clearance, or (2) proteinuria flare defined as persistent increase in proteinuria > 0.5–1.0 g/day after achieving complete remission; doubling to > 1 g/day after achieving partial remission. The time of renal flare (month of the year) was recorded to determine the effect of seasonal variation on lupus nephritis flares. Results The median age for the patients was 33 years (IQR = 13); 92% of patients were females. The median duration of lupus was 7 years (IQR = 6). The median serum creatinine was 1.4 mg/dl, median serum urea level was 32, and median UPCR was 2.4 gm/dl. The highest incidence of flares occurred in June (14%) and July (12.5%) ( p = 0.003). Conclusion Seasonal pattern of LN flare was observed in our study in Egyptian cohort of patients, with most flares observed during meteorological summertime. Larger studies are needed to confirm this seasonal pattern. Key Points • Flares of lupus nephritis are common in patients with systemic lupus erythromatosus. • A seasonal pattern of flares of lupus nephritis was observed in our study. This seasonal pattern has been observed by previous studies in variable ethnicities and variable climatic circumstances.