Changing trends in presentation and indications of biopsy in lupus nephritis: data from the Spanish Registry of Glomerulonephritis

Background With the ageing population and changes in the indications of diagnostic and protocol biopsies in systemic lupus erythematosus in recent years, an impact on the incidence and presentation of lupus nephritis (LN) is expected. The aim of this study was to analyse the epidemiological changes regarding clinical and histological presentation of LN in kidney biopsies performed from 1994 to 2019 included in the Spanish Registry of Glomerulonephritis. Methods We analysed data from 28 791 kidney biopsies from 130 Spanish hospitals comparing demographic, clinical and histological data. We divided the cohort according to the age of onset of LN into pediatric onset (50 years). Results The incidence of LN has decreased from 9.6% of all kidney biopsies in the period 1994–2013 to 7% in the last quarter of the observation period (2014–2019) (P Conclusions The frequency of biopsy-proven LN has been decreasing in recent years, despite an increasing number of repeat biopsies. Late-onset LN is increasing, presenting with worse kidney function but fewer proliferative lesions compared with younger-onset LN.