Current Status and Temporal Changes in Lupus Nephritis in Japan: Analysis of the Japan Renal Biopsy Registry
Hidekazu Ikeuchi, Takaya Ozeki, Shoichi Maruyama, Naotake Tsuboi, Takahiro Tsuji, Hitoshi Sugiyama, Keiju HiromuraABSTRACT
Aim
This study evaluated temporal changes in the clinical and histological features of lupus nephritis at first renal biopsy in Japan.
Methods
This retrospective observational study used Japan Renal Biopsy Registry data. Patients undergoing their first renal biopsy in 2018–2021 were compared with a historical cohort from 2007 to 2012. Clinical characteristics and histological classes based on the International Society of Nephrology/Renal Pathology Society classification were compared.
Results
The study included 331 patients in the historical cohort and 682 in the recent cohort. The recent cohort was older (median age, 42 vs. 37 years; p = 0.014), with a higher proportion aged 60 years or older (19.2% vs. 10.6%; p < 0.001). Histological class distribution differed significantly between cohorts. Class IV (±V) lesions were less frequent in the recent cohort (34.3% vs. 44.1%), whereas Class II and Class III (±V) lesions were numerically more frequent. The lower odds of Class IV (±V) lesions persisted after adjustment for age group (odds ratio, 0.676; 95% confidence interval, 0.516–0.886; p = 0.005). Amongst patients with Class III/IV lesions, pure Class III lesions were more frequent and pure Class IV lesions were less frequent in the recent cohort.
Conclusion
The recent first‐biopsy cohort was older and had a lower proportion of Class IV (±V) lesions than the historical cohort, even after age adjustment. These findings suggest temporal changes in LN in Japan, although the greater proportion of missing histological classification data in the historical cohort should be considered when interpreting the histological differences.