Clinical Features and Treatment Outcomes of Minimal Change Disease Across Age Groups: A Retrospective Cohort Study

Background: Minimal change disease (MCD) exhibits distinct age-related clinical patterns. This study investigated differences in disease behaviour and therapeutic outcomes in MCD patients across various age groups. Methods: This retrospective observational cohort study enrolled patients with MCD who were diagnosed in the Department of Nephrology at the First Affiliated Hospital of Xi'an Jiaotong University between February 2016 and December 2023. General information, biochemical indices, 24-hour urine protein, treatment regimens, remission, and relapse status were collected, with a follow-up period of no less than 6 months. Results: A total of 320 patients were included in the study: 217 males and 103 females with a median age of 34 years (interquartile range [IQR] 21–54) at the time of renal biopsy. The median albumin (ALB) level at diagnosis was 18.30 g/L (IQR 15.2–22.3), the median urine protein level was 4.32 g/day (IQR 2.96–5.84), and the median serum creatinine level was 67.00 μmol/L (IQR 54.00–90.50). Acute kidney injury (AKI) occurred in 21.56% of patients (69 out of 320), with age-specific incidences of 8% in patients aged under 18 years, 15.88% in patients aged 18–50 years, and 38% in patients aged 50 years and over (p < 0.001). The initial treatment for 248 out of 320 cases was glucocorticoids alone, Meanwhile, 71 patients (22.2%) required a combination of glucocorticoids and either calcineurin inhibitors, cyclophosphamide, or CD20 monoclonal antibodies because an adequate dose of glucocorticoids alone could not be administered. The median follow-up period was 48.07 months (30.85–69.65), during which six deaths and four cases of loss to follow-up occurred. Overall, frequent relapses/steroid dependence were observed in 7.5% of patients. For patients under 18, aged 18–50, and over 50, the frequent relapses/steroid dependence figures were 16%, 7.65%, and 3% (p = 0.015). Conclusion: Frequent relapses/steroid dependence is more prevalent in patients under the age of 18. Conversely, acute kidney injury is more common in adults aged 50 years and over.