Minimal change disease has an excellent prognosis in children, with steroid responsiveness and eventual remission even in those with frequent relapses as children progress into adulthood. Even among adults, the prognosis has been described as favorable, with eventual remission rates of over 80% after corticosteroids, albeit with slightly longer courses in some cases. Szeto and colleagues in a recent issue of AJKD report on their experience from Hong Kong with the largest case series of adult’s with minimal change disease, and provide data on long-term outcomes. The authors have assembled a cohort of 340 adults (defined as age > 18 years) with biopsy-proven minimal change disease. The study period spans 20 years (from 1984 to 2004), with excellent data on long term outcomes.
Firstly, they confirm earlier reports that the overall median time to remission is longer in adults, at 10 weeks, compared to less than 8 weeks in children. Among the presenting features, about 20% had microscopic hematuria and hypertension. However, a relatively lower proportion of patients presented with acute kidney injury (AKI), about 14%, compared to 18-55% in previous studies. Though the reason for this discrepancy was not clear, it may impact the generalizability of the results.
Secondly, the response to treatment also yielded some interesting findings. About 10% were steroid resistant, and another quarter were frequent relapsers. This too is within the range of previously reported literature. Though a large proportion of the frequently relapsing adults received second line therapy (mostly cyclophosphamide or cyclosporine, and levamisole in a few cases), only 13 of 33 patients with steroid resistance did so. Notably, not all the patients with steroid resistance ended up with focal segmental glomerulosclerosis (FSGS) – only 6 of the 12 who had a second biopsy had this diagnosis.
Lastly, the median duration of follow up was 14 years (174.7 months to be precise). The rich data shows that minimal change disease is associated with significantly higher rates of kidney failure needing renal replacement therapy than previously understood, with just under 10% (mostly those with steroid resistance) ending up on dialysis. Moreover, patient survival was also lower than what one would expect at 90.8% at 10 years, again lowest in those with steroid resistance. Not surprisingly, age at diagnosis (categorized as either older or younger than 50 years) was also strongly associated with patient survival.
Another point worth highlighting is the impact of not just the disease, but that of the treatment. Sixty patients developed diabetes, fifteen had “neuropsychiatric problems” (severity not clear, but severe enough to make it into the database), and another six developed avascular bone necrosis. Lest the clinician decide that the clinical outcomes of the disease merit strong medicine, these adverse drug effects should give pause for contemplation.
To summarize, Szeto and colleagues report a richly detailed tapestry of data on features and outcomes of minimal change disease in adults.
Dr. Swapnil Hiremath
AJKD Blog Contributor