Factors influencing the course and the response to treatment in primary focal segmental glomerulosclerosis

BACKGROUND The clinical course of primary focal segmental glomerulosclerosis (FSGS) varies and there is considerable controversy as to which factors are of importance in determining prognosis or response to therapy. The aim of this study was to identify clinical, pathological or immunohistochemical features at biopsy that could identify patients with progressive disease who might benefit from treatment, and predict long-term outcome. METHODS The clinical and pathological findings of 33 adult patients with primary FSGS were retrospectively analysed in order to identify features at biopsy that could be predictive of outcome or response to treatment. For this purpose an immunohistochemical study was also performed, using monoclonal antibodies against intracellular adhesion molecules-1, C5b-9, alpha 3 beta 1 integrin, alpha-smooth-muscle actin (SMA), and TGF-beta1. RESULTS At biopsy 17 patients (51%) were nephrotic and 16 (49%) non-nephrotic. Of the nephrotic patients, 11 were treated and six received only symptomatic therapy. Initial treatment with prednisolone (Pred) for 6-12 months (average 9 months) resulted in remission in 64% of nephrotic patients. To those with partial or no response, cyclosporin (CsA) or cyclophosphamide was given. At the end of follow-up (mean 57 months) three nephrotic patients (28%) were in complete remission, six (54%) in partial remission, and two (18%) did not respond to the treatment. In the seven treated non-nephrotic patients, Pred induced a complete remission in two (28%), a partial remission in three (44%), while two patients (28%) did not respond. Plasma creatinine remained stable in nephrotic patients who responded and it almost doubled in non-responders. Plasma creatinine also remained unchanged in treated non-nephrotic patients who responded to Pred, while two non-responders reached end-stage renal disease (ESRD). In contrast, 50% of untreated nephrotic patients and 67% of untreated non-nephrotic patients progressed to ESRD. Multivariate analysis showed only age and plasma creatinine at biopsy to have an independent predictive value for renal survival in nephrotic patients. This analysis also demonstrated that only the severity of interstitial fibrosis predicted the response to the treatment. In addition, the tubulointerstitial but not the glomerular expression of C5b-9, alpha 3 beta 1 integrin, alpha-SMA, and TGF-beta1 was significantly more extensive in non-responders and correlated with renal function at biopsy. However, only tubulointerstitial expression of TGF-beta1 independently correlated with the degree of renal function impairment at biopsy, but none of the above markers independently predicted renal survival or response to therapy. CONCLUSIONS Nephrotic patients with FSGS may benefit from a more prolonged course of Pred. Nephrotic patients responding to treatment have a significantly better renal survival than non-responders. Age and plasma creatinine at biopsy are independent risk factors leading to ESRD. The severity of tubulointerstitial fibrosis is predictive of response to therapy.