LONG-TERM OUTCOME ACCORDING TO RENAL HISTOLOGICAL LESIONS IN 118 PATIENTS WITH MONOCLONAL GAMMOPATHIES

Background. The prognosis of monoclonal gammopathies with multiple mye loma and renal involvement is poor, and the indication for renal repla cement therapy is controversial. Few studies address the value of rena l histology for determining prognosis according to initial pathology f indings. Methods. We studied the course of 118 patients with multiple myeloma according to renal biopsy lesions. The monoclonal component wa s identified and quantified in serum and urine. Tumor cell mass was cl assified as stage 1, 2 or 3, according to Durie and Salmon, End-points were death, or survival on dialysis, or serum creatinine level at las t examination. Results. Renal biopsy showed myeloma kidney in 48 cases (41%), AL-amyloidosis in 35 (30%), light chain deposit disease in 22 (19%), chronic tubulointerstitial nephritis in 12 (10%) and cryoglobul inaemic kidney with multiple myeloma in 1. Maintenance haemodialysis w as required in 46 patients (39%), earlier (P<0.0001) in myeloma kidney (mean: 3 months after diagnosis) than in AL-amyloidosis (mean: 15 mon ths) and light chain deposit disease (mean: 18 months), Median surviva l was 12 months in myeloma kidney, 24 months in AL-amyloidosis and 48 months in light chain deposit disease. Dialysis increased survival in light chain deposit disease, in contrast with myeloma kidney and AL-am yloidosis patients whose survival was shorter when dialysed. The main cause of death during first year of dialysis was cardiac involvement i n AL-amyloidosis, and sepsis or cardiac insufficiency in myeloma kidne y. There was a trend to increased survival with multidrug chemotherapy which seemed to slow progression to end-stage renal failure. At last follow-up (median: 12 months, range 1-297), 65 (55%) patients had died . By multivariate analysis, independent predictors of survival were: a ge < 70, serum creatinine less than or equal to 300 mu mol/l, and seru m calcium less than or equal to 2.5 mmol/l, Conclusions. Initial renal biopsy helps predict prognosis in patients with multiple myeloma and renal involvement. Maintenance haemodialysis is a reasonable indicatio n in light chain deposit disease and AL-amyloidosis, especially in pat ients aged <70, Multidrug therapy tends to prolong survival and slow p rogression to end-stage renal disease.