Cytotoxic drug treatment of reactive amyloidosis in rheumatoid arthritis with special reference to renal insufficiency.

Twenty-two patients with amyloidosis secondary to rheumatoid arthritis were randomised and followed prospectively in order to determine whether treatment with cytotoxic drugs could postpone the development of end-stage renal failure. The diagnosis of amyloidosis was based on albuminuria, amyloid-positive rectal and/or abdominal fat aspiration and/or renal biopsies. Renal function was followed by repeated 51Cr-EDTA measurements of the glomerular filtration rate (GFR). Urinary albumin and serum-creatinine were found unreliable as predictors of renal function. GFR declined more rapidly in the patient group receiving only symptomatic drugs and no cytotoxic drugs (NT-group). After an initial decline, the GFR in the cytotoxic drug treatment group (T-group), mean treatment quotient 79%, levelled off and remained constant for a considerable time. The mean observation time was 45.7 months in the NT-group and 53.5 months in the T-group. Seven out of eleven patients in the NT-group developed end-stage renal disease, compared to two out of eleven patients in the T-group. The cumulative proportion of survivors in the NT-group at 36 and 60 months was 71% and 27% respectively. The corresponding figures in the T-group were 89% and 89%. The difference in favour of the cytotoxic drug-treated group was significant (p less than 0.04).