PROGRESSION OF CHRONIC-RENAL-FAILURE IN A HISTORICAL GROUP OF PATIENTS WITH NEPHROPATHIC CYSTINOSIS

In a historical group of 205 patients with infantile or adolescent cys tinosis treated without cysteamine, the rate of deterioration of renal function was analysed retrospectively. Patient survival curves and re nal survival data are presented. Longitudinal data of serum creatinine values (n = 3280) in 157 patients were plotted for each patient, smoo thed by the method of the running medians and grouped into 12 serum cr eatinine classes. In every patient the age at the last smoothed serum creatinine value observed in each serum creatinine class was determine d. These virtual age values were then summarized per serum creatinine class, expressed as median and centiles and plotted, thus describing t he ''natural'' course of the disease. In 9 pairs of affected siblings the rate of progression showed a median difference of about 12 months. Our data describe the ''natural'' course of nephropathic cystinosis a nd can be used as a prognostic aid for recently detected patients. The data can also be applied for the assessment of the influence of new t herapeutic strategies on the rate of progression of renal failure in c ystinotic patients.