Intervention thresholds and ceilings can determine the haemoglobin outcome distribution in a haemodialysis population

We have explored the consequences of setting different thresholds and ceilings for erythropoietin dose changes in two randomized controlled studies of renal anaemia management based on an established algorithm. STUDY 1: A large (n=236) unselected haemodialysis cohort was randomized to monthly intervention (increased erythropoietin (Epo)) at haemoglobin (Hb) levels falling below either 10.5 g/dl (group A) or 11.5 g/dl (group B) and followed for 6 months. The mean Hb was 0.6 g/dl higher in the 11.5 g/dl threshold group (11.1 g/dl vs 11.7 g/dl) at 6 months (P=0.001++). The Epo dose did not differ between them (median 133 IU/kg/week, Interquartile range (IQR) 86-217 and 140, IQR 74-227 respectively) (P=NS(**)). STUDY 2: A large (n=211) unselected haemodialysis cohort was randomized to a reduction in Epo dose at Hb levels above either 12.0 g/dl (group C) or 13.0 g/dl (group D). The Hb outcome at 8 months differed between group C (mean 11.5 g/dl, SD 1.4) and group D (12.2, SD 2.1) (P=0.03++). The Epo dose did not significantly differ between groups C and D (median 60 IU/kg/week, IQR 32-142 and 71, IQR 38-117 respectively) (P=NS(**)). Study 1 showed that an intervention threshold of 11.0 g/dl with a mean Hb outcome of 11.6 g/dl and SD 1.6 g/dl would produce the desired UK Renal Association Standards outcome of 85% Hb > or =10.0 g/dl. Study 2 demonstrated that a ceiling of 12.0 g/dl narrowed the range of Hb values (P:<0.001##), achieving a SD of 1.37 g/dl, and reduced the number of patients with a Hb >13.0 g/dl from 25 to 12%. This narrowing of the distribution has cost implications for reaching minimum standards in a haemodialysis population. Formal use of threshold and ceiling values for intervention within an anaemia management system enabled the haemodialysis population outcome mean and SD to be literally prescribed.