The impact on resources of increased adequacy targets in haemodialysis

Jon D. Stratton, Roger N. Greenwood and Ken Farrington

Lister Hospital Renal Ward Stevenage Hertfordshire UK Email: jon.stratton{at}lister.org.uk

Sir,

Adequacy of haemodialysis is difficult to define. In terms of small solute clearance the UK Renal Association recommends a Kt/V of 1.2 [1]. The National Cooperative Dialysis Study demonstrated the benefits of achieving a target Kt/V greater than 0.8 and nPCR greater than 0.8 but implied no added benefit for Kt/V greater than 1 [2,3]. Subsequent work has cast doubt on this threshold and suggested improved survival with increasing Kt/V [4,5]. Early results from the HEMO study appear to suggest that the benefits might be confined to sub-groups rather than the whole haemodialysis population [6]. Assuming that blood and dialysis fluid flow rates and membrane sizes have already been optimized, the only means of increasing Kt/V is to increase dialysis duration or frequency. We have looked at the resource implications for our patients, staff and facilities of increasing dialysis duration to achieve higher adequacy targets.

Our dialysis facility comprises a central dialysis unit in our main hospital and two satellite units. The central unit and one satellite unit run at full capacity, the second satellite has recently been established and still has some potential capacity. Each of our 259 haemodialysis patients has an individually tailored dialysis prescription based on a two-pool model equation taking into account residual renal function [7]. Sixty-one per cent dialyse with a Kt/V of 1.2, the remainder dialyse at an increased level; 27% have a Kt/V greater than 1.4. We have remodelled the dialysis prescriptions to achieve a Kt/V of 1.4 for all patients with a current Kt/V less than 1.4.

To achieve this, the current mean dialysis time of 179±47 min will increase to 202±54 min; a 12.9% increase. Twenty-seven per cent of our population already achieve a Kt/V of 1.4 so would not increase their time. For the remainder, 85% would have their dialysis time extended between 20 and 45 min, a mode of 35 min (Figure 1). The units' total weekly dialysis time would increase from 2120 to 2392 h. To accommodate this increased dialysis load the total number of dialysis stations would increase from 45 to 50. Whilst the capacity of the main unit and the full satellite unit combined would fall from 209 to 188 patients, the number of patients dialysing in the not-yet-at-capacity satellite would increase from 50 to 71 patients to accommodate the patients displaced. The estimated dialysis capacity of our whole facility would fall by 10% from 322 to 289 patients. At a continued dialysis population increase rate of 12% per annum, capacity within our establishment would be reached more than 18 months earlier than planned.

The increased associated financial costs would be almost entirely accounted for by step-up expenses. Consumable costs would change little. The cost of an individual dialysis session would increase marginally with additional dialysis fluid usage. Staff redistribution would mirror patient redistribution, but an 8% expansion in nursing numbers would still be required, based on our current staffing formula. Taking into account the new dialysis facilities required and loss of capacity, we estimate that our annual expenditure on dialysis would increase by 15% in the first year, and ~11% per year thereafter. We have not taken into account any savings, which might stem from decreased hospital admissions and reduced erythropoietin use, if increased delivered adequacy translated into clinical improvements. Other financial savings in health provision would hopefully mirror the improved patient morbidity. To counter this, if life expectancy on dialysis improved, our current net dialysis population increase would be >12%.

Increasing haemodialysis adequacy targets to a Kt/V of 1.4, even in a sub-population of haemodialysis patients, would have a significant impact on already stretched resources. The resource impact of modified treatment targets should be assessed and addressed prior to their implementation.



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Fig. 1.  Additional dialysis times with increased Kt/V.

 
References

  1. Royal College of Physicians and Renal Association. The Treatment of Adult Patients with Renal Failure, 2nd Edn. Royal College of Physicians,1997
  2. Harter HR. Review of significant findings from the National Cooperative Dialysis Study (NCDS). Kidney Int1983; 23 [Suppl 3]:S107–S112
  3. Gotch FA, Sargent JA. A mechanistic analysis of the National Cooperative Dialysis Study (NCDS). Kidney Int1985; 28:526–534[ISI][Medline]
  4. Parker T, Husni L, Huang W, Lew N, Lowrie E. Survival of haemodialysis patients in the United States is improved with greater quantity of dialysis. Am J Kidney Dis1994; 23:670–680[ISI][Medline]
  5. Charra B. Improving adequacy improves haemodialysis outcome. EDTNA ERCA J2000; 26:6–10[Medline]
  6. Mitka M. How to reduce mortality in hemodialysis patients still a puzzle. J Am Med Assoc2002; 287:2643–2644[Free Full Text]
  7. Tattersall JE, DeTakats D, Chamney P, Greenwood RN, Farrington K. The post-haemodialysis rebound: predicting and quantifying its effect on Kt/V. Kidney Int1996; 50:2094–2102[ISI][Medline]




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