[Cost of maintenance immunosuppressive drugs in kidney transplantation]

We calculated the cost of maintenance immunosuppression (ISM) in 405 kidney transplant patients under treatment for more than one year, classifying them according to the combination of drugs used and whether the ISM continued to be the same as initially indicated (primary ISM), or a later adaptation. Basic clinical data were also acquired on the through levels of drugs and the use and cost of the associated medication.

The mean doses in mg/kg/day and the trough levels in ng/ml were: cyclosporin (Cs), 2.7 +/- 0.9 and 123 +/- 5; tacrolimus (T), 0.09 +/- 0.06 y 7.3 +/- 2.9; Mycophenolate mofetil (MMF), 21.6 +/- 6.8 and 3.3 +/- 2.4. The proportion of patients with doses of steroids (EST) below 5 mg/day among patients treated with MMF was 60% in association with Cs and 73% with T. The cost related to EST and azathioprine (AZA) is very low; the mean cost per patient and day for Cs, T and MMF, was 7.08, 12.59 and 9.53 euros, respectively. The annual cost per patient depending on treatment was, in euros: EST + AZA, 204; Cs or without AZA and/or EST: 2,555; T with or without AZA and/or EST: 4,616; Cs plus MMF with/without EST: 6,136; T plus MMF with/without EST: 7,212. In cases of primary ISM, the difference between the two treatments with MMF drops so, low that its loses statistical significance (7,206 and 6,443 euros). This is because the dose of MMF is 50% higher in cases treated with Cs, even though there is no difference in the trough level of MMF. The use of hypolipidemic agents (with a mean annual cost of 451 euros) is much lower in treatments with T in comparison with Cs (13.8% vs 41.4%, p < 0.001). No significant differences could be established between T and Cs regarding the use of hypotensive agents and the frequency of postransplant insulin dependent diabetes.

The treatment of ISM with T is more expensive than Cs based treatment but the difference is reduced in combination with MMF because of the use of lower doses of MMF in the association of T with MMF. The considerable economic impact of ISM would justify the provision of greater resources to the rationalisation of the treatments currently being applied.