Impact of the new drugs in the cost of maintenance immunosuppression of renal transplantation. Is it justified?

BACKGROUND

The new immunosuppressive drugs control acute rejection better, and have potentially short-term economic advantages. However, their long-term cost-effectiveness must still be determined. The Spanish study of chronic transplant nephropathy provides data that facilitates the assessment of the economic importance of maintenance immunosuppression (MI).

METHODS

We determined the frequency of use of the different MI drugs and their combinations in three renal transplantation cohorts performed in 1990, 1994 and 1998 (total: 3279), and their evolution over time. Based on the real costs found in a medium-sized service in our country at the end of 2000, the mean annual costs of MI drugs were calculated. We performed a multivariate analysis of graft survival in the 1998 cohort.

RESULTS

In 1990 and 1994, cyclosporine (CsA) with or without azathioprine (AZA) was used almost exclusively as the initial MI drug. In 1998, 76% received mycophenolate mofetil (MMF) and 20% tacrolimus (TAC). During their follow-up, a growing number of patients from the 1990 and 1994 groups were converted to MMF (12 and 17%) and TAC (4 and 8%), while the treatment of those from 1998 remained stable. Using prices from the year 2000, the mean cost of the MI at the end of the first year in 1998 (5380) was almost double that of 1994 (2902) and 1990 (2855). In these two groups, the mean cost remained stable until 1996; afterwards, it increased in both, more rapidly in the 1994 (24.8%) than in the 1990 (17.3%) group, although it remained significantly inferior to that of 1998. Correction for the evolution of the drug prices and the peseta purchasing value lessened these changes in an important way. The new regimens allowed for the withdrawal of steroids in a greater proportion of cases; TAC was associated with a less frequent use of lipid-lowering drugs and antihypertensive drugs. In the whole patient group, the regimens with MMF and/or TAC showed a tendency to greater mean life of the organs, but without reaching statistical significance in the multivariate analysis of patients in 1998.

CONCLUSIONS

The introduction of new drugs in the MI applied in Spain has had an important economic impact since 1996. Their cost-effectiveness is still pending confirmation in our country.