Gabriel Rodriguez Algarra

Bio: Gabriel Rodriguez Algarra is an academic researcher. The author has contributed to research in topics: Population. The author has an hindex of 1, co-authored 1 publications receiving 5 citations.

Effect of the immunosuppressive treatment on long-term renal graft survival

Abstract: Background. Although new immunosuppressive agents have improved the results of renal transplants (RTs), long-term graft loss remains high. We evaluated the impact of different immunosuppressive regimens on patient and graft survival. Methods. Data from 3365 patients receiving cadaver RTs in Spain during the years 1990, 1994 and 1998 were retrospectively analysed. All data were entered into a specially designed database. Graft and patient survival rates were estimated by the Cox regression method and results expressed as percentage survival. A maximum-likelihood estimate of the projected graft half-life (median value) was calculated by Weibull regression. Results. In 1990 graft and patient survival differed significantly from the other treatment years (P ¼ 0.0006 and P ¼ 0.0101, respectively). The risk of graft loss was significantly higher for cyclosporine (CsA), prednisone (P) and azathioprine (Az) than for CsA þ P, which in turn was higher than for CsA þ P plus polyclonal antibodies [antilymphocyte globulin (ALG)/antithymocyte globulin (ATG)]. Risk of patient death was also significantly higher for CsA þ P þ Az than for CsA þ P. No significant differences between treatment groups were found in graft and patient survival for 1994 and 1998. The projected median graft life for patients with the most used immunosuppressive regimen for each year was 12.9 years for CsA þ P þ Az and 15.6 years for CsA þ P plus mycophenolate mofetil (MMF). Conclusions. Triple therapy with Az in 1990 and 1994 and with MMF in 1998 were the most frequently used immunosuppressive regimens in the Spanish kidney transplant population. The best results were seen after induction therapy with polyclonal antibodies.

Evaluation of the cost effectiveness of sirolimus versus tacrolimus for immunosuppression following renal transplantation in the UK

Abstract: Introduction: Immunosuppressive therapy is required to prevent graft rejection. Calcineurin inhibitors such as tacrolimus are paradoxically toxic to the kidney, whereas sirolimus (rapamycin; Rapamune®) is not generally associated with the nephrotoxicity of CNIs. The purpose of this study was to evaluate the relative cost utility of sirolimus versus tacrolimus for the primary prevention of graft rejection in renal transplant recipients in the UK. Methods: A stochastic simulation model was constructed using clinical trial and observational data comparing the two treatments. Time duration was up to 20 years. Costs were from a UK NHS perspective, valued at 2003 prices and discounted at 6%. Benefits were discounted at 1.5%. Simulated events included patient and graft survival, haemodialysis, peritoneal dialysis, re-transplants and acute rejection. Costs were summed for events and various maintenance therapies. Utility was differentially accredited depending upon survival and using the alternative renal replacement therapies. Outcome was predicted using post-transplant creatinine levels up to 3 years. Extensive statistical economic and sensitivity analyses were undertaken. Results: Over the 10-year horizon, sirolimus gained 0.72 years (discounted) of functioning graft over tacrolimus, resulting in an incremental cost per year of functioning graft that was dominant. Over a 20-year time horizon, the cost effectiveness of sirolimus over tacrolimus further improved with an average discounted gain in years of a functioning graft of 1.8 years, resulting in an incremental cost-utility ratio that was also dominant. The number of haemodialysis events was 48 243 for sirolimus recipients versus 127 829 for those receiving tacrolimus and peritoneal dialysis events 40 872 versus 105 249, respectively. Similar values were obtained when real-life observational data on tacrolimus use in Cardiff, Wales were entered into the model. Using data from Cardiff, sirolimus remained dominant over tacrolimus under all scenarios. Conclusion: Our study suggests that sirolimus may be more cost effective than tacrolimus for the primary prevention of graft rejection in renal transplant recipients in the UK. Sirolimus was economically ‘dominant’ under almost all scenarios investigated. This finding was robust using statistical economic analysis and univariate sensitivity analysis.

On the Statistical Law of Life

Abstract: In this paper we derive a statistical law of Life. It governs the probability of death, or complementary of survival, of the living organisms. We have deduced such a law coupling the widely used Weibull statistics, developed for describing the distribution of the strength of solids, with the universal model for ontogenetic growth only recently proposed by West and co-authors. The main idea presented in this paper is that cracks can propagate in solids and cause their failure as sick cells in living organisms can cause their death. Making a rough analogy, living organisms are found to behave as growing mechanical components under cyclic, i.e., fatigue, loadings and composed by a dynamic evolutionary material that, as an ineluctable fate, deteriorates. The implications on biological scaling laws are discussed. As an example of application, we apply such a statistical law to large data collections on human deaths due to cancer of various types recorded in Italy: a relevant agreement is observed.

An estimation of the chronic rejection of kidney transplant using an eternal Weibull regression: a historical cohort study.

Abstract: Background: We estimated the chronic rejection of kidney transplant using an eternal Weibull regression. Methods: In this historical cohort study, we enrolled all patients with chronic renal failure who were admitted to Shahid Labbafinejad medical center (Tehran, Iran) from 1984 to 2003. Using Matlab 7.0, we considered the eternal proportion θ , as a logistic-type function of the covariates and modified the survival function. We estimated the survival function in unmodified and modified forms using Weibull distribution. Results: The chance of chronic rejection was 1.95 times higher among those who received a kidney transplant before 1996. Considering all cases who received renal transplantation after 1984, males had a chance of rejection 20% less than females. Next to the eternity, Weibull model was fitted to patients who received renal transplantation after 1996. Treatment protocol was changed after 1996 expecting fewer chronic rejections; thereafter, the eternal proportion was estimated to be 0.81. This seems quite considerable as a percentage of non-failure cases. Conclusion: Providing a non-zero eternal proportion, the modified model would be superior over the unmodified model.