Is it still worthwhile to perform quarterly cd4+ t lymphocyte cell counts on hiv-1 infected stable patients?

Antonio Di Biagio, Marta Ameri, Davide Sirello, Giovanni Cenderello, Enrico Di Bella, Lucia Taramasso, Barbara Giannini, Mauro Giacomini, Claudio Viscoli, Giovanni Cassola, Marcello Montefiori

In the last 20 years routine T CD4+ lymphocyte (CD4+) cell count has proved to be a key factor to determine the stage of HIV infection and start or discontinue of prophylaxis for opportunistic infections. However, several studies recently showed that in stable patients on cART a quarterly CD4+ cell count monitoring results in limited (or null) clinical relevance. The research is intended to investigate whether performing quarterly CD4+ cell counts in stable HIV-1 patients is still recommendable and to provide a forecast of the cost saving that could be achieved by reducing CD4+ monitoring in such a category of patients. The study is based on data referring to all HIV-infected patients > 18 years of age being treated at two large infectious diseases units located in the metropolitan area of Genoa, Italy. The probability of CD4+ cell counts dropping below a threshold value set at 350 cells/mm(3) is assessed using confidence intervals and Kaplan-Meier survival estimates, whereas multivariate Cox analysis and logistic regression are implemented in order to identify factors associated with CD4+ cell count falls below 350 cells/mm(3). Statistical analysis reveals that among stable patients the probability of maintaining CD4+ >350 cell/mm(3) is more than 98%. Econometric models indicate that HCV co-infection and HIV-RNA values >50 copies/mL in previous examinations are associated with CD4+ falls below 350 cells/mm(3). Moreover, results suggest that the cost saving that could be obtained by reducing CD4+ examinations ranges from 33 to 67%. Empirical findings shows that patients defined as stable at enrollment are highly unlikely to experience a CD4+ value <350 cell/mm(3) in the space/arc of a year. The research supports a recommendation for annual CD4+ monitoring in stable HIV-1 patients.