A new study published in the American Journal of Kidney Diseases has found a survival advantage among DaVita dialysis patients who use the company's pharmacy.

The study was conducted by the Chronic Disease Research Group, who analyzed the hospitalizations and mortality of more than 50,000 DaVita patients using data from the United States Renal Data System. The study looked at 8,864 DaVita patients that used the DaVita Rx pharmacy service between 2006 and 2008. The control group was 43,013 DaVita patients using other pharmacies to receive their medications. The study authors included Eric D. Weinhandl, MS, Thomas J. Arneson, MD,  and Wendy L. St. Peter.

(Phosphorus-lowering drugs linked to lower mortality in dialysis patients)

In an intention-to-treat analysis,, the researchers said they found that dialysis patients who received DaVita Rx program services were 8% less likely to die and accumulated 2% fewer hospital admissions and 6% fewer hospital days during the study period. In an as-treated analysis, associations were more pronounced. Dialysis patients who received DaVita pharmacy services were 21% less likely to die and accumulated 7% fewer hospital admissions and 14% fewer hospital days.

The authors noted that the associations in the intention-to treat analyses may be attenuated "because analyses ignore both disenrollment from the pharmacy program (23% after one year) and new enrollment among control patients (17% after one year)." However, the authors write, associations in as-treated analyses may be exaggerated.  "If patients who discontinued were sicker than those who continued, risk ratios may be biased away from unity," they wrote.

The authors also noted that the DaVita dialysis patients were not randomly assigned to receive integrated pharmacy services and the as-treated analyses may be biased because of informative censoring by disenrollment from the pharmacy program and because data regarding use of integrated pharmacy services were lacking.