Chain dialysis company DaVita was taken by surprise when CMS recently introduced a star-rating program for dialysis facilities, and the company is urging the agency to make major changes to the program, which takes effect in October. DaVita executives said they support programs that rate performance but they dislike that the program grades on a curve, and they said its metrics are ill-suited to dialysis facilities and the program is out of sync with the end-stage renal disease quality rating...