Federal regulators say they are moving to make once-confidential data about the performance of kidney dialysis clinics more readily available to the public.

The move, disclosed in a letter to Sen. Charles Grassley, R-Iowa, follows a ProPublica investigation last year that revealed substandard care and weak oversight in some clinics.

Officials with the Centers for Medicare and Medicaid Services told Grassley they are now providing Dialysis Facility Reports, statistical compilations on each of the nation's 5,000-plus dialysis clinics, to anyone upon request. They also said they were trying to add the reports to Medicare's Dialysis Facility Compare website.

Practically speaking, patients already have access to the data, though not from the government: ProPublica obtained the reports from CMS late last year under the Freedom of Information Act and posted them in December.

Still, the plan reflects a shift in approach for CMS, which has used public money to collect and analyze the data in the reports for more than a decade but has never shared it with the almost 400,000 Americans whose lives depend on dialysis.

CMS regulates dialysis clinics because most dialysis treatments are paid for by Medicare under a special entitlement created in 1972. In December, Grassley pressed the agency to spell out what steps it was taking to improve the system, which has among the highest mortality and hospitalization rates in the industrialized world.

His request was prompted by ProPublica's stories, which showed that patients often received treatment in environments that were unsafe or unsanitary. Our review of eight years of inspection records for more than 1,500 clinics turned up hundreds of lapses in care, some of which led to patient injuries or deaths. Though clinics are supposed to be checked once every three years on average, we found that hundreds had not been inspected for five years or more.

In their response to Grassley, CMS officials acknowledged that more than one-third of states had fallen short of inspection targets in fiscal year 2009. They said they had introduced tougher standards that had improved the quality of these checks, making them more comprehensive.

Since 2006, the agency also has introduced more frequent, targeted inspections for underperforming facilities, and officials said they were considering hiring an outside contractor to assist states with overdue inspections.

Grassley said the changes described by CMS were welcome, if overdue.

"More scrutiny and transparency are good for consumers," he said. "However, it shouldn't take an investigative media exposé and pressure from Congress to make these improvements happen. Ensuring decent care at dialysis facilities should be standard operating procedure for CMS. Patients deserve it, and the taxpayers are paying for it."

According to CMS' letter, there are still plenty of opportunities for further progress: 15 percent of the dialysis clinics inspected in the last two fiscal years were found to have deficiencies serious enough to warrant termination from the Medicare program if left uncorrected. The citations handed out most frequently were for inadequate infection control procedures and substandard physical conditions.

CMS officials told Grassley they were working with other federal agencies on an initiative to reduce infections in dialysis clinics and would be releasing an action plan summarizing the agency's dialysis-related efforts later this year.