The kidneys filter waste products and water from the blood. Hemodialysis is a procedure that uses a machine to filter the blood when kidneys stop working. During hemodialysis, patients are connected to the machine by tubes that allow their blood to pass through the machine and then back into their blood vessels. Patients receiving hemodialysis usually receive treatment for 3 to 4 hours several times per week in special dialysis centers. Although hemodialysis is a lifesaving procedure for patients with kidney failure, they are at risk for poor health outcomes, including hospitalization and death. Guidelines for hemodialysis recommend several measures to indicate the quality of care that hemodialysis centers provide. However, it is uncertain whether patients whose care meets these performance measures have better outcomes than those whose hemodialysis care does not meet these measures. The quality-of-care measures include 2 laboratory tests, hemoglobin and albumin, at or above defined levels. Hemoglobin shows whether a patient has anemia (low blood counts). Albumin shows nutritional status. A third measure considers whether patients have fistulas. A fistula is a surgically created connection between an artery and a vein near the skin surface. Other studies have shown that using a fistula instead of other methods to gain access to the patient's blood results in fewer patient complications. The fourth measure shows the efficiency of the filtering process.