The Centers for Medicare and Medicaid Services (CMS) made changes to the 5-star rating system for nursing homes. The ratings are based on three measures: onsite inspections, quality measures, and staffing levels. CMS introduced strengthened quality measures to more accurately assess quality and standardize measures for post-acute care. Nearly a third of nursing homes will now receive lower scores under the toughened standards, with only 49% receiving the top two ratings of 4 or 5 stars compared to previously 80%. Changes taking effect in 2015 include factoring the use of anti-psychotic drugs and improved calculations for staffing levels.