Medicare’s fraud-finding contractors should investigate instances in which companies keep patients longer, charge more for care and classify clients for more intense and expensive services than needed, the study released today by the inspector general found.

The findings, based on audits of nursing-home billings between 2006 and 2008, “raise concerns about the potentially inappropriate use of higher-paying” billing codes, said the report by the Health and Human Services Department’s Office of Inspector General. It recommends that Medicare, the U.S. health insurance program for the elderly and disabled, consider changing its payment method for nursing home services.

The program covers as much as 100 days of nursing-home services for beneficiaries who require skilled care or rehabilitation following a hospitalization of at least three consecutive days. Care can be provided in a hospital or free- standing facility.

Medicare plans to target an undisclosed list of nursing homes with “questionable billing” practices, according to the report. The program specifically is examining “special-nursing facilities” for patients who are recovering from an injury or are disabled.

The report didn’t mention any specific companies. Susan Moss, vice president of communications with Louisville, Kentucky-based Kindred, the largest publicly traded U.S. company by number of beds, didn’t immediately respond to a telephone message requesting comment. Bernadette Bell, a spokeswoman for Irvine, California-based Sun Healthcare, the second-largest by beds, also didn’t respond immediately to a telephone message.