The Cleveland Clinic says 5,400 hundred patients who made recent office visits were mistakenly billed for more expensive operating room procedures.
Officials said the hospital is crediting the patients' accounts for the overcharges and is apologizing in letters and phone calls.
Clinic spokeswoman Heather Phillips said a coding error in an automated billing system was discovered April 24 following complaint calls from patients. She said that the glitch affected people who went to clinic doctors' offices for a variety of treatments during March and April.
Phillips did not have a total dollar amount for the overcharges.
Cleveland Clinic Chief Financial Officer Steven Glass said about 1% of the clinic's patients were billed too much.