Under the Connecitcut's "adverse event" reporting law, hospitals are required to inform the state Department of Public Health when patients suffer certain serious unintended harm. The legislation was intended to compel hospitals to improve care and help patients assess the quality of the state's medical facilities. But since that law was revised five years ago, thousands of incidents that injured or killed patients have been hidden from the public by hospitals and the state health department, the Hartford Courant reports.