The U.S. Food and Drug Administration is warning patients and doctors, who use at-home or in-the-office medical devices to monitor levels of the blood thinner warfarin, that certain test strips used with the devices may provide inaccurate results and should not be relied upon to adjust the drug dosage. Medical product distributor Terrific Care/Medex Supply LLC issued a voluntary recall of certain Roche Diagnostics test strip lots used with CoaguChek test meter devices last month. The FDA classified this action as a Class I recall, the most serious type of recall, which means use of these devices may cause serious injuries or death. This recall is related to the November 2018 Roche Diagnostics Recall, the manufacturer of CoaguChek meters and test strips.