This article has been updated with a comment from Roche.

NEW YORK (360Dx) – Roche has voluntarily recalled its CoaguChek XS PT test strips for monitoring patient response to the blood thinner warfarin, according to the US Food and Drug Administration.

The recall affects certain lot numbers and package sizes that were manufactured and distributed between January 12 and October 29 of this year and involves more than 1.1 million packages.