RESUMO
BACKGROUND: To assess factors affecting the prolongation of the international normalized ratio (INR) with concurrent warfarin and ciprofloxacin use. METHODS: A retrospective case-control study was performed at a single, 2,000-bed tertiary hospital between January 2007 and December 2009. Thirty-three patients who were on warfarin and ciprofloxacin concurrently were enrolled. Demographics and clinical data were collected from medical records. RESULTS: Nine patients were assigned to the case group (prolonged INR) and 19 patients to the control group (normal INR). Activities of daily living (ADL) and total number of classes of medications taken demonstrated significant differences between the groups (15.33 vs. 7.11, p<0.001; 7.11 vs. 5.47, p=0.041). No bleeding complications occurred during this study. CONCLUSION: As ADL reflects patient performance status and general condition of an individual, we conclude that a poor general condition is associated with coagulopathy in persons concurrently using warfarin and ciprofloxacin.