Reliability of International Normalized Ratio Results in the CoaguChek Pro II System in a Clinical Setting

The National Institute of Cardiology has previously used the CoaguChek(®) XS Plus system (Roche Diagnostics International Ltd), comparing capillary blood prothrombin time/international normalized ratio (PT/INR) results with those obtained using BCS-XP/Thromborel (Siemens). We assessed the reliability of PT/INR results using the third-generation CoaguChek Pro II system, the CoaguChek XS Plus system, and cobas(®) t 411 for citrated plasma analysis. Venous and capillary PT/INR were measured (N = 204). Spearman's correlation, Bland-Altman, and concordance analysis between methods were conducted. Spearman's correlation coefficients between venous/capillary INR were high for CoaguChek Pro II versus CoaguChek XS Plus (r = 0.994), CoaguChek Pro II versus cobas t 411 (r = 0.967), and CoaguChek XS Plus versus cobas t 411 (r = 0.968). Good concordance was observed among capillary methods (concordance coefficient [κ] = 0.888) and remaining relationships (P < .001 for all): cobas t 411 versus CoaguChek XS Plus (κ = 0.696) and cobas t 411 versus CoaguChek Pro II (κ = 0.684). In conclusion, good agreement was observed between CoaguChek Pro II, CoaguChek XS Plus, and cobas t 411.