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ePaper created 2014-10-06, 13:17:01 | version 1.33.00
2.5–3.5 (77.9%), corresponding to a therapeutic range of 2.0–3.5, and most patients were managed using acenocoumarol (77.6%). Some patients were managed with phenprocoumon (22.2%) and only seven patients (0.2%) received warfarin. Due to the low number of patients on warfarin, subgroup analysis was not performed for this medication. The patients were observed for a median of 1.44 years, or 1.20 years after the 90-day familiarization period [interquartile range (IQR) 0.49–1.76]. Data were observed from patients using CoaguChek XS for slightly longer (median of 1.37 years with an IQR of 0.95–1.83) versus INRatio2 (median of 1.06 years, IQR 0.33–1.72). The difference in observation time has been corrected for in the subsequent analyses. Overall Quality of INR Management Overall, 83.9% of measured INR values were within therapeutic range, resulting in a time in therapeutic range of 87.9% (Table 1). For international reference, these values correspond to a time in target range of 68.9%, although therapy was not aimed at maintenance in this narrower range. Independent of the definition of the range, only 0.085 INR measurements per month (2.4% per patient) were classified as critical values (INR \1.5 or [5.0), from an overall average of 2.8 INR measurements per month, with no statistically significant difference between critical values per month for the two INR monitors (P = 0.97). Univariate Analysis of Surrogate Markers Taken together, gender, indication, the target range, and the choice of medication consistently impacted the different surrogate metrics, although the amount of the impact was small. In contrast, patient age and choice of INR monitor only showed a small and not statistically significant effect on the most important surrogate parameters of good INR control (TTR and critical values). Comparing the effect on the TTR of the same set of patient characteristics across the two monitors using a univariate analysis, the overall difference in the effect of the two monitors was not statistically significant (P = 0.079) and only became statistically significant in defined subgroups (without a correction for multiple testing) (Table 2). However, some differences were observed in the patient distribution among the two monitors, with INRatio2 being used disproportionally more often in males, patients with an age of 45–74 years, patients with atrial fibrillation asa primary indication,patientswith a target INR range of 2.5–3.5, and patients receiving phenprocoumon. To take these differences in distribution into account, a multivariate analysis was subsequently performed. Clinical Events Self-reported minor clinical events (Table 3) were infrequently recorded by patients, with a total of 4,043 minor events being reported in the 5,185 patient-years observed. For CoaguChek XS 2,117 events were reported in 2,682 patient-years observed (average of 0.790 events per patient-year); for INRatio2 these figures were 1,926 events in 2,503 patient- years (average of 0.769 events per patient- year). The leading minor events were bruises (45%; 1,804 events) and nose bleeds (19%; 774 events), together accounting for more than half of the minor events, followed by conjunctival bleeds (11%) resulting in a reported impairment of vision (7%), blood in urine (6%), blood in stool (5%), black stool (3%), muscle bleeds and thromboembolism (2% each), and joint bleeds Adv Ther