Validity of CoaguChek S for home monitoring of anticoagulant therapy in pediatrics.

BACKGROUND

CoaguChek S (Roche Diagnostics, Canada) is a portable device designed to monitor international normalized ratio (INR) by capillary puncture. Although the device is used in pediatrics, no study has evaluated its validity in patients of this population.

OBJECTIVE

To evaluate the validity of CoaguChek S as an in-home INR monitor in patients younger than 18 years of age.

METHODS

Data were based on 129 INR pairs collected from nine patients younger than 18 years of age followed up at an anticoagulation clinic between March 1, 2000, and January 19, 2004. The INRs from both the laboratory and CoaguChek S were used to evaluate concordance between the two methods using the intraclass correlation coefficient.

RESULTS

The overall intraclass correlation coefficient between the CoaguChek S and the laboratory was 0.75 (95% CI 0.66 to 0.82). On average, CoaguChek S underestimated INRs by 0.11+/-0.54 units compared with those of the laboratory. INRs of 3.5 units and higher obtained with CoaguChek S were, on average, 0.49+/-1.09 units higher than those obtained in the laboratory.

CONCLUSIONS

CoaguChek S appears to be a valid instrument for in-home INR monitoring for most patients younger than 18 years of age, with INR targets of 2.0 to 3.0 followed up by an anticoagulant therapy clinic's program. However, caution must be used when interpreting INRs higher than 3.5. Parents should perform a second test to confirm all CoaguChek S INR results higher than 4.0.