Appropriateness of digoxin level monitoring

To evaluate the proportion of inappropriate digoxin level determinations. We performed a retrospective analysis of 210 randomly selected digoxin plasma level determinations in inpatients. Appropriateness criteria were defined combining existing criteria from the literature. The main outcome measure was the proportion of digoxin levels assessed as inappropriate using a priori defined criteria. Of the 210 digoxin levels assessed, 125 (59%; 95% confidence interval [CI] 52-66%) were considered inappropriate, 81 (39%; 95% CI: 32-45%) were appropriate, and 4 (2%) determinations could not be evaluated. Of the 125 levels assessed as inappropriate, the majority (79%) was performed as routine monitoring. Extrapolating the results to all digoxin level determinations in inpatients at our institution resulted in estimated yearly costs of CHF 28,025 (approximately B 18,995) for inappropriate digoxin level determinations. The majority of digoxin plasma levels determinations were assessed as inappropriate. This was mainly due to the lack of an adequate indication and due to incorrect timing of drawing the blood samples. With regard to indication, routine monitoring was the reason for the majority of levels assessed as inappropriate.