Aims Enoxaparin and tinzaparin, two low-molecular-weight heparins (LMWH), are used in paediatrics with multiples advantages such as facility of administration, reduced frequency of side effects, reduced drug interaction. However, their use is at higher risk of error in prescription, dosage, dilution or administration.¹ The monitoring of efficacy is based on the dosage of anti-Xa level with a target between 0.5 and 1 IU/mL (0.4 to 1.2 IU/mL tolerated in our hospital).^2,3,4 This dosage is performed on a routine basis in patients with curative treatment. A protocol was written by a multidisciplinary team (nephrologist, neonatologist, haematologist, cardiologist, paediatrician and pharmacist) in order to standardize the prescriptions of LMWH within the hospital for patients aged between 0 and 18. The aim of this study consists in the analysis of prescriptions of enoxaparin and tinzaparin and the anti-Xa levels before/after the dissemination of the protocol during the summer of 2017.

Methods This is a retrospective observational study in our mother-child teaching hospital in France. Any patient hospitalized in 2016 and 2018 and who received a prescription for enoxaparin or tinzaparin was included in the study. Exclusion criteria were: patients hospitalized in obstetrics and gynaecology and patients over 18 years old. Prescribing throughout the hospital is computerized and involves PCS® software (IBM, Armonk, NY, USA). Data collected concerned the patient (age, weight, first anti-Xa level, unit), the drug prescribed (dosage expressed in IU, first dosage expressed in IU/kg depending on the patient’s age and/or weight, the frequency of administration and the dilution when necessary and if it is conform to the protocol). This study has been approved by our ethics review board in March 2019.

Results In 2016 2,246 prescriptions for 630 patients were analyzed (601 patients had only enoxaparin, 7 only tinzaparin and 22 had a switch between the two heparins). In 2018 we studied 2,061 prescriptions for 629 patients (591 patients had only enoxaparin, 10 only tinzaparin and 28 had a switch). The conformity was improved concerning the first dose expressed in IU/kg (34.8% then 52.1% for enoxaparin and 69.2% then 80.0% for tinzaparin), the dosage and frequency (28.7% then 43.8% for enoxaparin and 69.2% then 80.0% for tinzaparin), the dilution specified (66.7% then 73.1%) and the dilution conform to protocol (29.4% then 66.4%). However, we observed a slight decrease in the conformity concerning the unit in IU/administration (84.5% then 80.2%) with dose expressed in mL, mg or ‘referred to protocol’. The rate of conform first anti-Xa levels (between 0.4 and 1.2 IU/mL) improved from 26.6% among 158 dosages in 2016 to 44.1% among 118 dosages in 2018.

Conclusions The overall results show an improvement in the prescription of enoxaparin and tinzaparin and in the anti-Xa levels since the dissemination of the protocol for prescribing physicians. This whole protocol will be presented in the poster and may be used by other hospitals.

References

1. Fanikos J, Stapinski C, Koo S, et al. Medication errors associated with anticoagulant therapy in the hospital. Am J Cardiol 2004;94:532–535.

2. Monagle P, Chan AKC, Goldenberg NA, et al. Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines, Chest. 2012;141:e737S-e801S.

3. Andrade-Campos MM, Montes-Limón AE, Fernandez-Mosteirin N, et al. Dosing and monitoring of enoxaparin therapy in children: experience in a tertiary care hospital. Blood Coagul Fibrinolysis. Int J Haemost Thromb 2013:24:194–8.

4. Ahuja TM, Mousavi L, Klejmont, et al. Enoxaparin dosing and antiXa monitoring in specialty populations: a case series of renal-impaired, extremes of body weight, pregnant, and pediatric patients. J Formul Manag 2018;43:609–614.