Use of Low Molecular Weight Heparin for DVT Prophylaxis in a Pediatric Inpatient Population: Incidence of Bleeding Complications and Accuracy of ICD-9CM Codes

Background: LWMH (low molecular weight heparin) is frequently used in the adult inpatient population to prevent the development of DVT (deep venous thrombosis). However, in the pediatric population, there has been little published data regarding the use of LMWH prophylaxis or the potential side effect of bleeding. Unlike the adult population, there are no established guidelines concerning prophylactic LMWH use with children to minimize these complications.

Methods: Billing data was used to identify inpatients ages 0–18 years prescribed LMWH for DVT prevention between 2004–2008 at Nationwide Children’s Hospital. A chart review of the physician and nursing progress notes of these records was performed to determine indications for LMWH and bleeding complications using previously published definitions of major and minor bleeding. The LMWH dose, dosing schedule, duration of LMWH exposure, and demographic information was also collected from the charts. The International classification of Diseases, Ninth Revision, Clinical Modification (ICD-9CM) codes for a variety of bleeding complications were obtained from discharge abstracts. We determined if there was any correlation between bleeding complication and patient age, gender, race, LMWH dose, dosing schedule, or duration of LMWH exposure using Chi square and Fisher’s Exact Test. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the initial ICD-9CM codes for major, minor, and all bleeding complications.

Results: We reviewed 139 charts of pediatric patients who received LMWH for DVT prophylaxis. The average duration of exposure to LMWH was 18.3 days (range 1 to 213 days), with a median exposure of 8 days. 60% of patients received 40mg QD, 12% received 30mg BID, and 27% (primarily preadolescent patients) received a different dosing schedule. Of the 139 patients, 59% were trauma patients and 32% were transfers to our inpatient rehab facility. Based on the chart review, there were 15 patients with a total of 17 bleeding complications, 6 major and 11 minor. This result of 4.3% of patients having a major bleeding complication is similar to adult studies, where the incidence is approximately 3%. No patients went on to develop DVT after being started on LMWH. Patients who received longer durations of LMWH exposure were more likely to have a bleeding event. There was no statistically significant difference in age, gender, race, or LMWH dosing between patients who did and did not develop bleeding complications. There were only 2 records containing ICD-9CM codes for major bleeding complications and there were 0 records containing ICD-9CM codes for minor bleeding. From the our chart review, it was determined that there were a total of 3 patients who experienced major bleeding that could have had a code and 11 patients who had minor bleeding that could have had a code. For major bleeding, the ICD-9CM codes had the following sensitivity, specificity, positive and negative predictive values respectively: 67%, 100%, 100%, and 99.27%. For minor bleeding, the ICD-9CM codes had the following sensitivity, specificity, and positive and negative predictive values respectively: 0%, 100%, N/A, and 92%. Of note, 9 out of the 11 minor bleeding complications were seen in trauma patients and could potentially be explained by their injury pattern.

Discussion: Our findings showed a relatively low level of bleeding complications among children 0–18 years receiving LMWH for DVT prophylaxis, with even fewer patients having major bleeding. We identified no failures (DVT occurrences) in our patient population. Over half of patients receiving LMWH prophylaxis were trauma patients. In our hospital, ICD-9CM codes were somewhat successful at identifying major bleeds but were ineffective at identifying minor bleeds. However, in the trauma population, the etiology of minor bleeding (LMWH vs. injury pattern) is difficult to ascertain from retrospective chart review. This study demonstrates that in a small sample, LMWH prophylaxis appears to be safe and effective. However, the true incidence of bleeding complications would be better measured by prospective cohort studies.