Changes in body mass index following venous thromboembolism in children: a prospective cohort study

Background: We hypothesized that acute pediatric venous thromboembolism (VTE) is associated with an increase in body mass index (BMI) over time. We posited that if children gain weight following VTE, targeted interventions may be advised clinically or tested in future studies. Objectives: The objectives of our study were to investigate BMI changes from VTE diagnosis to 3 and 6 months after diagnosis, identify predictors, and calculate the prevalence of overweight and obesity. Methods:: In this prospective cohort study, we followed 63 participants (mean age, 12.8 years [SD, 5]) for 6 months following first episode of acute VTE. We chose percentage of BMI₉₅ (%-of-BMI₉₅) instead of absolute BMI as a measure of weight to standardize across sex and age and used change in %-of-BMI₉₅ as a measure of weight change. Δ%-of-BMI₉₅ was the primary outcome measure documenting change over time, categorized as increased if Δ%-of-BMI₉₅ was >0, unchanged if Δ%-of-BMI₉₅ was 0, and decreased if Δ%-of-BMI₉₅ was <0. To assess BMI changes, we created a prespecified subgroup of participants who required intensive care unit (ICU) vs those who did not. Results: Sixty-two percent of participants were overweight/obese at diagnosis. Mean %-of-BMI₉₅ was 102.5% (95% CI, 95-109). The Δ%-of-BMI₉₅ at 3 and 6 months after diagnosis was, 1.5 (95% CI, −0.8 to 3.6) and 2.2 (95% CI, −0.6 to 5.2), respectively. We identified 3 predictors of weight change: non-ICU stay and longer length of stay predicted weight gain, whereas a higher %-of-BMI₉₅ at diagnosis in the ICU cohort correlated with decreased BMI. Conclusion: BMI increases following pediatric VTE except those in the ICU. Weight-based counseling and lifestyle changes represent potential targeted interventions after VTE.