(From the March 2015 Issue of PediatricsOnline)
Chronic renal diseases account for an estimated 5 percent of all childhood venous thromboembolism (VTE) cases, but until now, the distribution and risk factors for subgroups of this population have not been elucidated. A recent publication by researchers at Nationwide Children’s Hospital in collaboration with researchers at the Centers for Disease Control and Prevention found that the overall risk of VTE among children with chronic renal diseases depends on disease sub-group; comorbidities; recent surgery, trauma or infection; and hemodialysis. In addition, the study demonstrated that both in-hospital mortality and health care expenditures are several-fold higher among children with VTE compared to those without.
“Determining which subgroups of children with chronic renal disease are at risk for VTE is key to better monitoring for these patients,” says William E. Smoyer, MD, a co-author on the publication who is a nephrologist and director of the Center for Clinical and Translational Research at Nationwide Children’s. “It’s also the first step toward preventing this potentially deadly complication.”
The study, published in the journal Pediatric Nephrology, examined VTE events within six months of an initial diagnosis of any chronic renal disease among children included in the MarketScan® Research databases from 2003-2012. The database yielded diagnostic information, health care utilization data and health care expenditures for nearly 23,000 children with chronic renal diseases.
In total, VTE affected 0.55 percent of children with chronic renal diseases. Only 0.32 percent of children with congenital anomalies of the urinary system were affected with VTE, but as many as 6.32 percent of all children on hemodialysis experienced an event. VTE was also significantly more common among older children, those with a recent infection and those with an additional non-renal, chronic condition who had also experienced a recent trauma or surgery.
“Although VTE incidence was low in the chronic renal disease population overall, its occurrence is a clinically significant problem. Because of the short follow-up time utilized in this study, the frequency of VTE was likely underestimated,” says Bryce A. Kerlin, MD, lead author on the study and a hematologist specializing in blood clotting disorders at Nationwide Children’s. “An extended follow-up period may have identified children with recurring VTE or VTE with later onset.”
According to Dr. Kerlin, who is also director of The Joan Fellowship in Pediatric Hemostasis-Thrombosis and a principal investigator in the Center for Clinical and Translational Research, the incidence of VTE was associated with a drastic increase in both the risk of in-hospital mortality and overall health care expenditures.
“When VTE did occur, it put children at 12 times the risk of in-hospital mortality and resulted in 16 times the average inpatient health care expenditures in comparison to that for children without VTE during the study period,” Dr. Kerlin explains. “The complication resulted in a four-fold increase in outpatient expenditures as well.”
Children with VTE were admitted to the hospital more than twice as often as patients without VTE. They also attended nearly three times as many clinic visits and had more than three times the number of prescriptions filled, according to the study.
“If disease severity determines the likelihood of VTE, it’s quite possible that the differences in expenditures and health care utilization are driven by the intense management required for more serious underlying kidney disease,” says Dr. Smoyer, who also is vice president of The Research Institute at Nationwide Children’s and a professor of pediatrics at The Ohio State University College of Medicine. “But understanding when patients are most at risk for VTE may help nephrologists and hematologists adjust their treatment appropriately.”
Dr. Kerlin believes the findings are also crucial to advancing the development of therapies intended to prevent this potentially fatal complication.
“Children with chronic renal diseases suffer from significantly increased morbidity and mortality when they develop blood clots,” says Dr. Kerlin, also an associate professor of pediatrics at The Ohio State University College of Medicine. “Studies like this one may lead to studies defining the best methods to prevent this life-threatening complication.”
Dr. Smoyer and Dr. Kerlin are both funded by the National Institute of Diabetes and Digestive and Kidney Diseases. Ongoing research in their laboratories is focused on improving the health of children with kidney diseases and the mechanisms involved in their predisposition to develop blood clots.
Kerlin BA, Smoyer WE, Tsai J, Boulet SL. Healthcare burden of venous thromboembolism in childhood chronic renal diseases. Pediatric Nephrology, 2014 Dec 7. [Epub ahead of print.]