Nuclear kidney scans in children with urinary tract infections increase costs and radiation exposure
Research Activities, October 2012, No. 386
Controversy exists among pediatricians as to the best way to evaluate a first urinary tract infection (UTI) in children. A UTI in children can be due to vesicoureteral reflux (VUR), which is the abnormal flow of urine from the bladder back up the tubes that connect the kidneys to the bladder. The disorder is associated with an increased risk of UTIs, which, if left untreated, can lead to kidney damage.
The traditional approach to diagnosing VUR in children with a first UTI uses an ultrasound of the kidneys followed by a radionuclide or fluoroscopic cystogram. A cystogram includes the discomfort of urethral catheterization and ionizing radiation exposure to the gonads during imaging. More recently, some pediatricians have favored starting with a nuclear scan of the kidneys, resorting to a cystogram only if scans are abnormal. They cite the benefit of lower detection of clinically insignificant VUR, fewer catheterizations, and a possible decrease in gonadal radiation.
A new study that looked at these two "bottom-up" and "top-down" methods found that using nuclear scans of the kidneys significantly increased not only costs, but also radiation exposure. The researchers used a decision model with a scenario of a 1-year-old child with a recent diagnosis of a first UTI. Prior published studies were reviewed to establish probability estimates and effective radiation dose estimates. Costs were estimated by averaging Medicare reimbursements for each diagnostic test. The traditional bottom-up approach resulted in an average radiation dose of 0.06 mSv. This increased to 0.72 mSv with the top-down nuclear scan approach.
Although small, there is a measurable increase in the long-term risk of developing cancer from the ionizing radiation exposure used with scans. The estimated population-level risk was 10.1 cancers per 100,000 patients for the top-down approach compared to 0.8 cancers for the bottom-up approach. Top-down imaging costs were estimated at $82.9 million for 100,000 children versus just $59.2 million for bottom-up imaging. The study was supported in part by the Agency for Healthcare Research and Quality (HS100063).
See "Economic and radiation costs of initial imaging approaches after a child's first febrile urinary tract infection," by Jonathan C. Routh, M.D., M.P.H., Frederick D. Grant, M.D., Paul J. Kokorowski, M.D., M.P.H., and others in Clinical Pediatrics 51(1), pp. 23-30, 2012.