Clinical Laboratory Strategies: July 9, 2009

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Rethinking Routine Urine Toxicology Screening
Test’s Utility Found Lacking in Pediatric Emergency Setting
By Genna Rollins

Routine urine toxicology screening as part of the medical clearance of psychiatric patients is a common practice in many hospitals. Prior studies involving adults have determined that this lab test generally does not add information not already obtained through patient history and physical exam, but that it does contribute to length of stay and costs associated with emergency department evaluations. Now, a new study described in this issue of Strategies examines the usefulness of routine urine toxicology screening in the pediatric emergency setting.

Many hospitals require medical clearance of patients prior to a psychiatric evaluation in the emergency department to exclude any medical causes of behavioral or psychiatric symptoms. The medical clearance typically includes results from a urine toxicology screen (UTS) test along with a physical examination and patient history. However, studies in adult populations indicate that routine UTS testing has little impact on medical decision-making in such circumstances. The utility of UTS testing in the pediatric emergency setting, which has not been evaluated extensively, is the focus of new research (Pediatr Emer Care 2009; 25:387-392). "In this study we were trying to see if ordering or not ordering the UTS made a difference in whether the patient was admitted or discharged, what the costs associated with UTS were, and how much it affected flow in the emergency department," explained lead author Jesusa Milalaine Fortu, MD, MSc, attending physician at Joe DiMaggio Children’s Hospital and Memorial Healthcare System in Hollywood, Fla.

The retrospective study involved the review of 652 medical records from patients between the ages of 8 and 17 seen in the emergency department during two 3-month periods and for whom there were UTS test results. The UTS used in the study detected seven substances, including marijuana, amphetamine, benzodiazepine, cocaine, tricyclic antidepressants, opiates, and barbiturates. A total of 267 charts in which the UTS was determined to have been medically indicated were excluded from the analysis. The researchers considered medically indicated UTS to be those in which patients were in motor vehicle accidents or presented with seizures, syncope, headache, altered mental status, ingestion of substances, chest pains or palpitations, or sexual assault. The researchers considered UTS to be routine in uncomplicated psychiatric patients who presented with aggressive or out-of-control behavior, intentional self-inflicted wounds, or symptoms of depression, but who did not show evidence of drug or alcohol ingestion or altered mental status.

A total of 385 charts meet the criteria for routine UTS and were included in the final analysis. Of these, 95% of patients with negative UTS results (n = 254/267) and 97% of patients with positive UTS results (n = 115/118) were referred for psychiatric treatment after evaluation. Overall, nearly 96% of patients were referred for psychiatric treatment regardless of the UTS results. The difference for treatment referral between patients with positive and negative UTS results was non-significant according to the Fisher exact test (p= 0.67). The researchers also explored whether there was a difference in the type of psychiatric treatment for patients with negative versus positive UTS results, but this also proved to be

non-significant: 24% of patients with negative UTS results were referred for outpatient psychiatric treatment, versus 22% with positive results; 4% of patients with negative UTS results were referred for partial hospitalization, versus 3% of patients with positive UTS; and 72% of patients with negative UTS results were referred for inpatient hospitalization, versus 75% with positive results. The authors concluded that "routine-driven UTS for the medical clearance of uncomplicated psychiatric patients in a pediatric ED did not influence the disposition and management of patients."

Although not a surprise, the results are important in advancing knowledge related to the management of uncomplicated psychiatric patients in the pediatric emergency setting, according to Gary Wasserman, DO, chief of the section of medical toxicology at Children’s Mercy Hospitals and Clinics in Kansas City, Mo. "The article presented a nice study using evidenced based medicine that simply backs up what people in clinical practice already knew for adult patients and suspected for pediatric patients—that drug screening of asymptomatic children is probably not very helpful in general." Wasserman was not involved in the study.

Wasserman also cautioned that UTS generates many well-known and some lesser-known false-positive results for certain medications, making its use all the more challenging in cases in which the UTS is not medically indicated. For example, cough suppressants containing dextromethorpan are known to produce UTS results positive for phencyclidine (PCP); on the other hand, he recently discovered that certain formulations of ranitidine produce UTS results positive for methamphetamine.

In examining the cost of UTS, the authors determined that for the 385 patients whose UTS testing was considered routine, that volume of testing represented approximately $60,000 in avoidable expenditures during the 6-month study period. They also found that the average elapsed time for the reporting of UTS results was 93 minutes; however, they cautioned that not performing UTS testing for routine cases would not necessarily translate into an equal amount of time savings for each patient’s emergency visit. Given the chaotic emergency department environment, "we can only infer that selective use of UTS may result in faster patient evaluation and discharge from the ED," the authors noted.

Fortu and Wasserman both believe the study should encourage facilities to examine their practices surrounding UTS screening for pediatric patients. "Hospitals might revisit whether or not it’s necessary. Every facility is different, but in our study we found that the UTS was not going to change anything, but it was going to cost time and money," said Fortu.

Wasserman suggested that laboratorians have a key role in instigating such analyses. "Laboratory people should get upset about a bunch of lab tests being ordered which they believe are not helpful," he contended. "They need to study the problem, analyze the results, and make changes in the institution, working with a physician to be a champion for doing so."

Wasserman and his colleagues performed a similar analysis involving trauma patients, concluded that UTS results did not add to patient management, and subsequently removed UTS from the standard protocols for trauma work-up. "What seems like a minor change can easily shorten patients’ wait in the emergency department by 1 hour," he explained. "To use lab resources wisely can make a huge difference: eliminating an unnecessary test can shorten lab turnaround time and free a technician to do another test that can be more worthwhile to the physician’s diagnosis."

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