Clinical Pearls & Morning Reports
Published May 31, 2023
Snelling et al. conducted a noninferiority trial in which children 5 to 15 years of age who presented to the emergency department with an isolated, acute, clinically non-angulated, distal forearm injury that required imaging for a suspected fracture were randomly assigned to undergo point-of-care ultrasonography or radiography. Read the NEJM Case Records of the Massachusetts General Hospital here.
Q: What specific clinical question did this trial hope to answer?
A: Nonrandomized studies have shown that ultrasonography performed by clinicians for the diagnosis of distal forearm fractures in children is accurate, timely, and generally preferred by children and parents to radiography as the reference standard. However, the use of ultrasonography as the initial diagnostic method has not been shown to be noninferior to radiography in terms of physical function of the arm.
Q: How was physical function of the injured arm measured in this trial?
A: The primary outcome was physical function of the arm at 4 weeks (28 days, with a window of ±3 days), as measured with the use of the Pediatric Upper Extremity Short Patient-Reported Outcomes Measurement Information System (PROMIS) tool. The PROMIS tool is validated for children and adolescents 5 to 15 years of age and assesses physical function of the arm by means of an eight-item questionnaire, with each item measured on a 5-point scale (range, 8 to 40, with higher score indicating better function).
A: The mean (±SD) PROMIS score at the 4-week follow-up in the per-protocol population was 36.4±5.9 points in the ultrasonography group and 36.3±5.3 points in the radiography group (mean difference, 0.1 point; 95% confidence interval [CI], -1.3 to 1.4). These findings indicate that ultrasonography was noninferior to radiography, because the lower boundary of the 95% confidence interval was higher than the noninferiority margin of -5 points. Findings of the intention-to-treat analysis were similar to those in the per-protocol analysis (mean difference, 0.1 point; 95% CI, -1.3 to 1.4). Participant-reported satisfaction at 4 weeks did not differ substantially between the two groups but appeared to be greater in the ultrasonography group than in the radiography group at 8 weeks (mean difference, -0.17 points; 95% CI, -0.33 to -0.01). No notable difference between the groups was seen in participant-reported pain at 1 week, 4 weeks, or 8 weeks. There was no substantial difference between the groups in the number of follow-up radiography films obtained up to week 8 (167 in the ultrasonography group and 183 in the radiography group; rate ratio, 0.91; 95% CI, 0.48 to 1.73).
A: A potential limitation of the trial was that differences in subsequent therapeutic interventions may have influenced the primary outcome separately from the initial diagnostic method. However, initial management according to diagnostic category, rates of follow-up reviews and imaging, and duration of immobilization were similar in the two groups. Other limitations included the participation of a small number of sites, with health care practitioners who were trained by a single emergency physician in emergency department hospital settings. Because the PROMIS tool was not validated for use in children younger than 5 years of age, children in that age group were excluded from this trial; however, children younger than 5 years of age may also benefit from the use of ultrasonography.