Sensitivity and Specificity of the Brachial Plexus Outcome Measure Activity Scale: A Retrospective Cohort Study

Upper limb impairments occur after incomplete recovery from brachial plexus birth injury (BPBI). Reconstructive surgeries are offered to address specific joint-level impairments; however, complete restoration is not possible. Thus, surgical decisions must carefully consider the goal of improving activity function within the child's life context. The Brachial Plexus Outcome Measure (BPOM) Activity scale is an outcome measure of upper limb activity limitation in children with BPBI. It measures the upper limb function on a 5-point ordinal scale, where a score of ≤3 is theoretically an indicator of surgical candidacy; however, no studies have validated this cutoff score. This study aimed to determine whether the BPOM Activity scale score of ≤3 can accurately identify children with BPBI who may benefit from reconstructive surgery.

A retrospective cohort study was conducted on children with BPBI (4-18 years). Two independent researchers screened the diagnostic, surgical, and outcome data from the health records and a BPBI database. Sensitivity, specificity, and receiver operating characteristic area under the curve (AUC) of ≤3 scores for shoulder, elbow/forearm, and wrist surgeries were used to identify discriminating ability. These analyses were repeated for all scores (≤1 to ≤5) to determine the best cutoff score.

Of the 502 patients screened, 251 were included. The sensitivity and specificity of ≤3 scores had acceptable to excellent discriminating ability for shoulder (90%, 72%, 0.81 AUC), elbow/forearm (89%, 90%, 0.89 AUC), and wrist (80%, 93%, 0.86 AUC) surgeries. Sensitivity, specificity, and AUC were the highest at the ≤3 score compared with other cutoff scores.

The BPOM Activity scale ≤3 cutoff score was able to identify children with BPBI who may benefit from upper limb reconstructive surgery.

These findings indicate that the BPOM Activity scale can help support shared decision-making for interventions to optimize upper limb function after BPBI.