Diagnostic Performance of the Strength‐Duration Test for Bedside Screening of Critical Illness Polyneuropathy and/or Myopathy: A Prospective, Cross‐Sectional Study

INTRODUCTION/AIMS: Critical illness polyneuropathy and/or myopathy (CIP/CIM) is a major cause of weakness in the intensive care unit (ICU). The availability of conventional electrodiagnostic testing may be limited. Alternative electrophysiologic methods, including the strength-duration test (SDT) and the stimulus electrodiagnosis test (SET), have been proposed as bedside screening adjuncts. This study aimed to evaluate the SDT's diagnostic metrics for CIP/CIM screening and to compare with the SET's performance. METHODS: This prospective, cross-sectional study included adult, mechanically ventilated ICU patients. Single assessment per patient comprised the peroneal simplified electrophysiological test (PENT), SDT, and SET. Using PENT as the reference test, we calculated the accuracy, sensitivity, specificity, predictive values, and likelihood ratios of SDT. Receiver operating characteristic curves were constructed to assess the discriminative performance and optimal cutoff. RESULTS: Sixty participants were enrolled, yielding 101 assessments, including bilateral evaluations when feasible. The SDT demonstrated an area under the curve (AUC) of 0.8 (95% CI: 0.7-0.8, p < 0.001), with an optimal cutoff of 600 mC. At this cutoff, SDT showed a sensitivity of 73% (95% CI: 61-82), specificity of 68% (95% CI: 53-81), accuracy of 71% (95% CI: 62-79), and positive likelihood ratio of 2.3 (95% CI: 1.41-3.78) for screening probable CIP/CIM. The SET yielded an AUC of 0.7 (95% CI: 0.6-0.8, p = 0.001). DISCUSSION: The SDT showed potential as a bedside screening adjunct for CIP/CIM in the ICU setting. Further multicenter studies are required to validate these findings and to define the role of SDT in clinical practice.