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Predictive value for weakness and 1-year mortality of screening electrophysiology tests in the ICU



Muscle weakness in long-stay ICU patients contributes to 1-year mortality. Whether electrophysiological screening is an alternative diagnostic tool in unconscious/uncooperative patients remains unknown. We aimed to determine the diagnostic properties of abnormal compound muscle action potential (CMAP), sensory nerve action potential (SNAP), and spontaneous electrical activity (SEA) for Medical Research Council (MRC)-defined weakness and their predictive value for 1-year mortality.


Data were prospectively collected during the EPaNIC trial (ClinicalTrials.gov: NCT00512122). First, sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of abnormal CMAP, SNAP, and SEA for weakness were determined. Subsequently, association between 1-year mortality and abnormal findings on electrophysiological screening was assessed by univariate and multivariate analyses correcting for weakness and other risk factors and the prediction model involved only a development phase.


A total of 730 patients were electrophysiologically screened of whom 432 were tested for weakness. On day 8, normal CMAP excluded weakness with a high NPV (80.5 %). By day 15, abnormal SNAP and the presence of SEA had a high PPV (91.7 and 80.0 %, respectively). Only a reduced CMAP on day 8 was associated with higher 1-year mortality [35.6 vs 15.2 % (p < 0.001)]. This association remained significant after correction for weakness and other risk factors [OR 2.463 (95 % CI 1.113–5.452), p = 0.026]. Also among conscious/cooperative patients without weakness, reduced CMAP was independently associated with a higher likelihood of death occurring during 1 year [HR 2.818 (95 % CI 1.074–7.391), p = 0.035].


The diagnostic properties of electrophysiological screening vary over time. Abnormal CMAP documented early during critical illness carries information about longer-term outcome, which should be further investigated mechanistically.

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We are indebted to all patients and their families for their participation in this study. The clinical trial assistants, in particular Alexandra Hendrickx, Sylvia Van Hulle, and Jenny Gielens, are acknowledged for administrative support. We are grateful to the ICU nursing and medical staff for excellent patient care. This work was supported by the Research Foundation-Flanders (FWO), Belgium (G.0399.12, G.0592.12). GH and MPC hold a Postdoctoral Fellowship from the Clinical Research Fund (KOF) of the University Hospitals Leuven, Belgium. GVdB, via the University of Leuven, receives structural research financing via the Methusalem program, funded by the Flemish Government (METH08/07) and holds an European Research Council (ERC) Advanced grant (AdvG-2012-321670) from the Ideas Program of the EU FP7.

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Correspondence to Greet Hermans.

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The authors declare that they do not have any conflict of interest.

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G. Hermans and H. Van Mechelen contributed equally.

Take-home message: The diagnostic properties of electrophysiological screening vary over time. Abnormal CMAP documented early during critical illness carries information about longer-term outcome.

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Hermans, G., Van Mechelen, H., Bruyninckx, F. et al. Predictive value for weakness and 1-year mortality of screening electrophysiology tests in the ICU. Intensive Care Med 41, 2138–2148 (2015). https://doi.org/10.1007/s00134-015-3979-7

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  • Electrophysiology
  • Intensive care
  • Muscle weakness
  • Mortality