Application of futility analysis to refine jitter recordings in myasthenia gravis

Pushpa Narayanaswami, Norberto Pantoja-Galicia, Rebecca A. Betensky, Seward B. Rutkove

Research output: Contribution to journalArticlepeer-review


Introduction: The current practice of single-fiber electromyography (SFEMG) requires that 20 fiber pairs with normal jitter be collected to exclude myasthenia gravis (MG). We applied principles of futility analysis from clinical trials in an attempt to reduce that requirement. Methods: We utilized conditional power futility analysis to assess the probability of an abnormal 20-pair SFEMG based on ongoing analysis of jitter as each pair is collected. Rules for early test termination in the presence of 0, 1, or 2 abnormal pairs were identified. These rules were then applied to previously collected SFEMG data. Results: SFEMG could be stopped at just 12 pairs if all are normal and at 17 pairs if 1 is abnormal. The rules successfully determined when SFEMG could be stopped in 104 of 106 (98%) studies originally reported to be normal. Conclusions: If the first 12 SFEMG pairs have normal jitter, the study can be terminated and interpreted as normal.

Original languageEnglish (US)
Pages (from-to)486-491
Number of pages6
JournalMuscle and Nerve
Issue number4
StatePublished - Apr 2012


  • Futility analysis, Jitter recording
  • Myasthenia gravis
  • Pepe-Anderson method, SFEMG
  • Single-fiber electromyography

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)


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