Abstract for presentation at Australian and New Zealand Association of Neurologists Annual Scientific Meeting 2008

Use of Respiratory Function Tests to Predict Survival in Amyotrophic Lateral Sclerosis

  • Dr Fusun Baumann, Department of Neurology, Royal Brisbane and Women's Hospital, Australia
  • Ms Nicole Hutchinson, Department of Neurology, Royal Brisbane and Women's Hospital, Australia
  • Dr Robert Henderson, Department of Neurology, Royal Brisbane and Women's Hospital, Australia
  • Mr Michael Brown, Department of Thoracic Medicine, Royal Brisbane and Women's Hospital, Australia
  • Dr James Douglas, Department of Thoracic Medicine, The Prince Charles Hospital, Australia
  • Dr Pamela McCombe, Department of Neurology, Royal Brisbane and Women's Hospital, Australia

    • Objective: The purpose of this study was to assess the ability of respiratory function tests (RFTs) to predict survival in ALS patients.
    Methods: Eighty patients with clinically-definite ALS underwent seated and supine forced vital capacity (FVC). The change in FVC from seated to supine (cFVC) along with maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured. The rate of decline in FVC was calculated in a subgroup of patients who had a minimum of two sequential RFTs. Probability of survival was calculated using the Kaplan-Meier method. Receiver operating characteristic curves were used in order to identify respiratory parameters that would best predict one-year survival.
    Results: Seated FVC, supine FVC, rate of decline in FVC, MIP and MEP were significantly associated with survival, whereas cFVC was not. An abnormal supine FVC (<80% predicted) was more sensitive (81%) for death at one year compared to seated FVC (70%). A rapid rate of decline in FVC (>3.6% predicted per month) and diminished MIP or MEP were highly sensitive (100%) for death at one year. Conversely, a slow rate of decline and a normal MIP or MEP (>70 cmH20) were highly predictive for one-year survival. Rate of decline in FVC was the most highly correlated predictor of one-year survival.
    Conclusion: Our data support the importance of the rate of change in respiratory muscle function as predictive of survival rather than single measures. Comparison of the change in FVC from seated to supine has no advantage over supine measures alone.

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