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Effect and impact of mechanical ventilation in myotonic dystrophy type 1: a prospective cohort study
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  • Published on:
    First study on effect and impact of mechanical ventilation in myotonic dystrophy type 1
    • Ghilas Boussaïd, PT, PhD CIC 1429, INSERM, AP-HP, Hôpital Raymond Poincaré, 92380 Garches, France
    • Other Contributors:
      • Hélène Prigent, MD, PhD
      • Pascal Laforet, MD, PhD
      • Annane Djillali, MD, PhD
      • David Orlikowski, MD, PhD
      • Frédéric Lofaso, MD, PhD

    We thank Dr. Seijger and colleagues for their analysis. These queries are legitimate and most of the answers are in the online repository. Indeed, in order to comply with the guidelines for letters to Thorax (no more than 1000 words and 2 tables / figures), we could not include all our descriptive and univariate analysis.

    We agree that the analysis of survival of patients with type 1 myotonic dystrophy is complex. Our results in Figure 1 and Table R1 demonstrated that patients who refused to initiate NIV, or who delayed NIV initiation, had both a more severe respiratory function and a higher risk for severe event (invasive ventilation or death). Independently from determining whether these severe complications were due to the severity of the initial respiratory function, the lack of compliance to treatment or both, we believe that it was important to underline the presence of this triptych, which is not observed with other neuromuscular groups, such as Duchenne muscular dystrophy where the acceptance of NIV increases with the respiratory dysfunction severity.

    Our suggestion that failure to adhere to home mechanical ventilation was associated with increased mortality (tracheostomy excluded), was based on a Cox model analysing predictors of 10-year mortality among NIV users (Table 1). The Cox model was used to evaluate death risk ratios associated with NIV adherence category and was adjusted for other risk factors described in the literature. The covariates i...

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    Conflict of Interest:
    None declared.
  • Published on:
    Reply to ‘effect and impact of mechanical ventilation in myotonic dystrophy type 1: a prospective cohort study.’
    • Charlotte Seijger, Pulmonologist in training University of Groningen, University Medical Center Groningen, Department of Pulmonary Diseases and Home mechanical ventilation,
    • Other Contributors:
      • Marieke Duiverman, Pulmonologist
      • Jellie Nieuwenhuis, pulmonologist
      • Baziel van Engelen, neurologist
      • Peter Wijkstra, pulmonologist

    To the editor,

    We read with great interest the paper of Boussaïd et al.1. They showed that Myotonic Dystrophy type 1 (DM1) patients who refused or delayed non-invasive ventilation were at higher risk for severe events, the latter defined as invasive ventilation or death. In the NIV users, risk of death was associated with orthopnoea and adherence to therapy. The investigators concluded that non-use or poor adherence of home mechanical ventilation (HMV) may be associated with increased mortality. Despite the importance of these findings several comments can be made.

    First, survival analyses in DM1 patients are complex due to heterogeneity and several other factors which have to be taken into account if the effects of HMV are assessed. For example not only the variance of reduced pulmonary function but also neuromuscular deficits, apathy, cardiac conduction disturbances, presence of obstructive or central sleep apnea do all influence the clinical condition and prognosis of these patients2. In addition, there remains the possibility that hypercapnia might not always be a result of ventilatory pump failure and that HMV might not be effective3. Correction for these confounders is needed to investigate the real effect of HMV. Moreover, both groups differ in vital capacity and presence of hypercapnia at baseline. So, we are not sure whether the risk of a severe event is really higher in the l/noNIV group than in the other groups. Therefore the presented difference...

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    Conflict of Interest:
    None declared.