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• Strong conclusions made on limited and inconsistent evidence
  Thomas Radtke, Sarah Nevitt
  Published on: 1 December 2018

• Published on: 1 December 2018

  Strong conclusions made on limited and inconsistent evidence

  • Thomas Radtke, Senior Researcher Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland
  • Other Contributors:
    • Sarah Nevitt, Research Associate

  To the Editor,

  We read with great interest the systematic review by Joschtel et al.1 on the effects exercise training on physical and psychological health in children with pediatric respiratory diseases such as asthma, bronchiectasis, bronchopulmonary dysplasia and cystic fibrosis (CF). Undoubtedly, the authors should be commended for their effort that they have put into this systematic review on an important research topic. However, we would like to take the opportunity to express some methodological concerns related to the CF studies included in this review.

  Joschtel et al.1 included studies on children, adolescents and young adults aged between 4 and 21 years and excluded those with a study population mean age of 21 years. These contradictory criteria have led to a false inclusion of one study 2 that included patients aged 12-40 years (although with a mean (SD) age of 19.5 (6.4) and 19.4 (5.3) for the intervention and control groups, respectively). Other studies 3 4, in which the mean age of the participants is <21 years were not considered for this review. Specifically, 3 out of 4 groups from the Kriemler et al. study 3 would qualify to be included in this review. Joschtel et al.1 did not publish a review protocol and therefore pre-specified inclusion and exclusion criteria cannot be verified.

  Joschtel et al.1 have conducted a meta-analysis on peak oxygen uptake (VO2peak), despite substantial heterogeneity of study characteristics (i.e., study...

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  To the Editor,

  We read with great interest the systematic review by Joschtel et al.1 on the effects exercise training on physical and psychological health in children with pediatric respiratory diseases such as asthma, bronchiectasis, bronchopulmonary dysplasia and cystic fibrosis (CF). Undoubtedly, the authors should be commended for their effort that they have put into this systematic review on an important research topic. However, we would like to take the opportunity to express some methodological concerns related to the CF studies included in this review.

  Joschtel et al.1 included studies on children, adolescents and young adults aged between 4 and 21 years and excluded those with a study population mean age of 21 years. These contradictory criteria have led to a false inclusion of one study 2 that included patients aged 12-40 years (although with a mean (SD) age of 19.5 (6.4) and 19.4 (5.3) for the intervention and control groups, respectively). Other studies 3 4, in which the mean age of the participants is <21 years were not considered for this review. Specifically, 3 out of 4 groups from the Kriemler et al. study 3 would qualify to be included in this review. Joschtel et al.1 did not publish a review protocol and therefore pre-specified inclusion and exclusion criteria cannot be verified.

  Joschtel et al.1 have conducted a meta-analysis on peak oxygen uptake (VO2peak), despite substantial heterogeneity of study characteristics (i.e., study durations ranged from <3 weeks up to 3 years; comparison of supervised versus non-supervised studies using different training modalities in different settings etc). Excluding the Hebestreit et al.2 study, which does not meet the age inclusion criterion of 4 to 21 years, the effects on VO2peak became smaller [standardized mean difference (SMD) 0.77 mL.kg-1.min-1 95% CI 0.25 to 1.29 versus 0.70 mL.kg-1.min-1 95% CI 0.12 to 1.29]. Further, it could be argued that the in-hospital trial by Selvadurai et al.5, in which children were treated for an acute infectious pulmonary exacerbation, is not comparable with the other studies in a meta-analysis, where children were treated as outpatients and those in unstable clinical condition were excluded. If this study is also excluded, the effects on VO2peak are no longer existent (SMD 0.77 mL.kg-1.min-1 95% CI 0.25 to 1.29 versus SMD 0.54 mL.kg-1.min-1 95% CI -0.04 to 1.12).

  The authors1 also did a meta-analysis on health-related quality of life (HRQoL) in patients with asthma and CF and concluded that their analysis shows “a large significant effect size for HRQoL (SMD 1.36, 95% CI 0.42 to 2.30)” and that “exercise training significantly improves HRQoL in children with asthma and CF”. It is important to note that the meta-analysis for CF was based on two small-sized studies (n=22 and n=20) from the same research group 6 7, of which one study showed a statistically significant result in favor of exercise training. The authors of the original publications assessed HRQoL with the validated Cystic Fibrosis Questionnaire (CFQ-R) - the younger children ( 11 years) were interviewed and children >12 years completed the questionnaire themselves. In both original studies, no statistically significant effects were reported for HRQoL after exercise training.6 7 The authors of the two studies reported pre- and post median (min, max) values for the exercise and control groups, respectively. We could not reproduce the HRQoL data in the forest plot (Figure 4) by Joschtel et al.1 following Cochrane handbook instructions (as the authors report using for their analysis) for the conversion of median (ranges) into mean (standard deviation) values.

  Finally, systematic reviews aim to provide patients and healthcare professionals with the best available evidence on a specific topic and are used to guide healthcare decisions. However, conclusions drawn from systematic reviews (and meta-analysis) that are based on questionable methodology and non-reproducible data are unlikely to be helpful for either patients or healthcare professionals.

  References

  1. Joschtel B, Gomersall SR, Tweedy S, et al. Effects of exercise training on physical and psychosocial health in children with chronic respiratory disease: a systematic review and meta-analysis. BMJ Open Sport Exerc Med 2018;4(1):e000409.
  2. Hebestreit H, Kieser S, Junge S, et al. Long-term effects of a partially supervised conditioning programme in cystic fibrosis. Eur Respir J 2010;35:578-83.
  3. Kriemler S, Kieser S, Junge S, et al. Effect of supervised training on FEV1 in cystic fibrosis: A randomised controlled trial. J Cyst Fibros 2013;12:714-20.
  4. Del Corral T, Cebria IIMA, Lopez-de-Uralde-Villanueva I, et al. Effectiveness of a Home-Based Active Video Game Programme in Young Cystic Fibrosis Patients. Respiration 2018;95:87-97.
  5. Selvadurai HC, Blimkie CJ, Meyers N, et al. Randomized controlled study of in-hospital exercise training programs in children with cystic fibrosis. Pediatr Pulmonol 2002;33:194-200.
  6. Santana Sosa E, Groeneveld IF, Gonzalez-Saiz L, et al. Intrahospital weight and aerobic training in children with cystic fibrosis: a randomized controlled trial. Med Sci Sports Exerc 2012;44:2-11.
  7. Santana-Sosa E, Gonzalez-Saiz L, Groeneveld IF, et al. Benefits of combining inspiratory muscle with 'whole muscle' training in children with cystic fibrosis: a randomised controlled trial. Br J Sports Med 2014;48:1513-7.

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  Conflict of Interest:
  None declared.

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