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• The effect of living at high altitude and living in urban settings on lung function decline
  Dinh S Bui, Caroline J Lodge
  Published on: 14 November 2018

• Published on: 14 November 2018

  The effect of living at high altitude and living in urban settings on lung function decline

  • Dinh S Bui, Epidemiologist School of population and global health, the University of Melbourne
  • Other Contributors:
    • Caroline J Lodge, Epidemiologist

  We read with interest the findings of Miele et al. on the relationship between environmental exposures and decline in lung function (1). The authors reported that living in urban settings and living at high altitude were associated with accelerated decline in pre-bronchodilator FEV1 and FVC. Investigating the effects at area level is important from a public health perspective and extra analysis on this valuable dataset as suggested below will help to untangle these links further.
  Study participants were recruited from four settings in Peru: Lima, Tumbles, urban Puno and rural Puno (1). Urban living and high-altitude dwelling (as binary variables) were defined based on these four settings. The authors compared the effect of urban living (Lima and urban Puno) with rural living (Tumbes and rural Puno); and the effect of high-altitude dwelling (urban Puno and rural Puno) with low-altitude dwelling (Lima and Tumbes). It is possible that the observed independent effects found by the authors of urban living and high-altitude dwelling may be driven by the urban Puno group (high altitude and urban living). In other words, there may be an interaction between urban living and high-altitude dwelling and investigating this potential interaction would be informative.
  As discussed by the authors, the adverse effect of high-altitude dwelling on lung function decline may partly be related to hypoxia and adverse effects from living in urban settings may be related to outdoor air...

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  We read with interest the findings of Miele et al. on the relationship between environmental exposures and decline in lung function (1). The authors reported that living in urban settings and living at high altitude were associated with accelerated decline in pre-bronchodilator FEV1 and FVC. Investigating the effects at area level is important from a public health perspective and extra analysis on this valuable dataset as suggested below will help to untangle these links further.
  Study participants were recruited from four settings in Peru: Lima, Tumbles, urban Puno and rural Puno (1). Urban living and high-altitude dwelling (as binary variables) were defined based on these four settings. The authors compared the effect of urban living (Lima and urban Puno) with rural living (Tumbes and rural Puno); and the effect of high-altitude dwelling (urban Puno and rural Puno) with low-altitude dwelling (Lima and Tumbes). It is possible that the observed independent effects found by the authors of urban living and high-altitude dwelling may be driven by the urban Puno group (high altitude and urban living). In other words, there may be an interaction between urban living and high-altitude dwelling and investigating this potential interaction would be informative.
  As discussed by the authors, the adverse effect of high-altitude dwelling on lung function decline may partly be related to hypoxia and adverse effects from living in urban settings may be related to outdoor air pollution and comorbid conditions (2, 3). Investigating interaction between high-altitude dwelling and urban living may help tease out the underlying drivers of accelerated lung function decline. It is also critical to understand what factors in these areas mediate the adverse impact on lung function decline and the data could be further analysed to investigate potential mediators. These analyses are the first step to translation of this evidence to public health measures.
  We additionally note that the high-altitude dwelling group had higher prevalence of COPD at baseline (Table 1) and it appeared that COPD was not adjusted for in the final model (Table 3) (1). If this is the case, the inbalance of COPD may have confounded the association between high-altitude dwelling and lung function decline. We have shown that lung function trajectories leading to COPD often exceed the normal rate of decline (4). Therefore, it is also highly likely that, in this analysis, lung function decline may vary between those who have COPD and those who do not, which warrants an interaction analysis.
  Understanding the adverse effect of residential place (i.e. urban and high-altitude dwelling) on lung function decline would have significant public health implications. Further research is needed to tease out the important drivers of these observed effects.

  References
  1. Miele CH, Grigsby MR, Siddharthan T, Gilman RH, Miranda JJ, Bernabe-Ortiz A, Wise RA, Checkley W. Environmental exposures and systemic hypertension are risk factors for decline in lung function. Thorax 2018.
  2. Rice MB, Ljungman PL, Wilker EH, Dorans KS, Gold DR, Schwartz J, Koutrakis P, Washko GR, O'Connor GT, Mittleman MA. Long-term exposure to traffic emissions and fine particulate matter and lung function decline in the Framingham heart study. Am J Respir Crit Care Med 2015; 191: 656-664.
  3. Schikowski T, Schaffner E, Meier F, Phuleria HC, Vierkotter A, Schindler C, Kriemler S, Zemp E, Kramer U, Bridevaux PO, Rochat T, Schwartz J, Kunzli N, Probst-Hensch N. Improved air quality and attenuated lung function decline: modification by obesity in the SAPALDIA cohort. Environmental health perspectives 2013; 121: 1034-1039.
  4. Bui DS, Lodge CJ, Burgess JA, Lowe AJ, Perret J, Bui MQ, Bowatte G, Gurrin L, Johns DP, Thompson BR, Hamilton GS, Frith PA, James AL, Thomas PS, Jarvis D, Svanes C, Russell M, Morrison SC, Feather I, Allen KJ, Wood-Baker R, Hopper J, Giles GG, Abramson MJ, Walters EH, Matheson MC, Dharmage SC. Childhood predictors of lung function trajectories and future COPD risk: a prospective cohort study from the first to the sixth decade of life. Lancet Respir Med 2018.

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  Conflict of Interest:
  None declared.

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