(M1230-04-19) Dysphagia Prevalence and Pollution

Purpose: Dysphagia, and difficulty swallowing more generally, is access to medicines issue and can be associated with a wide range of underlying conditions. Many are neurological, such as stroke, Alzheimer’s disease (dementia), and Parkinson’s disease; but there are non-neurological conditions as well, such as gastro-esophageal reflux disease (GERD)^1,2. Whether driven by an underlying medical condition or simply a preference, dysphagia or difficulty swallowing medicines can negatively impact treatment adherence and its expected outcomes. So, patients’ access to effective treatment can be lessened by these swallowing problems but making more dysphagic-friendly dosage forms available can mediate this effect by making the medicine easier to take^3,4. Moreover, many patients with adherence problems due to dysphagia may be undiagnosed⁵. Air pollution may be responsible for an inflamed or irritated throat that makes compliance with any chronic condition’s treatment by oral solid more difficult^6,7. Here, we build on the emergent evidence of the relationship between dysphagia and air pollution and examine the prospect of using pollution data as a predictor of dysphagia prevalence, which may be addressed using more dysphagic-friendly dosage forms.

Methods: The published prevalence measures for dysphagia and our own estimates from prior research on the measures of air pollution were compared using correlation^8,9,10. Air quality index (AQI) data from the World Health Organization (WHO) were collected until 2016, and World Air Quality Index (WAQI) data were collected from 2016^11,12. These data sources were combined to provide annual average pollution figures for each country. The WAQI data by respondent locations was weighted for our survey estimates (data availability permitting). The dysphagia prevalence estimates were taken from literature identified using Clarivate, and from a previous four-country survey in 2021. Dysphagia prevalence data is limited, with only a total of 7 measures of dysphagia prevalence in 6 countries. This scarcity encouraged both our prior survey and the interest in the more available pollution data. We used two approaches to the correlation calculation. One has two more observations of dysphagia prevalence, and the other has fewer prevalence estimates but more detailed pollution data. We calculated the correlation associated with 7 dysphagia prevalence estimates for which we could find at least annual air pollution measures (Table 1). For five of these prevalence estimates, we had daily air pollution data, which allowed us to calculate an average correlation for the year of the prevalence estimate using air pollution data from the first day of the relevant year to the last.

Results: The correlation between pollution and dysphagia prevalence was found to be 0.55 using the 7 available pairs of data. Using the more detailed daily pollution data, we calculated correlations for each day of the year, from the first to the last. This allows inclusion of a wider range of data, for the greatest flexibility in matching the annual prevalence estimates to a relevant air pollution measure. The average correlation calculated through the relevant year of the prevalence measure and daily pollution in 5 countries is 0.73 and less than 14 percent of these daily correlations were below 0.50.

Conclusion: A reasonably strong correlation between dysphagia prevalence and pollution measures may allow pollution, to serve as a bellwether for more difficult and expensive data on dysphagia prevalence. We found that higher pollution measures were often associated with a greater prevalence of dysphagia. Provision of dysphagic-friendly dosage forms of medicines may improve health outcomes by improving treatment adherence.

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2. Cho SY, Choung RS, Saito YA, et al. Prevalence and risk factors for dysphagia: a USA community study. Neurogastroenterol Motil. 2015 Feb;27(2):212-9. doi: 10.1111/nmo.12467.
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11. World Health Organization. (n.d.). SDG indicator 11.6.2 concentrations of fine particulate matter (PM2.5). World Health Organization. Retrieved April 2022, from https://www.who.int/data/gho/data/indicators/indicator-details/GHO/concentrations-of-fine-particulate-matter-(pm2-5)
12. World Air Quality Index (WAQI) Project. (n.d.). Air Quality Historical Data Platform. aqicn.org. Retrieved 2022, from https://aqicn.org/data-platform/register/

Acknowledgments: Not applicable
Disclaimers: Not applicable

Funding: Not applicable
Conflict of Interest Statements: JC, AG, and CW are employees of Viatris. The authors have no other conflicts to declare.