We thank Drs. Chang, Wei and Liu for their interest in our paper on the ageing gastrointestinal tract,¹ as expressed in their letter.² We would like to make a few clarifications in response.

The most important point to clarify is that missing data were not an issue of concern in our analyses, and did not affect the findings. Therefore, the use of multiple imputations and sensitivity analysis suggested by the authors is not relevant to our study. The gastrointestinal symptom data from the 54,127 individuals, whose survey responses we analysed, did not have any missing data points. This reflects one of the strengths of the Internet-based electronic survey methodology we used, where responses can be automatically checked and answers enforced page by page by the survey software in order to prevent missing data.

Chang et al. also commented that it would have been important to include variables in our study on lifestyle factors, socioeconomic factors and chronic comorbidities, as well as doing sub-group analyses by country or centre, in order to reveal disparities in care and to guide tailoring of intervention strategies. We agree that examining healthcare disparities and elucidating ways to improve healthcare related to disorders of gut–brain interaction (DGBI) are important research aims. However, these were not the goals of our study, which explicitly focused on examining whether older individuals in society generally have lower DGBI prevalence rates. However, future investigations of age differences in DGBI would do well to include assessment of lifestyle and socioeconomic factors, as these might be relevant to understanding the causes of reduced DGBI rates with advancing age. In particular, differences between younger and older adults in living conditions, lifestyle and daily stress, as well as generational differences in emotional factors, could play a role. We hope that our paper will spur further studies that can reveal the factors that explain the mysterious universal ageing-related decline in DGBI rates in populations across the world that we described.

AUTHOR CONTRIBUTIONS

Ami D. Sperber: Writing – original draft; conceptualization. Tamar Freud: Writing – review and editing. Olafur S. Palsson: Writing – original draft; conceptualization. Shrikant I. Bangdiwala: Writing – review and editing. Magnus Simren: Writing – review and editing.

LINKED CONTENT

This article is linked to Sperber et al papers. To view these articles, visit https://doi.org/10.1111/apt.18103 and https://doi.org/10.1111/apt.18225