I read the article by Chang et al. (1) with some interest. However, there are several aspects of their article that I believe need further explanation.
The authors have previously published data on the same cohort of patients reporting no change in symptoms over a 12-year period (2). Out of their original cohort of 86 subjects, current data are only presented on 15% or 13 subjects. While the authors admit that there has been an attrition rate in follow-up due to the expected mortality and morbidity, to suggest that these 13 subjects somehow represented the entire original cohort maybe stretching things. The authors report that the 73 people who were not followed up for this report who were in the original cohort did not differ in regard to BMI, duration of diabetes, symptoms, or autonomic function scores. However, if the cohort of 13 presented in the study were truly representative, then if 8 of the 13 (i.e., 61.5%) had symptoms at baseline, then about 53 (i.e., 61.5%) subjects from the original cohort of 86 must have had symptoms. If we assume that those 13 people presented in the current study were in this cohort of 53, this means an additional 40 people who are not included in the presented data. It becomes harder to agree with the authors when they say that the data they present is representative of the entire cohort when they only present data on 13 out of 53 of the people who (potentially) had symptoms at the outset.
In addition, the current dataset is heavily biased toward those with type 1 diabetes—12 people with and only 1 with type 2 diabetes—while the original cohort of 86 had 67 people with type 1 diabetes and 20 with type 2 diabetes (3).
It is a possibility that those people who the authors have followed up with may be a self-selecting group who have been relatively well compared with those (84% of the initial cohort or 75% of the survivors) people who died or became too unwell to be reassessed during the course of follow-up. Therefore the results are not applicable to most people with diabetes as a whole. Indeed, as reported in their earlier work, 25% of patients in the original cohort had died after 10 years of follow-up (4). The authors had suggested that in those people who had died, the duration of diabetes, the presence and severity of the neuropathy, and esophageal transit time were worse. There is nothing to suggest that those people who had died in the current study were not due to similar problems. Thus those who lived long enough to be followed up may have an element of those “survivors” mentioned earlier.
Thus, while the data that the authors have presented are interesting, I feel that for the reasons outlined, they are not “unselected,” and the results must be interpreted with some caution.
Acknowledgments
No potential conflicts of interest relevant to this article were reported.
