Author's Reply to Letter to Editor in response to the article “Rising mortality rates linked to type-2 diabetes and obesity in the United States: An observational analysis from 1999 to 2022”

We read the letter by Khan¹ regarding our study² with great interest. We appreciate the comments regarding the interpretation of age-adjusted mortality rates (AAMR) and annual percentage changes (APCs) in our study.

The APC analysis identifies statistically significant trend changes in mortality rates based on segmented regression modeling conducted with Joinpoint software in our study³. Joinpoint is made by the National Cancer Institute specifically for trend analysis of epidemiological data. It objectively detects inflection points in the data. In our case, the model determined that a significant change in AAMR trajectory began in 2017, even though the steepest visual increase in AAMR appears after 2019. This difference arises as APC considers both the magnitude and statistical significance of rate changes over time, which may not always align precisely with visual trends, especially when year-to-year fluctuations occur. This is reported in figure S1B and table S2 of our study².

Moreover, to help readers who might not be familiar with the interpretation of AAMRs in the context of APCs, we created a bar graph as indicated in figure 2 depicting a 3.5-fold increase in AAMR after 2019². This highlights the impact of the COVID-19 pandemic on mortality in patients with type 2 diabetes and obesity.