[Correspondence] The oldest-old in China – Authors’ reply
We agree with Fuzhong Li and Peter Harmer that our data1 have limitations, including the unmeasured burden of non-communicable disease. In fact, we acknowledge this in our paper, and conclude that “further studies need to include chronic diseases”. Li and Harmer also point out that we did not assess the magnitude of rural–urban differences, and Tomohiro Morita and colleagues describe our rural–urban dichotomy as “too simplistic”. We agree that an investigation of rural–urban differences is important, which is why we adjusted for rural–urban residence as a covariate in our study.