Reply to Li et al.: Estimate of the association between TB risk and famine intensity is robust to various famine intensity estimators


We thank Li et al. (1) for their interest in our paper (2) and agree that different approaches to estimating famine intensity, expressed here as the cohort size shrinkage index (CSSI), could affect estimates of its association with tuberculosis (TB) risk in the birth cohort directly impacted by famine. We acknowledge their contention that our published CSSI estimates could be biased upward due to postfamine increases in fertility that suggest delayed births. However, the proposal to use only prefamine (1953 to 1957) births to estimate the counterfactual size of the famine cohort (1958 to 1962) strikes us as ill-advised, since it ignores secular increases in cohort size that are clearly observable in data for Sichuan Province (Fig. 1) and for China as a whole (3). We respond here by examining alternative approaches to estimating the counterfactual cohort size and their impacts on estimates of the association between CSSI and the TB incidence rate ratio in the 1958-to-1962 birth cohort.

Proceedings of the National Academy of Sciences of the United States of America
Jon Zelner
Jon Zelner
Associate Professor