Response to editor.

We read the letter carefully and agree with the opinion of Collins et al. on the adverse effects of multiple factors on the accuracy of the predictive models. Regarding sample size and applicability of our model, first of all, we admit that our sample size is indeed limited, which affects the accuracy of the prediction model to a certain extent. As we all know, the efficiency of the derived predictive model increases with the increase of sample size and the improvement of the data.