Feasibility of coding-based Charlson comorbidity index for hospitalized patients in China, a representative developing country oleh Liyi Mo, Zhen Xie, Guohui Liu, Qiang He, Zhiming Mo, Yanhua Wu, Wenji Wang, Feng Ding, Yuanjiang Liao, Li Hao, Chen Lu, Jin Sun, Libin Xu, Yusheng Zhang, Rizwangul Ghappar, Hongwei Peng, Xiaohong Wei, Jinglie Xie, Yuanhan Chen, Xinling Liang, on behalf of China collaborative study on acute kidney injury