Exposure to the Chinese famine of 1959–61 in early life and long-term health conditions: a systematic review and meta-analysis

Background: Most Chinese people over 55 years old today have experienced the Great Leap Forward Famine of 1959-61. Many reports suggested that the famine could have profound long-term health effects for exposed birth cohorts. A systematic review and meta-analysis was carried out to summarize reported famine effects on long-term health. Methods: Relevant reports were identified by searching PubMed, Embase, Chinese Wanfang Data and Chinese National Knowledge Infrastructure databases. Long-term health conditions were compared in exposed birth cohorts and unexposed controls. Fixed-effects models and random-effects models were used to combine results on adult overweight, obesity, type 2 diabetes, hyperglycaemia, hypertension, the metabolic syndrome and schizophrenia. The heterogeneity across reports was assessed. Subgroup analyses were carried out using reported famine severity, provincial mortality during famine, sex and other report characteristics. Results: In all, 36 reports were eligible for systematic review and 21 could be used for meta-analysis. The number of events we analysed ranged from 1029 for hyperglycaemia to 8973 for hypertension. As reported by others, overweight, type 2 diabetes, hyperglycaemia, the metabolic syndrome, and schizophrenia were more common among adults born during the famine compared with controls born after the famine. By contrast, there were no increases in overweight odds ratio (OR) 0.68; 95% confidence interval (CI): 0.27-1.72, type 2 diabetes (OR 0.96; 95% CI: 0.73-1.28), hyperglycaemia (OR 0.99; 95% CI: 0.72-1.36) or the metabolic syndrome (OR 1.11; 95% CI: 1.00-1.22) comparing adults born during the famine with controls born either after or before the famine. For schizophrenia, the effect estimates (OR 1.60; 95% CI: 1.50-1.70, combining control groups) were similar in the two scenarios. Conclusions: Our findings suggest that uncontrolled age differences between famine and post-famine births could explain most effects commonly attributed to the famine. For more reliable estimates of long-term famine effects in China, other analyses will be needed with age-appropriate controls and better information on the severity and timing of the famine in the populations included.