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.