Previous studies have pointed to rise in diabetes, high blood pressure and other chronic conditions compared to control groups, but researchers at Columbia University's Mailman School of Public Health have now called this into question.
In a re-analysis, the Columbia researchers compared outcomes in famine births to control groups combining births from both before and after the famine – instead of those born only after.
"The results of our analysis were unexpected and point to an unrecognised flaw in common famine reports. Using only controls born after the famine, famine births will be older than controls and this will make them less healthy than controls," said L H Lumey, MD, PhD, professor of Epidemiology at the Mailman School and senior author.
Because many studies differed in study design and analytical methods and were carried out in different regions in China, the Columbia researchers undertook a systematic review and meta-analysis of available reports to summarise the data, generate estimates of homogeneity of reported famine effects, consider possible implications for public health, and formulate suggestions for future studies.
The researchers used several databases including PubMed, Embase, Chinese Wanfang Data, and Chinese National Knowledge Infrastructure to conduct the review. More than 13,000 records of long-term health conditions were initially reviewed for those exposed and unexposed to the famine. The number of events that were analysed ranged from 1,029 for hyper-glycaemia to 8,973 for hypertension. Most Chinese over age 55 today have been exposed to the famine at some point of their early life.
No systematic difference
The analysis did not find a link between increased cases of overweight, type 2 diabetes, hyperglycaemia or metabolic syndrome when comparing adults born during the famine with controls born either after or before the famine.
There was, however, a slight increase in the rate of schizophrenia when comparing those born during with the famine, with those born both before and after.
"Beyond age effects, we were also interested in health outcomes comparing births in rural and urban areas and in regions with extreme and less severe famine - which some studies had reported - and we did not find any systematic differences. We think that better indicators of famine exposure are needed," noted Chihua Li, doctoral candidate in the Department of Epidemiology and the study's first author.
The researchers said reliable estimates of the long-term impact of the Chinese famine were important because the famine experience could have substantially increased the risk of major chronic diseases in later life among the Chinese population.
"As a next step, we will therefore continue with systematic analyses of study results from on-going health surveys in China for more reliable estimates of long term famine effects" said Dr Lumey.
"Significant improvements are needed in the design and analysis of these studies for more reliable estimates of the long-term impact of the famine," he added.
Findings are published online in the International Journal of Epidemiology.