Debate around J-curve and mortality risk – Scientists continue to criticize Lancet articles
Over the last decades, observational studies have shown that individuals who abstain entirely from the consumption of alcoholic beverages might be worse off than moderate drinkers. Several recent studies have tried to discredit this J-shaped relationship between drinking and all-cause mortality, pointing to a ‘no-safe level’ of drinking.
Wood and colleagues for example, challenge the long-standing conclusion that a glass of wine a day with the meals might lower the cardiovascular disease risk and could even be beneficial for the long-term health.
Since its first publication in April this year, several researchers have criticized the authors’ conclusion and consider the scientists’ decision to take out non-drinkers from their analysis as scientifically invalid.
Two new critiques challenge the study by the Global Burden of Disease collaborators (GBD) published in August 2018, also in the The Lancet. This study pooled global data on deaths and disability and concluded that the “level of consumption that minimizes health loss is zero”.
The worldwide media headlines reported: “no safe level of alcohol consumption, major study concludes” and “The safest level of drinking is none, says alcohol study”.
Prof. Sir David Spiegelhalter (Univesity of Cambridge) pointed out that the absolute risks, not reported in the paper, were small and based on a rather opaque statistical model. The paper only provided relative risks for serious harm, including a 0.5% increased risk at one drink per day and no estimates of the absolute risks from light drinking were given. The Lancet recognized that such reporting was not in line with the journal’s own guidelines and asked the authors for the absolute figures which resulted in the following quote: “914 people in 100,000 15-95 year olds would develop a condition in one year, if they did not drink but 918 individuals in 100,000 who drank one alcoholic drink a day would develop an alcohol-related health problem in a year.”
Putting this into perspective, for every 25,000 people having an extra drink per day, only one more person would experience a serious alcohol-related condition each year. Since one standard drink of 10 g alcohol per day adds up to 3,65 kg a year, equivalent to 16 bottles of 40 vol% ABV gin, which corresponds to 400,000 bottles of gin shared between 25,000 people to give rise to ONE case of serious harm. Viewed this way, the author’s claim that their results should lead public health bodies “to consider recommendations for abstention” looks weakly supported by scientific evidence at best. Thus, a risk that was neither statistically nor practically significant became a major headline story.
Spiegelhalter questions the ethical conduct of researchers who may mislead the media, and consequently the public, to make their findings relevant. It is time for everyone to take responsibility when communicating health risks in science. According to him “it is the responsibility of every researcher and journal editor to consider the wider effects of what they publish and to publish data true to the results that they have found”.
Commentary by Prof. Sir David Spiegelhalter of Cambridge University
Prof. Kari Poikolainen (Helsinki University, main research interests: causes and consequences of alcohol intake and other addictive substances) challenges the assumptions made in the statistical model of the study about alcohol-attributable deaths and suggests that both, consumption levels at national level and estimates of the burden attributable to alcohol are overestimated. As he summarizes his analysis: “there is a lot of hot air in the Lancet study”.
Critique Prof. Kari Poikolainen of Helsinki University