To the long list of ways that smoking can kill you, experts should add one more cause of death – suicide.
So say some sharp-eyed readers of the New England Journal of Medicine.
In February, the trio spied a report in the journal that examined more than 100,000 deaths among smokers and former smokers who participated in one of five long-term health studies. The analysis concluded that the 21 diseases officially tied to smoking accounted for only 83% of the observed deaths. Most of the other deaths could be blamed on conditions like hypertension, liver cirrhosis and rare cancers – all of which were more likely to afflict smokers than nonsmokers, the study said.
The authors of that report noted that "a small proportion" of smokers' deaths were due to suicide. But they dismissed the idea that there was any true link between the two.
Not so fast, wrote Dr. Jitender Sareen, Karver Zaborniak and Margaret Green of the University of Manitoba in Winnipeg. They tracked down the supplementary data and came to a different conclusion about smoking and suicide risk.
Women who smoked were 4.4 times more likely to kill themselves compared with women who had never smoked, the data showed. Among men, smokers were 3.2 times more likely to commit suicide than were men with no history of smoking.
Those risk ratios were greater than the increases reported for many other causes of death that the study cited, the Canadians wrote in a letter published Wednesday in New England Journal of Medicine.
For instance, smokers were 2.2 to 2.5 times more likely than nonsmokers to die of infections and 1.9 to 2.1 times more likely to die of kidney failure. Smoking was also associated with a 30% increased risk of fatal breast cancer and a 40% increased risk of fatal prostate cancer.
In fact, among the 11 life-ending conditions the study authors linked to smoking, only one – ischemic disorders of the intestines – had a higher risk ratio for both men and women than suicide. For men, the risk ratio for cirrhosis was also higher than for suicide.
The data in the original study came from the Nurses' Health Study I, the Women's Health Initiative, the Health Professionals Follow-up Study, the Cancer Prevention Study II and the National Institutes of Health-AARP Diet and Health Study. But that's not the only evidence linking smoking to suicide risk, the Canadians wrote. A meta-analysis that pooled the results of 15 different studies found that current smokers were 81% more likely to commit suicide compared with people who had never smoked. Those results were published in 2012 in the Journal of Psychiatric Research.