Sex matters less and less when it comes to mortality rates

November 14/2016

New trends show that low-income women have a shorter life expectancy than high-income men in Canada, according to University of Toronto researchers who conducted one of the first and largest Canadian studies to examine gender-based mortality differences.

“This study is important because it looks like male and female mortality rates are actually going to converge,” said Laura Rosella, the study’s lead author and Assistant Professor at the Dalla Lana School of Public Health.

Historically, male mortality has always been higher than their female counterparts across all ages and causes and it was thought to have a biological basis, but this study finds the gap is closing, which has implications for healthcare and social systems. It also illustrates the persistent social inequalities between men and women, and challenges some of the clinical thinking that women always live longer.

“The converging mortality rates for men and women suggest that it’s a social phenomenon — we’re seeing the delayed effects of women taking up risky behaviours like drinking, smoking, and poor eating habits — and for the first time, some men are living longer than some women,” said Rosella, who is also an adjunct scientist at the Institute for Clinical Evaluative Sciences (ICES)  and scientist at Public Health Ontario.

“It also may be that since women tend to assume the caregiver role, they bear more of the family responsibilities while sacrificing their own needs. For example, the kids will eat before them or they’ll take others to the doctor before going themselves,” said Rosella, noting that the social inequities facing women are worsening over time.

The study, “The narrowing mortality gap between men and women over two decades: A registry based study in Ontario, Canada,” published today in BMJ Open, analyzed data from 1.7 million deaths in the Ontario Registrar’s General Death file from 1992 to 2012. The research team calculated absolute mortality — the rate which men and women are currently at compared to the mortality rate where they started — and relative mortality — the percent change based on where people start from. Then they measured sex differences for all-cause and cause-specific mortality, looking specifically at the following causes of death: circulatory, cancers, respiratory and injuries.

They found that men and women are living longer overall, but from the year 2000 onwards, men experienced more gains in all categories. Mortality rates of high income males were lower than those seen among low-income females, relative mortality declines were greater among males than females for cancer, respiratory, and injury-related deaths, and the largest absolute mortality gains were seen among men over the age of 85 years.

This phenomenon is observed globally as well. There is an even bigger disparity in the United States and it’s less pronounced in Europe, where social systems are more robust. Canada, even with its universal health care, falls in the middle.

The overall mortality gains underscore the positive impact of improved medical interventions, but the findings suggest that men are benefitting more than women. One potential reason, explains Rosella, is that physicians may not perceive women’s risk to be as high as men’s for heart disease or other chronic diseases that are the top killers in Canada.

“We should be paying attention to these demographic shifts as it affects all aspects of our health system, from clinical care delivery to preventive and wellness services,” said Rosella.

“There are going to be a lot more older men — 80 years and up — than society has seen before and these men tend to rely more on their spouse for support so we’ll need to adjust social supports for older men to provide alternative caregiver support.”