Women vs men: Which is more likely to develop a chronic disease?

Regardless of sex, you will probably develop at least one chronic disease by the end of your life, according to the results of a recent study published in the International Journal of Epidemiology. However, men have a higher risk of developing a chronic disease sometime in their lives compared with women, due to modifiable lifestyle habits.

Chronic diseases caused two-thirds of deaths worldwide, according to figures from the World Health Organization. Most of these deaths were due to cancer, cardiovascular disease, chronic respiratory disease, or diabetes. In light of this figure, it is surprising how few studies have been done to determine the impact of chronic diseases on health and survival.

Researchers undertook this study, therefore, to assess the associations between age, five modifiable lifestyle risk factors, and the incidence of a first chronic disease. Modifiable lifestyle factors included BMI, cigarette smoking, alcohol consumption, unhealthy diet, and physical inactivity. Chronic diseases included diabetes, lung cancer, myocardial infarction (MI), stroke (including transient ischemic attack), congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD).

“Whereas many chronic conditions could have been selected, we focused on these six diseases based on: their known associations with the modifiable lifestyle risk factors; high prevalence; and impact on health status, morbidity and mortality,” wrote lead author Ryan Ng, doctoral candidate, Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Ontario, Canada, and colleagues. “We intentionally sought to include diseases with known associations with: the modifiable lifestyle risk factors; high prevalence; and impact on health status, morbidity and mortality.”

For their study, Ng and fellow researchers analyzed data from 112,870 participants (56.2% women) of the Canadian Community Health Survey (CCHS), a cross-sectional survey of self-reported personal health status and components of health, which was conducted between January 1, 2000, and December 31, 2014. The CCHS represents 98% of the Canadian population over 12 years. The primary endpoint of the study was age to first chronic disease.

According to their findings, men were more likely than women to eat less fruits and vegetables, and be heavy drinkers, overweight or obese, current or former smokers, and more physically active. They were also less likely to be non-drinkers. Women were, on average, older.

During the course of the study, 15.1% of participants developed at least one chronic disease, for an overall incidence of 1.98 chronic diseases per 100 person-years. Men had a higher incidence of chronic disease than women (2.09 vs 1.90 per 100 person-years, respectively).

Diabetes occurred most frequently (40.9%), followed by COPD (32.8%), stroke (9.6%), CHF (8.2%), MI (5.9%), and lung cancer (2.6%). Only 1.9% of the study cohort (primarily women) died before developing one of these diseases.

Here are other interesting findings:

• Not consuming alcohol was associated with a higher risk of diabetes and MI in both men and women.
• Unhealthy BMI increased the risk of diabetes in both men and women.
• Current smoking was associated with all chronic diseases except CHF in women, and in men, with all chronic diseases except COPD, lung cancer, and MI.
• Not eating fruits and vegetables daily was associated with a higher risk of diabetes in both men and women.
• Decreased physical activity increased the risks of CHF and stroke in women, but decreased their risk of MI. In men, it increased the risks of lung cancer, COPD, and diabetes.

Ng and colleagues also found that, from a relative hazard perspective, women had a higher magnitude of association between lifestyle factors and age to first chronic disease than men. However, from a cumulative incidence perspective, men had a higher cumulative incidence of all diseases than women. 

“The discrepancy can be attributed to the high burden of unhealthy lifestyle factors in males compared with females,” they wrote.

Of all diseases, diabetes and COPD were the ones most likely to occur earliest. And, surprisingly, not drinking alcohol increased the risk of all six chronic diseases compared with light drinking.

“These findings agree with several existing studies showing that moderate consumption of alcohol is associated with reduced incidence of chronic diseases like coronary heart disease and diabetes,” noted the authors.

Not surprisingly, they also found a dose-response relationship for BMI and the risk of developing a first chronic disease.

In women, the greatest risk for a first chronic disease occurred in current heavy smokers compared with light smokers. Further, former heavy smokers had a greater risk than former light smokers.

Men and women, it seems, have different risks for different chronic diseases that seem to be tied to several modifiable risk factors. But there were some similarities.

“In both sexes, the relative hazard of any first chronic disease increased as the daily consumption of fruits and vegetables decreased. For both sexes, less physical activity increased the hazard of any of the six chronic diseases,” concluded Ng and colleagues. 

This study was supported by the Canadian Institutes of Health Research Partnerships for Health System Improvement and the Ontario Ministry of Health and Long-Term Care, and assisted by the Institute for Clinical Evaluative Sciences.