Researchers don’t know whether the later diagnoses are due to genetics, the environment, possible biases in the healthcare system—or some combination of reasons.
The study of health data from 6.9 million Danish people found, across hundreds of diseases, women on average were diagnosed when they were about four years older than the age at which the conditions were recognized in men.
“We’re not just looking at one disease here, we’re looking at all diseases and we are looking at an entire population, from cradle to grave,” lead author Søren Brunak from the University of Copenhagen tells Reuters Health by phone.
On average, women received cancer diagnoses 2.5 years after men. They received diagnoses for metabolic diseases, such as diabetes, 4.5 years later.
“[This] actually surprised us quite a lot,” Mr. Brunak says. “Men generally have a tendency to get to the doctor later. … So presumably the difference in onset is even larger.”
Brunak and his team considered incidence rates of diseases in the 18 broad categories of the ICD-10 diagnosis system managed by the World Health Organization.
The study wasn’t designed to explain the causes of the differences. Another limitation is that researchers only looked at diagnoses made in hospitalized patients.
Dr. Noel Bairey Merz, director of the Barbra Streisand Women’s Heart Center at the Cedars-Sinai Smidt Heart Institute, who was not involved in the study, pointed out to Reuters Health that the study, therefore, lacks information on age at diagnosis for people who didn’t require hospitalization.
“On the other hand,” she says, “being hospitalized is a sign of a serious illness, so [that] adds significance to the diagnosis and supports that disease onset may be later in women.”
Mr. Brunak’s study, published Feb. 8 online in Nature Communications, showed that osteoporosis was a notable exception to the trend.1 Here, women were typically diagnosed before they suffered a fracture, while the opposite was true for men.
“I am fascinated by this study, which generally confirms all that I present in my Stanford course on Sex and Gender in Human Physiology and Disease,” says Marcia Stefanick, director of Stanford University’s Women’s Health and Sex Differences in Medicine Center.
“When men get diseases that most healthcare professionals consider ‘women’s diseases,’ they are diagnosed at later, more serious stages, and vice versa,” Ms. Stefanick, who was not involved with the study, told Reuters Health in an email.