Unlike some previous studies, an analysis of U.S. Army personnel found that the incidence of ankylosing spondylitis was similar between men and women, according to data published in Arthritis Care and Research.

“Despite the impact of AS, its incidence rates remain sub-optimal characterized”, Michael H. Weisman, MD, from Stanford University School of Medicine, and colleagues wrote. “The only published population-based study of the incidence of AS in the United States looked at clinically recognized cases of AS in Olmsted County, Minnesota, over a 30-year period from 1980 to 2009. ”

“The overall reported age-adjusted incidence was 3.1 / 100,000 patient-years, and men were three times more likely to have the disease than women,” they added. “The studied population was relatively homogeneous, being 100% white in 1980-1989 and 80% white between 2000 and 2009. Substantial decrease in the male / female AS prevalence ratio from 1.7 to 1.21 during this period. . This study did not report on the racial distribution of its subjects. “

To examine any gender-based differences in the incidence of AS, Weisman and colleagues analyzed the Stanford Military Data Repository, a longitudinal electronic collection of data.

administrative and medical records of active-duty personnel of the United States Army. Focusing on the period from March 2014 to June 2017, the researchers included in their analysis a total of 728,556 people who underwent guideline-directed screening for chronic back pain.

Demographic and military data were obtained through official personnel records at Defense Manpower Data Center. Clinical data was accessed through the Military Health System Data Repository, which archives information from worldwide electronic health care records provided to U.S. service members in military and civilian health facilities. The primary endpoint was incident SA.

According to the researchers, a total of 438 people – or 0.06% of the included population – were diagnosed with AS at least once during the study period. The total incidence of AS was 27.22 per 100,000 person-years. Male patients had a slightly, but not significantly, lower incidence of AS, at 26.53 per 100,000 person-years, than female patients, at 31.36 (IRR = 1.16; CI at 95%: 0.91-1.49).

The researchers noted that the incidence of AS in women aged 24 and under was almost twice that of men (IRR = 1.93; 95% CI: 1.13, 3.29) . Although female patients had a lower incidence rate than men among 45 to 54 years old, the difference was not statistically significant (IRR = 0.77; 95% CI: 0.33-1.79 ).

In multivariate logistic regression analysis, the adjusted odds for SA were slightly, but not significantly, lower in men than in women (aOR = 0.79; 95% CI: 0.61-1.02 ). The odds of AS increased “relatively monotonously” with age, resulting in a more than seven-fold increase in patients 45 years of age and older, compared to younger patients (aOR = 7.3; CI: 5.7-10.3). The researchers further found that white patients had an adjusted 39% higher odds of being diagnosed with AS, compared to black patients (CI: 1.01-1.66).

“This study is the first of its kind to examine the incidence of AS in the United States among a large working-age adult population that is racially and ethnically similar to the American population,” Weisman said. Healio Rheumatology. “We found that the incidence of AS in men and women is relatively comparable when we looked at a population that undergoes regular medical screening coupled with free universal health care.”