Osteoporosis more common with AS than general population: Study
Women had a 4.38 times higher risk of developing osteoporosis than men
People with ankylosing spondylitis (AS) are more likely to develop osteoporosis than the general population, and also seem to develop it earlier in life, according to data from a large medical database in Israel.
The risk of the bone condition was particularly higher for women, older patients, and people with a history of alcohol abuse or cancer. Obesity was deemed a protective factor against the condition.
“Increased awareness regarding the earlier detection of osteoporosis in patients with AS are paramount as earlier detection allows for earlier treatment and therefore preventing undesirable clinical sequalae including physical disability and more importantly fractures,” the researchers wrote in the study, “The risk of osteoporosis in patients with ankylosing spondylitis—A large retrospective matched cohort study,” which was published in Medicina Clínica.
AS is a chronic inflammatory arthritis that mainly affects the spine, particularly the joints that connect the pelvis with the base of the spine.
Due to widespread inflammation and reduced physical activity in these patients, osteoporosis — a condition marked by reduced bone density and bone fragility that increases the risk of bone fractures — is a common complication of AS.
Its prevalence and associated risk factors remain fairly unknown, however, with the few available studies being based on small patient groups.
Assessing incidence of osteoporosis in AS
To address that, a team led by researchers in Israel examined data from a large electronic medical record in Israel, the Clalit health services, to compare the incidence of osteoporosis in AS patients and the general population.
Their study included records from 5,476 patients (66.2% males) with a mean age of 48.1 who were diagnosed between 2002-2018 and 27,657 healthy people matched in age and sex. The participants were followed for a mean of seven years (range 1-16).
Among AS patients, around half (56%) were treated with nonsteroidal anti-inflammatory drugs, 11% received disease-modifying anti-rheumatic medications, and 30% were treated with tumor necrosis factor (TNF) inhibitors, such as Humira (adalimumab), Remicade (infliximab), or Enbrel (etanercept).
Results showed the incidence of osteoporosis was significantly higher in AS patients than in the control population (4.7% vs. 2.8%). Using statistical analyses, the researchers estimated that people with AS were 2.64 times more likely to develop osteoporosis.
AS patients also had significantly higher mortality rates — 8.5% vs. 8.1% — and developed osteoporosis significantly earlier, at a mean age of 59.1, versus 63.9 for the controls. While osteoporosis incidence increased over time in both groups, it remained significantly higher in AS patients, regardless of sex.
Because there were differences in patients versus controls in rates of smoking, obesity, high blood pressure, diabetes, and elevated levels of fat molecules, the researchers also took these into account. Osteoporosis still remained independently associated with AS with these factors, with patients showing a 1.83 higher risk than controls.
Women had a 4.38 times higher risk of developing osteoporosis than men and people with a history of alcohol abuse had a 2.08 times higher risk. Cancer and older age also were significant risk factors, while obesity was protective against osteoporosis, with obese patients having a 29% lower risk of developing it.
“Our study confirms the higher incidence and earlier development of osteoporosis in patients with AS. Such finding highlights the increased need of awareness and earlier detection of such comorbidity allowing prompt treatment to prevent undesired sequalae including increased risk of fractures,” the researchers said.