Gender Seems to Influence AS Patients’ Experiences with TNF Inhibitors, Study Suggests

The report, “Although female patients with ankylosing spondylitis score worse on disease activity than male patients and improvement in disease activity is comparable, male patients show more radiographic progression during treatment with TNF-α inhibitors,” was published in the journal Seminars in Arthritis and Rheumatism.

According to the American College of Rheumatology, ankylosing spondylitis tends to start during a person’s teens and 20s and affects males two to three times more often than females.

Clinical presentation also seem to change with sex — while women tend to experience greater disease activity and lower physical ability and quality of life, men are more prone to develop spinal radiographic damage.

A pooled analysis of clinical trials also suggests that treatment with TNF inhibitors, or anti-TNF therapy — a mainstay in arthritis treatment — is not as effective for relieving AS symptoms felt by women as it is in men.

When evaluating patient outcomes, it is important to note the possible sex differences, especially because most AS outcomes in clinical practice are based on patient-reported assessments. For instance, in clinical routine little is known about the clinical status of males and females before and after starting treatment with TNF inhibitors.

Researchers from the University Medical Center Groningen, in the Netherlands, wanted to understand what these differences are, not only in terms of disease activity and disease outcome but also in treatment response, before and during anti-TNF treatment.

The team analyzed data from 254 AS patients (69% male) who had started their first treatment with a TNF blocking agent — infliximab (brand name Remicade), etanercept (sold as Enbrel) or adalimumab (sold as Humira) — at two medical centers in the Netherlands. The data included clinical assessments at study start (baseline) and at three months or two years after treatment initiation.

At baseline, before initiating therapy with anti-TNF medications, female patients scored significantly worse than male patients on some disease activity indicators — including patient-reported BASDAI and ASDAS, as well as the number of tender joints.

In contrast, other measures such as swollen joints, history of extra-articular manifestations, and C-reactive protein (CRP) in blood (a marker of inflammation) — a more objective measure — were comparable between sexes.

Women self-reported a worse physical function and lower quality of life, measured through the surveys BASFI and ASQoL.

In contrast, men had more spinal kyphosis (roundback) and greater spinal damage seen on X-rays — again, two more objective measures.

Despite these initial differences, all patients showed significant improvement in clinical assessments of disease activity, physical function, quality of life, and spinal mobility after starting TNF inhibitors.

At both three months and two years, changes from study start in these clinical assessments were comparable between male and female patients, indicating that treatment was effective both in male and female patients.

However, the most important outcome, progression in spinal radiographic damage over two years, was significantly higher in men compared to women.

Also, subjective measures of disease activity were still significantly higher in female patients compared to male patients at two years of follow-up. Female patients also more frequently switched to another TNF inhibitor during follow-up.

“Importantly, although female patients switched more often between TNF-a inhibitors, short-term (three months) and long-term (two years) change in clinical assessments (including disease activity) was comparable between genders, except men showed more radiographic progression after two years than women,” the researchers concluded.