Hematologic Malignancy Risk Higher Among Older Patients With Ankylosing Spondylitis

Compared with the general population, patients with ankylosing spondylitis (AS) aged 65 years and older have an increased risk of developing hematologic malignancies, including multiple myeloma, chronic lymphocytic leukemia, and non-Hodgkin lymphoma, according to study findings published in Mayo Clinic Proceedings.

Researchers conducted a national, population-based, retrospective cohort study using data from Medicare beneficiaries in the US between January 1999 and December 2010. Patients with AS and inflammatory bowel disease (IBD) were considered as the disease control group and those without AS or IBD were considered as the unaffected control group.

A total of 12,451 patients with AS, 234,905 with IBD, and 10,975,340 participants without AS or IBD were included in the study. During the study period, 297 hematologic malignancies developed in the AS group, 4538 in the IBD group, and 128,239 in the unaffected control group.

With regard to incidence rate of hematologic malignancies, older patients with vs without AS had an increased risk of developing non-Hodgkin lymphoma (1.39; 95% CI, 1.05-1.61), chronic lymphocytic leukemia (CLL; 1.50; 95% CI, 1.17-1.92), and multiple myeloma (1.52; 95% CI, 1.12-2.06). Risks were comparable between the IBD and AS groups.

In addition, the researchers conducted a systematic review of the literature focused on age-associated risk of hematologic malignancies in the AS population, identifying 21 relevant studies that analyzed risk among young and middle-aged patients. Results from the review indicated that hematologic malignancy risk was not increased in the AS patient population, although 2 studies reported increased risk for multiple myeloma.

Study limitations included the inability to assess risks related to sex or other demographic features due to relatively small number of events, the inability to assess for risk differences according to disease activity levels due to lack of measurements of chronic inflammatory activity, and the inability to exclude the possibility that environmental factors, specifically ionizing radiation exposure, may have affected the study results.

“Clinicians who care for older patients with AS should be aware of the elevated risk of non-Hodgkin lymphoma/CLL and multiple myeloma,” the study authors said. “Our results…suggest that if an [older] patient with AS and a history of TNFi use experiences development of non-Hodgkin lymphoma/CLL or multiple myeloma, the malignancy should not necessarily be attributed to [tumor necrosis factor inhibitor] treatment,” they added.