A significant association between low bone mass and the presence of bone erosions in patients with psoriatic arthritis suggests there is a relationship between the two in these patients.
Though osteoclasts play a role in both, the relationship between erosions and bone mass in PsA is poorly understood.
Dr. Allen Anandarajah, of the allergy, immunology, and rheumatology unit at the University of Rochester, New York, evaluated data on 1,456 patients with the disease from the Consortium of Rheumatology Researchers of North America (CORRONA) database. “We found the people who had erosions were more likely to have low bone mass,” compared with those who don't have erosions, Dr. Anandarajah said at the annual European Congress of Rheumatology.
The study looked at the association between T scores at the lumbar spine and the presence or absence of erosions, adjusting for steroid use, gender, methotrexate use, other disease-modifying antirheumatic drug use, and the use of biologics, as well as for weight, age, body mass index, and disease index.
Of the patients, 567 (40%) had erosions and 889 (60%) had no erosions. The mean age of patients with erosions was 42 years, significantly younger than the patients with none, whose mean age was 45. Significantly more men (51.5%) had erosions than did women (48.5%).
The association between the presence of bone erosions and lower T scores of the lumbar spine was significant, with significantly lower T scores of the lumbar spine among patients with erosions, compared with those who had no erosions. (Focal erosions could be anywhere, he said, noting that the patients in the database usually had x-rays of the hands and feet. But the database includes information on any x-ray that revealed an erosion.)
“These patients do have low bone mass and … the mechanism between erosions and generalized bone loss or osteoporosis could be a common factor,” Dr. Anandarajah said.