Bone-density testing interval and transition to osteoporosis in patients with rheumatoid arthritis

The study aims to evaluate the rate of transition to osteoporosis in 360 RA patients and estimate the rescreening intervals of bone mineral density (BMD) testing. Osteoporosis was newly developed in 24.8 % during mean follow-up of 7.4 years. The estimated time of a BMD testing interval was dependent on the baseline T-score in RA patients.

Although BMD testing is routinely performed in RA patients, the interval between BMD tests has not been determined.

We retrospectively recruited 360 consecutive female patients with RA, who underwent repeated BMD testing, with a mean age of 53.7 ± 10.2 years and a mean follow-up duration of 7.4 ± 5.0 years. We stratified the study participants into five groups based on their baseline T-score range. The testing interval was defined as the estimated time for 10 % of patients in each subgroup to transition to osteoporosis. Competing-risk analyses were performed with sensitivity analysis by menopausal status and risk factors for transition to osteoporosis.

At baseline, 15 % of screened patients had osteoporosis, and during follow-up, that proportion increased to 24.8 %. The estimated BMD testing interval for 10 % of patients to develop osteoporosis was 9.6 years for those with normal BMD, 7.6 years for those with mild osteopenia, 4.7 years for those with moderate osteopenia, and 2.1 years for those with severe osteopenia. No significant risk factor for transition to osteoporosis was identified in this cohort.

Our data indicate that osteoporosis will develop in less than 10 % of female RA patients during rescreening intervals of approximately 9 years for those with normal bone density at baseline, 7 years for those with mild osteopenia, 4 years for those with moderate osteopenia, and 2 years for those with severe osteopenia at baseline. BMD interval in RA patients could be adjusted according to their baseline BMD T-scores.