Ankylosing spondylitis (AS) is a chronic inflammatory disease associated with an increased risk of osteoporosis and fractures. TNF inhibitors have been used to treat AS, but their effect on bone is unclear. Thus, we conducted a meta-analysis to study the effect of TNF inhibitors on spine and hip BMD in patients with AS.
Two authors independently searched MEDLINE and PubMed for longitudinal studies that had assessed the effect of TNF inhibitors on BMD in patients with AS. Studies with a minimum follow-up period of 1 year were included.
Seven longitudinal studies and one randomized control trial were included, with a total of 568 AS patients (mean age range of 36-48 years and disease duration of 9-17 years). Lumbar spine BMD increased by 5.1% (95% CI: 4.0-6.1%, p = 0.00000) after 1 year of treatment with TNF inhibitors and by 8.6% (95% CI: 6.8-10.3%, p < 0.00001) after 2 years. Significant improvements in total hip BMD were also noted after 1 [1.8% (1.0-2.5%)] and 2 years [2.5% (1.9-3.0%)]. Compared to baseline, femoral neck BMD remained stable after 1 year [0.7% (-0.8% to 2.2%), p = 0.34]. No significant heterogeneity was noted amongst the included studies.
TNF inhibitors can increase lumbar spine and total hip BMD and maintain femoral neck BMD for up to 2 years in patients with AS. More research is needed to assess the effect of TNF inhibitors on bone quality and fracture risk.