Disc space narrowing is associated with an increased vertebral fracture risk in postmenopausal women: the OFELY Study.

UNLABELLED: We have analyzed the relationship between spine osteoarthritis and fractures in the OFELY cohort. Despite a higher BMD associated with spine OA, the risk of fragility fractures is not reduced. Disc space narrowing is associated with an increased risk of vertebral fracture. These data indicate that the risk of osteoporotic fracture should not be underestimated in women with spine OA.

INTRODUCTION: Although osteoarthritis (OA) and osteoporosis both increase with age, their co-existence is uncommon. A higher BMD in OA is well documented, but a reduction of the fracture risk is still controversial. Our objective was to analyze the risk of fracture in postmenopausal women with spine OA.

MATERIALS AND METHODS: In a cross-sectional study, spine OA was evaluated by lateral radiographs according to the method of Lane, and BMD was measured by DXA in 559 postmenopausal women from the OFELY cohort (mean age, 68 +/- 8 years; range, 58-94 years) 8 years after their inclusion into the study. Previous fragility fractures, all confirmed by radiographs, were prospectively registered during the annual follow-up for 8 years, and vertebral fractures were evaluated with spine radiographs. Severity of OA was assessed by scoring on osteophytes and disc narrowing on a four-point scale from 0 (normal) to 3 (severe) and graded as 0 (normal), 1 (mild osteophyte and/or narrowing), or 2 (moderate or severe osteophyte and/or narrowing).

RESULTS: Osteophytes and disc narrowing were present in 75% and 64%, respectively, of women at the lumbar spine and in 88% and 51%, respectively, at the thoracic spine, increasing with age. BMD of the spine, hip, and whole body increased with the severity of osteophytosis, whereas severity of narrowing was associated with a higher BMD only at the spine. Ninety-six fractures, including 48 vertebral fractures, occurred before OA assessment. No significant association was found between spine OA and all fragility fractures. In contrast, disc narrowing was associated with an increased risk of vertebral fracture with an odds ratio (95% CI) of 3.2 (1.1-9.3) after adjusting for age, body mass index, and BMD. The risk of vertebral fracture increased with the severity of disc narrowing. In comparison with the score 0, the odds ratio increased from 2.8 (0.9-8.7) to 4.6 (1.2-16.9) in women with mild to severe disc narrowing score.

CONCLUSIONS: Despite a higher BMD, women with spine OA do not have a reduced risk of fracture. Disc narrowing is associated with a significant increased vertebral fracture risk.