Corticosteroids do not alter the threshold for vertebral fracture

Corticosteroid use is one of the most important secondary causes of osteopo rosis. Generally, it has been believed that in addition to its effect on bo ne mineral density (BMD), it also causes an alteration in bone quality that means that fractures occur at a lower BMD than might be expected. To estab lish if this is the case, we have compared the relationship between BMD and vertebral fracture in patients receiving corticosteroids with that in pati ents who had never received such therapy. Information was gathered on those patients who had been referred to the participating centers and had both B MD measurements and lateral thoracolumbar radiographs. In all, 452 patients (391 female) were identified; of these 82 (63 female) were receiving corti costeroids. There was no significant difference in BMD between the patients on corticosteroids and those with other suspected causes of osteoporosis. Vertebral fractures were present in 53% of patients on steroids compared wi th 35% of those who had no such treatment (p = 0.0035). The fractures were more likely to be multiple in patients on corticosteroids (p = 0.0042). How ever, if the relationship between bone density and fracture is investigated by plotting the cumulative prevalence of fracture against the bone density , measured by T score, the median BMD for fractures actually was marginally lower in patients on steroids, -2.74 (95% confidence interval [CI], -2.77 to -2.70) compared with -2.65 (95% CI, -2.66 to -2.65) in those who had not received steroids. Our results fail to support the notion that the fractur e threshold is altered in patients on long-term steroids and suggest that t he same diagnostic criteria should be used for osteoporosis in patients whe ther or not they are taking corticosteroid therapy.