We found a high prevalence of osteoporotic vertebral fractures in patients with CD and decreased BMD (T score <−1). The prevalence of vertebral fractures—that is, manifest osteoporosis—was 21.8%. In 34 of 156 CD patients, we demonstrated one or more vertebral fractures. A total of 63 fractures, 50 fx. in 25 patients (16%, 15 female) and 13 fxd. in nine patients (5.8%, three female) were found.
CD patients are at high risk for low BMD but the prevalence of vertebral fractures of clinical relevance has not previously been thoroughly assessed. The few data on IBD related vertebral fractures were based on self administered questionnaires,33
or case reports.2,4,6,7,21,31
Bernstein and colleagues32
demonstrated a 40% greater incidence of fractures at any site among patients with IBD than in the general population, with an age specific incidence rate ratio of 1.54 for spine fractures in CD, indicating an increased incidence of vertebral fractures of approximately 50%. Vestergaard and colleagues33
showed an increased risk of low energy fractures in female patients with CD.
Our data represent the first prospective study investigating the prevalence of vertebral fractures based on a standardised evaluation regimen of x
rays of the thoracic and lumbar spine, analogous to the criteria of EVOS.38
The EVOS study was an epidemiological study that investigated the radiographic prevalence of vertebral fractures in men and women aged 50 years and over.40
In our study, the prevalence of vertebral fractures (21.8%) was higher compared with the mean centre prevalence in EVOS (12%) and compared with the prevalence in the EVOS study centre in Heidelberg (16.4%), located in southern Germany in common with our study centre.40
This difference is interesting due to the older age of the patients in the EVOS study (64.8 v
35.9 years in our study) and the fact that in EVOS, no differential diagnosis of fractures (osteoporotic v
others) was done. In the European Prospective Osteoporosis Study (EPOS),39
the overall prevalence of osteoporotic fractures was 10.6%, and the prevalence in the Heidelberg study centre was 11.5%, making the difference between their results and our results even more remarkable.
The association between postmenopausal osteoporosis and the development of vertebral compression fractures is well described.26
Each SD decline in BMD possibly increases the fracture risk approximately twofold.41–43
The prevalence of vertebral fractures increases the risk of developing further fractures by up to 10-fold,26
with a positive correlation with the number of prevalent fractures.44
This risk is extremely high in new incident fractures.45
Our data showed a higher prevalence of fractures in patients with osteoporosis (29%) compared with osteopenia (19%; NS). Lumbar BMD was significantly higher in the 122 patients without vertebral fractures, supporting the hypothesis that decreased BMD is a risk factor for vertebral fractures. By subgroup analysis of patients with one versus those with two or more fractures, no significant differences were found regarding age, or femoral or lumbar BMD. Whether there is a significant prevalence of fractures in CD patients with a normal BMD (T score >−1) cannot be answered by this study.
Even though the number of vertebral fractures was negatively correlated with vertebral and femoral bone density reported by Mann and colleagues,46
no correlation between the number of vertebral fractures per patient and BMD at any site was found in our study. Patients with osteoporosis were slightly older than patients with osteopenia, and the 34 patients with vertebral fractures were only a little older than the 122 patients without vertebral changes, suggesting a weak correlation with age. However, there were a larger number of young patients aged <30 years with vertebral fractures.
Our data showed a high rate of clinically silent fractures in CD patients with manifest osteoporosis, according to the criteria of the WHO.34
The fractures were clinically evident only in four patients. Severe clinical osteoporosis, including back pain, height loss, spinal deformity, and disability was already present in these young patients. The fractures in the other 30 patients were not evident clinically. These data are consistent with other reports that only one third of x
ray assessed vertebral fractures are clinically detected.26
We demonstrated that reduced BMD, a common problem in patients with CD, is not only a surrogate marker with no clinical relevance but is associated with a high prevalence of vertebral fractures. This implies that it is worthwhile paying even more attention to this extraintestinal complication of CD, especially among young patients. Although hormone replacement therapy,47
and a simple schedule of regular physical activity50
reduces the rate of bone loss or increases BMD in patients with CD, the optimum strategy for prevention and therapy has yet to be established.