Our data represent the first case–control study consecutively compiled in a monographic unit during a 1-year period, pairing controls and cases during the same period of time. The study included patients with CD or UC and involved assessment of BMD in all subjects, measuring the prevalence of vertebral fractures with a semiquantitative method and measuring biochemical parameters related to bone metabolism.
In this study, the proportion of morphometric vertebral fractures in patients with IBD was significantly higher (38.3%) than that in the control population (13.7%). After analyzing other publications, the prevalence of osteoporotic fractures in patients with IBD varies according to the different studies. Some authors found a low prevalence (<14%) of vertebral fractures in IBD [11
], and others observed prevalences between 20% and 27% [3
]. An adequate number of cases was included in some studies, although only IBD populations were assessed without comparison with control populations [3
]. In other studies, the incidence of fracture in patients with IBD was estimated based on previous imaging studies without using a semiquantitative method [18
]. Other studies only included patients with CD [8
] or patients with low bone mass [8
] without comparing them with a control group of healthy subjects studied in parallel. The prevalence of fractures found in the present study is higher than that in previous studies, and this could be explained by differences between the sources used for data collection and different objectives.
Differences in the prevalence of fractures between patients with CD or UC have not been observed in line with other authors [16
]. Although many authors have reported a higher prevalence of vertebral fractures in patients with CD [8
], there are also studies that found a higher prevalence of fractures in patients with UC [3
Patients with IBD developed fractures at earlier ages than did controls, consistent with other publications [8
]. Only Bernstein et al. presented conflicting data in patients <50
years of age with IBD [19
The prevalence of vertebral fractures in our control group was somewhat lower than that in large-population studies in Europe, although in those studies, the included patients were older; thus, it is expected that the prevalence is higher [20
The risk of fracture due to impact in our population was higher than that in other studies (OR, 4.03%; 95% CI, 1.652–9.847; p
0.002). There are published studies that found no differences in fracture risk among patients with IBD and control populations [22
]. Other authors have shown a low risk of fracture in patients with IBD (RR, 1.2–1.5) [24
]. A study of a Canadian population showed an increased risk of fracture in patients with UC (RR, 1.54 vs. 1.90) [18
]. These studies included a large number of patients and controls, but the information comes from questionnaires administered to patients without radiological confirmation of the fracture. In our study, the higher risk is explained by more exhaustive detection that was based on radiological study.
Like the results of most authors, our results show a significantly lower BMD in patients with IBD than in controls in both the lumbar spine and femur [3
]. Differences in age or type of disease have not been found, consistent with other studies [9
Back pain, a clinical expression of vertebral fracture, was not related to the presence of morphometric fracture. Back pain was present in both groups (IBD and healthy subjects) regardless of vertebral fracture. Silent fractures were observed in 58.54% of patients with IBD and in 35.0% of healthy subjects. Therefore, this clinical manifestation is not considered useful for the diagnosis of fracture [8
Menopause has scarcely been studied in patients with IBD in relation to osteoporotic fractures. In some studies, the appearance of fractures has been found to have no relationship with menopause, which is similar to our results [17
]. In our study, premenopausal women had a higher number of fractures than did postmenopausal women. It is noteworthy that in the group of premenopausal women with IBD, BMD already showed significantly lower values, and 12 cases of fractures were reported at an average age of 31.8
years. Sex hormone deficiency had no significant influence on either vertebral fracture or low BMD in our patients, even as a known risk factor for low bone mass.
Corticosteroid use remains a controversial issue in the development of osteoporotic fractures in patients with IBD. The need for corticosteroid treatment in many cases of IBD has led to the hypothesis that this may be an important factor involved in the appearance of osteoporotic fractures. It is well known that corticoids exert a deleterious effect on bone, and, although contradictory results have been published in patients with IBD [10
], some authors propose corticosteroid use as a predictive factor for osteoporotic fracture [11
]. Others, in accordance with our results, do not consider corticosteroid use to be causal of fracture in patients with IBD [10
Our results show a poor association between the incidence of fracture and high doses of corticoids. Oddly, in our study, those patients with higher doses and continuous corticosteroid use showed a lower number of fractures than did those only treated during exacerbation of the disease. The fact that most patients only used corticosteroids for short periods of time (exacerbation phase) may explain the less pernicious effect on bone.
The biochemical and bone remodeling parameters assessed in this study did not show significant differences in patients with IBD with or without fractures or in healthy subjects.
However, a high proportion of patients with IBD showed suboptimal levels of vitamin D (30
ng/ml) for correct bone metabolism, although the levels were not different from those in control subjects. These data have been corroborated by other studies [30
Differences in CRP were not found between patients with or without fractures. The IBD group did not show inflammatory activity at the time of inclusion in this study, which justifies our results.
OPG serum levels were similar in patients with and without fractures. Several authors [34
] justify elevated OPG levels in IBD patients with chronic bowel inflammatory activity. In our study, patients were not in an acute phase of the disease, and osteoporotic fractures did not occur at the time of inclusion. It is likely that OPG levels were not different in the studied patients when evaluating for the presence of fractures or lower bone masses because of these differences.