Systematic review of the prevalence and development of osteoporosis or low bone mineral density and its risk factors in patients with inflammatory bowel disease

Table 3 Overview of most relevant risk factors for low bone mineral density or osteoporosis

Risk factors for reduced BMD	CD	CD + UC	Comments
General risk factors
Gender[5,6,9,10]	+/-	+	Female gender was found to be significantly correlated by Leslie et al[20] (2009) investigating both CD and UC patients. In CD studies, Haugeberg et al[5] found female gender to be a predictive factor for osteoporosis. Jahnsen et al[6] found men to have lower Z-scores than women, whereas Schoon et al[10] found no significant association.
Age[2,3,5,9]	+	+/-	Age was significantly associated in the CD studies. However, Haugeberg et al[5] found patients with reduced BMD to be significantly younger than those without reduced BMD.
Weight[2,3,5,9]	+, -1	+	Low weight was found to be a risk factor for low BMD in both CD + UC cohorts. In CD cohorts, Andreassen et al[15] (1999) found a significant positive correlation only in males. Haugeberg et al[17] found a positive correlation between weight and BMD for both genders.
BMI[2,5,6,9]	+/-	+	Leslie et al[20] (2009), the only study investigating BMI in CD + UC, found a positive correlation between BMI and BMD. Haugeberg et al[17] found a significant association for CD patients in a bivariate analysis, but not in a multiple linear regression analysis.
Steroid treatment[2,3,5,6,9]	+/-2	-	Multiple risk factors related to steroid usage were investigated. No correlation was found in CD + UC. However, most CD studies did find a correlation.
Height[3,5,9]	+/-	+/-
Smoking[3,5,6]	-	-
Vitamin D supplement[3-5]	-	-
Calcium supplement[3-5]	-	-
Serum 25(OH)D[1,5,8]	+/-	+/-
Serum calcium[1,5,8]	-	-
Serum parathyroid hormone[1,5,8]	+/-	+
Disease-specific risk factors
UC diagnosis[3,9]	Not relevant	-
CD diagnosis[3,6,9]	Not relevant	+/-
Disease location[1,3,5]	-	-
Disease duration[2,3,5,6]	+3,-	-
Surgery[2,3,5,6]	+/-	-

¹Only in females.

²Only in males.

³Postmenopausal females. A plus sign means that a significant association was found and a minus sign means that no association was found. If studies found different results, both signs are present. CD: Crohn’s disease; UC: Ulcerative colitis; BMI: Body mass index; BMD: Bone mineral density; +: Positive association; -: No association; +/-: Significant association and no association were found, depending on the study and/or statistical analysis carried out.