Microscopic colitis is a risk factor for low bone density: a systematic review and meta-analysis

Background:Microscopic colitis (MC) is a chronic inflammatory disease of the large bowel characterized by watery diarrhea, substantially decreasing the patient's quality of life. Scarce data suggest that MC is associated with low bone density (LBD). Objectives:We aimed to assess whether MC is a risk factor for LBD and the proportion of patients with MC having LBD. Design:A systematic review and meta-analysis of studies reporting bone density measurements in MC patients. Data Sources and Methods:We systematically searched five databases from inception to October 16, 2021 (Pubmed, Embase, Cochrane, Scopus, and Web of Science). We used the random-effect model to calculate pooled odds ratios (ORs) and pooled event rates with 95% confidence intervals (CIs). To ascertain the quality of evidence of our outcomes, we followed the recommendations of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) Working Group. Results:The systematic search yielded a total of 3046 articles. Four articles were eligible for quantitative synthesis. All of them used age- and sex-matched controls to evaluate LBD occurrence among patients with MC. The odds of having LBD were twofold increased (OR = 2.13, CI: 1.42-3.20) in the presence of MC, the odds of osteopenia occurrence were 2.4 (OR = 2.45, CI: 1.11-5.41), and of osteoporosis 1.4 (OR = 1.42, CI: 0.65-3.12). The proportion of LBD was 0.68 (CI: 0.56-0.78), osteopenia was 0.51 (CI: 0.43-0.58), and osteoporosis was 0.11 (CI: 0.07-0.16) among the MC population. Our findings' certainty of the evidence was very low following the GRADEPro guideline. Conclusion:Our data demonstrate that MC is associated with a twofold risk for LBD. Based on our findings, we suggest screening patients for bone mineral density upon diagnosis of MC. Further prospective studies with higher patient numbers and longer follow-up periods on this topic are needed. Registration:Our protocol was prospectively registered with PROSPERO (CRD42021283392). Plain language summaryInvestigating microscopic colitis as a risk factor for having low bone density in a literature overview and statistical approachMicroscopic colitis (MC) is an underdiagnosed chronic inflammatory large bowel disease, characterized by watery diarrhea, which substantially impacts the patient's quality of life. The etiology of MC is still unclear but is suspected to be multifactorial. Moreover, low bone density (LBD) has been associated with the disease. Scarce data investigate the relationship of MC with LBD, although they share common risk factors, like advanced age and female sex. LBD has two forms; the mild is osteopenia and the severe form is osteoporosis. The most severe complications of osteoporosis are osteoporotic fractures, which can culminate in a life-threatening state and amplify the hospital expenses burden.Our primary aim was to assess if MC increases the risk of LBD. Furthermore, we estimated the proportions of bone mineral changes in the MC population.Following a rigorous methodology, our data suggest that MC doubles the odds of LBD. Furthermore, we have shown that two-thirds of the MC population suffers from bone density decrease, half of them have osteopenia, and one in 10 MC patients has osteoporosis.In conclusion, we highly suggest screening patients with MC for bone mineral density at the moment of diagnosis.