Effect of co-morbidities on fracture risk: Findings from the Global Longitudinal Study of Osteoporosis in Women (GLOW)

Abstract

Introduction Greater awareness of the relationship between co-morbidities and fracture risk may improve fracture-prediction algorithms such as FRAX. Materials and methods We used a large, multinational cohort study (GLOW) to investigate the effect of co-morbidities on fracture risk. Women completed a baseline questionnaire detailing past medical history, including co-morbidity history and fracture. They were re-contacted annually to determine incident clinical fractures. A co-morbidity index, defined as number of baseline co-morbidities, was derived. The effect of adding the co-morbidity index to FRAX risk factors on fracture prevention was examined using chi-squared tests, the May-Hosmer test, c index and comparison of predicted versus observed fracture rates. Results Of 52,960 women with follow-up data, enrolled between October 2006 and February 2008, 3224 (6.1%) sustained an incident fracture over 2 years. All recorded co-morbidities were significantly associated with fracture, except for high cholesterol, hypertension, celiac disease, and cancer. The strongest association was seen with Parkinson’s disease (age-adjusted hazard ratio [HR]: 2.2; 95% CI: 1.6–3.1; P<0.001). Co-morbidities that contributed most to fracture prediction in a Cox regression model with FRAX risk factors as additional predictors were: Parkinson’s disease, multiple sclerosis, chronic obstructive pulmonary disease, osteoarthritis, and heart disease. Conclusion Co-morbidities, as captured in a co-morbidity index, contributed significantly to fracture risk in this study population. Parkinson’s disease carried a particularly high risk of fracture; and increasing co-morbidity index was associated with increasing fracture risk. Addition of co-morbidity index to FRAX risk factors improved fracture prediction.

Glucocorticoid exposure and fracture risk in patients with new-onset rheumatoid arthritis

“…We note, however, that incidence rates of vertebral and hip fracture observed among patients unexposed or exposed to low levels of steroids in our study are comparable to those reported for post-menopausal women aged 50-70 years in the general population [31,32]. In contrast to previous studies of glucocorticoid users with diverse disease [15,[33][34][35][36][37], we may have better isolated the impact of glucocorticoid use on fracture risk by focusing on incident RA patients and, thus, decreasing the potential for disease-related confounding. This approach also reduced the heterogeneity in patterns of steroid use, which varies by disease.…”

Guidelines for the diagnosis, prevention and management of osteoporosis

“…Comorbidities to be mentioned include rheumatoid arthritis and connective tissue diseases, diabetes, chronic obstructive pulmonary disease, chronic inflammatory bowel diseases, AIDS, Parkinson's disease, multiple sclerosis, conditions associated with severe motor disability. Of note, individuals with type 1 or type 2 diabetes tend to fracture at a higher BMD as compared to non-diabetic subjects, therefore the risk of fracture is partially independent of BMD in this population (7)(8)(9)(10)(11)(12)(13)(14)(15).…”

Bone health and multiple sclerosis

“…45 This study found that the predictive power of the FRAX algorithm was improved when specific co-morbidities, including MS, were incorporated.…”