Reduced Bone Loss Is Associated With Reduced Mortality Risk in Subjects Exposed to Nitrogen Bisphosphonates: A Mediation Analysis

Bisphosphonates, potent antiresorptive agents, have been found to be associated with mortality reduction. Accelerated bone loss is, in itself, an independent predictor of mortality risk, but the relationship between bisphosphonates, bone loss, and mortality is unknown. This study aimed to determine whether the association between bisphosphonates and mortality is mediated by a reduction in the rate of bone loss. Participants from the population-based Canadian Multicentre Osteoporosis Study were followed prospectively between1996 and 2011. Comorbidities and lifestyle factors were collected at baseline and bone mineral density (BMD) at baseline and at years 3 (for those aged 40 to 60 years), 5, and 10. Rate of bone loss was calculated using linear regression. Information on medication use was obtained yearly. Bisphosphonate users grouped into nitrogen bisphosphonates (nBP; alendronate or risedronate) and etidronate and non-users (NoRx) were matched by propensity score, including all baseline factors as well as time of treatment. Cox's proportional hazards models, unadjusted and adjusted for annual rate of bone loss, were used to determine the association between nBP and etidronate versus NoRx. For the treatment groups with significant mortality risk reduction, the percent of mortality reduction mediated by a reduction in the rate of bone loss was estimated using a causal mediation analysis. There were 271 pairs of nBP and matched NoRx and 327 pairs of etidronate and matched NoRx. nBP but not etidronate use was associated with significant mortality risk reduction (hazard ratios [HR] = 0.61 [95% confidence interval 0.39-0.96] and 1.35 [95% CI 0.86-2.11] for nBP and etidronate, respectively). Rapid bone loss was associated with more than 2-fold increased mortality risk compared with no loss. Mediation analysis indicated that 39% (95% CI 7%-84%) of the nBP association with mortality was related to a reduction in the rate of bone loss. This finding provides an insight into the mechanism of the relationship between nBP and survival benefit in osteoporotic patients. © 2019 American Society for Bone and Mineral Research.

Risk of subsequent fractures and mortality in elderly women and men with fragility fractures with and without osteoporotic bone density: the Dubbo Osteoporosis Epidemiology Study

Half of fragility fractures occur in individuals with nonosteoporotic BMD (BMD T-score > -2.5); however, there is no information on postfracture adverse events of subsequent fracture and mortality for different BMD levels. The objective of this work was to determine the risk and predictors of subsequent fracture and excess mortality following initial fracture according to BMD. The subjects were community-dwelling participants aged 60+ years from the Dubbo Osteoporosis Epidemiology Study with incident fractures followed from 1989 to 2011. The outcome measurements were as follows: risk of subsequent fracture and mortality according to BMD categorized as normal (T-score < -1), osteopenia (T-score ≤ -1 and > -2.5), and osteoporosis (T-score ≤ -2.5). There were 528 low-trauma fractures in women and 187 in men. Of these, 12% occurred in individuals with normal BMD (38 women, 50 men) and 42% in individuals with osteopenia (221 women, 76 men). The relative risk (RR) of subsequent fracture was >2.0-fold for all levels of BMD (normal BMD: 2.0 [1.2 to 3.3] for women and 2.1 [1.2 to 3.8] for men; osteopenia: 2.1 [1.7 to 2.6] for women and 2.5 [1.6 to 4.1] for men; and osteoporosis 3.2 [2.7 to 3.9] for women and 2.1 [1.4 to 3.1] for men. The likelihood of falling and reduced quadriceps strength contributed to subsequent fracture risk in women with normal BMD. By contrast with subsequent fracture risk, postfracture mortality was increased particularly in individuals with low BMD (age-adjusted standardized mortality ratio [SMR] for osteopenia 1.3 [1.1 to 1.7] and 2.2 [1.7 to 2.9] for women and men, respectively, and osteoporosis 1.7 [1.5 to 2.0] and 2.7 [2.0 to 3.6] for women and men, respectively). This study demonstrates the high burden of subsequent fracture in individuals with normal BMD and osteopenia, and excess mortality particularly for those with osteopenia (and osteoporosis). These findings highlight the importance of these fractures and underscore the gap in evidence for benefit of antiosteoporotic treatment for fragility fracture, in those with only mildly low BMD.

Disease factors in early rheumatoid arthritis are associated with differential risks for cardiovascular events and mortality depending on age at onset: a 10-year observational cohort study

OBJECTIVE

To investigate, within the first 2 years of diagnosis with rheumatoid arthritis (RA), associations between disease-related measures and cardiovascular disease (CVD) and mortality in patients with RA onset before and after 65 years of age.

METHODS

The study population (n = 741; 67.5% women) was derived from the Better Anti-Rheumatic Pharmaco Therapy (BARFOT) early RA cohort, recruited 1993-1999. The mean age was 55 years (SD 14.7). The outcomes were incident CVD events and all-cause mortality until 2010. Area under the curve (AUC) for disease measures at inclusion, 1 and 2 years, and decrease in measures after 1 year were calculated.

RESULTS

In all, 177 CVD events and 151 deaths occurred over 10 years of observation. In adjusted Cox regression analyses, seropositivity for rheumatoid factor (RF) or anticitrullinated protein antibodies (ACPA); white blood (cell) count at diagnosis; and AUC of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and visual analog scale (VAS)-pain were associated with higher CVD risk among patients with disease onset before 65 years of age. Among patients with disease onset after 65 years, larger decreases in CRP, ESR, health assessment questionnaire (HAQ), and use of methotrexate decreased CVD risk, whereas use of glucocorticoids heightened CVD risk. AUC of CRP, ESR, HAQ, and HAQ after 2 years was related to risk of death in both age groups. Seropositivity and AUC for VAS-pain in the younger group and use of glucocorticoids in the elderly were associated with poorer survival.

CONCLUSION

Early treatment of RA may improve longterm outcomes. Presence of RF or ACPA associates with CVD and mortality among RA patients with disease onset before 65 years. Age stratification may improve evaluation of risk for CVD and mortality in early RA.