Sedentary behavior does not predict low BMD nor fracture-population-based Canadian Multicentre Osteoporosis Study

Sedentary behavior (SB) or sitting is associated with multiple unfavorable health outcomes. Bone tissue responds to imposed gravitational and muscular strain with there being some evidence suggesting a causal link between SB and poor bone health. However, there are no population-based data on the longitudinal relationship between SB, bone change, and incidence of fragility fractures. This study aimed to examine the associations of sitting/SB (defined as daily sitting time), areal BMD (by DXA), and incident low trauma (fragility) osteoporotic fractures (excluding hands, feet, face, and head). We measured baseline (1995-7) and 10-yr self-reported SB, femoral neck (FN), total hip (TH), and lumbar spine (L1-L4) BMD in 5708 women and 2564 men aged 25 to 80+ yr from the population-based, nationwide, 9-center Canadian Multicentre Osteoporosis Study. Incident 10-yr fragility fracture data were obtained from 4624 participants; >80% of fractures were objectively confirmed by medical records or radiology reports. Vertebral fractures were confirmed by qualitative morphological methods. All analyses were stratified by sex. Multivariable regression models assessed SB-BMD relationships; Cox proportional models were fit for fracture risk. Models were adjusted for age, height, BMI, physical activity, and sex-specific covariates. Women in third/fourth quartiles had lower adjusted FN BMD versus women with the least SB (first quartile); women in the SB third quartile had lower adjusted TH BMD. Men in the SB third quartile had lower adjusted FN BMD than those in SB first quartile. Neither baseline nor stable 10-yr SB was related to BMD change nor to incident fragility fractures. Increased sitting (SB) in this large, population-based cohort was associated with lower baseline FN BMD. Stable SB was not associated with 10-yr BMD loss nor increased fragility fracture. In conclusion, habitual adult SB was not associated with subsequent loss of BMD nor increased risk of fracture.

Current and Future Anti-VEGF Agents for Neovascular Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the most common cause of legal blindness in developed countries. Neovascular (ie, wet) AMD is currently managed with intravitreal therapy. Traditional treatments (ie, bevacizumab, ranibizumab, aflibercept) provide high-efficacy therapy but can also require frequent dosing. Newer and future anti-VEGF therapies aim to decrease injection frequency through eitherlonger half life or port-delivery systems (brolucizumab, conbercept, KSI-301, ranibizumab). This review outlines current anti-VEGF treatments and ways by which their duration might be extended.

Simulated effects of early menopausal bone mineral density preservation on long-term fracture risk: a feasibility study

Prevention of early menopausal bone loss may reduce the future burden of osteoporosis. In this modelling exercise, an osteoporosis prevention strategy involving 5-year infusions of zoledronic acid, beginning early in menopause, reduced long-term fracture risk and the proportion of aging women with femoral neck densitometric osteoporosis. This strategy warrants further evaluation.

INTRODUCTION

Preventing early menopausal bone loss may substantially reduce the future burden of osteoporosis. We modelled the effects of infrequent zoledronic acid infusions on long-term fracture risk.

METHODS

Data from the Canadian Multicentre Osteoporosis Study (CaMos) were used to determine the expected natural history of femoral neck areal bone mineral density (BMD) and fracture risk (using FRAX®) from ages 50-80 for women with no antiresorptive drug exposures. We modelled the effects of three infusions of zoledronic acid (at ages 50, 55, 60) on long-term fracture risk, assuming this intervention would preserve BMD until age 65 years, followed by losses mirroring early menopausal BMD loss.

RESULTS

At age 65, untreated women and zoledronic acid recipients had expected mean (SD) femoral neck T-scores of - 1.5(1.0) and - 0.8(1.0), 10-year major osteoporotic fracture (MOF) risks of 9.8%(5.0) and 8.0%(3.7) and hip fracture risks of 1.7%(2.4) and 0.8%(1.2), respectively. At age 80, untreated women and zoledronic acid recipients had expected femoral neck T-scores of - 1.9(0.9) and - 1.4(0.9), MOF risks of 17.9%(8.2) and 14.9%(6.4) and hip fracture risks of 6.3%(6.2) and 4.4%(4.5), respectively. The expected proportion of women with femoral neck T-score ≤ - 2.5 was 14.9% for untreated women and 3.8% for zoledronic acid recipients at age 65, increasing to 28.1% and 12.0%, respectively, at age 80. Numbers-needed-to-treat to prevent one case of densitometric osteoporosis were 9 at age 65 and 5 at age 80.

CONCLUSION

Infrequent infusions of zoledronic acid, initiated early in menopause, are expected to reduce long-term fracture risk and result in a substantial reduction in the proportion of women with densitometric osteoporosis after age 65.

A Risk Assessment Tool for Predicting Fragility Fractures and Mortality in the Elderly

Existing fracture risk assessment tools are not designed to predict fracture-associated consequences, possibly contributing to the current undermanagement of fragility fractures worldwide. We aimed to develop a risk assessment tool for predicting the conceptual risk of fragility fractures and its consequences. The study involved 8965 people aged ≥60 years from the Dubbo Osteoporosis Epidemiology Study and the Canadian Multicentre Osteoporosis Study. Incident fracture was identified from X-ray reports and questionnaires, and death was ascertained though contact with a family member or obituary review. We used a multistate model to quantify the effects of the predictors on the transition risks to an initial and subsequent incident fracture and mortality, accounting for their complex interrelationships, confounding effects, and death as a competing risk. There were 2364 initial fractures, 755 subsequent fractures, and 3300 deaths during a median follow-up of 13 years (interquartile range [IQR] 7-15). The prediction model included sex, age, bone mineral density, history of falls within 12 previous months, prior fracture after the age of 50 years, cardiovascular diseases, diabetes mellitus, chronic pulmonary diseases, hypertension, and cancer. The model accurately predicted fragility fractures up to 11 years of follow-up and post-fracture mortality up to 9 years, ranging from 7 years after hip fractures to 15 years after non-hip fractures. For example, a 70-year-old woman with a T-score of -1.5 and without other risk factors would have 10% chance of sustaining a fracture and an 8% risk of dying in 5 years. However, after an initial fracture, her risk of sustaining another fracture or dying doubles to 33%, ranging from 26% after a distal to 42% post hip fracture. A robust statistical technique was used to develop a prediction model for individualization of progression to fracture and its consequences, facilitating informed decision making about risk and thus treatment for individuals with different risk profiles. © 2020 American Society for Bone and Mineral Research.

Vertebral Fractures: Which Radiological Criteria Are Better Associated With the Clinical Course of Osteoporosis?

STUDY PURPOSE

Morphometric methods categorize potential osteoporotic vertebral fractures (OVF) on the basis of loss of vertebral height. A particular example is the widely used semiquantitative morphometric tool proposed by Genant (GSQ). A newer morphologic algorithm-based qualitative (mABQ) tool focuses on vertebral end-plate damage in recognizing OVF. We used data from both sexes in the Canadian Multicentre Osteoporosis Study (CaMos) to compare the 2 methods in identifying OVF at baseline and during 10 years of follow-up.

MATERIALS AND METHODS

We obtained lateral thoracic and lumbar spinal radiographs (T4-L4) 3 times, at 5-year intervals, in 828 participants of the population-based CaMos. Logistic regressions were used to study the association of 10-year changes in bone mineral density (BMD) with incident fractures.

RESULTS

At baseline, 161 participants had grade 1 and 32 had grade 2 GSQ OVF; over the next 10 years, only 9 of these participants had sustained incident GSQ OVF. Contrastingly, 21 participants at baseline had grade 1 and 48 grade 2 mABQ events; over the next 10 years, 79 subjects experienced incident grade 1 or grade 2 mABQ events. Thus, incident grades 1 and 2 morphologic fractures were 8 times more common than morphometric deformities alone. Each 10-year decrease of 0.01 g/cm² in total hip BMD was associated with a 4.1% (95% CI: 0.7-7.3) higher odds of having an incident vertebral fracture.

CONCLUSIONS

This analysis further suggests that morphometric deformities and morphologic fractures constitute distinct entities; morphologic fractures conform more closely to the expected epidemiology of OVF.

Testing a theoretical model of imminent fracture risk in elderly women: an observational cohort analysis of the Canadian Multicentre Osteoporosis Study

We examined the underlying relationship between fracture risk factors and their imminent risk. Results suggested that having past year fracture, worse past year general health, worse past year physical functioning, and lower past year BMD T-score directly predicted higher imminent fracture risk. Past year falls indirectly predicted imminent risk through physical functioning and general health.

INTRODUCTION

This study aimed to examine direct and indirect effects of several factors on imminent (1 year) fracture risk.

METHODS

Data from women age 65 and older from population-based Canadian Multicentre Osteoporosis Study were used. Predictors were identified from study years 5 and 10, and imminent fracture data (1-year fracture) came from years 6 and 11 (year 5 predicts year 6, year 10 predicts year 11). A structural equation model (SEM) was used to test the theoretical construct. General health and physical functioning were measured as latent variables using items from the 36-Item Short Form Health Survey (SF-36) and bone mineral density (BMD) T-score was a latent variable based on observed site-specific BMD data (spine L1-L4, femoral neck, total hip). Observed variables were fractures and falls. Model fit was evaluated using root mean square error of approximation (RMSEA), Tucker Lewis index (TLI), and comparative fit index (CFI).

RESULTS

The analysis included 3298 women. Model fit tests showed that the SEM fit the data well; χ²(172) = 1122.10 < .001, RMSEA = .03, TLI = .99, CFI = .99. Results suggested that having past year fracture, worse past year general health, worse past year physical functioning, and lower past year BMD T-score directly predicted higher risk of fracture in the subsequent year (p < .001). Past year falls had a statistically significant but indirect effect on imminent fracture risk through physical functioning and general health (p < .001).

CONCLUSIONS

We found several direct and indirect pathways that predicted imminent fracture risk in elderly women. Future studies should extend this work by developing risk scoring methods and defining imminent risk thresholds.

Vertebral Fractures in Individuals With Type 2 Diabetes: More Than Skeletal Complications Alone

OBJECTIVE

We aimed to assess whether individuals with type 2 diabetes (T2D) have increased risk of vertebral fractures (VFs) and to estimate nonvertebral fracture and mortality risk among individuals with both prevalent T2D and VFs.

RESEARCH DESIGN AND METHODS

A systematic PubMed search was performed to identify studies that investigated the relationship between T2D and VFs. Cohorts providing individual participant data (IPD) were also included. Estimates from published summary data and IPD cohorts were pooled in a random-effects meta-analysis. Multivariate Cox regression models were used to estimate nonvertebral fracture and mortality risk among individuals with T2D and VFs.

RESULTS

Across 15 studies comprising 852,705 men and women, individuals with T2D had lower risk of prevalent (odds ratio [OR] 0.84 [95% CI 0.74-0.95]; I ² = 0.0%; P _het = 0.54) but increased risk of incident VFs (OR 1.35 [95% CI 1.27-1.44]; I ² = 0.6%; P _het = 0.43). In the IPD cohorts (N = 19,820), risk of nonvertebral fractures was higher in those with both T2D and VFs compared with those without T2D or VFs (hazard ratio [HR] 2.42 [95% CI 1.86-3.15]) or with VFs (HR 1.73 [95% CI 1.32-2.27]) or T2D (HR 1.94 [95% CI 1.46-2.59]) alone. Individuals with both T2D and VFs had increased mortality compared with individuals without T2D and VFs (HR 2.11 [95% CI 1.72-2.59]) or with VFs alone (HR 1.84 [95% CI 1.49-2.28]) and borderline increased compared with individuals with T2D alone (HR 1.23 [95% CI 0.99-1.52]).

CONCLUSIONS

Based on our findings, individuals with T2D should be systematically assessed for presence of VFs, and, as in individuals without T2D, their presence constitutes an indication to start osteoporosis treatment for the prevention of future fractures.

Primary versus Tertiary Care Follow-Up of Low-Risk Differentiated Thyroid Cancer: Real-World Comparison of Outcomes and Costs for Patients and Health Care Systems

BACKGROUND

An unprecedented rise in the prevalence of low-risk well-differentiated thyroid cancer (TC) has been reported in several countries, which is partly due to an increased utility of sensitive imaging techniques. The outcome of these cancers has generally remained excellent and the overall 5-year survival is almost 100%. However, the extended follow-up strategy for these patients remains unclear and while the initial management is done in specialist centres some experts opt to follow them on a long-term basis while others discharge them to primary care after the initial management. The effectiveness of one strategy versus the other has not been studied.

METHODS

We conducted a real-world comparison to assess the outcome of low-risk TC (AJCC stage I) with undetectable thyroglobulin (TG) 2 years after radio-iodine (I-131) therapy. The outcome from Halifax (NS, Canada) and London (ON, Canada), where all TC patients are routinely followed by the tertiary care team, was compared with that from Edmonton (AB, Canada), where patients are routinely discharged to primary care.

RESULTS

All patients were diagnosed between January 1, 2006, and December 31, 2011. The mean follow-up in primary care after discharge was 62.2 months and in tertiary care it was 64.6 months (p = 0.43). Rates of recurrence were similar in both groups, i.e., 1.1% in primary care and 1.3% in tertiary care (p = 0.69). Ultrasound surveillance was conducted in 56.5% of the patients in primary care and 52.6% of the tertiary care group (p = 0.26). The rate of annual unstimulated TG testing per patient was 0.58 (range 0-14) in primary care and 0.96 (range 0-6) in tertiary care (p = 0.06). More patients in primary care (86%) than in tertiary care (29.9%) consistently had thyroid-stimulating hormone levels within the target range (p < 0.001). The mean healthcare cost, based on a single follow-up visit with a blood test and ultrasound in the primary care group was CAD 118.01 and in the tertiary care group it was CAD 164.12.

CONCLUSION

Our study shows that extended follow-up of low-risk TC patients is perfectly feasible in primary care and provides significant economic benefit for the healthcare system.

Predictors of imminent non-vertebral fracture in elderly women with osteoporosis, low bone mass, or a history of fracture, based on data from the population-based Canadian Multicentre Osteoporosis Study (CaMos)

Using data from the Canadian Multicentre Osteoporosis Study, several risk factors predictive of imminent (2-year) risk of low-trauma non-vertebral fracture among high-risk women were identified, including history of falls, history of low-trauma fracture, poorer physical function, and lower T score. Careful consideration should be given to targeting this population for therapy.

PURPOSE

Fracture risk assessment has focused on a long-term horizon and populations with a broad risk range. For elderly women with osteoporosis or low bone mass, or a history of fragility fractures ("high-risk women"), risk prediction over a shorter horizon may have greater clinical relevance.

METHODS

A repeated-observations design and data from the Canadian Multicentre Osteoporosis Study were employed. Study population comprised women aged ≥ 65 years with T score (total hip, femoral neck, spine) ≤ - 1.0 or prior fracture. Hazard ratios (HR) for predictors of low-trauma non-vertebral fracture during 2-year follow-up were estimated using multivariable shared frailty model.

RESULTS

The study population included 3228 women who contributed 5004 observations; 4.8% experienced low-trauma non-vertebral fracture during the 2-year follow-up. In bivariate analyses, important risk factors included age, back pain, history of falls, history of low-trauma fracture, physical function, health status, and total hip T score. In multivariable analyses, only four independent predictors were identified: falls in past 12 months (≥ 2 falls: HR = 1.9; 1 fall: HR = 1.5), low-trauma fracture in past 12 months (≥ 1 fracture: HR = 1.7), SF-36 physical component summary score (≤ 42.0: HR = 1.6), and total hip T score (≤ - 3.5: HR = 3.7; > - 3.5 to ≤ - 2.5: HR = 2.5; > - 2.5 to ≤ - 1: HR = 1.3).

CONCLUSIONS

Imminent risk of low-trauma non-vertebral fracture is elevated among high-risk women with a history of falls or low-trauma fracture, poorer physical function, and lower T score. Careful consideration should be given to identifying and targeting this population for therapy.

Incident Fragility Fractures Have a Long-Term Negative Impact on Health-Related Quality of Life of Older People: The Canadian Multicentre Osteoporosis Study

Although the short-term impact of incident fragility fractures on health-related quality of life (HRQL) of older people has been confirmed, we lack long-term evidence. We explored the impact of incident fragility fractures on HRQL, among people aged 50 years and older, using 10-year prospective data from the Canadian Multicentre Osteoporosis Study (CaMos). This study was based on data from 7753 (2187 men and 5566 women) participants of CaMos. The HRQL, measured through the Health Utility Index (HUI), was captured at baseline and year 10. The incident fragility fractures were recorded over 10 years of follow-up at spine, hip, rib, shoulder, pelvis, or forearm. Multivariable regression analysis was conducted to measure the mean difference, termed as deficit, in the HUI scores for participants with and without fractures. We examined the effects of single or multiple fragility fractures, time (fractures that occurred between year 1 to 5 and 6 to 10) and recovery to the prefracture level. Incident spine and hip fractures were associated with significant deficits (varied from -0.19 to -0.07) on the HUI scores. Hip and spine fractures were associated with negative impact on mobility, self-care, and ambulation. Fractures that occurred closer to the follow-up assessment were associated with significant impact on HRQL compared to fractures occurring a long time before it, except for hip fracture (deficits lasted 5 years or longer). Similarly, multiple hip (-0.14), spine (-0.16), and rib (-0.21) fractures significantly impacted the HRQL of women. Women with a hip fracture never recovered to their prefracture level score (OR = 0.41; 95% confidence interval [CI], 0.19 to 0.98). Our analysis suggests that single and multiple hip fractures as well as multiple spine and rib fractures strongly impact the HRQL of older people over a prolonged period of time. © 2019 American Society for Bone and Mineral Research.

Parity and lactation are not associated with incident fragility fractures or radiographic vertebral fractures over 16 years of follow-up: Canadian Multicentre Osteoporosis Study (CaMos)

Parity and lactation showed no associations with incident clinical fragility fractures or radiographic vertebral compression fractures in the 16-year CaMos prospective study. Parity was associated with slightly greater decline in femoral neck but not hip or spine areal bone mineral density (aBMD), while lactation showed no associations with aBMD change.

PURPOSE

Pregnancy and especially lactation cause loss of bone mass and microarchitectural changes, which temporarily increase fracture risk. After weaning, aBMD increases but skeletal microarchitecture may be incompletely restored. Most retrospective clinical studies found neutral or even protective associations of parity and lactation with fragility fractures, but prospective data are sparse. CaMos is a randomly selected observational cohort that includes ~ 6500 women followed prospectively for over 16 years.

METHODS

We determined whether parity or lactation were related to incident clinical fragility fractures over 16 years, radiographic (morphometric and morphologic) vertebral fractures over 10 years, and aBMD change (spine, total hip, and femoral neck) over 10 years. Parity and lactation duration were analyzed as continuous variables in predicting these outcomes using univariate and multivariate regression analyses.

RESULTS

Three thousand four hundred thirty-seven women completed 16 years of follow-up for incident clinical fractures, 3839 completed 10 years of morphometric vertebral fracture assessment, 3788 completed 10 years of morphologic vertebral fracture assessment, and 4464 completed 10 years of follow-up for change in aBMD. In the multivariate analyses, parity and lactation duration showed no associations with clinical fragility fractures, radiographic vertebral fractures, or change in aBMD, except that parity associated with a probable chance finding of a slightly greater decline in femoral neck aBMD.

CONCLUSIONS

Parity and lactation have no adverse associations with clinical fragility or radiographic vertebral fractures, or the rate of BMD decline over 10 years, in this prospective, multicenter study of a randomly selected, population-based cohort of women.

Frailty and Risk of Fractures in Patients With Type 2 Diabetes

OBJECTIVE

We aimed to explore whether frailty was associated with fracture risk and whether frailty could modify the propensity of type 2 diabetes toward increased risk of fractures.

RESEARCH DESIGN AND METHODS

Data were from a prospective cohort study. Our primary outcome was time to the first incident clinical fragility fracture; secondary outcomes included time to hip fracture and to clinical spine fracture. Frailty status was measured by a Frailty Index (FI) of deficit accumulation. The Cox model incorporating an interaction term (frailty × diabetes) was used for analyses.

RESULTS

The analysis included 3,149 (70% women) participants; 138 (60% women) had diabetes. Higher bone mineral density and FI were observed in participants with diabetes compared with control subjects. A significant relationship between the FI and the risk of incident fragility fractures was found, with a hazard ratio (HR) of 1.02 (95% CI 1.01-1.03) and 1.19 (95% CI 1.10-1.33) for per-0.01 and per-0.10 FI increase, respectively. The interaction was also statistically significant (P = 0.018). The HR for per-0.1 increase in the FI was 1.33 for participants with diabetes and 1.19 for those without diabetes if combining the estimate for the FI itself with the estimate from the interaction term. No evidence of interaction between frailty and diabetes was found for risk of hip and clinical spine fractures.

CONCLUSIONS

Participants with type 2 diabetes were significantly frailer than individuals without diabetes. Frailty increases the risk of fragility fracture and enhances the effect of diabetes on fragility fractures. Particular attention should be paid to diabetes as a risk factor for fragility fractures in those who are frail.

Comparative Analysis of the Radiology of Osteoporotic Vertebral Fractures in Women and Men: Cross-Sectional and Longitudinal Observations from the Canadian Multicentre Osteoporosis Study (CaMos)

We compared two methods for osteoporotic vertebral fracture (VF) assessment on lateral spine radiographs, the Genant semiquantitative (GSQ) technique and a modified algorithm-based qualitative (mABQ) approach. We evaluated 4465 women and 1771 men aged ≥50 years from the Canadian Multicentre Osteoporosis Study with available X-ray images at baseline. Observer agreement was lowest for grade 1 VFs determined by GSQ. Among physician readers, agreement was greater for VFs diagnosed by mABQ (ranging from 0.62 [95% confidence interval (CI) 0.00-1.00] to 0.88 [0.76-1.00]) than by GSQ (ranging from 0.38 [0.17-0.60] to 0.69 [0.54-0.85]). GSQ VF prevalence (16.4% [95% CI 15.4-17.4]) and incidence (10.2/1000 person-years [9.2; 11.2]) were higher than with the mABQ method (prevalence 6.7% [6.1-7.4] and incidence 6.3/1000 person-years [5.5-7.1]). Women had more prevalent and incident VFs relative to men as defined by mABQ but not as defined by GSQ. Prevalent GSQ VFs were predominantly found in the mid-thoracic spine, whereas prevalent mABQ and incident VFs by both methods co-localized to the junction of the thoracic and lumbar spine. Prevalent mABQ VFs compared with GSQ VFs were more highly associated with reduced adjusted L₁ to L₄ bone mineral density (BMD) (-0.065 g/cm² [-0.087 to -0.042]), femoral neck BMD (-0.051 g/cm² [-0.065 to -0.036]), and total hip BMD (-0.059 g/cm² [-0.076 to -0.041]). Prevalent mABQ VFs compared with prevalent GSQ were also more highly associated with incident VF by GSQ (odds ratio [OR] = 3.3 [2.2-5.0]), incident VF by mABQ (9.0 [5.3-15.3]), and incident non-vertebral major osteoporotic fractures (1.9 [1.2-3.0]). Grade 1 mABQ VFs, but not grade 1 GSQ VFs, were associated with incident non-vertebral major osteoporotic fractures (OR = 3.0 [1.4-6.5]). We conclude that defining VF by mABQ is preferred to the use of GSQ for clinical assessments. © 2017 American Society for Bone and Mineral Research.

Population-Wide Impact of Non-Hip Non-Vertebral Fractures on Mortality

Data on long-term consequences of non-hip non-vertebral (NHNV) fractures, accounting for approximately two-thirds of all fragility fractures, are scanty. Our study aimed to quantify the population-wide impact of NHNV fractures on mortality. The national population-based prospective cohort study (Canadian Multicentre Osteoporosis Study) included 5526 community dwelling women and 2163 men aged 50 years or older followed from July 1995 to September 2013. Population impact number was used to quantify the average number of people for whom one death would be attributable to fracture and case impact number to quantify the number of deaths out of which one would be attributable to a fracture. There were 1370 fragility fractures followed by 296 deaths in women (mortality rate: 3.49; 95% CI, 3.11 to 3.91), and 302 fractures with 92 deaths in men (5.05; 95% CI, 4.12 to 6.20). NHNV fractures accounted for three-quarters of fractures. In women, the population-wide impact of NHNV fractures on mortality was greater than that of hip and vertebral fractures because of the greater number of NHNV fractures. Out of 800 women, one death was estimated to be attributable to a NHNV fracture, compared with one death in 2000 women attributable to hip or vertebral fracture. Similarly, out of 15 deaths in women, one was estimated to be attributable to a NHNV fracture, compared with one in over 40 deaths for hip or vertebral fracture. The impact of forearm fractures (ie, one death in 2400 women and one out of 42 deaths in women attributable to forearm fracture) was similar to that of hip, vertebral, or rib fractures. Similar, albeit not significant, results were noted for men. The study highlights the important contribution of NHNV fractures on mortality because many NHNV fracture types, except for the most distal fractures, have serious adverse consequences that affect a significant proportion of the population. © 2017 American Society for Bone and Mineral Research.

The association between sclerostin and incident type 2 diabetes risk: a cohort study

OBJECTIVE

To determine whether sclerostin is associated with fasting glucose, insulin levels, insulin resistance or increased risk of incident type 2 diabetes.

BACKGROUND

Type 2 diabetic patients have a higher risk of fractures. Recent studies suggest sclerostin, a regulator of osteoblast activity, is associated with diabetes.

MATERIALS AND METHODS

Sclerostin levels were obtained from 1778 individuals with no history of type 2 diabetes participating in the population-based Canadian Multicentre Osteoporosis Study (CaMos) cohort. Participants were followed until diagnosis of type 2 diabetes, death or end of the study period (31 December 2013). The relationship of sclerostin with fasting glucose, insulin levels and homoeostatic model assessment-insulin resistance (HOMA-IR) was studied in linear regression models. Cox proportional hazards models were used to determine the association of sclerostin levels and the risk of incident type 2 diabetes during a mean 7·5 years of follow-up.

RESULTS

Fasting glucose, fasting insulin levels and HOMA-IR were weakly correlated with sclerostin levels (Spearman's correlation coefficient: 0·11, P < 0·05; -0·09, P < 0·05; and -0·07, P = 0·02, respectively). Multiple linear regression analyses confirmed a significant association between sclerostin and fasting insulin and HOMA-IR but no significant association with fasting glucose levels. Sclerostin levels were not found to be significantly associated with the risk of incident type 2 diabetes (HR: 1·30; 95% CI: 0·37-4·57).

CONCLUSIONS

We observed an association between sclerostin levels with fasting insulin levels and HOMA-IR, but there was no clear association with type 2 diabetes risk. Further studies are needed to understand the role of sclerostin in type 2 diabetes.

Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score

Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' densitometers, because different densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) densitometers at year 10 of follow-up. TBS was calculated for L1-L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic densitometers in men (Pearson r = -0.36, p <0.0001) and in women (Pearson r = -0.33, p <0.0001); significant correlations were not seen when TBS was measured on GE Lunar densitometers (Pearson r = 0.00 in men, Pearson r = -0.02 in women). Age-adjusted linear regression models confirmed significant interactions between BMI and densitometer manufacturer for both men and women (p < 0.0001). In contrast, comparable positive correlations were observed between BMD and BMI on both Hologic and GE Lunar densitometers in men and women. In conclusion, BMI significantly affects TBS values in men and women when measured on Hologic but not GE Lunar densitometers. This finding has implications for clinical and research applications of TBS, especially when TBS is measured sequentially on DXA densitometers from different manufacturers or when results from different machines are pooled for analysis.

Morphometric changes correlate with poor psychological outcomes in patients with acromegaly

OBJECTIVE

Acromegaly is frequently associated with altered facial appearance at the time of diagnosis. Furthermore, acromegaly is also associated with adverse psychological outcomes. We conducted a single-centre, cross-sectional study comparing patients with growth hormone vs non-functioning pituitary adenomas (NFA) to assess the association between morphometric changes and psychological outcomes and illness perception of patients with acromegaly.

METHODS

A seven-step scale was developed to grade morphometric changes based on facial photographs. In addition, all patients were asked to draw an image of their own body and an image of what they considered to be an average healthy body and complete seven psychological questionnaires. We recruited 55 consecutive patients in each of the two groups who had undergone surgery with or without radiation therapy (RT).

RESULTS

Our data showed that the clinician-rated morphometric scale was highly reliable in assessing facial changes, with 93/99 (Intraclass correlation coefficient (ICC)=0.95 (0.93-0.97)) graded as similar by independent raters. The mean (s.d.) grading for Acro and NFA patients on the clinician-rated morphometric scale were 3.5 (1.3) and 0.41 (0.35) respectively (P<0.0001). A higher clinician-rated morphometric score was also predictive of a poorer score on the drawing test.

CONCLUSIONS

Our study demonstrates a correlation between physical changes associated with acromegaly and poor psychological outcomes, whereas no such correlation existed with modes of therapy, disease control status, RT, malignancy, initial or recent GH/IGF1 or secondary hormonal deficiency. Our data support the utility of the morphometric scale as a clinical tool for grading facial changes.

Associations of Protein Intake and Protein Source with Bone Mineral Density and Fracture Risk: A Population-Based Cohort Study

High dietary protein has been hypothesized to cause lower bone mineral density (BMD) and greater fracture risk. Previous results are conflicting and few studies have assessed potential differences related to differing protein sources.

OBJECTIVE

To determine associations between total protein intake, and protein intake by source (dairy, non-dairy animal, plant) with BMD, BMD change, and incident osteoporotic fracture.

DESIGN/SETTING

Prospective cohort study (Canadian Multicentre Osteoporosis Study). Participants/Measures: Protein intake was assessed as percent of total energy intake (TEI) at Year 2 (1997-99) using a food frequency questionnaire (N=6510). Participants were contacted annually to ascertain incident fracture. Total hip and lumbar spine BMD was measured at baseline and Year 5. Analyses were stratified by group (men 25-49 y, men 50+ y, premenopausal women 25-49 y, and postmenopausal women 50+ y) and adjusted for major confounders. Fracture analyses were limited to those 50+ y.

RESULTS

Intakes of dairy protein (with adjustment for BMI) were positively associated with total hip BMD among men and women aged 50+ y, and in men aged 25-49. Among adults aged 50+ y, those with protein intakes of <12% TEI (women) and <11% TEI (men) had increased fracture risk compared to those with intakes of 15% TEI. Fracture risk did not significantly change as intake increased above 15% TEI, and was not significantly associated with protein source.

CONCLUSIONS

In contrast to hypothesized risk of high protein, we found that for adults 50+ y, low protein intake (below 15% TEI) may lead to increased fracture risk. Source of protein was a determinant of BMD, but not fracture risk.

Immunohistochemical localisation and effect of matrix metalloproteinases and their inhibitors on canine spontaneous periodontitis

Periodontitis is commonly observed in dogs. In human medicine, it is well documented that matrix metalloproteinases (MMPs) are involved in the destruction of the periodontium. Therefore, the aim of this prospective study was to investigate the impact of MMPs and their inhibitors, the TIMPs (tissue inhibitors of metalloproteinases), on canine periodontitis. The oral cavities of 57 dogs were examined clinically and radiologically. Gingival biopsies were obtained from the examined dogs and histologically analysed via haematoxylin and eosin stained sections. Immunohistological detection of MMP-2, MMP-3, MMP-8 and MMP-9 as well as TIMP-1 and TIMP-2 was performed by the avidin-biotin peroxidase complex technique. All sections were evaluated by light microscopy. Statistically significant positive correlations were detected between the histologically verified degree of inflammation and the expression of MMP-2, MMP-3, MMP-8 and MMP-9 as well as between changes in collagen fibre content and the occurrence of MMP-2, MMP-8 and MMP-9. Concerning TIMP-1 and TIMP-2, non-significant, generally negative correlations were observed. In summary, in canine periodontitis, an increased expression of the above mentioned MMPs and a tendentially decreased expression of TIMPs are present. In conclusion, in canine periodontitis, a MMP-TIMP imbalance is suggestive of contributing to the destruction of the periodontium.

Characteristics of hyperparathyroid states in the Canadian multicentre osteoporosis study (CaMos) and relationship to skeletal markers

CONTEXT

PTH is an essential regulator of mineral metabolism; PTH hypersecretion may result in hyperparathyroidism including normocalcaemic, primary and secondary hyperparathyroidism.

OBJECTIVE

To examine the characteristics of participants with hyperparathyroid states and the relationship to bone mineral density (BMD).

DESIGN AND PARTICIPANTS

A cross-sectional study of 1872 community-dwelling men and women aged 35+ years (mostly Caucasian) with available serum PTH from Year 10 Canadian Multicentre Osteoporosis Study follow-up (2005-07). PTH was determined using a second-generation chemiluminescence immunoassay.

OUTCOME MEASURES

L1-L4, femoral neck and total hip BMD.

RESULTS

We established a PTH reference range (2·7-10·2 pmol/l) based on healthy participants (i.e. normal serum calcium, serum 25-hydroxyvitamin D, kidney function and body mass index, who were nonusers of antiresorptives, glucocorticoids and diuretics and not diagnosed with diabetes or thyroid disease). Participants with PTH levels in the upper reference range (5·6-10·2 pmol/l), representing a prevalence of 10·7%, had lower femoral neck and total hip BMD, by 0·030 g/cm(2) [95% confidence interval: 0·009; 0·051] and 0·025 g/cm(2) (0·001; 0·049), respectively, than those with levels 2·7-5·6 pmol/l. Participants with normocalcaemic and secondary hyperparathyroidism also had lower total hip BMD than those with levels 2·7-5·6 pmol/l, and CaMos prevalences of normocalcaemic, primary and secondary hyperparathyroidism were 3·3%, 1·4% and 5·2%, respectively.

CONCLUSION

We found reduced BMD in participants with accepted hyperparathyroid states but also a notable proportion of other participants that might benefit from having lower PTH levels.

Ten-year incident osteoporosis-related fractures in the population-based Canadian Multicentre Osteoporosis Study - comparing site and age-specific risks in women and men

BACKGROUND

Population-based incident fracture data aid fracture prevention and therapy decisions. Our purpose was to describe 10-year site-specific cumulative fracture incidence by sex, age at baseline, and degree of trauma with/without consideration of competing mortality in the Canadian Multicentre Osteoporosis Study adult cohort.

METHODS

Incident fractures and mortality were identified by annual postal questionnaires to the participant or proxy respondent. Date, site and circumstance of fracture were gathered from structured interviews and medical records. Fracture analyses were stratified by sex and age at baseline and used both Kaplan-Meier and competing mortality methods.

RESULTS

The baseline (1995-97) cohort included 6314 women and 2789 men (aged 25-84 years; mean±SD 62±12 and 59±14, respectively), with 4322 (68%) women and 1732 (62%) men followed to year-10. At least one incident fracture occurred for 930 women (14%) and 247 men (9%). Competing mortality exceeded fracture risk for men aged 65+years at baseline. Age was a strong predictor of incident fractures especially fragility fractures, with higher age gradients for women vs. men. Major osteoporotic fracture (MOF) (hip, clinical spine, forearm, humerus) accounted for 41-74% of fracture risk by sex/age strata; in women all MOF sites showed age-related increases but in men only hip was clearly age-related. The most common fractures were the forearm for women and the ribs for men. Hip fracture incidence was the highest for the 75-84 year baseline age-group with no significant difference between women 7.0% (95% CI 5.3, 8.9) and men 7.0% (95% CI 4.4, 10.3).

INTERPRETATION

There are sex differences in the predominant sites and age-gradients of fracture. In older men, competing mortality exceeds cumulative fracture risk.

Choice of lumbar spine bone density reference database for fracture prediction in men and women: a population-based analysis

The diagnosis of osteoporosis in men is controversial, although most studies demonstrate similar fracture rates for men and women with the same level of hip bone mineral density (BMD). Whether this applies to the lumbar spine is currently uncertain and has important implications with respect to choice of reference population for T-score calculation and osteoporosis diagnosis. This question was specifically addressed in the population-based Canadian Multicentre Osteoporosis Study cohort of 4745 women and 1887 men ages 50+ yr at the time of baseline lumbar spine dual energy x-ray absorptiometry. In up to 10 yr of observation, incident clinical major osteoporotic fractures occurred in 110 men (5.8%) vs 543 women (11.4%) (p < 0.001). Mean lumbar spine BMD in men was greater than in women, both among those with and those without incident major osteoporotic fracture (p < 0.001). Men were at slightly lower risk for incident major osteoporotic fracture than women for an equivalent lumbar spine BMD (age- and BMD-adjusted rate ratio 0.75, 95% confidence interval 0.60-0.93, p = 0.008) with similar findings after adjustment for the World Health Organization fracture risk assessment clinical risk factors or competing mortality. No significant sex difference in the BMD relationship was seen for vertebral fractures (clinical or radiographic) or for all fractures. In summary, this large population-based longitudinal cohort study found similar or lower fracture risk for men vs women after adjustment for absolute lumbar spine BMD and additional covariates. The least complicated model for describing fracture risk is therefore to use the same reference lumbar spine data for generating T-scores in men and women.

Longitudinal changes in calcium and vitamin D intakes and relationship to bone mineral density in a prospective population-based study: the Canadian Multicentre Osteoporosis Study (CaMos)

OBJECTIVES

Our objective was to study changes in calcium and vitamin D intakes over time, and their cross-sectional and longitudinal associations with bone mineral density (BMD).

METHODS

We followed 9382 women and men aged ≥25 and 899 aged 16-24, for 10 and 2 years respectively.

RESULTS

Calcium and vitamin D intakes increased over time in adults, but decreased in women aged 16-18. The increased intakes in adults were largely attributable to the increased use of calcium and/or vitamin D supplements. Both the percentage of supplement users and average dose among users increased over time. There was nevertheless a high prevalence of calcium and vitamin D intake below the estimated average requirement. At baseline, higher calcium and vitamin D intakes were associated with higher total hip and femoral neck BMD in young men, and cumulatively high levels of calcium and vitamin D intakes over time contributed to better BMD maintenance at lumbar spine and hip sites in adult women.

CONCLUSIONS

Although total intakes, particularly of vitamin D, frequently fell below the Institute of Medicine recommendations despite an increase over time in supplement use, we found some positive associations between total calcium and vitamin D intake and bone health.

The Role of Morning Basal Serum Cortisol in Assessment of Hypothalamic Pituitary-Adrenal Axis

Purpose: The use of morning basal serum cortisol levels as an alternative to dynamic testing for assessment of hypothalamic-pituitary-adrenal (HPA) axis has previously been reported. The purpose of this study was to determine the lower and upper cutoff values that would obviate subsequent HPA axis testing. Methods: A single-centre, retrospective study from a tertiary care endocrinology clinic was conducted, analyzing data from 106 adult individuals referred for HPA axis testing who had undergone a 0800-0900 morning basal serum cortisol test followed by a standard dose (250 μg) adrenocorticotropin (ACTH) stimulation test. The ability of morning basal serum cortisol values to predict post-ACTH 30 or 60 minute peak cortisol value of > 500 or > 550 nmol/L was investigated. Results: A morning basal cutoff of < 128 nmol/L is sufficient for predicting a post-ACTH value < 550 nmol/L, and morning basal cutoff levels of > 243 nmol/L and > 266 nmol/L predict peak post-ACTH values of > 500 and > 550 nmol/L respectively, obviating the need for dynamic testing. Regression analysis further demonstrated the log-linear relationship between morning basal and peak levels, while also finding a significant decrease in peak post-ACTH levels for patients diagnosed with secondary hypothyroidism (76 nmol/L lower, p=0.003) or secondary hypogonadism (61 nmol/L lower, p=0.02). These data suggest that the risk of cortisol deficiency is significantly higher in individuals with additional pituitary insufficiencies. The odds ratios for cortisol deficiency in patients with history of isolated secondary hypothyroidism was 3.41 (p=0.015), with isolated secondary hypogonadism was 4.77 (p=0.002) and with both was 7.45 (p=0.0002). Conclusion: Morning basal serum cortisol levels show promise as an effective screening test for HPA insufficiency for most patients. Clinicians should consider the high probability of HPA insufficiency in patients with one or more pituitary insufficiencies.

The relationship between proton pump inhibitor use and longitudinal change in bone mineral density: a population-based study [corrected] from the Canadian Multicentre Osteoporosis Study (CaMos)

OBJECTIVES

Proton pump inhibitor (PPI) use has been identified as a risk factor for hip and vertebral fractures. Evidence supporting a relationship between PPI use and osteoporosis remains scant. Demonstrating that PPIs are associated with accelerated bone mineral density (BMD) loss would provide supportive evidence for a mechanism through which PPIs could increase fracture risk.

METHODS

We used the Canadian Multicentre Osteoporosis Study data set, which enrolled a population-based sample of Canadians who underwent BMD testing of the femoral neck, total hip, and lumbar spine (L1-L4) at baseline, and then again at 5 and 10 years. Participants also reported drug use and exposure to risk factors for osteoporosis and fracture. Multivariate linear regression was used to determine the independent association of PPI exposure and baseline BMD, and on change in BMD at 5 and 10 years.

RESULTS

In all, 8,340 subjects were included in the baseline analysis, with 4,512 (55%) undergoing year 10 BMD testing. After adjusting for potential confounders, PPI use was associated with significantly lower baseline BMD at the femoral neck and total hip. PPI use was not associated with a significant acceleration in covariate-adjusted BMD loss at any measurement site after 5 and 10 years of follow-up.

CONCLUSIONS

PPI users had lower BMD at baseline than PPI non-users, but PPI use over 10 years did not appear to be associated with accelerated BMD loss. The reasons for discordant findings between PPI use at baseline and during follow-up require further study.

Osteoporosis Canada 2010 guidelines for the assessment of fracture risk

Osteoporosis Canada's 2010 Clinical Practice Guidelines for the Diagnosis and Management of Osteoporosis in Canada focus on the clinical impact of fragility fractures, and on the assessment and management of women and men at high risk for fragility fracture. These guidelines now integrate a 10-year absolute fracture risk prediction into an overall management approach by using validated risk assessment tools. There currently is a large gap between optimal practices and those that are now being provided to Canadians with osteoporosis. These guidelines are part of a concerted effort to close this gap. Key changes from the 2002 guidelines of interest and relevance to radiologists are highlighted in this report.

Predicting fracture using 2D finite element modelling

A decrease in bone density at the hip or spine has been shown to increase the risk of fracture. A limitation of the bone mineral density (BMD) measurement is that it provides only a measure of a bone sample's average density when projected onto a 2D surface. Effectively, what determines bone fracture is whether an applied load exceeds ultimate strength, with both bone tissue material properties (can be approximated through bone density), and geometry playing a role. The goal of this project was to use bone geometry and BMD obtained from radiographs and DXA measurements respectively to estimate fracture risk, using a two-dimensional finite element model (FEM) of the sagittal plane of lumbar vertebrae. The Canadian Multicentre Osteoporosis Study (CaMos) data was used for this study. There were 4194 men and women over the age of 50 years, with 786 having fractures. Each subject had BMD testing and radiographs of their lumbar vertebrae. A single two dimensional FEM of the first to fourth lumbar vertebra was automatically generated for each subject. Bone tissue stiffness was assigned based on the BMD of the individual vertebrae, and adjusted for patient age. Axial compression boundary conditions were applied with a force proportional to body mass. The resulting overall strain from the applied force was found. Men and women were analyzed separately. At baseline, the sensitivity of BMD to predict fragility fractures in women and men was 3.77% and 0.86%, while the sensitivity of FEM to predict fragility fractures for women and men was 10.8% and 11.3%. The FEM ROC curve demonstrated better performance compared to BMD. The relative risk of being considered at high fracture risk using FEM at baseline, was a better predictor of 5 year incident fragility fracture risk compared to BMD.

Spine-hip T-score difference predicts major osteoporotic fracture risk independent of FRAX(®): a population-based report from CAMOS

The WHO fracture risk assessment tool (FRAX(®)) estimates an individual's 10-yr major osteoporotic and hip fracture probabilities. When bone mineral density (BMD) is included in the FRAX calculation, only the femoral neck measurement can be used. Recently, a procedure was reported for adjusting major osteoporotic fracture probability from FRAX with femoral neck BMD based on the difference (offset) between the lumbar spine and the femoral neck T-score values. The objective of the current analysis was to independently evaluate this algorithm in a population-based cohort of 4575 women and 1813 men aged 50 yr and older from the Canadian Multicentre Osteoporosis Study. For women and men combined, there was a 15% (95% confidence interval 7-24%) increase in major osteoporotic fracture risk for each offset T-score after adjusting for FRAX probability calculated with femoral neck BMD. The effect was stronger in women than men, but a significant sex interaction was not detected. Among the full cohort, 5.5% had their risk category reclassified after using the offset adjustment. Sex- and age-dependent offsets (equivalent to an offset based on Z-scores) showed improved risk classification among individuals designated to be at moderate risk with the conventional FRAX probability measurement. In summary, the T-score difference between the lumbar spine and femoral neck is an independent risk factor for major osteoporotic fractures that is independent of the FRAX probability calculated with femoral neck BMD.

Fracture prediction and calibration of a Canadian FRAX® tool: a population-based report from CaMos

A new Canadian WHO fracture risk assessment (FRAX®) tool to predict 10-year fracture probability was compared with observed 10-year fracture outcomes in a large Canadian population-based study (CaMos). The Canadian FRAX tool showed good calibration and discrimination for both hip and major osteoporotic fractures.

INTRODUCTION

The purpose of this study was to validate a new Canadian WHO fracture risk assessment (FRAX®) tool in a prospective, population-based cohort, the Canadian Multicentre Osteoporosis Study (CaMos).

METHODS

A FRAX tool calibrated to the Canadian population was developed by the WHO Collaborating Centre for Metabolic Bone Diseases using national hip fracture and mortality data. Ten-year FRAX probabilities with and without bone mineral density (BMD) were derived for CaMos women (N = 4,778) and men (N = 1,919) and compared with observed fracture outcomes to 10 years (Kaplan-Meier method). Cox proportional hazard models were used to investigate the contribution of individual FRAX variables.

RESULTS

Mean overall 10-year FRAX probability with BMD for major osteoporotic fractures was not significantly different from the observed value in men [predicted 5.4% vs. observed 6.4% (95%CI 5.2-7.5%)] and only slightly lower in women [predicted 10.8% vs. observed 12.0% (95%CI 11.0-12.9%)]. FRAX was well calibrated for hip fracture assessment in women [predicted 2.7% vs. observed 2.7% (95%CI 2.2-3.2%)] but underestimated risk in men [predicted 1.3% vs. observed 2.4% (95%CI 1.7-3.1%)]. FRAX with BMD showed better fracture discrimination than FRAX without BMD or BMD alone. Age, body mass index, prior fragility fracture and femoral neck BMD were significant independent predictors of major osteoporotic fractures; sex, age, prior fragility fracture and femoral neck BMD were significant independent predictors of hip fractures.

CONCLUSION

The Canadian FRAX tool provides predictions consistent with observed fracture rates in Canadian women and men, thereby providing a valuable tool for Canadian clinicians assessing patients at risk of fracture.

Fragility fractures and the osteoporosis care gap in women: the Canadian Multicentre Osteoporosis Study

Canadian women over 50 years old were studied over a 10-year period to see if those who sustained a fracture (caused by minimal trauma) were receiving the recommended osteoporosis therapy. We found that approximately half of these women were not being treated, indicating a significant care gap in osteoporosis treatment.

INTRODUCTION

Prevalent fragility fracture strongly predicts future fracture. Previous studies have indicated that women with fragility fractures are not receiving the indicated treatment. We aimed to describe post fracture care in Canadian women using a large, population-based prospective cohort that began in 1995-1997.

METHODS

We followed 5,566 women over 50 years of age from across Canada over a period of 10 years in the Canadian Multicentre Osteoporosis Study. Information on medication use and incident clinical fragility fractures was obtained during a yearly questionnaire or interview and fractures were confirmed by radiographic/medical reports.

RESULTS

Over the 10-year study period, 42-56% of women with yearly incident clinical fragility fractures were not treated with an osteoporosis medication. During year 1 of the study, 22% of the women who had experienced a fragility fracture were on treatment with a bisphosphonate and 26% were on hormone therapy (HT). We were not able to differentiate HT use for menopause symptoms vs osteoporosis. Use of bisphosphonate therapy increased over time; odds ratio (OR) for use at year 10 compared to use at year 1 was 3.65 (95% confidence interval (CI) 1.83-7.26). In contrast, HT use declined, with an OR of 0.07 (95%CI 0.02-0.24) at year 10 compared to year 1 of the study.

CONCLUSION

In a large population-based cohort study, we found a therapeutic care gap in women with osteoporosis and fragility fractures. Although bisphosphonate therapy usage improved over time, a substantial gap remains.

Risk factors for low BMD in healthy men age 50 years or older: a systematic review

SUMMARY

In this systematic review, we summarize risk factors for low bone mineral density and bone loss in healthy men age 50 years or older. Consistent risk factors were: age, smoking, low weight, physical/functional limitations, and previous fracture. Data specific to men has clinical and policy implications.

INTRODUCTION

Osteoporosis is a significant health care problem in men as well as women, yet the majority of evidence on diagnosis and management of osteoporosis is focused on postmenopausal women. The objective of this systematic review is to examine risk factors for low bone mineral density (BMD) and bone loss in healthy men age 50 years or older.

MATERIALS AND METHODS

A systematic search for observational studies was conducted in MEDLINE, Cochrane Database of Systematic Reviews, DARE, CENTRAL, CINAHL and Embase, Health STAR. The three main search concepts were bone density, densitometry, and risk factors. Trained reviewers assessed articles using a priori criteria.

RESULTS

Of 642 screened abstracts, 299 articles required a full review, and 25 remained in the final assessment. Consistent risk factors for low BMD/bone loss were: advancing age, smoking, and low weight/weight loss. Although less evidence was available, physical/functional limitations and prevalent fracture (after age 50) were also associated with low BMD/bone loss. The evidence was inconsistent or weak for physical activity, alcohol consumption, calcium intake, muscle strength, family history of fracture/osteoporosis, and height/height loss.

CONCLUSION

In this systematic review, we identified several risk factors for low BMD/bone loss in men that are measurable in primary practice.

DMP1 mutations in autosomal recessive hypophosphatemia implicate a bone matrix protein in the regulation of phosphate homeostasis

Hypophosphatemia is a genetically heterogeneous disease. Here, we mapped an autosomal recessive form (designated ARHP) to chromosome 4q21 and identified homozygous mutations in DMP1 (dentin matrix protein 1), which encodes a non-collagenous bone matrix protein expressed in osteoblasts and osteocytes. Intact plasma levels of the phosphaturic protein FGF23 were clearly elevated in two of four affected individuals, providing a possible explanation for the phosphaturia and inappropriately normal 1,25(OH)2D levels and suggesting that DMP1 may regulate FGF23 expression.

Anemia is an independent risk for mortality after acute myocardial infarction in patients with and without diabetes

INTRODUCTION

Anemia and diabetes are risk factors for short-term mortality following an acute myocardial infarction(AMI). Anemia is more prevalent in patients with diabetes. We performed a retrospective study to assess the impact of the combination of diabetes and anemia on post-myocardial infarction outcomes.

METHODS

Data relating to all consecutive patients hospitalized with AMI was obtained from a population-based disease-specific registry. Patients were divided into 4 groups: diabetes and anemia (group A, n = 716), diabetes and no anemia (group B, n = 1894), no diabetes and anemia (group C, n = 869), and no diabetes and no anemia (group D, n = 3987). Mortality at 30 days and 31 days to 36 months were the main outcome measures.

RESULTS

30-day mortality was 32.3% in group A, 16.1% in group B, 21.5% in group C, 6.6% in group D (all p < 0.001). 31-day to 36-month mortality was 47.6% in group A, 20.8% in group B, 34.3% in group C, and 10.4% in group D (all p < 0.001). Diabetes and anemia remained independent risk factors for mortality with odds ratios of 1.61 (1.41-1.85, p < 0.001) and 1.59 (1.38-1.85, p < 0.001) respectively at 36 months. Cardiovascular death from 31-days to 36-months was 43.7% of deaths in group A, 54.1% in group B, 47.0% in group C, 50.8% group D (A vs B, p < 0.05).

INTERPRETATION

Patients with both diabetes and anemia have a significantly higher mortality than those with either diabetes or anemia alone. Cardiovascular death remained the most likely cause of mortality in all groups.

Efficient transduction of nondividing cells by optimized feline immunodeficiency virus vectors

Second- and third-generation three-plasmid vector systems, termed FELIX, were constructed from feline immunodeficiency virus (FIV). To enhance vector production, the weak FIV long terminal repeat promoter was replaced with the human cytomegalovirus enhancer/promoter. To construct a minimal system in which Gag-Pol was the only viral protein present, the cytoplasmic transport element was used in place of the FIV Rev-RRE system to facilitate nuclear export of Gag-Pol and the transfer vector. Unconcentrated vector titers routinely exceeded 1 x 10(6) IU/mL for most constructs tested. Second- and optimized third-generation vectors were capable of efficiently infecting G1/S- and G2/M-arrested cells. FIV-based FELIX vectors transduced human dendritic cells, hepatocytes, and aortic smooth muscle with efficiencies similar to that of a control 3T3 cell line. All three of these primary cell types were transducible by both the second- and third-generation FELIX vectors, demonstrating that FIV Gag-Pol alone contains the determinants necessary for transduction of primary cells. In cross-packaging tests, we observed that HIV Gag-Pol does not substantially package FIV vectors; consequently, use of such vectors in human immunodeficiency virus-infected cells should not lead to efficient mobilization of the inserted gene. Thus, this FIV-based vector system offers high efficiency and stable delivery of genes to numerous nondividing and primary cell types, opening new avenues for biological inquiry into normal human cells.

Adenosine receptors as potential therapeutic targets

Recent studies indicate a widening role for adenosine receptors in many therapeutic areas. Adenosine receptors are involved in immunological and inflammatory responses, respiratory regulation, the cardiovascular system, the kidney, various CNS-mediated events including sleep and neuroprotection, as well as central and peripheral pain processes. In this review, the physiological role of adenosine receptors in these key areas is described with reference to the therapeutic potential of adenosine receptor agonists and antagonists.

Diimidazo[1,2-c:4',5'-e]pyrimidines: adenosine agonist activity demonstrated by microphysiometry

Silicon-based microphysiometry, measuring extracellular acidification rate of cells in culture, demonstrated that a series of diimidazo[1,2-c:4',5'-e]pyrimidines were agonists at the human adenosine A1 receptor. 5-amino-7,8-dihydro-3-ribofuranose-8-(R)-(phenyl)-3H-diimidazo [1,2-c:4',5'-e]pyrimidine (2a) had an EC50 of 100 microM and reached 90% of the Emax produced by R-PIA.

Antisense-mediated inhibition of parathyroid hormone-related peptide production in a keratinocyte cell line impedes differentiation

We have used antisense RNA technology to inhibit endogenous PTH-related peptide (PTHRP) production in an established human keratinocyte cell line, HPK1A, to assess the role of PTHRP as a modulator of cell differentiation. Initially to determine the specificity of any alterations in cell function that might be observed, HPK1A cells and Rat-2 fibroblasts (which do not synthesize PTHRP) were both infected with the same retrovirus (pYN) containing antisense PTHRP. In contrast to antisense-infected HPK1A cells (HPK1A-AS), which show accelerated growth indices when endogenous PTHRP production is blocked, antisense-infected Rat-2 cells (Rat-2-AS) displayed no increase in cell proliferation. Consequently, this alteration in HPK1A cell function appeared to be specific to the inhibition of PTHRP production. In HPK1A-AS cells, no PTHRP transcript was observed in cytoplasmic RNA, and none was sequestered in a nuclear RNA preparation. Therefore, hybridization with the antisense strand appears to destabilize PTHRP mRNA, leading to rapid disappearance of the sense-antisense heteroduplex. We then examined the effect of PTHRP inhibition on keratinocyte differentiation using three indices. PTHRP inhibition in HPK1A-AS cells resulted in reduced high mol wt keratin production, as assessed by immunocytochemistry. Expression of mRNA encoding transglutaminase and involucrin was decreased in HPK1A-AS cells compared to that in control cells under conditions of high ambient calcium. Involucrin protein levels were also diminished in HPK1A-AS cells in parallel with the reduced levels of involucrin gene expression. These data, therefore, show that interference with PTHRP production inhibits expression of maturation-specific keratinocyte indices and indicate that endogenous PTHRP acts to enhance differentiation in this keratinocyte model.

Parathyroid hormone-related peptide

Parathyroid hormone-related peptide (PTHRP) was discovered through its ability to cause parathyroid hormone (PTH)-like effects in malignancy-associated hypercalcemia (MAH). It shares limited amino-terminal sequence homology with PTH and can thus interact with PTH receptors. It was originally isolated, cloned, and sequenced from tumors of patients with MAH. The human PTHRP gene is complex and can generate 3 peptide isoforms of 139, 141, and 173 amino acids. The gene encoding PTHRP in other species is somewhat simpler and generally results in only a single isoform; however, there is marked interspecies amino acid sequence homology in the protein product up to residue 111. PTH and PTHRP genes have similar structural organizations and it is believed that these 2 genes have a common ancestral origin and may have arisen through an ancient gene duplication. There are now several region specific radioimmunoassays, as well as immunoradiometric assays, which have been developed and which have all demonstrated elevated circulating levels of PTHRP in patients with MAH. PTHRP is expressed in a wide variety of tissues and, in addition to its classical PTH-like activities, it may have a local or systemic role in calcium regulation in the fetus and perhaps in the neonate. It may also act locally as a smooth muscle relaxant and a vasorelaxant. Its local role in some fetal tissues and in keratinocytes may take the form of a regulator of cell growth and/or differentiation. Thus when antisense RNA technology was used to inhibit endogenous PTHRP production in an established human keratinocyte cell line, PTHRP was found to inhibit growth and enhance differentiation. Irrespective of its precise normal role however, PTHRP provides a potential therapeutic target in MAH and, with improved methods of detection, may also be useful as a tumor marker.

Enhanced growth of a human keratinocyte cell line induced by antisense RNA for parathyroid hormone-related peptide

We have used antisense RNA technology to inhibit endogenous parathyroid hormone-related peptide (PTHRP) production in the established human keratinocyte cell line, HPK1A, in order to assess the role of PTHRP as a potential modulator of cell growth. Rat PTHRP cDNA was cloned into the replication defective retroviral vector pYN in an antisense orientation and a stable cell line (HPK1A-AS) was generated after infection by amphotropic virus and selection by the neomycin derivative, G418. Expression of the transfected antisense sequence was confirmed with an RNA sense probe for PTHRP. The effect of the retrovirally mediated gene transfer on the endogenous PTHRP transcript was examined with an RNA antisense probe which demonstrated an absence of the endogenous transcript in HPK1A-AS cells. A 1.6-kilobase transcript was, however, present in equivalent quantities in both uninfected HPK1A and pYN-infected (HPK1A-pYN) cells. Immunocytochemistry and assessment of PTHRP secretion into the medium using an NH2-terminal radioimmunoassay and a UMR 106 adenylate cyclase bioassay confirmed the absence of PTHRP in HPK1A-AS cells. Examination of the inhibition of PTHRP production on cell growth demonstrated a reduction in doubling time and an increase in [3H]thymidine incorporation. Cell cycle analysis showed an increase in the proportion of the cell population in the S phase (relative to G0/G1) in HPK1A-AS cells compared to HPK1A or HPK1A-pYN cells. These data, therefore, indicate that endogenous PTHRP acts as an effective inhibitor of cell growth in this keratinocyte model and that this action occurs, at least in part, by diminishing entry into the S phase of the cell cycle. Furthermore, the antisense RNA method is a potent one to evaluate the cellular actions of PTHRP.

Synthesis and characterization of extended and deleted recombinant analogues of parathyroid hormone-(1-84): correlation of peptide structure with function

Recombinant analogues of human parathyroid hormone [hPTH-(1-84)] were expressed in Escherichia coli harboring plasmids containing synthetic genes under the control of the lac promoter. The level of expression of the gene encoding the truncated analogue, hPTH-(3-84), was greater than that of the gene encoding full-length hPTH-(1-84) but less than that of the gene encoding proparathyroid hormone (hProPTH). This may be due in part to the relative efficiency of translation of the mRNA as suggested by secondary structure analysis and in part because of enhanced stability of the extended peptide. Formylmethionyl derivatives of hProPTH and of hPTH-(3-84) and underivatized hPTH-(3-84) were purified by HPLC, and their identity was confirmed by NH2-terminal sequencing and amino acid analysis. The bioactivity of these recombinant peptides was then tested in skeletal and renal adenylate cyclase assays in vitro and in assays examining effects on plasma and urine calcium and phosphate levels and on urine cyclic AMP levels in vivo. The NH2-terminally extended analogue fMet-hProPTH displayed 10% of the in vitro activity of hPTH-(1-84) and was a partial agonist in vivo. The peptides hPTH-(3-84) and fMet-hPTH-(3-84) were inert in vitro and were very weak in vitro antagonists when compared to the NH2-terminal analogue bovine [Nle8,18Tyr34]PTH-(3-34)-NH2. In vivo, hPTH-(3-84) and the bPTH-(3-34) analogue, when assayed at a 10:1 molar ratio relative to bPTH-(1-84), were each inert, and neither demonstrated antagonist activity at these concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Facial (syn–anti) stereoselectivity in the Diels–Alder reactions of spiro(bicyclo[2.2.2]octane-2,1′-[2,4]cyclopentadiene)

Spiro(bicyclo[2.2.2]octane-2,1′-[2,4]cyclopentadiene) (3) has been synthesized in ten steps, and its Diels–Alder cycloadditions, both thermal and catalysed, have been studied with a variety of Z-ethylenic dienophiles. No significant differences in facial stereoselectivity were observed. This suggests that, in the exo region, the distance between the addends at the transition state is approximately the same in all the cases studied.

syn–anti Stereoselection in the Diels–Alder reactions of spiro[bicyclo[2.2.2]octane-2,1′-[2,4]cyclopentadiene]

No significant differences were found between the syn to anti adduct ratios established for the Diels–Alder cycloadditions, both thermal and catalysed, of spiro[bicyclo[2.2.2]octane-2,1′-[2,4]cyclopentadiene] (1) to a variety of dienophiles. This suggests that, in the exo region, the distance between the addends at the transition state is approximately the same in all the cases studied.