[Show abstract][Hide abstract] ABSTRACT: Thinness is a risk factor for fractures, but the effect of obesity on fracture risk is less clear. We found an association between measures of obesity and prevalence and number of vertebral deformities in women but not in men, in a cross-sectional study of 1,011 participants aged 50-80 years.
Low body weight is well recognised as a risk factor for fractures, but the association between overweight and fracture risk is less well described. This cross-sectional study describes the association between measures of obesity and vertebral deformities in 1,011 male and female participants in the Tasmanian Older Adult Cohort study.
Vertebral deformities (anterior wedging) of T4-L4 were determined by morphometric dual-emission X-ray absorptiometry. Body fat was assessed as weight, body mass index (BMI), waist-hip ratio (WHR), waist circumference and DXA measures of trunk fat (in percent) and total fat mass.
The mean age of participants was 63 ± 7 years, and mean BMI was 28 ± 5. Prevalent thoracic vertebral deformities were associated with increasing weight [standardised β (Sβ) 0.29, p = 0.003], BMI (Sβ 0.33, p < 0.001), trunk fat (Sβ 0.20, p = 0.03), waist circumference (Sβ 0.19, p = 0.03) and fat mass (Sβ 0.23, p = 0.03), but not the WHR in women, and only with decreasing total fat mass in men. In addition, the number of vertebral deformities increased as weight, BMI or fat mass increased in women (all p < 0.05) but decreased with increasing total fat mass in men. Associations between fat mass and vertebral deformities were mainly linear, but there was some evidence of a threshold effect in women with a BMI ≥ 35.
There is a deleterious association between increasing amounts of body fat in women but not in men and the prevalence and number of vertebral deformities, which may reflect loading of the thoracic spine.
Osteoporosis International 08/2011; 23(1):67-74. DOI:10.1007/s00198-011-1741-8 · 4.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sex hormones and reproductive factors may be important for osteoarthritis (OA). The aim of this study was to describe the associations of parity, use of hormone replacement therapy (HRT) and oral contraceptives (OCs) with cartilage volume, cartilage defects and radiographic OA in a population-based sample of older women.
Cross-sectional study of 489 women aged 50-80 years. Parity, use of HRT and OC was assessed by questionnaire; knee cartilage volume and defects by magnetic resonance imaging and knee joint space narrowing (JSN) and osteophytes by X-ray.
Parity was associated with a deficit in total knee cartilage volume [adjusted β=-0.69 ml, 95% confidence interval (CI) -1.34, -0.04]. Increasing parity was associated with decreasing cartilage volume in both the tibial compartment and total knee (both P trend <0.05). Parity was also associated with greater cartilage defects in the patella compartment [adjusted odds ratio (OR)=2.87, 95% CI=1.39, 5.93] but not other sites. There was a consistent but non-significant increase in knee JSN (OR=2.78, 95% CI=0.75, 10.31) and osteophytes (OR=1.69, 95% CI=0.59, 4.82) for parous women. Use of HRT and/or OC was not associated with cartilage volume, cartilage defects or radiographic change.
Parity (but not use of HRT or OC) is independently associated with lower cartilage volume primarily in the tibial compartment and higher cartilage defects in the patella compartment in this population-based sample of older women.
Osteoarthritis and Cartilage 08/2011; 19(11):1307-13. DOI:10.1016/j.joca.2011.07.020 · 4.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives
This pilot study describes the physiological attributes of jockeys and track-work riders in Tasmania and investigates whether these attributes are associated with falls.
All jockeys and track-work riders licensed in Tasmania were invited to participate. The study group consisted of eight jockeys (two female, six male) and 20 track-work riders (14 female, six male). Measures of anthropometry, balance, reaction time, isometric strength, vertical jump, glycolytic and aerobic fitness, flexibility and body composition were conducted. Tests were designed to assess specific aspects of rider fitness and performance relevant to horse racing. For a subset of participants (n=14), the authors obtained information on falls and injuries. The authors used Poisson regression to estimate incidence rate ratios.
Jockeys had better balance, a faster mean reaction time, a lower fatigue index and a higher estimated V.O2max than their track-work riding counterparts. Jockeys were also younger and smaller in stature than track-work riders, and when differences in body mass were taken into account, they had a greater muscular strength and muscular (alactic) power. Important factors found to be associated with falls were lower aerobic and anaerobic fitness, greater muscular strength and power, and riding with the full foot in the stirrup irons compared with riding on the ball of the foot.
This pilot study shows that physiological attributes of jockeys and track-work riders can predict their risk of falling and are measurable using methods feasible for large-scale fieldwork.
BMJ Open 06/2011; 1(1):e000142. DOI:10.1136/bmjopen-2011-000142 · 2.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Thoroughbred jumps racing jockeys have a fall rate greater than their flat racing counterparts. Previous studies have focused on factors that contribute to falls by horses but, to date, there has not been a study of risk factors for falls to jockeys in jumps races. Data on race-day falls were extracted from stipendiary stewards reports lodged with Principal Racing Authorities following each race meeting. Denominator data were provided by Racing Information Services Australia on races conducted from August 2002 until July 2009. Univariable and multivariable analyses, estimating incidence rate ratios, were conducted using Poisson regression. In multivariable analysis in hurdle racing, important predictors of falls were higher club level, larger field size, greater prize money, provisionally licensed jockeys and older jockeys. There were significant interactions between jockey licence and prize money; jockey age and previous rides this meeting; race grade and race distance; horse age and field size; and club level and field size. In steeplechase racing, important predictors were type of jump with lowest fall rates in races over Mark III jumps compared to standard fences, provisionally licensed jockeys, jockeys having had previous rides at a meeting, and larger field size. There were significant interactions between the number of previous starts by the horse and field size; race distance and prize money; and race distance and previous rides this meeting. This study has identified factors for falls in jumps racing that could form the basis for targeted strategies to improve occupational health and safety standards.
[Show abstract][Hide abstract] ABSTRACT: There is inconsistent evidence regarding the association between moderate alcohol consumption and bone mineral density (BMD). The aim of this study was to describe the associations between total and beverage-specific alcohol intake and bone loss in older men and women.
A total of 862 randomly selected subjects (mean age 63 years, range 51-81, 51% men) were studied at baseline and 2 years later. BMD was assessed by dual-energy X-ray absorptiometry. Beverage specific and total alcohol intake was assessed by food-frequency questionnaire. Falls risk was determined using the short form Physiological Profile Assessment. Incident fractures were ascertained by questionnaire.
Total alcohol intake in men positively predicted change in BMD at the lumbar spine and hip (β=0.008% and 0.006% per year per gram, P<0.05) after adjustment for confounders, but there was no significant association between alcohol intake and change in BMD in women. Lumbar spine BMD at baseline was negatively associated with frequency of spirits/liquor drinking in men (β=-0.01 g/cm(2) per category, P=0.045) and was positively associated with frequency of beer drinking (low alcohol) in women (β=0.034 g/cm(2) per category, P=0.002). Change in lumbar spine BMD was positively associated with the frequency of red wine drinking in men (β=0.08% per year per class, P=0.046). Neither beverage-specific nor total alcohol intake was associated with falls risk or fracture.
Alcohol intake especially red wine might prevent bone loss in older men but not women, whereas low-alcohol beer may be protective in women and spirits/liquor may be deleterious in men.
European journal of clinical nutrition 02/2011; 65(4):526-32. DOI:10.1038/ejcn.2011.9 · 2.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is controversy about whether pain and radiographic osteoarthritis (ROA) predict subsequent cartilage loss. The aim of this study was to describe the relationship between ROA, pain and cartilage loss in the knee.
We studied randomly selected subjects at baseline and approximately 2.9 years later (n= 399). The presence of ROA was assessed at baseline with a standing anteroposterior semiflexed radiograph scored using the Osteoarthritis Research Society International atlas for osteophytes (OP) and joint space narrowing (JSN). Pain was assessed by the Western Ontario McMaster Osteoarthritis Index. Subjects' medial and lateral tibial cartilage volumes were determined by magnetic resonance imaging at both time points.
In cross-sectional analysis, both medial and lateral tibial cartilage volumes were lower in those with ROA. Any medial ROA predicted medial tibial cartilage loss (3.2% (standard deviation (SD) 5.6) vs 1.9% (SD 5.3) per annum) while any lateral ROA predicted both medial (4.0% (SD 6.0) vs 2.2% (SD 5.3) per annum) and lateral (3.5% (SD 5.8) vs 1.6% (SD 4.2) per annum) tibial cartilage loss (all P < 0.05). In multivariate analysis, JSN and OP at both medial and lateral sites had independent dose-response associations with tibial cartilage loss at both sites. Pain was an independent predictor of lateral, but not medial, tibial cartilage loss after taking ROA into account.
Subjects with ROA (either JSN or OP) and, to a lesser extent, pain lose cartilage faster than subjects without ROA and the more severe the ROA the greater the rate of loss. These findings have implications for the design of clinical trials.
Internal Medicine Journal 02/2011; 42(3):274-80. DOI:10.1111/j.1445-5994.2011.02438.x · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is considerable controversy whether maternal peanut ingestion during pregnancy might influence sensitization in later life. Objective To examine whether maternal peanut ingestion during pregnancy might increase sensitization in the offspring.
A population-based longitudinal cohort study with 16 years follow-up was conducted (N=373). Subjects were recruited at birth as part of an infant health study. Maternal antenatal peanut consumption was documented at birth and peanut and rye sensitization were determined by measurement of serum-specific IgE at age 16.
Peanut sensitization was common (14%). In the entire cohort (n=310), there was no association between antenatal peanut ingestion and peanut sensitization (P=0.17). However, there was a strong association between antenatal peanut ingestion and decreased risk of rye sensitization and peanut sensitization in those (n=201) without a family history (FH) of asthma (Rye OR 0.30, 95% CI 0.14-0.63, P=0.001 and Peanut OR 0.18, 95% CI 0.04-0.78, P=0.02). There was an increased risk of rye sensitization in those (n=108) with a FH of asthma and antenatal peanut ingestion (Rye OR 2.69, 95% CI 1.11-6.51 P=0.03). It was considered that these sensitizations were likely to be related to the presence of IgE antibodies to cross-reacting carbohydrate epitopes common to rye and peanut allergens.
Antenatal peanut ingestion may influence the development of IgE antibody to cross-reacting carbohydrate epitopes in later life. Genetic factors may modify this association.
[Show abstract][Hide abstract] ABSTRACT: Genomewide association studies (GWAS) are a powerful method for identifying genes of small to moderate effect involved in common heritable diseases. A phase 1 GWAS was performed in an Australian and UK cohort of postmenopausal female probands (age 50-85 years) with extreme truncate selection for FN BMD (1.5<|z-score|<4), with 317,000 SNPs genotyped using Illumina HumanHap300 chips. 130 SNPs, selected for further study based on the initial results, were genotyped in families selected from the FAMOS cohort (proband FN or LS BMD z-score <-1, n=429 families including 1286 individuals) using Sequenom MALDI-TOF technology. PLINK was used to test association in the GWA component, and QTDT to test total association controlling for linkage in the confirmation family study. For a range of different genetic models, the phase 1 component of 140 subjects has equivalent power to a cohort study of 850-920 unselected individuals. Overall genotyping success rate was 99.6% in phase 1 and 93.1% in phase 2. No gene achieved genomewide statistical significance in the phase 1 screen (as expected due to small sample size). However, 31 markers achieved p-values of 10-5 to 10-7. One SNP, rs10904952, was associated with FN BMD in both phase 1 (P=0.0021) and phase 2 (P=0.00072) studies. Combining these findings, the overall level of significance for this SNP is 4.86x10-6. This SNP lies in the gene encoding ST8 alpha-n-acetyl-neuraminide alpha-2,8-sialyltransferase 6 (ST8SIA6), a protein that interacts with fetuin-alpha, which controls apatite formation and bone and tissue mineralisation. Four other SNPs lying in ST8SIA6 were associated with FN BMD with p-values of 0.0078-0.00048 in the phase 1 study. This study suggests that polymorphisms of ST8SIA6 influence FN BMD in the general population. Whilst the finding did not achieve genomewide significance in the discovery cohort, association was confirmed in the replication cohort, despite modest study power. A much larger cohort of cases with extreme high and low BMD is being recruited for further studies. If confirmed, ST8SIA6 represents a novel gene associated with BMD. The mechanism underlying the association and its effect on fracture risk have yet to be determined.
[Show abstract][Hide abstract] ABSTRACT: Objective. Although there is a well-established sex difference in the prevalence and severity of OA, the mechanism for this is not clear. The aim of this study was to examine the potential role of BMD and BMC in explaining gender differences in knee cartilage volume. Methods. A total of 153 subjects aged 25-60 years, 81% female, were recruited. MRI was performed of the dominant knee. Cartilage volume was measured using validated methods. Total body BMD and content was measured using DXA. Results. Total body BMC and BMD was significantly associated with medial cartilage volume in both sexes. However, the associations were stronger in men for BMC (B = 0.52; 95% CI 0.21, 0.83; P for difference = 0.001) and BMD (B = 2242; 95% CI 443, 4041; P for difference = 0.05). Similar results were obtained in the lateral tibial compartment. No significant association was obtained between total body BMD and BMC and patella cartilage volume in either men or women. Conclusions. In this relatively healthy population, we found a positive relationship between total body BMD and BMC and tibial cartilage volume in the medial and lateral compartments. These relationships were stronger in men than women. Thus, the results of this study may provide some insight into the sex differences in knee cartilage volume, which may in turn facilitate our understanding of the pathogenesis of OA.
[Show abstract][Hide abstract] ABSTRACT: To determine the associations between body adiposity and change in serum 25-(OH)D levels over 2.6 years, and if these associations are mediated by metabolic and inflammatory factors in older adults.
This is a longitudinal study of 859 randomly selected subjects (mean 62 years, range 51-80, 49% women). Serum 25-hydroxyvitamin D [25-(OH)D] was assessed by radioimmunoassay at baseline and 2.6 years later. Baseline serum level of leptin was assessed by radioimmunoassay and interleukin (IL)-6 by a chemiluminescent immunoassay in the first 183 subjects.
In multivariable analyses, body mass index, trunk fat percentage and waist-to-hip ratio were significant predictors of increased incident vitamin D deficiency [a 25-(OH)D < 50 nmol L⁻¹ at follow-up when ≥50 nmol L⁻¹ at baseline] and decreased recovery of vitamin D deficiency [a 25-(OH)D ≥ 50 nmol L⁻¹ at follow-up when < 50 nmol L⁻¹ at baseline]. Change in 25-(OH)D levels per annum was also independently predicted by baseline leptin (β: -0.09/unit, 95% CI: -0.17, -0.03), IL-6 (β: -0.68/quartile, 95% CI: -1.35, -0.02) and total cholesterol/high-density lipoprotein (HDL) ratio (β: -0.51, 95% CI: -0.88, -0.14). The associations between body adiposity measures and change in 25-(OH)D completely disappeared after adjustment for leptin, diminished after adjustment for IL-6, but remained unchanged after adjustment for total cholesterol/HDL ratio. All associations were independent of season and sun exposure.
Body fat is not simply a passive reservoir for 25-(OH)D. In addition to season and sun exposure, 25-(OH)D levels appear to be determined by metabolic and, to a lesser extent, inflammatory factors, and these appear to mediate the effects of adiposity on change in 25-(OH)D.
Journal of Internal Medicine 11/2010; 268(5):501-10. DOI:10.1111/j.1365-2796.2010.02267.x · 6.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The role of inflammation in osteoarthritis (OA) pathogenesis is unclear, and the associations between inflammatory cytokines and cartilage loss have not been reported. We determined the associations between serum levels of interleukin (IL)-6 and tumor necrosis factor-α (TNF-α), knee radiographic OA (ROA) and cartilage loss over 2.9 years in older adults.
A total of 172 randomly selected subjects (mean 63 years, range 52-78, 47% female) were studied at baseline and approximately 3 (range 2.6-3.3) years later. IL-6 and TNF-α were assessed by radioimmunoassay. T1-weighted fat-suppressed magnetic resonance imaging of the right knee was performed at baseline and follow-up to determine knee cartilage volume. Knee ROA of both knees was assessed at baseline.
At baseline, quartiles of IL-6 and TNF-α were associated with increased prevalence of medial tibiofemoral joint space narrowing (OARSI grade ≥ 1) in multivariate analyses [odds ratio (OR): 1.42 and 1.47 per quartile, respectively, both P<0.05]. Longitudinally, baseline IL-6 predicted loss of both medial and lateral tibial cartilage volume (β: -1.19% and -1.35% per annum per quartile, P<0.05 and P<0.01, respectively), independently of TNF-α. Change in IL-6 was associated with increased loss of medial and lateral tibial cartilage volume (β: -1.18% and -1.06% per annum per quartile, both P<0.05) and change in TNF-α was also negatively associated with change in medial cartilage volume (β: -1.27% per annum per quartile, P<0.05).
Serum levels of IL-6 and TNF-α are associated with knee cartilage loss in older people suggesting low level inflammation plays a role in the pathogenesis of knee OA.
Osteoarthritis and Cartilage 11/2010; 18(11):1441-7. DOI:10.1016/j.joca.2010.08.016 · 4.17 Impact Factor