Nichola Dalzell

Effects of gender, anthropometric variables, and aging on the evolution of hip strength in men and women aged over 65

Although gender differences in fall rates may partly explain the higher prevalence of fractures in elderly women than men, male bones may also be intrinsically stronger or suffer less structural degradation with age than those of women. We used hip structural analysis (HSA) to study gender differences in hip geometry and bone mineral density (BMD) as they evolved over time in elderly white men and women with the aim of identifying candidate biological pathways leading to heightened risk of hip fracture. We recruited 443 women and 439 men aged 67-79 years from a diet and cancer prospective population-based cohort study to a study of hip bone loss. Hip BMD was measured on two occasions 2-5 years apart by dual-energy X-ray absorptiometry and HSA software used to derive BMD and structural parameters at the narrow neck (NN), the intertrochanter (IT), and the shaft (S) regions. Structural indices calculated in each region were cross-sectional area (CSA)-amount of bone surface area in the cross section after excluding soft tissue space; section modulus (Z)-an index of bending resistance, subperiosteal width, endocortical width, cortical thickness; and cortical buckling ratio (CBR)-a measure of cortical instability. Compared to men, women had lower values of BMD, CSA, Z, subperiosteal width, endocortical width, and cortical thickness in all regions, except S endocortical width, after adjusting for weight, height, and age (P < 0.0001). CBR was higher in women than in men (P < 0.0001) in all regions. Longitudinal analysis of rates of change revealed faster rates of BMD decline in women than in men at the Hologic total hip, Hologic femoral neck, and IT regions (P < 0.029). Women had faster rates of subperiosteal and endosteal expansion than men at the NN (P < 0.011) and IT (P < 0.049) and faster increase in Z at the NN (P = 0.029). At the IT region, cortical thinning was faster in women than in men (P = 0.037) and CBR increased at a faster rate in women (P = 0.011). In conclusion, Z is lower in women than in men and expansion of the proximal femur occurs in both sexes, being faster in women than in men. Z does not decline at the same rate as BMD, implying that part of the effect of aging on BMD is due to expansion of the bony envelope without loss of bone mineral content. Faster expansion in the female femoral neck may in turn lead to greater fragility if wider diameter and thinner cortices become locally unstable.

Refractive error, axial length and anterior chamber depth of the eye in British adults: the EPIC-Norfolk Eye Study

Purpose To describe the distribution, and demographic and socioeconomic correlates of refractive error and related ocular biometry in an older British population. Methods Refractive error was measured using an auto-refractor without cycloplegia. Pseudophakic individuals and those who had undergone refractive surgery were excluded from analysis. Axial length and anterior chamber depth were measured using partial coherence laser interferometry. Occupation category and highest educational achievement were recorded. Results Biometric data were available for 2519 people (1090 men, 1429 women; 93.2% of all participants) aged 48 to 88 years. Refractive data were available for both eyes in 2210 bilaterally phakic participants. Among phakic individuals, axial length of the eye was strongly inversely correlated with refractive error in both men and women (p<0.001). Axial length of the eye was strongly, independently related to height, weight and social class, but most strongly related to educational achievement. In contrast, anterior chamber depth varied with age and sex, but not with socioeconomic status. There was a significant inverse association between anterior chamber depth and refraction in women (p<0.001) but not in men (p=0.495). Conclusion Refractive error in this predominantly white older UK population was associated with axial biometry and sociodemographic characteristics. Educational status was the strongest determinant of axial length.

Is QUS or DXA Better for Predicting the 10-Year Absolute Risk of Fracture?†‡

Although quantitative ultrasound (QUS) is known to be correlated with BMD and bone structure, its long‐term predictive power for fractures in comparison with DXA is unclear. We examined this in a sample of men and women in the European Prospective Investigation into Cancer (EPIC)‐Norfolk who had both heel QUS and hip DXA between 1995 and 1997. From 1455 participants (703 men) 65–76 yr of age at baseline, 79 developed a fracture over 10.3 ± 1.4 yr of follow‐up. In a sex‐stratified Cox proportional‐hazard model including age, height, body mass index, prior fracture, smoking, alcohol intake, and total hip BMD, a 1 SD decrease in BMD was associated with a hazard ratio (HR) for fracture of 2.26 (95% CI: 1.74–2.95). In the multivariable model with heel broadband ultrasound attenuation (BUA) in place of BMD, HR for a 1 SD decrease in BUA was 2.04 (95% CI: 1.55–2.69). Global measures of model fit showed relative superiority of the BMD model, whereas the area under the receiving operator characteristic (ROC) curve was slightly higher for the BUA model. Using both Cox models with BMD and BUA measures, we calculated exact 10‐yr absolute risk of fracture for all participants and categorized them in groups of <5%, 5% to <15%, and ≥15%. Comparison of groupings based on two models showed a total reclassification of 28.8% of participants, with the greatest reclassification (∼40%) among the intermediate‐ and high‐risk groups. This study shows that the power of QUS for prediction of fractures among the elderly is at least comparable to that of DXA. Given the feasibility and lower cost of ultrasound measurement in primary care, further studies to develop and validate models for prediction of 10‐yr risk of fracture using clinical risk factors and QUS are recommended.

Intraocular Pressure and Corneal Biomechanics in an Adult British Population: The EPIC-Norfolk Eye Study

PURPOSE To describe the distribution and determinants of intraocular pressure (IOP) and indices of corneal biomechanics in an adult British population. METHODS Goldmann-equivalent IOP (IOPg), corneal mechanical characteristics (corneal hysteresis, CH; corneal resistance factor, CRF), and IOP adjusted for corneal factors (IOPcc) were measured. Ocular biometric characteristics were also measured in 4184 consecutive individuals aged 48 to 91 years recruited from the European Prospective Investigation into Cancer (EPIC)-Norfolk cohort. Sociodemographic data were recorded with a standardized questionnaire. Blood pressure and anthropometric data were recorded by trained staff according to a standard protocol. RESULTS Mean IOP was similar to that reported in previous United Kingdom population studies (IOPg: 16.0 mm Hg, SD 3.68). These data confirmed systolic blood pressure as the major identifiable correlate of IOP. There was a significant positive association between IOP and axial length of the eye. The IOPg, but not IOPcc, was higher in the women than in the men. No difference in IOP between the different age groups was identified. CRF and CH varied with IOPg, age, sex, and axial length of the eye. CONCLUSIONS The study provided current population-based values for IOP and corneal biomechanical parameters. Mean IOP in this British population was very similar to levels previously reported over 40 years ago. There was no identifiable relationship between IOP and age within this cohort with an older age range, in contrast to previous studies. Systolic blood pressure was identified as the major correlate of IOP.

The effect of including quantitative heel ultrasound in models for estimation of 10-year absolute risk of fracture

The role of quantitative ultrasound (QUS) in clinical practice is debatable. An unanswered question is that whether combining QUS and BMD measurements could improve the prediction of fracture risk. We examined this in a sample of men and women in the European Prospective Investigation into Cancer (EPIC)-Norfolk who had both heel QUS and hip DXA between 1995 and 1997 and were followed for any incident fracture up to 2007. From 1455 participants (703 men) aged 65-76 years at baseline, 79 developed a fracture over 10.3+/-1.4 years of follow-up. Two separate sex-stratified Cox proportional-hazard models were used including clinical risk factors and total hip BMD. Heel broadband ultrasound attenuation (BUA) was also included in the second model. Global measures of model fit, area under ROC curve, and the Hosmer-Lemeshow statistic showed relative superiority of the model including BUA. Using each model, we calculated 10-year absolute risk of fracture for all participants and categorized them in groups of < 5%, 5% to < 15%, and > or = 15%. Comparison of groupings showed a total re-classification of 16.6% of participants after inclusion of BUA with the greatest re-classification (30.7%) among the group with intermediate risk. Adding a QUS measurement to models based on clinical risk factors and BMD improves the predictive power of models and suggests that further attention should be paid to QUS as a clinical tool for fracture risk assessment.

Physical activity and ocular perfusion pressure: the EPIC-Norfolk eye study.

PURPOSE To examine the relationship between physical activity and ocular perfusion pressure (OPP), a consistent risk factor for glaucoma. METHODS The relationship between previous physical activity and current OPP in 5650 participants aged 48 to 90 who attended the first (1993-1997) and third (2006-2010) health check as part of the European Prospective Investigation into Cancer (EPIC)-Norfolk study was examined. Usual combined physical activity at work and leisure was assessed using a validated instrument. Individuals were categorized as inactive, moderately inactive, moderately active, or active. Three IOP measurements were obtained (Ocular Response Analyzer [ORA]; Reichert, Inc., Depew, NY). Mean Goldmann correlated IOP (IOPg) from one eye was used in the analysis. Systolic and diastolic blood pressure (BP) were recorded as the mean of two measurements taken with a sphygmomanometer. Associations between physical activity and low (≤40 mm Hg) mean OPP (2/3 mean arterial pressure - IOP) and low (≤50 mm Hg) diastolic OPP (diastolic BP - IOP) were tested using logistic regression, adjusting for age, sex, body mass index, social class, IOP, and BP. RESULTS Active people had a lower risk of mean OPP ≤ 40 mm Hg and diastolic OPP ≤ 50 mm Hg after adjusting for age, sex, social class, and body mass index (odds ratio, 0.75; 95% confidence interval [CI], 0.60-0.93; P < 0.01) and (odds ratio, 0.73, 95% CI, 0.58-0.93; P = 0.01), respectively. The association between physical activity and perfusion pressure was independent of IOP, but largely mediated through diastolic BP. CONCLUSIONS Lower levels of physical activity were associated with lower OPP. Further research is needed to investigate the potential benefit of increased physical activity as a safe and simple method of modifying glaucoma risk.

The EPIC-Norfolk Eye Study: rationale, methods and a cross-sectional analysis of visual impairment in a population-based cohort

Objectives To summarise the methods of the European Prospective Investigation of Cancer (EPIC)-Norfolk Eye Study, and to present data on the prevalence of visual impairment and associations with visual impairment in the participants. Design A population-based cross-sectional study nested within an on-going prospective cohort study (EPIC). Setting East England population (the city of Norwich and its surrounding small towns and rural areas). Participants A total of 8623 participants aged 48–92 years attended the Eye Study and underwent assessment of visual acuity, autorefraction, biometry, tonometry, corneal biomechanical measures, scanning laser polarimetry, confocal scanning laser ophthalmoscopy, fundal photography and automated perimetry. Outcome measures Visual impairment was defined according to the WHO classification and the UK driving standard, and was based on presenting visual acuity. Summary measures of other ophthalmic measurements are also presented. Results The prevalence (95% CI) of WHO-defined moderate-to-severe visual impairment and blindness was 0.74% (0.55% to 0.92%). The prevalence (95% CI) of presenting visual acuity worse than the UK driving standard was 5.87% (5.38% to 6.37%). Older age was significantly associated with visual impairment or blindness (p<0.001). Presenting visual acuity worse than UK driving standard was associated with older age (p<0.001), female sex (p=0.005) and lower educational level (p=0.022). Conclusions The prevalence of blindness and visual impairment in this selected population was low. Visual impairment was more likely in older participants, women and those with a lower educational level.

Cross-sectional associations between different measures of obesity and muscle strength in men and women in a British cohort study

ObjectivesThe relationship between obesity and grip strength, a key indicator of sarcopenia, has been inconsistently reported. We aimed to examine associations between grip strength and both body mass index (BMI), a clinical indicator of total adiposity, and waist circumference (WC), an indicator of central adiposity.DesignCross-sectional study.Setting and ParticipantsData collected from 8,441 men and women, aged 48–92 years old, who attended the third health examination of the European Prospective Investigation into Cancer-Norfolk study was used.MeasurementsMaximum grip strength (Smedley dynamometer), BMI (weight/height2) and WC (measured at the natural waist) were ascertained at a research clinic. The associations between grip strength and adiposity measures were explored using linear regression with adjustment for age, height, social class, physical activity, prevalent disease, smoking status and alcohol intake.ResultsMen and women were examined separately and those in the upper quartile of BMI were 2.70kg (95%CI 2.07, 3.33) and 1.46kg (95%CI 1.05, 1.86) stronger respectively than those in the bottom quartile (P trends <0.001). Grip strength also increased weakly with increasing WC. However, including both BMI and WC in the same regression model revealed an inverse association between grip strength and WC, whilst the previously observed association with BMI strengthened. For every 10cm increase in WC, grip strength was 3.56kg (95%CI 3.04, 4.08) lower in men and 1.00kg (95%CI 0.74, 1.24) lower in women.ConclusionsLarger overall body mass, indicated by higher BMI, is associated with stronger grip strength but high WC, a clinical indicator of central obesity, is associated with lower grip strength. Abdominal fat is the most metabolically active adipose tissue and this provides a clue to potential mechanisms underlying relationships between fat and skeletal muscle. Additionally, it reinforces the recommendation to measure WC in clinical practice, especially when BMI is below obese ranges.

Visual acuity, self-reported vision and falls in the EPIC-Norfolk Eye study

Purpose To examine the relationship between visual acuity (VA) and self-reported vision (SRV) in relation to falls in 8317 participants of the European Prospective Investigation into Cancer-Norfolk Eye study. Methods All participants completed a health questionnaire that included a question regarding SRV and questions regarding the number of falls in the past year. Distance VA was measured using a logMAR chart for each eye. Poor SRV was defined as those reporting fair or poor distance vision. The relationship between VA and SRV and self-rated falls was analysed by logistic regression, adjusting for age, sex, physical activity, body mass index, chronic disease, medication use and grip strength. Results Of 8317 participants, 26.7% (95% CI 25.7% to 27.7%) had fallen in the past 12 months. Worse VA and poorer SRV were associated with one or more falls in multivariable analysis (OR for falls=1.31, 95% CI 1.04 to 1.66 and OR=1.32, 95% CI 1.09 to 1.61, respectively). Poorer SRV was significantly associated with falls even after adjusting for VA (OR=1.28, 95% CI 1.05 to 1.57). Conclusions SRV was associated with falls independently of VA and could be used as a simple proxy measure for other aspects of visual function to detect people requiring vision-related falls interventions.

Uncorrected refractive error in older British adults: the EPIC-Norfolk Eye Study

Aim To investigate the prevalence of, and demographic associations with, uncorrected refractive error (URE) in an older British population. Methods Data from 4428 participants, aged 48–89 years, who attended an eye examination in the third health check of the European Prospective Investigation into Cancer-Norfolk study and had also undergone an ophthalmic examination were assessed. URE was defined as ≥1 line improvement of visual acuity with pinhole-correction in the better eye in participants with LogMar presenting visual acuity (PVA) <0.3 (PVA <6/12). Refractive error was measured using an autorefractor without cycloplegia. Myopia was defined as spherical equivalent ≤−0.5 dioptre, and hypermetropia ≥0.5 dioptre. Results Adjusted to the 2010 midyear British population, the prevalence of URE in this Norfolk population was 1.9% (95% CI 0.6% to 3.1%). Lower self-rated distance vision was correlated with higher prevalence of URE (ptrend<0.001). In a multivariate logistic regression model adjusting for age, gender, retirement status, educational level and social class, independent significant associations with URE were increasing age (ptrend<0.001) and having hypermetropic or myopic refractive error. Wearing distance spectacles was inversely associated with URE (OR 0.34, 95% CI 0.21 to 0.55, p<0.001). There were 3063 people (69.2%) who wore spectacles/contact lenses for distance vision. Spectacle wear differed according to type of refractive error (p<0.001), and use rose with increasing severity of refractive error (ptrend<0.001). Conclusion Although refractive error is common, the prevalence of URE was found to be low in this population reflecting a low prevalence of PVA<0.3.