Some Remarks on the Approximation of Transitional Density in Stochastic Differential Equations

Aijt-Sahalia (2002) introduced a method to estimate transitional probability densities of di®usion processes by means of Hermite expansions with coe±cients determined by means of Taylor series. This note describes a numerical procedure to ¯nd these coe±cients based on the calculation of moments. One advantage of this procedure is that it can be used e®ectively when the mathematical operations required to ¯nd closed-form expressions for these coe±cients are otherwise infeasible.

Lateral bone density variations in the scoliotic spine

Adolescent Idiopathic Scoliosis (AIS) is the most common deformity of the spine, affecting 2-4% of the population. Previous studies have shown that the vertebrae in scoliotic spines undergo abnormal shape changes, however there has been little exploration of how AIS affects bone density distribution within the vertebrae. Existing pre-operative CT scans of 53 female idiopathic scoliosis patients with right-sided main thoracic curves were used to measure the lateral (right to left) bone density profile at mid-height through each vertebral body. This study demonstrated that AIS patients have a marked convex/concave asymmetry in bone density for vertebral levels at or near the apex of the scoliotic curve. To the best of our knowledge, the only previous studies of bone density distribution in AIS are those of Périé et al [1,2], who reported a coronal plane ‘mechanical migration’ of 0.54mm toward the concavity of the scoliotic curve in the lumbar apical vertebrae of 11 scoliosis patients. This is comparable to the value of 0.8mm (4%) in our study, especially since our patients had more severe scoliotic curves. From a bone adaptation perspective, these results suggest that the axial loading on the scoliotic spine is strongly asymmetric.

Lateral bone density variations in the scoliotic spine

Adolescent Idiopathic Scoliosis (AIS) is the most common deformity of the spine, affecting 2-4% of the population. Previous studies have shown that the vertebrae in scoliotic spines undergo abnormal shape changes, however there has been little exploration of how scoliosis affects bone density distribution within the vertebrae. In this study, existing CT scans of 53 female idiopathic scoliosis patients with right-sided main thoracic curves were used to measure the lateral (right to left) bone density profile at mid-height through each vertebral body. Five key bone density profile measures were identified from each normalised bone density distribution, and multiple regression analysis was performed to explore the relationship between bone density distribution and patient demographics (age, height, weight, body mass index (BMI), skeletal maturity, time since Menarche, vertebral level, and scoliosis curve severity). Results showed a marked convex/concave asymmetry in bone density for vertebral levels at or near the apex of the scoliotic curve. At the apical vertebra, mean bone density at the left side (concave) cortical shell was 23.5% higher than for the right (convex) cortical shell, and cancellous bone density along the central 60% of the lateral path from convex to concave increased by 13.8%. The centre of mass of the bone density profile at the thoracic curve apex was located 53.8% of the distance along the lateral path, indicating a shift of nearly 4% toward the concavity of the deformity. These lateral bone density gradients tapered off when moving away from the apical vertebra. Multi-linear regressions showed that the right cortical shell peak bone density is significantly correlated with skeletal maturity, with each Risser increment corresponding to an increase in mineral equivalent bone density of 4-5%. There were also statistically significant relationships between patient height, weight and BMI, and the gradient of cancellous bone density along the central 60% of the lateral path. Bone density gradient is positively correlated with weight, and negatively correlated with height and BMI, such that at the apical vertebra, a unit decrease in BMI corresponds to an almost 100% increase in bone density gradient.

The role of land use and psycho-social factors in high density residents' work travel mode choices : implications for sustainable transport policy

Imperatives to improve the sustainability of cities often hinge upon plans to increase urban residential density to facilitate greater reliance on sustainable forms of transport and minimise car use. However there is ongoing debate about whether high residential density land use in isolation results in sustainable transport outcomes. Findings from surveys with residents of inner-urban high density dwellings in Brisbane, Australia, suggest that solo car travel accounts for the greatest modal share of typical work journeys and attitudes toward dwelling and neighbourhood transport-related features, residential sorting factors and socio-demographics, alongside land use such as public transport availability, are significantly associated with work travel mode choice. We discuss the implications of our findings for transport policy and management including encouraging relatively sustainable intermodal forms of transport for work journeys.

Sensitivity of proximal femoral stiffness and areal bone mineral density to changes in bone geometry and density

Areal bone mineral density (aBMD) is the most common surrogate measurement for assessing the bone strength of the proximal femur associated with osteoporosis. Additional factors, however, contribute to the overall strength of the proximal femur, primarily the anatomical geometry. Finite element analysis (FEA) is an effective and widely used computerbased simulation technique for modeling mechanical loading of various engineering structures, providing predictions of displacement and induced stress distribution due to the applied load. FEA is therefore inherently dependent upon both density and anatomical geometry. FEA may be performed on both three-dimensional and two-dimensional models of the proximal femur derived from radiographic images, from which the mechanical stiffness may be redicted. It is examined whether the outcome measures of two-dimensional FEA, two-dimensional, finite element analysis of X-ray images (FEXI), and three-dimensional FEA computed stiffness of the proximal femur were more sensitive than aBMD to changes in trabecular bone density and femur geometry. It is assumed that if an outcome measure follows known trends with changes in density and geometric parameters, then an increased sensitivity will be indicative of an improved prediction of bone strength. All three outcome measures increased non-linearly with trabecular bone density, increased linearly with cortical shell thickness and neck width, decreased linearly with neck length, and were relatively insensitive to neck-shaft angle. For femoral head radius, aBMD was relatively insensitive, with two-dimensional FEXI and threedimensional FEA demonstrating a non-linear increase and decrease in sensitivity, respectively. For neck anteversion, aBMD decreased non-linearly, whereas both two-dimensional FEXI and three dimensional FEA demonstrated a parabolic-type relationship, with maximum stiffness achieved at an angle of approximately 15o. Multi-parameter analysis showed that all three outcome measures demonstrated their highest sensitivity to a change in cortical thickness. When changes in all input parameters were considered simultaneously, three and twodimensional FEA had statistically equal sensitivities (0.41±0.20 and 0.42±0.16 respectively, p = ns) that were significantly higher than the sensitivity of aBMD (0.24±0.07; p = 0.014 and 0.002 for three-dimensional and two-dimensional FEA respectively). This simulation study suggests that since mechanical integrity and FEA are inherently dependent upon anatomical geometry, FEXI stiffness, being derived from conventional two-dimensional radiographic images, may provide an improvement in the prediction of bone strength of the proximal femur than currently provided by aBMD.

Correspondence : lymphedema following breast cancer

Lymphedema—a chronic, disabling sequela of breast cancer treatment—is finally receiving the research attention it deserves. The work published by Norman et al1 in the January issue of Journal of Clinical Oncology supports the findings of this emerging literature, which demonstrates that lymphedema is common following breast cancer treatment, but that higher estimates are observed when self-report is used to assess lymphedema status compared with other measures such as circumferences, perometry, or bio-impedance spectroscopy. While Norman et al reported that the majority of cases occur within 2 years of diagnosis, work by us2 and others3 have demonstrated that the majority of cases (70% to 80%) occur within the first 12 months after diagnosis. Collectively, this work advocates for the measurement of lymphedema being included within routine presurgical and postsurgical care. However, until we know more about the effectiveness of lymphedema treatment, clinicians may remain skeptical about active screening for lymphedema.

Does lymphedema following breast cancer warrant clinical attention?

Secondary lymphedema (swelling) after breast cancer treatment usually develops on the hand, arm, shoulder, and/or breast on the treated side. It is commonly associated with the presence of other upper-body symptoms, such as pain and aching1; it impacts physical and psychosocial functioning and adversely influences quality of life.2 Moreover, it is considered incurable, progressive, and difficult to treat. Arguably, lymphedema is the most problematic and dreaded treatment-related complication of breast cancer.3

Exercise for health : a breast cancer recovery program - quality of life benefits [Conference Abstract]

Introduction: Five-year survival from breast cancer in Australia is 87%. Hence, ensuring a good quality of life (QOL) has become a focal point of cancer research and clinical interest. Exercise during and after treatment has been identified as a potential strategy to optimise QOL of women diagnosed with breast cancer.----- Methods: Exercise for Health is a randomised controlled trial of an eight-month, exercise intervention delivered by Exercise Physiologists. An objective of this study was to assess the impact of the exercise program during and following treatment on QOL. Queensland women diagnosed with unilateral breast cancer in 2006/07 were eligible to participate. Those living in urban-Brisbane (n=194) were allocated to either the face-to-face exercise group, the telephone exercise group, or the usual-care group, and those living in rural Queensland (n=143) were allocated to the telephone exercise group or the usual-care group. QOL, as assessed by the Functional Assessment of Cancer Therapy-Breast (FACT-B+4) questionnaire, was measured at 4-6 weeks (pre-intervention), 6 months (mid-intervention) and 12 months (three months post-intervention) post-surgery.----- Results: Significant (P<0.01) increases in QOL were observed between pre-intervention and three months post-intervention 12 months post-surgery for all women. Women in the exercise groups experienced greater mean positive changes in QOL during this time (+10 points) compared with the usual-care groups (+5 to +7 points) after adjusting for baseline QOL. Although all groups experienced an overall increase in QOL, approximately 20% of urban and rural women in the usual-care groups reported a decline in QOL, compared with 10% of women in the exercise groups.----- Conclusions: This work highlights the potential importance of participating in physical activity to optimise QOL following a diagnosis of breast cancer. Results suggest that the telephone may be an effective medium for delivering exercise counselling to newly diagnosed breast cancer patients.

The prognostic significance of quality of life following breast cancer [Conference Abstract]

Introduction: Evidence suggests a positive association between quality of life (QOL). and overall survival(OS). among metastatic breast cancer (BC). patients, although the relationship in early-stage BC is unclear. This work examines the association between QOL and OS following a diagnosis of early-stage BC. ----- Methods: A population-based sample of Queensland women (n=287). with early-stage, invasive, unilateral BC, were prospectively observed for a median of 6.6 years. QOL was assessed at six and 18 months post-diagnosis using the Functional Assessment of Cancer Therapy, Breast FACT-B+4. questionnaire. Raw scores for the FACT-B+4 scales were computed and individuals were categorised according to whether QOL declined, remained stable or improved over time. OS was measured from the date of diagnosis to the date of death or was censored at the date of last follow-up. Risk ratios (RR) and 95% confidence intervals (CI). for the association between QOL and OS were obtained using Cox proportional hazards survival models adjusted for confounding characteristics. ----- Results: A total of 27 (9.4%). women died during the follow-up period. Three baseline QOL scales (emotional, general and overall QOL) were significantly associated with OS, with RRs ranging between 0.89 95% CI: 0.81, 0.98; P=0.01. and 0.98 (95% CI: 0.96, 0.99; P=0.03),indicating a 2%-11% reduced risk of death for every one unit increase in QOL. When QOL was categorised according to changes between six and 18 months post-diagnosis, analyses showed that for those who experienced declines in functional and physical QOL, risk of death increased by two- (95% CI: 1.43, 12.52; P<0.01) and four-fold (95% CI: 1.15, 7.19; P=0.02), respectively. Conclusions: This work indicates that specific QOL scales at six months post-diagnosis, and changes in certain QOL scales over the subsequent 12-month period (as measured by the FACT-B+4), are associated with overall survival in women with early-stage breast cancer.

Longitudinal patterns of weight in women diagnosed with breast cancer [Conference Abstract]

Introduction: Weight gain is a common concern following breast cancer and has been associated with negative health outcomes. As such, prevention of weight gain is of clinical interest. This work describes weight change between 6- and 18-months following a breast cancer diagnosis and explores the personal, treatment and behavioural characteristics associated with gains in weight. Methods: Body mass index was objectively assessed, at three-monthly intervals, on a population-based sample of women newly diagnosed with unilateral breast cancer (n=185). Changes in BMI between 6- and 18-months post-diagnosis were calculated, with gains of one or more being considered clinically detrimental to future health. Results: Approximately 60% of participants were overweight or obese at 6-months post-diagnosis. While BMI remained relatively stable across the testing period (range=27.3-27.8), 24% of participants experienced clinically relevant gains in BMI (median gains=1.9). Following adjustment for potential confounders, younger age (<45 years; Odds ratio, OR=9.8), being morbidly obese at baseline (OR=4.6) and receiving hormone therapy (OR=4.8) were characteristics associated with an increased odds (p<0.05) of gaining BMI. Other characteristics associated with gains in BMI were more extensive surgery and having a history of smoking, although these relationships were not supported statistically. In contrast, caring for younger children was associated with reduced risk of gaining BMI (OR=0.3, p=0.20). Conclusions: Clinically relevant weight gain between 6- and 18-months post-breast cancer diagnosis is an issue for one in four women, with certain subgroups being particularly susceptible. However, the majority of women diagnosed with breast cancer are overweight or obese and gains in body weight are common. Thus, interventions that address the importance of achieving and sustaining a healthy body weight, delivered to all women with breast cancer, may have greater public health impact than interventions targeting any specific breast cancer subgroup.

Preliminary Results from Exercise for Health : A Breast Cancer Recovery Project [Abstract]

The Exercise for Health program is a telephone-delivered exercise intervention for women with breast cancer (BC) living in regional Queensland. The effect of the program is being evaluated in the context of a randomised controlled trial. Consenting, newly diagnosed BC patients, treated in one of 8 regional Queensland hospitals, were randomly allocated to telephone-based exercise counselling (EC) or usual care (UC) at 6-weeks post-surgery. EC participants received an exercise workbook and 16 calls from an exercise physiologist over 8 months. Physical activity levels (PA) (Active Australia & CHAMPS), quality-of-life (FACTB+4), upper-body function (DASH) and fatigue (FACIT-Fatigue) were assessed at baseline (4-6 weeks post-surgery), 6- and 12-months post-surgery. Preliminary analyses of available 6-month data were conducted using t-tests and repeated measures ANCOVAs. Participating women (n=143; EC n=73, UC n=70) were aged 53±9 years and 30% met PA guidelines at baseline. Up to two thirds of the women received adjuvant therapy during the first 6 months following surgery. Greater improvements (mean change+SD) occurred for the EC vs UC group in weekly sessions of walking (1.83±4.3 vs -0.5±5.5, p=0.029) moderate-vigorous PA (5.0±6.5 vs -1.1±6.1, p=0.005) and strength training (1.9±2.9 vs -0.5±4.2 p<0.001), and in upper-body function, reflected by lower log-transformed disability scores (-0.34±0.44 vs -0.17±0.28, p=0.038). More EC than UC participants met PA guidelines at 6 months (46.3% vs 32.7%). Preliminary findings from this ongoing trial suggest that the telephone is a feasible and effective medium for delivering exercise counselling to newly diagnosed BC patients living in regional areas.

Recovery and exercise interventions following breast cancer [Abstract]

Over 13,000 women are diagnosed with breast cancer each year in Australia and approximately 90% of these women will survive longer than 5-years. However, survival following treatment for breast cancer is often associated with adverse physical and psychosocial side effects, which persist beyond treatment cessation. As incidence and survival rates associated with breast cancer continue to rise, there is an imperative need to understand the extent of treatment-related concerns and ways in which these concerns can be minimized and/or overcome. A growing body of scientific evidence demonstrates that extensive quality of life benefits can be attained through exercise during and following breast cancer treatment. Such benefits observed include improvements in psychosocial and physical outcomes, as well as better compliance with treatment regimens and reduced impact of disease symptoms and treatment-related side effects. There is also evidence to suggest that post-diagnosis physical activity can improve survival. However, the majority of women newly diagnosed with breast cancer in Australia are not sufficiently active and the majority experience further declines in their physical activity levels during treatment. Throughout the course of this presentation, which draws on data from cohort studies and randomized trials of exercise interventions conducted in Queensland, the potential benefits of exercising during and following breast cancer treatment, the exercise prescription recommended for breast cancer survivors, the limits of our evidence-based knowledge and the issues faced by clinicians and patients with respect to exercise following a cancer diagnosis will be discussed. The question is no longer whether people with breast cancer should be active during and following their treatment, but is how do health care professionals best assist people to become and stay active in an endeavor to live healthy lives beyond their cancer experience.

What determines the health-related quality of life among regional and rural breast cancer survivors?

Objective: To assess the health-related quality of life (HRQoL) of regional and rural breast cancer survivors at 12 months post-diagnosis and to identify correlates of HRQoL. Methods: 323 (202 regional and 121 rural) Queensland women diagnosed with unilateral breast cancer in 2006/2007 participated in a population-based, cross-sectional study. HRQoL was measured using the Functional Assessment of Cancer Therapy, Breast plus arm morbidity (FACT-B+4) self-administered questionnaire. Results: In age-adjusted analyses, mean HRQoL scores of regional breast cancer survivors were comparable to their rural counterparts 12 months post-diagnosis (122.9, 95% CI: 119.8, 126.0 vs. 123.7, 95% CI: 119.7, 127.8; p>0.05). Irrespective of residence, younger (<50 years) women reported lower HRQoL than older (50+ years) women (113.5, 95% CI: 109.3, 117.8 vs. 128.2, 95%CI: 125.1, 131.2; p<0.05). Those women who received chemotherapy, reported two complications post-surgery, had poorer upper-body function than most, reported more stress, reduced coping, who were socially isolated, had no confidante for social-emotional support, had unmet healthcare needs, and low health self-efficacy reported lower HRQoL scores. Together, these factors explained 66% of the variance in overall HRQoL. The pattern of results remained similar for younger and older age groups. Conclusions and Implications: The results underscore the importance of supporting and promoting regional and rural breast cancer programs that are designed to improve physical functioning, reduce stress and provide psychosocial support following diagnosis. Further, the information can be used by general practitioners and other allied health professionals for identifying women at risk of poorer HRQoL.