Time series analysis of the impact of tobacco control policies on smoking prevalence among Australian adults, 2001–2011

Objective: To determine the impact of tobacco control policies and mass media campaigns on smoking prevalence in Australian adults.
Methods: Data for calculating the average monthly prevalence of smoking between January 2001 and June 2011 were obtained via structured interviews of randomly sampled adults aged 18 years or older from Australia’s five largest capital cities (monthly mean number of adults interviewed: 2375). The influence on smoking prevalence was estimated for increased tobacco taxes; strengthened smoke-free laws; increased monthly population exposure to televised tobacco control mass media campaigns and pharmaceutical company advertising for nicotine replacement therapy (NRT), using gross ratings points; monthly sales of NRT, bupropion and varenicline; and introduction of graphic health warnings on cigarette packs. Autoregressive integrated moving average (ARIMA) models were used to examine the influence of these interventions on smoking prevalence.
Findings: The mean smoking prevalence for the study period was 19.9% (standard deviation: 2.0%), with a drop from 23.6% (in January 2001) to 17.3% (in June 2011). The best-fitting model showed that stronger smoke-free laws, tobacco price increases and greater exposure to mass media campaigns independently explained 76% of the decrease in smoking prevalence from February 2002 to June 2011.
Conclusion: Increased tobacco taxation, more comprehensive smoke-free laws and increased investment in mass media campaigns played a substantial role in reducing smoking prevalence among Australian adults between 2001 and 2011.

Muscle strength and areal bone mineral density at the hip in women: a cross-sectional study

BACKGROUND: Muscle strengthening exercises are promoted for building and maintaining a healthy skeleton. We aimed to investigate the relationship between muscle strength and areal bone mineral density (BMD) at the hip in women aged 26-97 years.

METHODS: This cross-sectional study utilises data from 863 women assessed for the Geelong Osteoporosis Study. Measures of hip flexor and abductor strength were made using a hand-held dynamometer (Nicholas Manual Muscle Tester). The maximal measure from three trials on each leg was used for analyses. BMD was measured at the hip using dual energy x-ray absorptiometry (DXA; Lunar DPX-L). Total lean mass, body fat mass and appendicular lean mass were determined from whole body DXA scans. Linear regression techniques were used with muscle strength as the independent variable and BMD as the dependent variable. Models were adjusted for age and indices of body composition.

RESULTS: Measures of age-adjusted hip flexor strength and hip abductor strength were positively associated with total hip BMD. For each standard deviation (SD) increase in hip flexor strength, the increase in mean total hip BMD (SD) was 10.4 % (p = 0.009). A similar pattern was observed for hip abductor strength, with an increase in mean total hip BMD of 22.8 % (p = 0.025). All associations between hip muscle strength and total hip BMD were independent of height, but were nullified after adjusting for appendicular lean mass or total lean mass.

CONCLUSIONS: There was a positive association observed between muscle strength and BMD at the hip. However, this association was explained by measures of lean mass.

Association between serum concentration of 25-hydroxyvitamin D and the risk of hip arthroplasty for osteoarthritis: result from a prospective cohort study

OBJECTIVES: There is ongoing debate regarding the optimal serum concentrations of 25-hydroxy-vitamin D for musculoskeletal health, including osteoarthritis (OA). The aim of this prospective cohort study was to determine whether serum 25-hydroxy-vitamin D concentrations were associated with the risk of hip arthroplasty for OA. DESIGN: This study examined 9135 participants from the Australian Diabetes, Obesity and Lifestyle Study who had serum 25-hydroxy-vitamin D measured in 1999-2000 and were aged ≥40 years at the commencement of arthroplasty data collection. The incidence of hip arthroplasty for OA during 2002-2011 was determined by linking cohort records to the Australian Orthopaedic Association National Joint Replacement Registry. RESULTS: Over an average 9.1 (standard deviation (SD) 2.7) years of follow-up, 201 hip arthroplasties for OA were identified (males n = 90; females n = 111). In males, a one-standard-deviation increase in 25-hydroxy-vitamin D was associated with a 25% increased incidence (HR 1.25, 95% CI 1.02-1.56), with a dose response relationship evident by quartiles of 25-hydroxy-vitamin D concentration (P for trend 0.04). These results were independent of age, body mass index (BMI), ethnicity, smoking status, physical activity, season of blood collection, latitude, hypertension and diabetes, area level disadvantage or after excluding those with extreme low 25-hydroxy-vitamin D concentrations. No significant association was observed in women (HR 1.10, 95% CI 0.87, 1.39). CONCLUSIONS: Increasing serum 25-hydroxy-vitamin D concentrations were associated with an increased risk of hip arthroplasty for OA in males, while no significant association was observed in females. The mechanism for the association warrants further investigation.

Perceived fairness of pay among people with and without disabilities: a propensity score matched analysis of working Australians

OBJECTIVES: Equity and fairness at work are associated with a range of organizational and health outcomes. Past research suggests that workers with disabilities experience inequity in the workplace. It is difficult to conclude whether the presence of disability is the reason for perceived unfair treatment due to the possible confounding of effect estimates by other demographic or socioeconomic factors. METHODS: The data source was the Household, Income, and Labor Dynamics in Australia (HILDA) survey (2001-2012). Propensity for disability was calculated from logistic models including gender, age, education, country of birth, and father's occupational skill level as predictors. We then used nearest neighbor (on propensity score) matched analysis to match workers with disabilities to workers without disability. RESULTS: Results suggest that disability is independently associated with lower fairness of pay after controlling for confounding factors in the propensity score matched analysis; although results do suggest less than half a standard deviation difference, indicating small effects. Similar results were apparent in standard multivariable regression models and alternative propensity score analyses (stratification, covariate adjustment using the propensity score, and inverse probability of treatment weighting). CONCLUSIONS: Whilst neither multivariable regression nor propensity scores adjust for unmeasured confounding, and there remains the potential for other biases, similar results for the two methodological approaches to confounder adjustment provide some confidence of an independent association of disability with perceived unfairness of pay. Based on this, we suggest that the disparity in the perceived fairness of pay between people with and without disabilities may be explained by worse treatment of people with disabilities in the workplace.

Association of different forms of bullying victimisation with adolescents' psychological distress and reduced emotional wellbeing

OBJECTIVE: The frequency and emotional response to bullying victimisation are known to be associated with adolescent mental ill health. A potentially important under-investigated factor is the form of bullying. Four common forms of bullying behaviours are name-calling, physical threats or harm, rumour spreading and social exclusion. To more comprehensively understand bullying victimisation in adolescence, we examined the association of all three factors (frequency, emotional response, form) to psychological distress and emotional wellbeing. METHOD: A stratified, random sample of adolescents (n = 10, 273; mean age = 14.33 years, standard deviation = 1.68 years) completed validated measures of bullying victimisation (Gatehouse Bullying Questionnaire), psychological distress (K10) and emotional wellbeing (Mental Health Inventory) in classroom time. Associations between the form of bullying victimisation and mental health outcomes were examined. RESULTS: Adolescents reported a high prevalence of all four forms of bullying: teased or called names (30.6%), rumour spreading (17.9%), social exclusion (14.3%) and physical threats or harm (10.7%). Victimisation was independently associated with significantly higher levels of psychological distress and reduced levels of emotional wellbeing for all forms of bullying. In particular, social exclusion had a strong association with mental ill health. Adolescents who experienced frequent bullying that was upsetting reported higher psychological distress and reduced emotional wellbeing. CONCLUSION: Different forms of bullying victimisation were independently associated with psychological distress and reduced emotional wellbeing. In particular, frequent and upsetting social exclusion requires a targeted and measured response by school communities and health practitioners.

Western diet is associated with a smaller hippocampus: a longitudinal investigation

Background: Recent meta-analyses confirm a relationship between diet quality and both depression and cognitive health in adults. While the biological pathways that underpin these relationships are likely multitudinous, extensive evidence from animal studies points to the involvement of the hippocampus. The aim of this study was to examine the association between dietary patterns and hippocampal volume in humans, and to assess whether diet was associated with differential rates of hippocampal atrophy over time. Methods: Data were drawn from the Personality and Total Health Through Life Study and focused on a subsample of the cohort (n = 255) who were aged 60-64 years at baseline in 2001, completed a food frequency questionnaire, and underwent two magnetic resonance imaging scans approximately 4 years apart. Longitudinal generalized estimating equation linear regression models were used to assess the association between dietary factors and left and right hippocampal volumes over time. Results: Every one standard deviation increase in healthy "prudent" dietary pattern was associated with a 45.7 mm³ (standard error 22.9 mm³) larger left hippocampal volume, while higher consumption of an unhealthy "Western" dietary pattern was (independently) associated with a 52.6 mm³ (SE 26.6 mm³) smaller left hippocampal volume. These relationships were independent of covariates including age, gender, education, labour-force status, depressive symptoms and medication, physical activity, smoking, hypertension and diabetes. While hippocampal volume declined over time, there was no evidence that dietary patterns influenced this decline. No relationships were observed between dietary patterns and right hippocampal volume. Conclusions: Lower intakes of nutrient-dense foods and higher intakes of unhealthy foods are each independently associated with smaller left hippocampal volume. To our knowledge, this is the first human study to demonstrate associations between diet and hippocampal volume concordant with data previously observed in animal models.

Comparison of anthropometric measures as predictors of cancer incidence: a pooled collaborative analysis of 11 Australian cohorts

Obesity is a risk factor for cancer. However, it is not known if general adiposity, as measured by body mass index (BMI) or central adiposity [e.g., waist circumference (WC)] have stronger associations with cancer, or which anthropometric measure best predicts cancer risk. We included 79,458 men and women from the Australian and New Zealand Diabetes and Cancer Collaboration with complete data on anthropometry [BMI, WC, Hip Circumference (HC), WHR, waist to height ratio (WtHR), A Body Shape Index (ABSI)], linked to the Australian Cancer Database. Cox proportional hazards models assessed the association between each anthropometric marker, per standard deviation and the risk of overall, colorectal, post-menopausal (PM) breast, prostate and obesity-related cancers. We assessed the discriminative ability of models using Harrell's c-statistic. All anthropometric markers were associated with overall, colorectal and obesity-related cancers. BMI, WC and HC were associated with PM breast cancer and no significant associations were seen for prostate cancer. Strongest associations were observed for WC across all outcomes, excluding PM breast cancer for which HC was strongest. WC had greater discrimination compared to BMI for overall and colorectal cancer in men and women with c-statistics ranging from 0.70 to 0.71. We show all anthropometric measures are associated with the overall, colorectal, PM breast and obesity-related cancer in men and women, but not prostate cancer. WC discriminated marginally better than BMI. However, all anthropometric measures were similarly moderately predictive of cancer risk. We do not recommend one anthropometric marker over another for assessing an individuals' risk of cancer.

Analysis of phasic and tonic electromyographic signal characteristics: electromyographic synthesis and comparison of novel morphological and linear-envelope approaches

The pattern of tonic and phasic components in an EMG signal reflects the underlying behaviour of the central nervous system (CNS) in controlling the musculature. One avenue for gaining a better understanding of this behaviour is to seek a quantitative characterisation of these phasic and tonic components. We propose that these signal characteristics can range between unvarying, tonic and intermittent, phasic activation through a continuum of EMG amplitude modulation. In this paper, we present two new algorithms for quantifying amplitude modulation: a linear-envelope approach, and a mathematical morphology approach. In addition we present an algorithm for synthesising EMG signals with known amplitude modulation. The efficacy of the synthesis algorithm is demonstrated using real EMG data. We present an evaluation and comparison of the two algorithms for quantifying amplitude modulation based on synthetic data generated by the proposed synthesis algorithm. The results demonstrate that the EMG synthesis parameters represent 91.9% and 96.2% of the variance of linear-envelopes extracted from lumbo-pelvic muscle EMG signals collected from subjects performing a repetitive-movement task. This depended, however, on the muscle and movement-speed considered (F=4.02, p<0.001). Coefficients of determination between input and output amplitude modulation variables were used to quantify the accuracy of the linear-envelope and morphological signal processing algorithms. The linear-envelope algorithm exhibited higher coefficients of determination than the most accurate morphological approach (and hence greater accuracy, T=8.16, p<0.001). Similarly, the standard deviation of the coefficients of determination was 1.691 times smaller (p<0.001). This signal processing algorithm represents a novel tool for the quantification of amplitude modulation in continuous EMG signals and can be used in the study of CNS motor control of the musculature in repetitive-movement tasks.

Antenatal dietary patterns and depressive symptoms during pregnancy and early post-partum

Perinatal depression is a debilitating disorder experienced during pregnancy and/or the first year post-partum. Recently, maternal dietary intake during pregnancy has emerged as a possible area of intervention for the prevention of mental disorders in women and their offspring. However, the relationship between antenatal diet quality and perinatal depressive symptoms remains poorly understood. The current study explored the predictive role of antenatal diet quality for antenatal and post-natal depressive symptoms. Pregnant women (n = 167) were recruited between February 2010 and December 2011. Women completed the Edinburgh Postnatal Depression Scale at time 1 [T1, mean weeks gestation = 16.70, standard deviation (SD) = 0.91], time 2 (T2, mean weeks gestation = 32.89, SD = 0.89) and time 3 (T3, mean weeks post-partum = 13.51, SD = 1.97) and a food frequency questionnaire at T1 and T2. Diet quality was determined by extracting dietary patterns via principal components analysis. Two dietary patterns were identified: 'healthy' (including fruit, vegetables, fish and whole grains) and 'unhealthy' (including sweets, refined grains, high-energy drinks and fast foods). Associations between dietary patterns and depressive symptoms were investigated by path analyses. While both 'healthy' and 'unhealthy' path models showed good fit, only one significant association consistent with study hypotheses was found, an 'unhealthy' diet was associated with increased depressive symptoms at 32 weeks gestation. Given that this association was cross-sectional, it was not possible to make any firm conclusions about the predictive nature of either dietary patterns or depressive symptoms. Dietary intervention studies or larger prospective studies are therefore recommended.

Subtyping based on readiness and confidence: the identification of help-seeking profiles for gamblers accessing web-based counselling

BACKGROUND AND AIMS: Problem gamblers are not a homogeneous group and recent data suggest that subtyping can improve treatment outcomes. This study administered three readiness rulers and aimed to identify subtypes of gamblers accessing a national web-based counselling service based on these rulers. METHODS: Participants were 1204 gamblers (99.4% problem gamblers) who accessed a single session of web-based counselling in Australia. Measures included three readiness rulers (importance, readiness and confidence to resist an urge to gamble), demographics and the Problem Gambling Severity Index (PGSI). RESULTS: Gamblers reported high importance of change [mean = 9.2, standard deviation (SD) = 1.51] and readiness to change (mean = 8.86, SD = 1.84), but lower confidence to resist an urge to gamble (mean = 3.93, SD = 2.44) compared with importance and readiness. The statistical fit indices of a latent class analysis identified a four-class model. Subtype 1 was characterized by a very high readiness to change and very low confidence to resist an urge to gamble (n = 662, 55.0%) and subtype 2 reported high readiness and low confidence (n = 358, 29.7%). Subtype 3 reported moderate ratings on all three rulers (n = 139, 11.6%) and subtype 4 reported high importance of change but low readiness and confidence (n = 45, 3.7%). A multinomial logistic regression indicated that subtypes differed by gender (P < 0.001), age (P = 0.01), gambling activity (P < 0.05), preferred mode of gambling (P < 0.001) and PGSI score (P < 0.001). CONCLUSIONS: Problem gamblers in Australia who seek web-based counselling comprise four distinct subgroups based on self-reported levels of readiness to change, confidence to resist the urge to gamble and importance of change.

BacHbpred: support vector machine methods for the prediction of bacterial hemoglobin-like proteins

The recent upsurge in microbial genome data has revealed that hemoglobin-like (HbL) proteins may be widely distributed among bacteria and that some organisms may carry more than one HbL encoding gene. However, the discovery of HbL proteins has been limited to a small number of bacteria only. This study describes the prediction of HbL proteins and their domain classification using a machine learning approach. Support vector machine (SVM) models were developed for predicting HbL proteins based upon amino acid composition (AC), dipeptide composition (DC), hybrid method (AC + DC), and position specific scoring matrix (PSSM). In addition, we introduce for the first time a new prediction method based on max to min amino acid residue (MM) profiles. The average accuracy, standard deviation (SD), false positive rate (FPR), confusion matrix, and receiver operating characteristic (ROC) were analyzed. We also compared the performance of our proposed models in homology detection databases. The performance of the different approaches was estimated using fivefold cross-validation techniques. Prediction accuracy was further investigated through confusion matrix and ROC curve analysis. All experimental results indicate that the proposed BacHbpred can be a perspective predictor for determination of HbL related proteins. BacHbpred, a web tool, has been developed for HbL prediction.

Influence of pacing on reliability of middle-distance cycling performance

The purpose of the present study was to examine the reliability of middle distance cycling time trials using fast-, even-, and slow-starts. Eighteen endurance-trained male cyclists [mean ± standard deviation; VO2peak 63.1 ± 6.1 mL⋅kg-1⋅min-1] performed nine cycling time trials where the total external work (96.5 ± 11.2 kJ) was identical to the better of two, 5-minute habituation time trials. Power output during the first quarter of the time-trials (24.1 ± 2.8 kJ) was fixed to induce fast-, even- or slow-starting strategies (60, 75 and 90 s, respectively). In consecutive sessions, participants performed three trials of each pacing condition although the order of these pacing conditions was counterbalanced. Average power output and performance time were unaffected by trial number in the fast- (P = 0.60), even- (P = 0.18) and slow-start (P = 0.53) trials. In all three pacing conditions, average power output was highly reliable and similar between trial 1 to 2 and trial 2 to 3 in fast- (standard error of measurement; SEM=8.3 and 8.2W), even (coefficient of variation; CV=2.8 and 2.4%) and slow-start (CV=2.4 and 1.5%) trials. In conclusion, the reproducibility of 5-min cycling time trials is unaffected by starting strategy and is acceptable following two selfpaced habituation trials. Research examining the influence of pacing strategies may therefore be conducted without the need for familiarisation trials using each individual pacing condition.