Karen Paxton

The study design and methodology for the ARCHER study - adolescent rural cohort study of hormones, health, education, environments and relationships

BackgroundAdolescence is characterized by marked psychosocial, behavioural and biological changes and represents a critical life transition through which adult health and well-being are established. Substantial research confirms the role of psycho-social and environmental influences on this transition, but objective research examining the role of puberty hormones, testosterone in males and oestradiol in females (as biomarkers of puberty) on adolescent events is lacking. Neither has the tempo of puberty, the time from onset to completion of puberty within an individual been studied, nor the interaction between age of onset and tempo. This study has been designed to provide evidence on the relationship between reproductive hormones and the tempo of their rise to adult levels, and adolescent behaviour, health and wellbeing.Methods/DesignThe ARCHER study is a multidisciplinary, prospective, longitudinal cohort study in 400 adolescents to be conducted in two centres in regional Australia in the State of New South Wales. The overall aim is to determine how changes over time in puberty hormones independently affect the study endpoints which describe universal and risk behaviours, mental health and physical status in adolescents. Recruitment will commence in school grades 5, 6 and 7 (10–12 years of age). Data collection includes participant and parent questionnaires, anthropometry, blood and urine collection and geocoding. Data analysis will include testing the reliability and validity of the chosen measures of puberty for subsequent statistical modeling to assess the impact over time of tempo and onset of puberty (and their interaction) and mean-level repeated measures analyses to explore for significant upward and downward shifts on target outcomes as a function of main effects.DiscussionThe strengths of this study include enrollment starting in the earliest stages of puberty, the use of frequent urine samples in addition to annual blood samples to measure puberty hormones, and the simultaneous use of parental questionnaires.

Endotracheal Tube Cuff Pressure before, during, and after Fixed-Wing Air Medical Retrieval

Abstract Background. Increased endotracheal tube (ETT) cuff pressure is associated with compromised tracheal mucosal perfusion and injuries. No published data are available for Australia on pressures in the fixed-wing air medical retrieval setting. Objective. After introduction of a cuff pressure manometer (Mallinckrodt, Hennef, Germany) at the Royal Flying Doctor Service (RFDS) Base in Dubbo, New South Wales (NSW), Australia, we assessed the prevalence of increased cuff pressures before, during, and after air medical retrieval. Methods. This was a retrospective audit in 35 ventilated patients during fixed-wing retrievals by the RFDS in NSW, Australia. Explicit chart review of ventilated patients was performed for cuff pressures and changes during medical retrievals with pressurized aircrafts. Pearson correlation was calculated to determine the relation of ascent and ETT cuff pressure change from ground to flight level. Results. The mean (± standard deviation) of the first ETT cuff pressure measurement on the ground was 44 ± 20 cmH2O. Prior to retrieval in 11 patients, the ETT cuff pressure was >30 cmH2O and in 11 patients >50 cmH2O. After ascent to cruising altitude, the cuff pressure was >30 cmH2O in 22 patients and >50 cmH2O in eight patients. The cuff pressure was reduced 1) in 72% of cases prior to take off and 2) in 85% of cases during flight, and 3) after landing, the cuff pressure increased in 85% of cases. The correlation between ascent in cabin altitude and ETT cuff pressure was r = 0.3901, p = 0.0205. Conclusions. The high prevalence of excessive cuff pressures during air medical retrieval can be avoided by the use of cuff pressure manometers. Key words: cuff pressure; air medical retrieval; prehospital

Defining the rest interval associated with the main sleep period in actigraph scoring

Actigraphy is increasingly used for sleep monitoring. However, there is a lack of standardized methodology for data processing and analysis, which often makes between study comparisons difficult, if not impossible, and thus open to flawed interpretation. This study evaluated a manual method for detection of the rest interval in actigraph data collected with Actiwatch 2. The rest interval (time in bed), defined as the bedtime and rise time and set by proprietary software, is an essential requirement for the estimation of sleep indices. This study manually and systematically detected the rest interval of 187 nights of recording from seven healthy males and three females, aged 13.5±0.7 (mean ± standard deviation) years. Data were analyzed for agreement between software default algorithm and manual scoring. Inter-rater reliability in manual scoring was also tested between two scorers. Data showed consistency between default settings and manual scorers for bedtime and rise time, but only moderate agreement for the rest interval duration and poor agreement for activity level at bedtime and rise time. Manual detection of rest intervals between scorers showed a high degree of agreement for all parameters (intraclass correlations range 0.864 to 0.995). The findings demonstrate that the default algorithm on occasions was unable to detect rest intervals or set the exact interval. Participant issues and inter-scorer issues also made difficult the detection of rest intervals. These findings have led to a manual detection protocol to define bedtime and rise time, supplemented with an event diary.

Urinary Sex Steroids and Anthropometric Markers of Puberty - A Novel Approach to Characterising Within-Person Changes of Puberty Hormones

Background/Aims The longitudinal relationships of within-individual hormone and anthropometric changes during puberty have not ever been fully described. The objectives of this study were to demonstrate that 3 monthly urine collection was feasible in young adolescents and to utilise liquid chromatography-tandem mass spectrometry assay methods for serum and urine testosterone (T), estradiol (E2) and luteinizing hormone (LH) in adolescents by relating temporal changes in urine and serum hormones over 12 months to standard measures of pubertal development. Methods A community sample of 104 adolescents (57 female) was studied over 12 months with annual anthropometric assessment, blood sampling and self-rated Tanner staging and urine collected every 3 months. Serum and urine sex steroids (T, E2) were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and LH by immunoassay. Results A high proportion (92%) of scheduled samples were obtained with low attrition rate of 6.7% over the 12 months. Urine hormone measurements correlated cross-sectionally and longitudinally with age, anthropometry and Tanner stage. Conclusion We have developed a feasible and valid sampling methodology and measurements for puberty hormones in urine, which allows a sampling frequency by which individual pubertal progression in adolescents can be described in depth.

Insights into Facebook Pages: an early adolescent health research study page targeted at parents

Abstract Facebook has been used in health research, but there is a lack of literature regarding how Facebook may be used to recruit younger adolescents. A Facebook Page was created for an adolescent cohort study on the effects of puberty hormones on well-being and behaviour in early adolescence. Used as a communication tool with existing participants, it also aimed to alert potential participants to the study. The purpose of this paper is to provide a detailed description of the development of the study Facebook Page and present the fan response to the types of posts made on the Page using the Facebook-generated Insights data. Two types of posts were made on the study Facebook Page. The first type was study-related update posts and events. The second was relevant adolescent and family research and current news posts. Observations on the use of and response to the Page were made over 1 year across three phases (phase 1, very low Facebook use; phase 2, high Facebook use; phase 3, low Facebook use). Most Page fans were female (88.6%), with the largest group of fans aged between 35 and 44 years. Study-related update posts with photographs were the most popular. This paper provides a model on which other researchers could base Facebook communication and potential recruitment in the absence of established guidelines.

Ghrelin and Peptide YY Change During Puberty: Relationships with Adolescent Growth, Development and Obesity.

Context Pubertal adolescents show strong appetites. How this is mediated is unclear, but ghrelin and peptide YY (PYY) play potentially important roles. Objective To measure ghrelin and PYY change in relation to pubertal growth. Design Three-year prospective cohort study. Setting Australian regional community. Participants Eighty healthy adolescents (26 girls; 54 boys) recruited at 10 to 13 years. Main Outcome Measures Fasting circulating total ghrelin, total PYY, IGF-1, insulin, leptin (via radioimmunoassay), estradiol and testosterone (via mass spectrometry), anthropometry, and body composition (via bioelectrical impedance). Results Adolescents exhibited normal developmental change. Mixed models revealed positive associations for ghrelin to age2 (both sexes: P < 0.05), indicating a U-shaped trend over time. Ghrelin was also inversely associated with IGF-1 (both sexes: P < 0.05), leptin in girls (P < 0.01), and insulin in boys (P < 0.05) and negatively correlated with annual height and weight velocity (both sexes: P ≤ 0.01). PYY showed no age-related change in either sex. Neither ghrelin nor PYY were associated with Tanner stage. Weight subgroup analyses showed significant ghrelin associations with age2 in healthy-weight but not overweight and obese adolescents (7 girls; 18 boys). Conclusions Adolescents showed a U-shaped change in ghrelin corresponding to physical and biochemical markers of growth, and no change in PYY. The overweight and obesity subgroup exhibited an apparent loss of the U-shaped ghrelin trend, but this finding may be attributed to greater maturity and its clinical significance is unclear. Further research on weight-related ghrelin and PYY trends at puberty is needed to understand how these peptides influence growth and long-term metabolic risk.

Risk-taking behaviours among younger adolescents in rural and regional New South Wales: preventing adverse health outcomes

Risk-taking behaviours during adolescence have negative short- and long-term health impacts. Maximizing the progress made through child health improvements and preventing the onset of adult ill-health require a much greater focus on health during adolescence. Understanding the biological and social factors that shape both risk and protective factors during adolescence provides the basis for effective prevention strategies. Effective prevention strategies require localized, disaggregated data to respond to heterogeneous life experiences. This paper reports on self-reported risk-taking behaviours among young adolescents growing up in rural communities in New South Wales, Australia. Quantitative analysis was undertaken to explore the relationship between risk-taking behaviour and key social determinants of health, including age, gender, cultural background and socio-economic status. It concludes that cross-cutting early intervention and prevention involving social work, youth work, education and health which builds young people’s resilience is likely to assist in the development of health-protective behaviours.