Rationale, design and methods for a community-based study of clustering and cumulative effects of chronic disease processes and their effects on ageing: the Busselton healthy ageing study

Abstract

BackgroundThe global trend of increased life expectancy and increased prevalence of chronic and degenerative diseases will impact on health systems. To identify effective intervention and prevention strategies, greater understanding of the risk factors for and cumulative effects of chronic disease processes and their effects on function and quality of life is needed.The Busselton Healthy Ageing Study aims to enhance understanding of ageing by relating the clustering and interactions of common chronic conditions in adults to function. Longitudinal (3–5 yearly) follow-up is planned.Methods/designPhase I (recruitment) is a cross-sectional community-based prospective cohort study involving up to 4,000 'Baby Boomers’ (born from 1946 to 1964) living in the Busselton Shire, Western Australia. The study protocol involves a detailed, self-administered health and risk factor questionnaire and a range of physical assessments including body composition and bone density measurements, cardiovascular profiling (blood pressure, ECG and brachial pulse wave velocity), retinal photography, tonometry, auto-refraction, spirometry and bronchodilator responsiveness, skin allergy prick tests, sleep apnoea screening, tympanometry and audiometry, grip strength, mobility, balance and leg extensor strength. Cognitive function and reserve, semantic memory, and pre-morbid intelligence are assessed. Participants provide a fasting blood sample for assessment of lipids, blood glucose, C-reactive protein and renal and liver function, and RNA, DNA and serum are stored. Clinically relevant results are provided to all participants. The prevalence of risk factors, symptoms and diagnosed illness will be calculated and the burden of illness will be estimated based on the observed relationships and clustering of symptoms and illness within individuals. Risk factors for combinations of illness will be compared with those for single illnesses and the relation of combinations of illness and symptoms to cognitive and physical function will be estimated.DiscussionThis study will enable a thorough characterization of multiple disease processes and their risk factors within a community-based sample of individuals to determine their singular, interactive and cumulative effects on ageing. The project will provide novel cross-sectional data and establish a cohort that will be used for longitudinal analyses of the genetic, lifestyle and environmental factors that determine whether an individual ages well or with impairment.

Associations between body mass index, lean and fat body mass and bone mineral density in middle-aged Australians: The Busselton Healthy Ageing Study

“…After excluding 32 participants taking medication for osteoporosis, and 24 from non-Caucasian backgrounds, a total of 1929 subjects (915 males and 1014 females) were included in this analysis. Pilot data from the first 300 subjects showed prevalence values for common risk factors such as obesity and overweight to be almost identical to those in the recent nationally representative Australian National Health Survey [16]. The study has received ethics approval from the University of Western Australia Human Research Ethics Committee (Number RA/4/1/2203) and written informed consent was obtained from each participant.…”

“…The strengths of our study include its large sample size, which allowed us to evaluate the associations of lean and fat mass with BMD in people at different levels of BMI; the narrow age range of participants and restriction of the analysis to Caucasians which minimizes potential confounding effects of age and ethnicity [13,37]; the use of generalized additive models to evaluate the dose-response relations of body weight and BMI with BMD, and the fact that study participants are representative of middle-aged Australians in general [16]. Our study also has limitations.…”

“…The design and rationale of the Busselton Healthy Ageing Study have been described previously [16]. Busselton is a coastal community in the south-west of Western Australia with a relatively stable population of predominantly European descent.…”

“…BMI between 18.5 and 24.99 kg/m 2 was regarded as normal, b18.5 underweight, [25][26][27][28][29].99 overweight and ≥30 obese according to WHO criteria [17]. Data on health history, medication use, and smoking habit were collected using a questionnaire [16]. The questionnaire did not include detailed dietary history such as calcium and protein intake, but did include a question regarding avoidance of dairy products.…”

“…The Busselton Healthy Ageing Study is a large, community-based study of 'Baby Boomers', defined as individuals born between 1946 and 1964 and who were aged 45-66 years at the time of baseline survey [16]. This is an important age group for implementing strategies to prevent age-related bone loss and future fracture.…”