The Dubbo Study

The Dubbo Study: an Australian prospective community study of the health of elderly

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The Dubbo Study: an Australian prospective community study of the health of elderly
Aust NZ J Med 1990; 20: 783-789.

Australia�s ageing population is an object of concern amongst scholars, health and social service providers, and policy makers. Despite the trend of growth in the elderly segment, few prospective studies have exclusively examined the elderly. Current information available concerning vascular risk factors in the elderly is incomplete and contradictory.

This report describes the study rationale for the Dubbo Study, an investigation which will attempt to upgrade the minimal data available on the elderly population. The goals of the study were to identify predictors of mortality, hospitalisation, and placement on long-term care facilities, and to study factors for chronic diseases and for disability in the elderly. The target population included all non-institutionalised citizens 60 years and over domiciled in the Dubbo Local Government Area and comprised 1693 men and 2167 women. The attendance rate was 73% of this. Clinical, biochemical and sociological data are reported at baseline and these results are the subject of further reports found on this website.

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Dubbo study of the elderly: sociological and cardiovascular risk factors at entry

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Dubbo study of the elderly: sociological and cardiovascular risk factors at entry
Aust NZ J Med 1991; 21:701-709.

In August 1988, a new prospective study of the elderly was initiated in the central-western NSW town of Dubbo. The goals of the Dubbo Study are to identify predictors of mortality, hospitalisation and placement in long-term care, with special risk factors for cardiovascular disease. The previous report described the study rationale, reasons for selection of the study site, methods and measures, participation rates and demography.

This report describes the expanded baseline findings of the Dubbo study, including: demographic, educational and economic data; tobacco and alcohol use, self medication and other habits; prescribed medication and in study diagnoses; medical contacts and past diagnoses; psychosocial variables, functional health and social support; heights and weights.

The baseline findings show that non-institutionalised elderly of Dubbo appear to be an adequately resourced, healthy group. However, their general health tends to decline with age, but their psychological states adjust to these �normal� age changes to reach positive levels of well-being even at older ages.

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Multiple medication use in the elderly: Use of prescription and non-prescription drugs in an Australian community setting

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Multiple medication use in the elderly: Use of prescription and non-prescription drugs in an Australian community setting
Med J Aust 1992; 157: 242-246.

Numerous studies have pointed to polypharmacy (multiple medication use) in the elderly as contributing to medication-related problems. An analysis of polypharmacy is required to develop some preventative strategies for the practice.

This report examines some biological and psychological predictors of polypharmacy, patterns of multiple drug use and relationships between the use of prescription and non-prescription items.

The study�s findings conclude that a disproportionately large number of subjects were using multiple prescription and non-prescription items simultaneously. 18 per cent of men and 25 per cent of women were currently using three or more classes of prescription drugs. The corresponding values for two or more classes of non-prescription drugs were 29 per cent and 44 per cent. Of those who were using multiple prescription drugs 56 per cent of men and 76 per cent of women were also using multiple non-prescription drugs.

Results highlighted that recent hospitalisation, increasing age, female gender and increasing depression were factors strongly associated with multiple prescription drug use. Female gender and increasing depression were the only factors strongly associated with multiple non-prescription drug use.

The findings suggest that ageing, depressed women be targeted for possible preventive action in relation to multiple drug use.

Link to full text copy of paper
Simons LA et al. Multiple medication use in the elderly: Use of prescription and non-prescription drugs in an Australian community setting. MJA 1992;157:242-246. ©The Medical Journal of Australia – reproduced with permission.

Low serum cholesterol is not associated with depression in the elderly: data from an Australian community study of the elderly

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Low serum cholesterol is not associated with depression in the elderly: data from an Australian community study of the elderly
Aust NZ J Med 1994:24;561-564.

Two studies carried out in California and France revealed that elderly men with low serum cholesterol manifested high depression scores. In contrast to these results a Finnish study and the preliminary data from an Australian study of the elderly in Dubbo did not find the same relationship between the two conditions.

The Dubbo Study questioned these conflicting results in 2805 men and women and determined whether low serum cholesterol is associated with depressive symptoms in older Australians.

The study did not observe a relationship between low serum cholesterol and depressive symptoms. However, ill health, disability and stressful life transitions, like death of a spouse and inadequate finances, were found to be directly associated with depressive symptoms.

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Risk factors for coronary heart disease in the prospective Dubbo Study of Australian elderly

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Risk factors for coronary heart disease in the prospective Dubbo Study of Australian elderly
Atherosclerosis 1995;117:107-118

Risk factors for coronary heart disease (CHD) in middle aged people have been well-defined and consistently included hypertension, smoking, lipid disorders, diabetes and family history. However, risk factor prediction by many of these factors in the elderly is more complex.

This report examines the clinical and socio-demographic predictors of CHD in Australian people over 60 living in Dubbo during an average 62 months follow up.

The study found that CHD incidence rates were higher in men than in women up until 79 years of age. Over 79 years, rates for recurrent CHD were higher in women.

A cox proportional hazards analysis found that significant predictors of all CHD were: advancing age, prior CHD, use of anti-hypertensive medication, diabetes, serum cholesterol, low density lipoprotein cholesterol, serum apolipoprotein B in men, serum triglycerides in women, high density lipoprotein cholesterol in men, lipoprotein(a) in women, and poorer self-rated health. However, serum cholesterol was not predictive of CHD in men over 74 years of age, and isolated systolic hypertension predicted CHD in women, but not in men. Overall, the coronary heart disease incidence in women lags behind that in men until 80 years and beyond.

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Predictors of mortality in the prospective Dubbo Study of Australian elderly

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Predictors of mortality in the prospective Dubbo Study of Australian elderly
Aust NZ J Med 1996;26:40-48

Risk factors for chronic disease in the elderly have received increased attention in past prospective population studies, with some emphasising socio-demographic predictors, and others emphasising clinical predictors. The US National Institute of Ageing�s �Established Populations for Epidemiologic studies of the Elderly� (EPESE) represents an integrated approach which has a stronger probability of finding the best set of predictors of mortality. A similar integrated approach was used in the prospective Dubbo study.

The purpose of this report is to examine clinical and socio-demographic predictors of all causes of mortality in the Dubbo study over an average of 62 months follow-up. Risk factors were analysed in a model which controlled for socio-demographic and behavioural characteristics.

In the study, 235 men (19 per cent) and 184 women (12 per cent) died, with 46 per cent of male deaths and 53 per cent of female deaths related to cardiovascular disease. Using a proportional hazard model, the study found significant predictors of mortality for men were older age, being married, smoking, drinking more than three alcoholic drinks per day, prior coronary heart disease, diabetes, use of anti-hypertensive medication and physical disability. For women, the significant predictors of mortality were older age, being married, sever hypertension, and poor to fair self-rated health.

High blood pressure also predicted mortality in people below 75 years, whereas lower blood pressure was associated with an increased risk of mortality in people over 75.

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Diabetes, mortality and coronary heart disease in the prospective Dubbo Study of Australian elderly

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Diabetes, mortality and coronary heart disease in the prospective Dubbo Study of Australian elderly
Aust NZ J Med 1996;26:66-74

Despite the majority of diabetic subjects being elderly, relatively few prospective studies have compared clinical and socio-demographic predictors of mortality and coronary heart disease (CHD) in the elderly with and without diabetes.

Of 1155 men and 1472 women examined, 9.2 per cent of men and 6.9 per cent of women manifested diabetes at baseline. The risk factors for all causes of mortality and for CHD outcomes were modelled separately in those with and without diabetes.

The results revealed that in members of the cohort with diabetes, all-causes mortality rates were approximately doubled. CHD incidence was approximately doubled in men and tripled in women. Stroke incidence was approximately doubled in women but little changed in men (comparing those with and without diabetes).

Significant predictors of mortality in diabetics were old age and current smoking. Contrasting those with and without diabetes, being married and a higher body mass index were greater risk factors for mortality in diabetics. The predictors of CHD in diabetics were old age, prior CHD, severe hypertension, low HDL cholesterol and self-rated health. Diabetics and non-diabetics differed in risk factors for CHD, with diabetics having greater risk of CHD if they also have a higher body mass index or a physical disability.

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Patterns and cost of post-acute care: a longitudinal study of people aged 60 and over in Dubbo

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Patterns and cost of post-acute care: a longitudinal study of people aged 60 and over in Dubbo
Aust NZ J Public Health 1996;20:19-26

In Australia there has been a decline in the length of stay of older people in hospital as day-only procedures and early discharge policies has had an increasing effect. These changes have caused concern about the shifting costs from acute to community care services.

This 12 months study involved 2805 people aged 60 years and over who were living in Dubbo and examined data on use of services by these individuals following hospitalisation.

The findings revealed a low rate of use of Home and Community Care (HACC) services post-discharge, with only a quarter of older people receiving any type of HACC service in the 12 weeks after discharge, and two-thirds of these received only one service. Less than 5 per cent received a service from a occupational therapist, physiotherapist or speech therapist. 78 per cent older people, however, visited a general practitioner following discharge. These different rates of use are directly attributed to funding mechanisms as general practitioners are reimbursed from public funds. Further the predictors of higher cost services, like HACC and higher post-discharge service costs, were linked to a patient�s assessed need, especially lack of home supports.

The study concluded that service coordination and coordination of programs of care were relatively weak and advised that more attention be paid to: redefining the role of the hospital discharge planner and general practitioner in meeting the needs of older people; increasing the availability of HACC and related allied heath services and improving the linkage between the acute, primary age-care service systems.

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Peak expiratory flow, mortality and coronary disease in the Australian elderly

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Peak expiratory flow, mortality and coronary disease in the Australian elderly
Med J Aust 1997;166:526-529.

A significant association between obstructive airways disease and risk of ischaemic heart disease (IHD) has been apparent for more than 30 years. However, the impact of respiratory disease in the elderly has been relatively under-researched.

This report analyses the relationship of peak expiratory flow (PEF) rate (as an indicator of respiratory disease) with mortality and ischaemic heart disease in the elderly.

During the study, 321 men (26 per cent) and 252 women (16 per cent) died. All-causes mortality was three (men) to four (women) times higher for those in PEF tertile I (most airway obstruction) than in tertile III (best lung function). Subjects in tertile I had a past history of respiratory disease, were current smokers, and were taking antihypertensive. IHD mortality and events showed similar trends.

The predominant cause of death in both sexes was IHD (35 per cent of deaths), and mortality from this cause also had a significant inverse relationship with PEF.

Link to full text copy of paper
Simons LA et al. Relationship of peak expiratory flow rate with mortality and ischaemic heart disease in elderly Australians. MJA 1997;166:526-529. ©The Medical Journal of Australia – reproduced with permission.

Risk factors for ischemic stroke. Dubbo Study of the elderly

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Risk factors for ischemic stroke. Dubbo Study of the elderly
Stroke 1998;29:1341-1346.

In Australia approximately one in four deaths are due to cardiovascular disease with one in ten being attributed to stroke. The risk factors for such deaths from stroke have not been fully clarified although indicators such as hypertension, atrial fibrillation and the occurrence of a previous stroke are strong factors for consideration.

This study, carried out over a period of 98 months, looks at particular indicators, which could determine an increased risk from stroke in 2805 men and women aged 60 years and over.

The study revealed that significant independent predictors of stroke were: advancing age, female sex (48 per cent lower risk), being married (30 per cent lower risk), prior history of stroke (227 per cent higher), use of anti-hypertensive drugs (37 per cent higher risk), belonging to the highest category of blood pressure reading (67 per cent higher risk), presence of atrial fibrillation (58 per cent higher risk), HDL cholesterol (36 per cent lower risk for each 1-mmol/L increment), impaired peak expiratory flow (77 per cent higher for tertile I than tertile III), physical disability (59 per cent higher risk), and depression score (41 per cent higher for tertile III than for tertile I).

These findings showed that in a proportion of the participants certain clinical signs, some of which could be better managed, were evident thus predicting the increased likelihood of both morbidity and mortality associated with ischemic stroke.

Link to full text copy of paper
Simons LA et al. Risk Factors for Ischemic Stroke: Dubbo Study of the Elderly. Stroke 1998;29:1341-1346. © Lippincott Williams & Wilkins – reproduced with permission.