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Epidemiology Research

North East Melbourne Stroke Incidence Study (NEMESIS)

Incidence Study

This is the largest major project being conducted within the Epidemiology Division. and is the largest incidence study of stroke conducted in Australia. The major aims of this project are to determine the incidence, costs, and outcome of stroke. This project has been funded with grants from the National Health and Medical Research Council (grants 914217, 974012) VicHealth, and the Austin Hospital Medical Research Foundation. Our major findings have included:

  1. Number of people with stroke. The number of people having a new stroke every year increases with age. Each year one new stroke occurs in every 900 people aged 45-54 years, in every 350 aged 55-64, in every 135 aged 65-74 years, in every 50 people aged 75-84 years, and in every 25 people aged 85 years and over. [1-4]
  2. The cost of first-ever stroke in 1997 was estimated to be $555 million in Australia in the first year, and the present value of lifetime costs was estimated to be $1.3 billion. [5-9]
  3. Informal care for stroke survivors represents a significant hidden cost to Australian society. This was of the order of $21.7 million in the first year after stroke for all first-ever strokes in Australia. [10]

An important outcome of this study is that it has provided the evidence base for the formation of policy for the management of stroke.

Long-term outcome after stroke

The main impetus for this follow up study of stroke patients was the lack of good information on the natural history of stroke categorised by their subtypes. This project will be the longest natural history study of stroke ever undertaken in Australia. It is being funded by grants from the National Health and Medical Research Council (grants 154600, 238304, 307900), the Foundation for High Blood Pressure Research, the Austin Hospital Medical Research Foundation, and Perpetual Trustees. The aims of this project are:

  • to determine long term outcome after stroke (to 10 years)
  • to investigate the costs of stroke subtypes in the long term (to 10 years)
  • to determine health care and community resource use by stroke patients
  • to determine ‘out-of-pocket’ costs to stroke patients as a component of total stroke-related costs.
  • to validate our current model of the costs of stroke subtypes.

We have already assessed many outcomes to 5 years. The major findings are:

  1. Handicap after stroke. The types of handicap most commonly observed among stroke patients are physical independence and occupation. Only half of the handicap observed could be explained by their disability. [13] Furthermore age, concurrent disability and physical impairment, depression and anxiety were independently associated with more handicap after stroke. [14] Therefore treating post-stroke depression and anxiety may be important ways to help reduce handicap after stroke.
  2. Quality of life after stroke. We have found that a quality of life measure developed in Australia is valid for measuring health-related quality of life after stroke. [15] In addition, almost 25% of survivors had a very poor quality of life at 2 years after stroke. The factors independently associated with quality of life at 2 years were handicap, physical impairment, anxiety, depression, disability, and age. Baseline factors independently associated with poor quality of life at 2 years after stroke were markers of stroke severity, female gender, and low socioeconomic status. [16] Similar factors were important at 5 years. [17] These results are important because they suggest that interventions targeting handicap and mood have the potential to improve health related quality of life independently of physical impairment and disability.
  3. Brief screening cognitive instruments poorly detect cognitive impairment. The ‘mini-mental state examination’ and the ‘informant questionnaire for cognitive decline in the elderly’ examination (IQCODE) detected cognitive impairment poorly, and had modest positive predictive value for detecting dementia. [18] The results are important because they show that these tests do not replace the need for detailed neuropsychological tests.
  4. There is significant cognitive impairment after stroke. At 3 months after stroke patients were more likely (than people without stroke) to suffer cognitive impairment. Furthermore, first-ever stroke was not associated with the presence of dementia at 12 months, but was associated with a greater risk of cognitive impairment (without dementia). [19, 20] These results highlight the relatively under-recognised cognitive consequences of stroke.
  5. Recurrent stroke contributes significantly to global cognitive decline after first-ever stroke. [21] Secondary prevention of stroke will be important in minimising stroke-related dementia.
  6. Control of hypertension after stroke is sub-optimal. Among 5 year survivors of stroke 82% were hypertensive. The majority of these people had controlled hypertension (63%), while 37% had uncontrolled hypertension. [22] These results highlight the importance of improving secondary prevention strategies in stroke survivors.
  7. The introduction of stroke units to Australian hospitals would significantly improve outcome after stroke. Although tPA is the most biologically potent intervention for stroke management in a stroke unit has the greatest population benefit. [23] This demonstrates the importance of setting up stroke units in hospitals worldwide.
  8. Depression is common in stroke survivors. At 5 years after stroke about one in five stroke survivors were suffering from depression. Only 22% of those with depression were taking an antidepressant medication. It is possible that some of these patients would benefit from treatment. In addition, 28% of those taking antidepressant medications were still depressed despite being treated. This could mean that the medications were not effective in treating their depression. [24]

References

  1. Thrift AG, Dewey HM, Macdonell RAL, McNeil JJ, Donnan GA. Stroke incidence on the east coast of Australia: the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2000;31:2087-2092.
  2. Thrift AG, Dewey HM, Macdonell RAL, McNeil JJ, Donnan GA. Incidence of the major stroke subtypes. Initial findings from the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2001;32:1732-1738.
  3. Thrift AG, Dewey HM, Sturm JW, Paul S, Gilligan AK, Srikanth VK, Macdonell RAL, McNeil JJ, Macleod MR, Donnan GA. Greater incidence of both fatal and non-fatal strokes in disadvantaged areas: the north east Melbourne stroke incidence study. Stroke. 2006;37:877-882.
  4. Dewey HM, Sturm J, Donnan GA, Macdonell RA, McNeil JJ, Thrift AG. Incidence and outcome of subtypes of ischaemic stroke: initial results from the north East melbourne stroke incidence study (NEMESIS). Cerebrovasc Dis. 2003;15:133-139.
  5. Dewey HM, Thrift AG, Mihalopoulos C, Carter R, Macdonell RAL, McNeil JJ, Donnan GA. Cost of stroke in Australia from a societal perspective: results from the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2001;32:2409-2416.
  6. Dewey HM, Thrift AG, Mihalopoulos C, Carter R, Macdonell RA, McNeil JJ, Donnan GA. Lifetime cost of stroke subtypes in Australia: findings from the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2003;34:2502-2507.
  7. Moodie ML, Carter R, Mihalopoulos C, Thrift AG, Chambers BR, Donnan GA, Dewey HM. Trial application of a Model of Resource Utilization, Costs, and Outcomes for Stroke (MORUCOS) to assist priority setting in stroke. Stroke. 2004;35:1041-1046.
  8. Mihalopoulos C, Cadilhac DA, Moodie ML, Dewey HM, Thrift AG, Donnan GA, Carter RC. Development and application of MORUCOS: an Australian economic model for stroke. Int J Technol Assess Health Care. 2005;21:499-505.
  9. Dewey HM, Thrift AG, Mihalopoulos C, Carter R, Macdonell RA, McNeil JJ, Donnan GA. 'Out of pocket' costs to stroke patients during the first year after stroke - results from the North East Melbourne Stroke Incidence Study. J Clin Neuroscience. 2004;11:134-137.
  10. Dewey HM, Thrift AG, Mihalopoulos C, Carter R, Macdonell RA, McNeil JJ, Donnan GA. Informal care for stroke survivors: results from the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2002;33:1028-1033.
  11. Dewey HM, Donnan GA, Freeman EJ, Sharples CM, Macdonell RAL, McNeil JJ, Thrift AG. Inter-rater reliability of the National Institutes of Health Stroke Scale: rating by neurologists and nurses in a community-based stroke incidence study. Cerebrovasc Dis. 1999;9:323-327.
  12. Dewey HM, Macdonell RAL, Donnan GA, McNeil JJ, Freeman EJ, Thrift AG, Sharples CM. Inter-rater reliability of stroke subtype classification by neurologists and nurses within a community-based stroke incidence study. J Clin Neuroscience. 2001;8:14-17.
  13. Sturm JW, Dewey HM, Donnan GA, Macdonell RA, McNeil JJ, Thrift AG. Handicap after stroke: how does it relate to disability, perception of recovery, and stroke subtype?: the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2002;33:762-768.
  14. Sturm JW, Donnan GA, Dewey HM, Macdonell RA, Gilligan AK, Thrift AG. Determinants of handicap after stroke: the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2004;35:715-720.
  15. Sturm JW, Osborne RH, Dewey HM, Donnan GA, Macdonell RAL, Thrift AG. Brief comprehensive quality of life assessment after stroke: the Assessment of Quality of Life (AQoL) instrument in the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2002;33:2888-2894.
  16. Sturm JW, Donnan GA, Dewey HM, Macdonell RA, Gilligan AK, Srikanth V, Thrift AG. Quality of life after stroke: the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2004;35:2340-2345.
  17. Paul SL, Sturm JW, Dewey HM, Donnan GA, Macdonell RA, Thrift AG. Long-term outcome in the North East Melbourne Stroke Incidence Study: predictors of quality of life at 5 years after stroke. Stroke. 2005;36:2082-2086.
  18. Srikanth V, Thrift AG, Fryer JL, Saling MM, Dewey HM, Sturm JW, Donnan GA. The validity of brief screening cognitive instruments in the diagnosis of cognitive impairment and dementia after first-ever stroke. Int Psychogeriatrics. 2006;18:295-305.
  19. Srikanth VK, Thrift AG, Saling MM, Anderson JFI, Dewey HM, Macdonell RAL, Donnan GA. Increased risk of cognitive impairment 3 months after mild to moderate first-ever stroke. A community-based propsective study of nonaphasic English-speaking survivors. Stroke. 2003;34:1136-1143.
  20. Srikanth VK, Anderson JFI, Donnan GA, Saling MM, Didus E, Alpitsis R, Dewey HM, Macdonell RAL, Thrift AG. Progressive dementia after first-ever stroke. A community-based follow-up study. Neurology. 2004;63:785-792.
  21. Srikanth VK, Quinn SJ, Donnan GA, Saling MM, Thrift AG. Long-term cognitive transitions, rates of cognitive change and predictors of incident dementia in a population-based first-ever stroke cohort. Stroke. 2006;37:2479-2483.
  22. Paul SL, Thrift AG. Control of hypertension 5 years after stroke in the North East Melbourne Stroke Incidence Study (NEMESIS). Hypertension. 2006,48:260-265.
  23. Gilligan AK, Thrift AG, Sturm JW, Dewey HM, Macdonell RAL, Donnan GA. Stroke units, tissue plasminogen activator and neuroprotection: which stroke intervention could provide the greatest community benefit? Cerebrovasc Dis. 2005;20:239-244.
  24. Paul SL, Sturm JW, Dewey HM, Macdonell RAL, Thrift AG. Prevalence of depression and use of antidepressant medication at 5 years post-stroke in the North East Melbourne Stroke Incidence Study (NEMESIS). Stroke. 2006.

Collaborations

Surveillance of vascular diseases and risk factors in rural India

Collaborators:
Dr Velandai Srikanth (Department of Medicine, Monash University)
Associate Professor Roger Evans (Department of Physiology, Monash University)
Dr Kartik Kalyanram and Dr Kamakshi Kartik, Rishi Valley Education Centre, India

Project. This study will be used to determine the extent of common non-communicable diseases and their risk factors in a rural region of Andhra Pradesh. We further aim to monitor how many people are having new vascular events (such as acute myocardial infarction and strokes) over a 5 year period. The information gained will be important for introducing prevention strategies among this rural community.

Surveillance system of non-communicable diseases in Viet Nam

Collaborators:
Dr Rob Granger (Menzies Research Institute)
Dr Velandai Srikanth (Menzies Research Institute and Department Medicine, Monash University)
Dr Gauden Galea (World Health Organisation)
Dr V Duong (Viet Nam Ministry of Health)
Dr T Albion (Menzies Research Institute)

Project. To set up surveillance for stroke in both a hospital and community setting. Little is known about the burden of stroke in Viet Nam. The results of this study will allow informed planning of highly effective national interventional programs in the prevention of non-communicable diseases. This project is being funded by Atlantic Philanthropies.

International Stroke Incidence Study Data Pooling Project

Collaborators:
Professor Peter Rothwell (University Department of Clinical Neurology, Oxford, UK), as well as collaborators from Auckland, Perth and Umbria

Project. This collaboration is confined to high-quality population-based stroke incidence studies, each of which has a high proportion of cases (>70%) with either brain-imaging or autopsy. Stroke is a heterogeneous disorder comprising three main subtypes (ischaemic stroke, intracerebral haemorrhage, and subarachnoid haemorrhage). Each subtype is likely to have different risk factors, different recurrence rates and different outcomes. In order to assess these differences accurately large sample sizes are required. By merging the data sets of high quality studies we will have adequate power to determine differences between the different aetiological subtypes of stroke. The results of this project will improve our understanding of differences in stroke incidence and outcome between countries.

Stroke Occurrence and Weather Patterns

Collaborators:
Associate Professor Valery Feigin (Auckland)
Associate Professor Birgitta Stegmeyer (Northern Sweden)
Professor Peter Rothwell (Oxfordshire)
Professor Craig Anderson (Perth)

Project. The primary aim of this collaboration is to evaluate relationships between weather change and the risk of occurrence of ischaemic stroke, intracerebral haemorrhage, and subarachnoid haemorrhage. The results of this study may lead to new methods of stroke prevention, including improvements to housing and better targeting of individuals at high risk of stroke.

Model of Resource Utilization and Costs, and Outcomes of Stroke (MORUCOS)

Collaborators:
Dominique Cadilhac (Public Health Division, National Stroke Research Institute)
Professor Rob Carter (Program Evaluation Unit, School of Population Health, University of Melbourne)
Dr Marj Moodie (Program Evaluation Unit, School of Population Health, University of Melbourne)

Project. This model comprises Australian population projections to 2030, life expectancy, and data on incidence and outcome of stroke, and costs of resources used by stroke patients. These data have been used to calculate the costs of stroke both short and long term. This model can be used to assess the costs of this disease in different regions of Australia (subject to available local data). The model is currently being updated so that it can be used to assess the cost-effectiveness of different primary and secondary interventions on stroke prevention. The results of this project will provide a firm evidence-base for the development of Australian health care policy for stroke.

Developing a common outcome measure for priority setting in stroke

Collaborators:
Dr Leonie Segal (Health Economics Unit, Monash University)
Dr Jonathan Sturm (Gosford and Wyong Hospitals, Gosford, NSW)

Project. Dr Segal has successfully derived a regression equation to transfer various outcome measures, used in osteoarthritis, to a utility (or quality of life) measure. The aim is to now assess the applicability of this technique to stroke; and to derive utility scores from other measures commonly used in stroke research. This study is being funded by the NHMRC (Grant No. 334048) and commenced in 2005. The results of this study will be useful for decision makers in comparing the performance of interventions across a range of diseases.

An assessment of genetic factors in stroke: a case-control study

Collaborators:
Dr Chris Levi (John Hunter Hospital)
Dr John Attia (University of Newcastle)
Professor Rodney Scott (Hunter Area Pathology Service)

Project. The aim of this study is to assess whether polymorphisms in the thrombolytic system (t-PA and PAI 1) are associated with stroke occurrence, severity, and functional outcome. This study is funded through a grant from the National Heart Foundation of Australia (grant G04S 1623). The results of this study will help us better understand the variability in response to the thrombolytic therapy, and thereby enable better targeting of this therapy towards those more likely to respond to this treatment.

Effects of socioeconomic inequalities on stroke risk and outcome

Collaborators:
Professor Craig Anderson (George Institute for International Health, Sydney)
Kristie Carter (George Institute for International Health, Sydney)

Project:
Our aim is to collate data from incidence studies conducted in Melbourne, Auckland and Perth to determine associations between socio-economic status and stroke subtype-specific incidence, case-fatality, dependency, health resource use, and institutionalisation. This project is well powered to provide reliable data on aetiological and mechanistic factors related to inequalities in the burden of stroke which can be used to influence health policy. This study is being funded by the National Heart Foundation of Australia (grant G05S 2003).

 

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SPEED (Stroke Pre hospital and Emergency department Evaluation and Diagnosis)

The aim of this research project is to evaluate patterns of  pre-hospital and in-hospital care associated with the early identification, evaluation and treatment of acute stroke.

Research Objectives

To document the current patterns and timelines of care for stroke patients residing in a defined geographic area of metropolitan Melbourne from the time of calling for ambulance assistance through to treatment in the emergency department and admission to the hospital ward or stroke unit:

 

 

 
  • to identify sources of delay in the care of stroke patients
  • to determine key time points for potential interventions to reduce delays in care
  • to determine the relationships between pre-hospital and emergency department care of acute stroke patients
  • to determine what factors influence or are associated with the decision to call for  ambulance assistance after stroke.

Study Description

For 6 months in 2004, all ambulance-transported stroke patients arriving from a geographically defined region in Melbourne (Australia) to one of three hospital emergency departments were assessed. Ambulance records and hospital medical records were analysed for each patient. Interviews were undertaken with both patient and the person who made the call for ambulance assistance.

For the first time in Australia the tapes of the call for ambulance assistance were reviewed to identify symptoms reported by callers and if they recognised the problem was “Stroke”. This was undertaken with the support of the Metropolitan Ambulance Service (Melbourne).

Expected Outcomes

It is hoped the results of the SPEED study will influence future strategies to reduce the delays experienced by stroke patients from the onset of symptoms to effective treatment in a stroke unit hospital. Reductions in delays will increase the opportunity for more patients to be included in acute stroke treatments that they may otherwise be excluded from.

Further information on this project can be obtained by contacting Ian Mosley at imosley@nsri.org.au