Auckland Regional Community Stroke Research Articles

Measuring stroke and transient ischemic attack burden in New Zealand: Protocol for the fifth Auckland Regional Community Stroke Study (ARCOS V).

Aim: The goal of this paper is to provide a protocol for conducting a fifth population-based Auckland Regional Community Stroke study (ARCOS V) in New Zealand. Methods and Discussion: In this study, for the first time globally, (1) stroke and TIA burden will be determined using the currently used clinical and tissue-based definition of stroke, in addition to the WHO clinical classifications of stroke used in all previous ARCOS studies, as well as more advanced criteria recently suggested for an "ideal" population-based stroke incidence and outcomes study; and (2) age, sex, and ethnic-specific trends in stroke incidence and outcomes will be determined over the last four decades, including changes in the incidence of acute cerebrovascular events over the last decade. Furthermore, information at four time points over a 40-year period will allow the assessment of effects of recent changes such as implementation of the FAST campaign, ambulance pre-notification, and endovascular treatment. This will enable more accurate projections for health service planning and delivery. Conclusion: The methods of this study will provide a foundation for future similar population-based studies in other countries and populations.

Stroke Incidence by Major Pathological Type and Ischemic Subtypes in the Auckland Regional Community Stroke Studies: Changes Between 2002 and 2011.

Major pathological stroke types (ischemic stroke [IS], primary intracerebral hemorrhage [ICH], and subarachnoid hemorrhage) and IS subtypes, have differing risk factors, management, and prognosis. We report changes in major stroke types and IS subtypes incidence during 10 years using data from the ARCOS (Auckland Regional Community Stroke Study) III performed during 12 months in 2002 to 2003 and the fourth ARCOS study (ARCOS-IV) performed in 2011 to 2012. ARCOS-III and ARCOS-IV were population-based registers of all new strokes in the greater Auckland region (population aged >15 years, 1 119 192). Strokes were classified into major pathological types (IS, ICH, subarachnoid hemorrhage, and undetermined type). Crude annual age-, sex-, and ethnic-specific stroke incidence with 95% confidence intervals was calculated. ISs were subclassified using TOAST (Trial of ORG 10172 in Acute Stroke Treatment) criteria into 5 etiologic groups. Rate ratios with 95% confidence intervals were calculated for differences in age-standardized rates between the 2 studies. In ARCOS-IV, there were 1329 (81%) ISs, 211 (13%) ICHs, 79 (5%) subarachnoid hemorrhages, and 24 (1%) undetermined type strokes. The proportional distribution of IS subtypes was 29% cardioembolism, 21% small-vessel occlusion, 15% large-artery atherosclerosis, 5% other determined etiology, and 31% undetermined type. Between 2002 and 2011, age-standardized incidence decreased for subarachnoid hemorrhage (rate ratios, 0.73; 95% confidence intervals, 0.54-0.99) and undetermined type (rate ratios, 0.14; 95% confidence intervals, 0.09-0.22). Rates were stable for IS and ICH. Among IS subtypes, large-artery atherosclerosis and small-vessel occlusion rates increased significantly. The frequency of all risk factors increased in IS. Ethnic differences were observed for both stroke subtype rates and their risk factor frequencies. A lack of change in IS and ICH incidence may reflect a trend toward increased incidence of younger strokes. Increased rates of large-artery atherosclerosis and small-vessel occlusion are associated with increased smoking and high blood pressure. Ethnic differences in the proportional distribution of pathological stroke subtypes suggest differential exposure and susceptibility to risk factors.

Incidence of Transient Ischemic Attack in Auckland, New Zealand, in 2011 to 2012.

There have been few recent population-based studies reporting the incidence (first ever) and attack rates (incident and recurrent) of transient ischemic attack (TIA). The fourth Auckland Regional Community Stroke study (ARCOS IV) used multiple overlapping case ascertainment methods to identify all hospitalized and nonhospitalized cases of TIA that occurred in people ≥16 years of age usually resident in Auckland (population ≥16 years of age is 1.12 million), during the 12 months from March 1, 2011. All first-ever and recurrent new TIAs (any new TIA 28 days after the index event) during the study period were recorded. There were 785 people with TIA (402 [51.2%] women, mean [SD] age 71.5 [13.8] years); 614 (78%) of European origin, 84 (11%) Māori/Pacific, and 75 (10%) Asian/Other. The annual incidence of TIA was 40 (95% confidence interval, 36-43), and attack rate was 63 (95% confidence interval, 59-68), per 100 000 people, age standardized to the World Health Organization world population. Approximately two thirds of people were known to be hypertensive or were being treated with blood pressure-lowering agents, half were taking antiplatelet agents and just under half were taking lipid-lowering therapy before the index TIA. Two hundred ten (27%) people were known to have atrial fibrillation at the time of the TIA, of whom only 61 (29%) were taking anticoagulant therapy, suggesting a failure to identify or treat atrial fibrillation. This study describes the burden of TIA in an era of aggressive primary and secondary vascular risk factor management. Education programs for medical practitioners and patients around the identification and management of atrial fibrillation are required.

Abstract WP181: Incidence of Transient Ischemic Attack in Auckland, New Zealand, in 2011-2012

Introduction: There have been few recent population studies reporting the burden of TIA. We aimed to determine the incidence (first ever in a lifetime) of TIA in an ethnically diverse population. Hypothesis: The incidence of TIA may vary by different ethnic group. Methods: The fourth Auckland Regional Community Stroke study (ARCOS IV) used multiple overlapping ascertainment methods to identify all hospitalized and non-hospitalized cases of definite TIA in people ≥16 years of age usually resident in Auckland (population ≥16 years was 1.12 million), over 12 months from March 2011. TIA was defined as an acute loss of focal cerebral or ocular function with symptoms lasting <24 hours, of presumed vascular cause. Patients with isolated vertigo, diplopia and non-focal symptoms were excluded. Results: There were 785 people with TIA [402 (51.2%) women, mean (SD) age 71.5 (13.8) years]. Of these, 614 (78%) were European, 32 (4.1%) Maori (indigenous people of New Zealand), 62 (8%) Pasifika (originating from the Pacific Islands) and 75 (10%) Asian/Others. Most (82%) TIA patients were seen in a hospital setting (emergency room, outpatient clinic or admitted). The annual age-standardized incidence of TIA was 40 (95% CI 36-43) per 100,000 people. The annual age-standardized incidence per 100,000 people of TIA was less in Maori (27; 95% CI 8-40) and Asian/Others (21; 95% CI 16-27) than in Europeans (45; 95% CI 41-50). Vascular risk factor profiles and treatment at presentation varied between the different ethnic groups. For example, non-Europeans were more likely to be diabetic (p<0.01), and Maori and Pasifika were less likely to be taking lipid-lowering therapy (p<0.01), than other groups. Conclusions: This study has demonstrated ethnic differences in the burden of TIA in an era of aggressive primary and secondary vascular risk factor management. We speculate that that the lower incidence of TIA seen in ethnic minorities may reflect a failure to seek medical attention as opposed to a true difference in incidence. If confirmed, programs targeting different ethnic groups, particularly those of lower socioeconomic status, and aimed at improving health literacy around vascular disease and reducing barriers to accessing health care, will be required.

Potential Gains and Costs from Increasing Access to Thrombolysis for Acute Ischemic Stroke Patients in New Zealand Hospitals

Treatment of ischemic stroke patients with tissue-type plasminogen activator (tPA) is known to be effective and cost-effective, yet the percentage of patients treated with thrombolysis in hospitals remains low. The purpose of this study is to examine whether providing thrombolysis in New Zealand hospitals is currently cost-effective and to estimate the amount that might be spent on campaigns aimed at increasing thrombolysis receipt rates. A decision-analytic model was developed and populated using health services data from the literature and the Auckland Regional Community Stroke Outcome Study. The cost-utilities of providing thrombolysis over one-year and patient lifetime were estimated. Using a threshold of NZ$20 000 (US$15 337) per quality-adjusted life year, the analysis identified the maximum amount that might be spent on campaigns aiming to increase rates of receipt of thrombolysis above their current levels. Monte Carlo simulations and probabilistic sensitivity analysis explored the robustness of the findings. Providing thrombolysis was cost-effective, especially when long-term costs and effects were considered (NZ$6641 or US$5093 per quality-adjusted life year). The results suggest that better management within hospitals would be more effective in increasing thrombolysis receipt rates (up to 17%) than campaigns aiming at higher awareness of stroke symptoms in the community. The amount that might be spent on a national campaign to increase rate of receipt of thrombolysis from its current level (3% of eligible patients) depended upon the effectiveness of the campaign, ranging from under NZ$6 million for New Zealand for an increase in rate to 30% to over $9 million for an increase in rate to 50%. While thrombolysis is a cost-effective treatment in New Zealand, resources should be devoted to campaigns, both within hospitals and in the community, to increase coverage.

Capturing the Stories behind the Numbers: The Auckland Regional Community Stroke Study (ARCOS IV), a Qualitative Study

Qualitative data can add value and understanding to more traditional epidemiological studies. This study was designed to complement the quantitative data from the incidence study the Auckland Regional Community Stroke Study or ARCOS-IV by using qualitative methods to uncover the richer detail of life as a stroke survivor, thereby extending our understanding of the impact of stroke. The aims of the study were to identify how the experience of recovery and adaptation changes over time after stroke; and to elicit the strategies people with stroke and their whānau/family use and find helpful in living life after stroke. The aim of this paper is to describe the methodology and also the challenges and advantages of embedding qualitative research into a large epidemiological study. Longitudinal study utilizing a Qualitative Description design in a subset of those taking part in the incidence study. Participants will be interviewed at 6, 12, 24, and 36 months after stroke. Semistructured interviews will explore three key areas: (1) issues of importance to people following a stroke and their whānau/family; (2) the perceived impact on people's sense of recovery, adaptation, and hopes; and (3) key strategies that people with stroke and their whānau/family use and find most helpful in living life after stroke. Thematic analysis will be conducted using iterative constant comparative methods. This methodology paper demonstrates the application of mixed methods in epidemiology. It also considers some of the practical and methodological issues that have emerged and may provide a useful framework for other qualitative projects in population-based studies.

Methodology of a Population-Based Stroke and TIA Incidence and Outcomes Study: The Auckland Regional Community Stroke Study (ARCOS IV) 2011–2012

Stroke is a leading cause of death and disability worldwide. Stroke burden is immense as it leads to premature deaths, leaves survivors with ongoing disabilities, and has a major financial impact on the individual, their families, and the community. Reliable, high-quality evidence is needed on stroke risk factors, incidence, and outcomes to provide information on how best to reduce this burden. Population-based studies are regarded as the 'gold-standard' of measuring disease burden but are not common due to the logistical and financial challenges they present. The Auckland Regional Community Stroke Studies are among a few in the world that have been carried out at a population level and at regular intervals. The aim of the fourth Auckland Regional Community Stroke Studies IV is to examine the current measures of stroke incidence, prevalence, and outcomes as well the trends over four decades. This article describes the methodology of the Auckland Regional Community Stroke Studies IV with stroke and transient ischemic attacks cases registered over a 12-month period from March 1, 2011 to February 29, 2012. The methodology described may be used as a guide in order to design similar population-based stroke incidence and outcome studies in other countries and populations, thus facilitating the collection of most consistent and accurate stroke epidemiological data.

Prevalence and Predictors of 6-Month Fatigue in Patients With Ischemic Stroke

Although persistent and significant fatigue affects the daily life of stroke survivors, there are no population-based studies examining the prevalence of fatigue in 6-month survivors of ischemic stroke and few studies of predictors of poststroke fatigue. This article examined data from the Auckland Regional Community Stroke study conducted in Auckland, New Zealand, in 2002 to 2003. Presence of fatigue was evaluated at 6 months in 613 patients with ischemic stroke using a Short Form 36 Vitality Score (energy and fatigue) of ≤ 47. Multivariate logistic regression analysis was used to determine predictors of fatigue development 6 months poststroke. The prevalence of fatigue was 30% (28% in men and 33% in women). There was a clear association between increased prevalence of fatigue and advancing age. The only baseline variables independently associated with an increased risk of developing fatigue at 6 months poststroke were prestroke incontinence and being of New Zealand European ethnicity. Being independent and living alone at baseline were associated with significant reduction in the risk of being fatigued at 6 months poststroke. Severe depression at 6 months was significantly and independently associated with being fatigued. The prevalence of fatigue found in our study is at the lower level of range reported in other studies. The prevalence of fatigue increased with advancing age, as found in most previous studies. Because fatigue can have a negative impact on stroke recovery, particular attention needs to be paid to those who are older, incontinent before stroke, and those who report severe symptoms of depression at 6 months after stroke.

Are Stroke Units Cost Effective? Evidence from a New Zealand Stroke Incidence and Population-Based Study

Acute stroke units in hospitals are known to be more costly than standard care, but proponents claim that the health gains will justify the expense. Yet, despite widespread adoption of stroke units, the evidence on the cost effectiveness of stroke units has been mixed, due in part to differences in the pathway of care across hospitals. The purpose of this study is to compare costs and outcomes for patients admitted to a stroke unit with those admitted to a general ward. Data on 530 stroke sufferers from a large incidence study of stroke (the Auckland Regional Community Stroke Outcome Study) were used. Cost of health services, places of discharge were identified at one-, six- and 12 months poststroke and were linked with long-term cost and survival five-years poststroke. A decision analytical model was developed, including the relationship between waiting time for discharge and probability of admission to stroke unit. Cost effectiveness was determined using a willingness to pay threshold of NZ$20 000 (US$15 234). Regression analysis suggested that there were no significant differences between patients admitted to a stroke unit and a general ward. The incremental cost-utility ratio for the first-year was NZ$42 813/quality-adjusted life year (US$32 610/quality-adjusted life year), but fell substantially to NZ$6747/quality-adjusted life year (US$5139/quality-adjusted life year) when lifetime costs and outcomes were considered. Probabilistic and one-way sensitivity analysis suggests that the results are robust to areas of uncertainty or delays in the pathway of care. Stroke unit care was cost effective in Auckland, New Zealand.

Cognitive and Functional Outcomes of 5-Year Subarachnoid Haemorrhage Survivors: Comparison to Matched Healthy Controls

Background and Purpose: While neuropsychological deficits have been the focus of research post-subarachnoid haemorrhage (SAH), population-based information on long-term neuropsychological impairment post-SAH are lacking. Neither the profile of long-term neuropsychological deficits nor its relationship to long-term functional outcomes has been established. Methods: This was a cross-sectional population-based study of long-term (5 years) neuropsychological and functional outcomes post-SAH. Participants were 27 five-year survivors of SAH previously enrolled in the Auckland Regional Community Stroke study (2002–2003). Twenty-six age-, gender- and ethnicity-matched controls were used to compare mood, functional (i.e. disability; handicap; quality of life, QoL) and neuropsychological outcomes (i.e. verbal memory, visual memory, executive functioning, language, processing speed and visuoperceptual abilities) of SAH survivors. Results: SAH survivors were more depressed and significantly more impaired in the areas of disability, handicap, and QoL than controls. SAH survivors also had significant cognitive deficits across domains when compared to controls. Depressed mood and baseline functioning were related to worse functional outcomes at 5 years post-SAH. Whilst poor cognitive functioning, particularly in the domains of visual memory and language, impacted long-term functional outcomes of SAH survivors. Conclusions: Five-year SAH survivors have many functional and cognitive deficits compared to matched controls. Language and visual memory emerged as independent factors associated with their current functioning.

Stroke Survivors Who Score Below Threshold on Standard Depression Measures May Still Have Negative Cognitions of Concern

There has been an increase in screening for depression in the physically ill. We explored whether important negative cognitions may be missed by conventional approaches to screening for depression in 2 independently conducted stroke studies with similar methods. The Auckland Regional Community Stroke (ARCOS) study was a prospective, population-based stroke incidence study conducted in Auckland, New Zealand, for 12 months in 2002 to 2003. The Stroke Outcomes Study was a prospective, hospital cohort study conducted in Leeds and Bradford, United Kingdom, for 33 months in 2002 to 2005. Symptoms of abnormal mood were assessed at 6 months in ARCOS with a single simple question, "Do you often feel sad and depressed?" and the 28-item General Health Questionnaire administered as part of a structured interview and in the Stroke Outcomes Study with the 28-item General Health Questionnaire and a single question about depressed mood taken from the Present State Examination. Mood data were available at 6 months from 770 ARCOS and 492 Stroke Outcomes Study participants. A significant proportion (up to 28%) of people who did not meet study criteria for depression reported important negative cognitions such as hopelessness, worthlessness, or suicidality. People who were older, dependent in activities of daily living, or not partnered were more likely to report negative cognitions. Important negative cognitions, including suicidal thoughts, may be missed when people are screened for depression after stroke. Screening alone is not an adequate substitute for a sensitive exploration of the psychological impact of stroke on the survivor.

Falls After Stroke

Falls are an important issue in older people. We aimed to determine the incidence, circumstances, and predictors of falls in patients with recent acute stroke. The Auckland Regional Community Stroke (ARCOS) study was a prospective population-based stroke incidence study conducted in Auckland, New Zealand (NZ) during 2002 to 2003. Among 6-month survivors, the location and consequences of any falls were ascertained by self-report as part of a structured interview. Multivariable logistic regression was used to establish associations between risk factors and "any" and "injurious" falls. Of 1104 stroke survivors who completed an interview, 407 (37%) reported at least 1 fall, 151 (37% of fallers, 14% of stroke survivors) sustained an injury that required medical treatment, and 31 (8% of fallers, 3% of stroke survivors) sustained a fracture. The majority of falls occurred indoors at home. Independent factors associated with falls were depressive symptoms, disability, previous falls, and older age. For injurious falls, the positively associated factors were female sex and NZ/European ethnicity and dependence before the stroke, whereas higher levels of activity and normal cognition were negatively associated factors. Falls are common after stroke, and their predictive factors are similar to those for older people in general. Falls prevention programs require implementation in stroke services.

The Impact of Stroke on Unpaid Caregivers: Results from the Auckland Regional Community Stroke Study, 2002–2003

Background: Few studies have assessed the longitudinal impact of providing unpaid care for stroke survivors. We aimed to describe the positive and negative impact of providing unpaid care and to identify independent predictors of poor carer outcome. Methods: The Auckland Regional Community Stroke study was a prospective population-based stroke incidence study conducted in Auckland, New Zealand, over a 12-month period in 2002–2003. Stroke survivors and their unpaid carers were assessed at 6 and 18 months after stroke onset using the Short Form 36 questionnaire and the Bakas Caregiving Outcomes Scale. Results: Data were available from 167 stroke survivor–carer pairs at 6 months and 62 pairs at 18 months. Unpaid carers reported lower health-related quality of life at 6 months after stroke than their age- and sex-matched counterparts in the New Zealand population. The impact of providing care was predominantly negative; however, approximately one third of the carers had improved relationships with the stroke survivor. No reliable predictors of carer burden were identified. Conclusions: This study re-emphasises the heavy burden of stroke on unpaid carers but was unable to identify factors that predicted carers at the greatest risk of experiencing a poor outcome. Effective strategies are needed to reduce the burden of providing unpaid care.

The Influence of Psychiatric Morbidity on Return to Paid Work After Stroke in Younger Adults

Few data exist on the determinants of return to paid work after stroke, yet participation in employment is vital to a person's mental well-being and role in society. This study aimed to determine the frequency and determinants of return to work, in particular the effect of early psychiatric morbidity, in a population-based study of stroke survivors. The third Auckland Regional Community Stroke (ARCOS) study was a prospective, population-based, stroke incidence study undertaken in Auckland, New Zealand during 2002 to 2003. After a baseline assessment early after stroke, data were collected on all survivors at 1 and 6 months follow-up. Multiple variable logistic regression was used to determine predictors of return to paid work. Data are reported with odds ratios (OR) and 95% confidence intervals (CI). Among 1423 patients registered with first-ever strokes, there were 210 previously in paid employment who survived to 6 months, of whom 155 (74%) completed the GHQ-28 and 112 (53%) had returned to paid work. Among those cognitively competent, psychiatric morbidity at 28 days was a strong independent predictor of not returning to work (Odds Ratio 0.39; 95% CI 0.22 to 0.80). Non-New Zealand European ethnicity (OR 0.40; 95% CI 0.17 to 0.91), prior part-time, as opposed to full-time, employment 0.36 (0.15 to 0.89), and not being functionally independent soon after the stroke 0.28 (0.13 to 0.59) were the other independent age- and gender-adjusted predictors of not successfully returning to paid work. About half of previously employed people return to paid employment after stroke, with psychiatric morbidity and physical disability being independent, yet potentially treatable, determinants of this outcome. Appropriate management of both emotional and physical sequelae would appear necessary for optimizing recovery and return to work in younger adults after stroke.

Stroke surveillance: population‐based estimates and projections for New Zealand

To estimate the incidence, prevalence and mortality of stroke in New Zealand (NZ) in 2001, projected to 2011. Multistate lifetable models were constructed using smoothed rates of first-ever stroke incidence and relative risks of mortality estimated from the most recent Auckland Regional Community Stroke (ARCOS) Study. Estimates of the burden of stroke in NZ were calculated by applying rates output by the model to the 2001 population. Stroke incidence, prevalence and mortality were then projected to 2011, assuming similar trends in stroke incidence and case fatality to those estimated between the 1991/92 and 2002/03 studies. A total of 5,200 first-ever strokes were estimated to have occurred in NZ in 2001. Rates of stroke rose exponentially with increasing age and were 20% higher among males than females at most ages. Nevertheless, the lifetable risk of stroke was lower for males (16%) than females (18%). On average, males survived a year longer than females after a first-ever stroke (9.0 vs. 8.2 years). The incidence rates of first-ever stroke declined by approximately 1% per year between 1991 and 2003. The lifetable risk of stroke remained stable for females but increased for males (from 14% to 16%) over this period. Stroke prevalence also increased by approximately 1% per year, whereas stroke-related mortality fell by 4% per year. If these trends continue, approximately 6,000 first-ever strokes (2% annual increase), 45,000 stroke survivors (2% annual increase) and 2,000 stroke-related deaths (1% annual decline) are expected in 2011. Stroke mortality is falling faster than stroke incidence. This, together with population growth and ageing, will lead to a rising burden of stroke-related disability over the next decade.

Improved Survival after Stroke: Is Admission to Hospital the Major Explanation? Trend Analyses of the Auckland Regional Community Stroke Studies

Background: There is uncertainty regarding the impact of changes in stroke care and natural history of stroke in the community. We examined factors responsible for trends in survival after stroke in a series of population-based studies. Methods: We used statistical models to assess temporal trends in 28-day and 1-year case fatality after first-ever stroke cases registered in 3 stroke incidence studies undertaken in Auckland, New Zealand, over uniform 12-month calendar periods in 1981–1982 (n = 1,030), 1991–1992 (1,305) and 2001–2002 (1,423). Cox proportional hazards regression was used to evaluate the significance of pre-defined ‘patient’, ‘disease’ and ‘service/care’ factors on these trends. Results: Overall, there was a 40% decline in 28-day case fatality after stroke over the study periods, from 32% (95% confidence interval, 29–35%) in 1981–1982 to 23% (21–25%) in 1991–1992 and then 19% (17–21%) in 2002–2003. Similar relative declines were seen in 1-year case fatality. In regression models, the trends were still significant after adjusting for patient and disease factors. However, further adjustment for care factors (higher hospital admission and neuroimaging) explained most of the improvement in survival. Conclusions: These data show significant downwards trends in case fatality after stroke in Auckland over 20 years, which can largely be attributed to improved stroke care associated with increases in hospital admission and brain imaging during the acute phase of the illness.

Frequency, Management, and Predictors of Abnormal Mood After Stroke

Mood disorders are an important consequence of stroke. We aimed to identify significant, clinically useful predictors of abnormal mood after stroke. The Auckland Regional Community Stroke (ARCOS) study was a prospective population-based stroke incidence study conducted in Auckland, New Zealand, over a 12-month period from 2002 to 2003. All patients were followed up 6 months after stroke onset and abnormal mood was assessed using the 28-item General Health Questionnaire (GHQ-28) administered as part of a structured telephone interview. Multivariate stepwise logistic regression was used to develop a predictive model for "caseness" (score of > or = 5 on the GHQ-28) based on several premorbid patient and clinical variables assessed at baseline and 28 days of follow up. Of patients available at 6 months (n=1172), complete data on mood was available from 739 (60%) patients and 27% (95% confidence interval, 24 to 30%) were defined as cases. Key baseline predictors of abnormal mood were disability and history of depression after adjustment for sex, age, and comorbidity, but the model failed to predict a large amount of the variation in caseness (C statistic 0.587). This study emphasizes the complex nature of mood disturbance after stroke and that multiple factors are likely to contribute to mood disorders. A simple, clinically applicable, predictive model in stroke care appears difficult to develop.

Ethnic disparities in incidence of stroke subtypes: Auckland Regional Community Stroke Study, 2002–2003

Limited population-based data exist on differences in the incidence of major pathological stroke types and ischaemic stroke subtypes across ethnic groups. We aimed to provide such data within the large multi-ethnic population of Auckland, New Zealand. All first-ever cases of stroke (n=1423) in a population-based register in 940 000 residents (aged 15 years) in Auckland, New Zealand, for a 12-month period in 2002-2003, were classified into ischaemic stroke, primary intracerebral haemorrhage (PICH), subarachnoid haemorrhage, and undetermined stroke, according to standard definitions and results of neuroimaging/necropsy (in over 90% of cases). Ischaemic stroke was further classified into five subtypes. Ethnicity was self-identified and grouped as New Zealand (NZ)/European, Maori/Pacific, and Asian/other. Incidence rates were standardised to the WHO world population by the direct method, and differences in rates between ethnic groups expressed as rate ratios (RRs), with NZ/European as the reference group. In NZ/European people, ischaemic stroke comprised 73%, PICH 11%, and subarachnoid haemorrhage 6%, but PICH was higher in Maori/Pacific people (17%) and in Asian/other people (22%). Compared with NZ/European people, age-adjusted RRs for PICH were 2.7 (95% CI 1.8-4.0) and 2.3 (95% CI 1.4-3.7) among Maori/Pacific and Asian/other people, respectively. The corresponding RR for ischaemic stroke was greater for Maori/Pacific people (1.7 [95% CI 1.4-2.0]), particularly embolic stroke, and for Asian/other people (1.3 [95% CI 1.0-1.7]). The onset of stroke in Maori/Pacific and Asian/other people began at significantly younger ages (62 years and 64 years, respectively) than in NZ/Europeans (75 years; p<0.0001). There were ethnic differences in the risk factor profiles (such as age, sex, hypertension, cardiac disease, diabetes, hypercholesterolaemia, smoking status, overweight) for the stroke types and subtypes. Compared to NZ/Europeans, Maori/Pacific and Asian/other people are at higher risk of ischaemic stroke and PICH, whereas similar rates of subarachnoid haemorrhage were evident across ethnic groups. The ethnic disparities in the rates of stroke types could be due to substantial differences found in risk factor profiles between ethnic groups. This information should be considered when planning prevention and stroke-care services in multi-ethnic communities.

1122 Stroke with atrial fibrillation: the Auckland regional community stroke study perspective

1122 Stroke with atrial fibrillation: the Auckland regional community stroke study perspective