30-Year Trends in Stroke Rates and Outcome in Auckland, New Zealand (1981-2012): A Multi-Ethnic Population-Based Series of Studies

Abstract

BackgroundInsufficient data exist on population-based trends in morbidity and mortality to determine the success of prevention strategies and improvements in health care delivery in stroke. The aim of this study was to determine trends in incidence and outcome (1-year mortality, 28-day case-fatality) in relation to management and risk factors for stroke in the multi-ethnic population of Auckland, New Zealand (NZ) over 30-years.MethodsFour stroke incidence population-based register studies were undertaken in adult residents (aged ≥15 years) of Auckland NZ in 1981–1982, 1991–1992, 2002–2003 and 2011–2012. All used standard World Health Organization (WHO) diagnostic criteria and multiple overlapping sources of case-ascertainment for hospitalised and non-hospitalised, fatal and non-fatal, new stroke events. Ethnicity was consistently self-identified into four major groups. Crude and age-adjusted (WHO world population standard) annual incidence and mortality with corresponding 95% confidence intervals (CI) were calculated per 100,000 people, assuming a Poisson distribution.Results5400 new stroke patients were registered in four 12 month recruitment phases over the 30-year study period; 79% were NZ/European, 6% Māori, 8% Pacific people, and 7% were of Asian or other origin. Overall stroke incidence and 1-year mortality decreased by 23% (95% CI 5%-31%) and 62% (95% CI 36%-86%), respectively, from 1981 to 2012. Whilst stroke incidence and mortality declined across all groups in NZ from 1991, Māori and Pacific groups had the slowest rate of decline and continue to experience stroke at a significantly younger age (mean ages 60 and 62 years, respectively) compared with NZ/Europeans (mean age 75 years). There was also a decline in 28-day stroke case fatality (overall by 14%, 95% CI 11%-17%) across all ethnic groups from 1981 to 2012. However, there were significant increases in the frequencies of pre-morbid hypertension, myocardial infarction, and diabetes mellitus, but a reduction in frequency of current smoking among stroke patients.ConclusionsIn this unique temporal series of studies spanning 30 years, stroke incidence, early case-fatality and 1-year mortality have declined, but ethnic disparities in risk and outcome for stroke persisted suggesting that primary stroke prevention remains crucial to reducing the burden of this disease.

Changes in survival and characteristics among older stroke unit patients—1994 versus 2012

“…Our main finding of unchanged survival appears surprising given the general decrease in stroke mortality worldwide (Feigin et al, ); however, secular trends in stroke case fatality within different populations are inconsistent, with some studies reporting decreasing fatality (Arboix et al, ; Feigin et al, ; Lee et al, ; Nimptsch & Mansky, ), while others report stable rates (Carrera et al, ; Feigin et al, ; Fuentes et al, ; Rothwell et al, ). The majority of studies on survival after stroke include nonhospitalized strokes (Feigin et al, ; Lecoffre et al, ; Lee et al, ; Numminen et al, ; Rothwell et al, ; Wieberdink et al, ), or strokes treated in hospital but not necessarily on an SU (Appelros et al, ; Arboix et al, ; Carrera et al, ; Nimptsch & Mansky, ). All of the patients in the present study received treatment on a comprehensive SU with consistent protocols, where the main treatment advance, thrombolysis, while improving outcomes for survivors, has not been shown to better survival (Wardlaw, Murray, Berge, & Zoppo, )—and this was also observed in our population by a nonsignificant HR in the adjusted Cox regression model (Supporting Information Table S1).…”

“…Existing studies reporting trends in stroke risk factors or outcomes include either both hospitalized and nonhospitalized patients (Feigin et al, ; Feigin, Lawes, Bennett, Barker‐Collo, & Parag, ; Lecoffre et al, ; Lee, Shafe, & Cowie, ; Numminen, Kaste, Aho, Waltimo, & Kotila, ; Rothwell et al, ; Wieberdink, Ikram, Hofman, Koudstaal, & Breteler, ), or patients treated in hospital, but not necessarily on an SU (Appelros et al, ; Arboix et al, ; Carrera, Maeder‐Ingvar, Rossetti, Devuyst, & Bogousslavsky, ; Nimptsch & Mansky, ). Several do not examine changes in survival outcomes (Bembenek et al, ; Lecoffre et al, ; Teuschl et al, ; Wieberdink et al, ), and none of these papers report on long‐term survival.…”

Predictors of mortality in Māori, Pacific Island, and European patients diagnosed with dementia at a New Zealand Memory Service

“…It is well established that antipsychotics increase the risk of mortality in people with dementia . The reason that this risk might be increased in Pacific Islanders and Māori may be due to their pre‐existing increased risk of stroke and cardiovascular events; however, these factors should be controlled for in our analysis as the final model included adjustment for comorbidity. We note that antipsychotics were less likely to be dispensed to Māori and Pacific Islanders compared with NZ Europeans, and this may be due to a clinical awareness of possible higher risk.…”

“…However, these factors have not been examined in an NZ population, which has a unique demography with differing rates of risk factors in different ethnic groups. For example, Māori and Pacific Islanders living in NZ have far higher rates of chronic diseases such as diabetes, obesity, and cardiovascular disease compared with NZ Europeans, so we might expect a higher risk of death in dementia. Understanding the predictors of survival in dementia is important to NZ health care decision makers who need to plan services for people with dementia and their families.…”

Incidence of Transient Ischemic Attacks in Sweden

“…Changes in incidence may also be indicative of changes in demand for different healthcare services. For example, studies have shown that both stroke incidence [5] and stroke severity [6] have decreased in both men and women during recent years, and this may be an after effect of improved prevention measures.…”