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the Osaka Medical Center for Health Science and Promotion (A.K., S.S., H. Imano, M.K., T.O., M.I., T.S.), Japan
Neyagawa Public Health Center (Y.N.), Japan
Yao Medical Association (M.S., H.O.), Japan
Department of Public Health Medicine (H. Iso), University of Osaka, Japan.
Abstract
Background and Purpose— Higher proportions of hemorrhagic stroke and lacunar infarction were reported in rural Japan compared with those in Western countries. We examined the relative proportions of stroke subtypes in an urban Japanese city where westernized lifestyles are more common than in rural areas.
Methods— Stroke registration was performed in 1992, 1997, and 2002 for residents 40 years of age who were admitted with acute strokes to all of the 10 hospitals with 90 beds in Yao City, Osaka, Japan. Strokes were classified as intraparenchymal hemorrhage, subarachnoid hemorrhage, or ischemic strokes (embolic infarction, large-artery occlusive infarction, lacunar infarction, and unclassified thrombotic infarction) by criteria using computed tomography or MRI.
Results— A total of 650 first-ever strokes were registered. The age-adjusted proportion of each stroke subtype was not significantly different among the 3 study periods in both men and women. Throughout the 3 periods, intraparenchymal hemorrhage, subarachnoid hemorrhage, and ischemic stroke accounted for 26%, 7%, and 65% in men, respectively. In women, the respective proportions were 29%, 21%, and 44%. The proportion of each subtype for total ischemic strokes was as follows: 51% to 61% lacunar infarction, 25% to 26% large-artery occlusive infarction, and 11% to 17% embolic infarction.
Conclusions— Our study showed that hemorrhagic stroke represented a large proportion of all strokes, especially among women, and lacunar infarction was the most common subtype of ischemic stroke among both men and women in Yao City, which differed from findings in Western countries.
Key Words: brain infarction epidemiology intracranial hemorrhages stroke classification
Introduction
According to population-based studies on stroke incidence conducted in the 1960s and 1970s, Japanese rural populations had a higher incidence of total stroke, in particular intraparenchymal hemorrhage, compared with those in the United States and European countries.1–4 The higher proportions of intraparenchymal hemorrhage and lacunar infarction in rural Japan than in US populations have been confirmed by epidemiological studies using computed tomography (CT) as a diagnostic tool since the 1970s.5–10
However, there have been few findings about the relative proportions of stroke subtypes in the Japanese urban population, where westernized lifestyles are more common than in rural areas. This study describes the proportions of stroke subtypes as estimated by data from hospital-based stroke registry in an urban Japanese city.
Subjects and Methods
The surveyed population were residents of Yao City, an urban city in Osaka Prefecture in Japan, with a total census of 274 777 (133 956 men and 140 821 women) in the calendar year 2000. Persons living in areas outside Yao City were not registered. Stroke registration was performed in 1992, 1997, and 2002 for residents aged 40 years who were admitted with acute strokes to all of the 10 hospitals with 90 beds in Yao City. Patients with an acute neurological illness were usually admitted to these hospitals, which provide diagnoses and acute care. The total number of beds of the participating 10 hospitals was 2149, which occupied 90% of the total 2391 beds of all 14 hospitals in the city in 1992. Among the 10 hospitals, 2 were closed between 1993 and 1996; therefore, 8 hospitals participated in 1997 and 2002. According to the official statistics about ambulance use, the proportion of residents who were transferred to neurosurgery departments in the participating hospitals among those in all hospitals, including those outside Yao City, was 92% (920 of 995) in 1992, 89% (1311 of 1476) in 1997, and 89% (1545 of 1740) in 2002. The proportion of persons aged 70 years among the subjects increased from 10% in 1992 to 17% in 2002 for men and from 17% in 1992 to 23% in 2002 for women.
All hospitalized residents who experienced a first stroke were registered. The hospital records for all patients with admission records of possible stroke or discharge diagnoses of stroke were reviewed by the study physicians (A.K. and Y.N.). Once a case was identified, we obtained information about neurological symptoms, medical history, and findings of several diagnostic tests, including CT, MRI, cerebral angiography, electrocardiography, and echocardiography.
The diagnosis of stroke was made according to the criteria of the National Survey of Stroke,11 which requires a constellation of neurological deficits of sudden or rapid onset lasting 24 hours or until death. We excluded stroke resulting from infection, trauma, malignancy, and vascular malformation. In addition, recurrent strokes and patients with asymptomatic lesions detected by brain imaging were excluded. Events were classified as intraparenchymal hemorrhage, subarachnoid hemorrhage, or ischemic strokes by CT or MRI using standardized criteria.12 A stroke case that was diagnosed clinically but showed no lesion on CT or MRI was classified as stroke of undetermined type. Ischemic stroke was categorized as embolic infarction or thrombotic infarction. A diagnosis of embolic infarction was made when evidence of an embolic source was present in the medical records and if imaging studies and a neurology consultation supported the diagnosis. Thrombotic infarctions were further classified as large-artery occlusive infarction, lacunar infarction, or unclassified thrombotic infarction based on the results of CT or MRI, according to the criteria of the Perth Community Stroke Study.13
We calculated age-adjusted proportions of stroke subtypes by the direct method of standardization to the age distribution of the total stroke patients to compare the proportions in 3 study periods as well as between men and women. Sex-specific proportions of stroke subtypes were examined because proportions of stroke subtypes were reported to vary between the sexes.5,7 Linear trends in the proportions in 1992, 1997, and 2002 were tested using the 2 test for trend. The study was approved in advance by the ethics committee of the Osaka Medical Center for Health Science and Promotion.
Results
A total of 650 first-ever strokes were recorded: 190 in 1992, 206 in 1997, and 254 in 2002. The highest proportion of patients comprised men 60 to 69 years of age and women 70 to 79 years of age or 80 years of age in each study period (Table 1).
The numbers and age-adjusted proportions of stroke subtypes among total strokes are shown in Table 2. The proportion of each stroke subtype did not significantly differ among the 3 study periods in either sex. Throughout the 3 periods, intraparenchymal hemorrhage, subarachnoid hemorrhage, and ischemic stroke accounted for 26%, 7%, and 65% of all strokes among men. For women, intraparenchymal hemorrhage and subarachnoid hemorrhage accounted for 29% and 21%, respectively, of all strokes, resulting in higher proportions of hemorrhagic stroke than ischemic stroke (50% versus 44%). The proportions of intraparenchymal hemorrhage, subarachnoid hemorrhage, and ischemic stroke were 31%, 10%, and 56%, respectively, among men 40 to 69 years of age, and 20%, 4%, and 73% among those 70 years of age. For women, the respective proportions were 29%, 27%, and 39% among those 40 to 69 years of age, and 31%, 14%, and 50% among those 70 years of age.
The age-adjusted proportions of stroke subtypes among ischemic strokes did not significantly differ among the 3 study periods in either sex (Table 3). Throughout the 3 periods, lacunar infarction, large-artery occlusive infarction, and embolic infarction accounted for 51%, 25%, and 17% of all ischemic strokes among men and 61%, 26%, and 11% among women. The proportions of lacunar infarction, large-artery occlusive infarction, and embolic infarction were 55%, 29%, and 12%, respectively, among men 40 to 69 years of age, and 48%, 22%, and 22% among those 70 years of age. For women, the respective proportions were 70%, 24%, and 4% among those 40 to 69 years of age, and 51%, 27%, and 19% among those 70 years of age.
Discussion
We observed a relatively high proportion of hemorrhagic stroke in Yao City between 1992 and 2002. Intraparenchymal hemorrhage accounted for 30% of all strokes in men and women. Furthermore, in women, subarachnoid hemorrhage constituted 20% of all strokes, and therefore about half of the strokes were hemorrhagic type in women. These proportions of stroke subtypes were similar to those from our previous study6 using the same criteria in rural Japan.
Findings from other community-based studies on first-ever stroke subtypes are shown in Table 4. Compared with the results from 3 hospital-based studies in the United States,8–10 the present study showed the higher proportions of both intraparenchymal hemorrhage and subarachnoid hemorrhage, which were similar to previous hospital-based studies in rural Japan5 as well as in Korea,14 although there may be differences in age distribution and criteria of diagnosis among the studies.
Reviewing population-based studies since the 1990s worldwide, we found that the proportion of intraparenchymal hemorrhage was reported to be highest in Chinese,22 followed by the proportions in rural Japanese7 and Chileans.21 The proportion of subarachnoid hemorrhage was highest in Finns,19 followed by the proportion in Japanese.7 The high proportion of hemorrhagic stroke in Japanese similar to other Asian populations may be attributed to environmental factors as well as genetic factors. The national survey of circulatory disorders with a representative sample of Japanese 30 years of age in 200023 showed that hypertension and heavy drinking, strong risk factors for hemorrhagic stroke, were common in Japan. The proportion of hypertension, defined as systolic pressure of 140 mm Hg, diastolic pressure of 90 mm Hg, or taking antihypertensive medication, was reported 57% in men and 45% in women. The proportion of heavy drinkers, defined as persons having >14 drinks per week, was 46% in men and 11% in women. The proportions of hypertension and heavy drinkers among Japanese seem to be higher than those among Americans,24 although full comparisons cannot be made.
The proportion of ischemic stroke was higher among men and women 70 years of age than among those 40 to 69 years of age. The higher proportion of ischemic stroke among older persons was reported from other studies.5,15–17,21 With regard to the subclassification of ischemic stroke, lacunar infarction accounted for >50% of all ischemic strokes in the present study, which was similar to previous studies in Japanese rural populations.6,25 The proportion of lacunar infarction in Japanese communities (51% to 61%) was much greater than that in the previous 3 American hospital-based studies (15% to 27%)8–10 and an Australian community-based study (10%).13 According to a recent nationwide hospital-based study of Japanese,26 the proportions of lacunar stroke, atherothrombotic infarction, and cardioembolic infarction were 39%, 33%, and 22%, respectively, but these findings were based on 156 large hospitals all over Japan, of which >50% equipped a specialized stroke care unit or intensive care unit. Therefore, in that study, it is possible that severe ischemic patients with cardioembolic or atherothrombotic stroke were likely to be admitted to the participating hospitals.
As for the study limitations, severe ischemic stroke cases can be transported to other stroke centers with dedicated stroke teams outside Yao City. However, according to the statistics of ambulance records, only 10% of the total ambulance patients were transported to hospitals outside Yao City. Furthermore, this proportion did not change in 3 survey periods. Thus, the transportation of patients out of the city is unlikely to affect the results substantially. Second, it is uncertain whether the present findings in Yao City were generalized to larger cities in Japan.
In conclusion, our study showed that hemorrhagic stroke represented a large proportion of all strokes, especially among women, and lacunar infarction was the most common subtype of ischemic stroke among both men and women in Yao City, which differed from findings in Western countries. We found no significant change in proportions of stroke subtypes during the last decade in this population. The present findings imply the importance of enhancing health care services to reduce case fatality among hemorrhagic stroke patients and to prevent stroke in Japan.
Appendix
The participating hospitals and the directors are listed in order of the number of eligible patients entered in the study. Ishinkai Yao Sougou Hospital: T. Mori, MD. Yao Tokusyukai Sougou Hospital: M. Fukuda, MD. Kouseikai Daiichi Hospital: T. Onishi, MD. Kijima Cyuo Hospital: N. Kijima, MD. Imagawa Hospital: T. Inoyama, MD. Yao Municipal Hospital: S.Yoneda, MD. Kijima Hospital Honin: H. Kijima, MD. Toho Yao Hospital: T. Umada, MD. Yao Eiwakai Hospital: K. Ozaki, MD. Meiwa Kinen Hospital: T. Katou, MD.
References
Aho K, Harmsen P, Hatano S, Marquardsen J, Smirnov VE, Strasser T. Cerebrovascular disease in the community: results of a WHO collaborative study. Bull World Health Organ. 1980; 58: 113–130.
Tanaka H, Ueda Y, Date C, Baba T, Yamashita H, Hayashi M, Shoji H, Owada K, Baba KI, Shibuya M, Kon T, Detels R. Incidence of stroke in Shibata, Japan: 1976–1978. Stroke. 1981; 12: 460–466.
Komachi Y, Tanaka H, Shimamoto T, Handa K, Iida M, Isomura K, Kojima S, Matsuzaki T, Ozawa H, Takahashi H, Tsunetoshi Y. A collaborative study of stroke incidence in Japan: 1975–1979. Stroke. 1984; 15: 28–36.
Ueda K, Hasuo Y, Kiyohara Y, Wada J, Kawano H, Kato I, Fujii I, Yanai T, Omae T, Fujishima M. Intracerebral hemorrhage in a Japanese community, Hisayama: incidence, changing pattern during long-term follow-up, and related factors. Stroke. 1988; 19: 48–52.
Suzuki K, Kutsuzawa T, Takita K, Ito M, Sakamoto T, Hirayama A, Ito T, Ishida T, Ooishi H, Kawakami K, Hirota K, Ogasawara T, Yoshida J, Tamura T, Hattori S, Iwabuchi S, Karouji Y, Waga T, Oosato Y, Yazaki K, Saito T, Oouchi T, Kojima S. Clinico-epidemiologic study of stroke in Akita, Japan. Stroke. 1987; 18: 402–406.
Sankai T, Miyagaki T, Iso H, Shimamoto T, Iida M, Tanigaki M, Naito Y, Sato S, Kiyama M, Kitamura A, Konishi M, Terao A, Doi M, Komachi Y. A population-based study of the proportion by type of stroke determined by computed tomography scan (in Japanese with English abstract). Nippon Koshu Eisei Zasshi. 1991; 38: 901–909.
Kubo M, Kiyohara Y, Kato I, Tanizaki Y, Arima H, Tanaka K, Nakamura H, Okubo K, Iida M. Trends in the incidence, mortality, and survival rate of cardiovascular disease in a Japanese community: the Hisayama study. Stroke. 2003; 34: 2349–2354.
Mohr JP, Caplan LR, Melski JW, Goldstein RJ, Duncan GW, Kistler JP, Pessin MS, Bleich HL. The Harvard Cooperative Stroke Registry: a prospective registry. Neurology. 1978; 28: 754–762.
Gross CR, Kase CS, Mohr JP, Cunningham SC, Baker WE. Stroke in south Alabama: incidence and diagnostic features–a population based study. Stroke. 1984; 15: 249–255.
Foulkes MA, Wolf PA, Price TR, Mohr JP, Hier DB. The Stroke Data Bank: design, methods, and baseline characteristics. Stroke. 1988; 19: 547–554.
Walker AE, Robins M, Weinfeld FD. The National Survey of Stroke. Clinical findings. Stroke. 1981; 12 (suppl 1): I13–I44.
Iso H, Rexrode K, Hennekens CH, Manson JE. Application of computer tomography-oriented criteria for stroke subtype classification in a prospective study. Ann Epidemiol. 2000; 10: 81–87.
Anderson CS, Jamrozik KD, Burvill PW, Chakera TM, Johnson GA, Stewart-Wynne EG. Determining the incidence of different subtypes of stroke: results from the Perth Community Stroke Study, 1989–1990. Med J Aust. 1993; 158: 85–89.
Korean Neurological Association. Epidemiology of cerebrovascular disease in Korea—a collaborative study, 1989–1990. J Korean Med Sci. 1993; 8: 281–289.
Lauria G, Gentile M, Fassetta G, Casetta I, Agnoli F, Andreotta G, Barp C, Caneve G, Cavallaro A, Cielo R, Mongillo D, Mosca M, Olivieri P. Incidence and prognosis of stroke in the Belluno province, Italy. First-year results of a community-based study. Stroke. 1995; 26: 1787–1793.
Carolei A, Marini C, Di Napoli M, Di Gianfilippo G, Santalucia P, Baldassarre M, De Matteis G, di Orio F. High stroke incidence in the prospective community-based L’Aquila registry (1994–1998). First year’s results. Stroke. 1997; 28: 2500–2506.
Kolominsky-Rabas PL, Sarti C, Heuschmann PU, Graf C, Siemonsen S, Neundoerfer B, Katalinic A, Lang E, Gassmann KG, von Stockert TR. A prospective community-based study of stroke in Germany–the Erlangen Stroke Project (ESPro): incidence and case fatality at 1, 3, and 12 months. Stroke. 1998; 29: 2501–2506.
Vemmos KN, Bots ML, Tsibouris PK, Zis VP, Grobbee DE, Stranjalis GS, Stamatelopoulos S. Stroke incidence and case fatality in southern Greece: the Arcadia stroke registry. Stroke. 1999; 30: 363–370.
Pajunen P, Paakkonen R, Hamalainen H, Keskimaki I, Laatikainen T, Niemi M, Rintanen H, Salomaa V. Trends in fatal and nonfatal strokes among persons aged 35 to 85 years during 1991–2002 in Finland. Stroke. 2005; 36: 244–248.
Thrift AG, Dewey HM, Macdonell RA, 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.
Lavados PM, Sacks C, Prina L, Escobar A, Tossi C, Araya F, Feuerhake W, Galvez M, Salinas R, Alvarez G. Incidence, 30-day case-fatality rate, and prognosis of stroke in Iquique, Chile: a 2-year community-based prospective study (PISCIS project). Lancet. 2005; 365: 2206–2215.
Jiang B, Wang WZ, Chen H, Hong Z, Yang QD, Wu SP, Du XL, Bao QJ. Incidence and trends of stroke and its subtypes in China: results from three large cities. Stroke. 2006; 37: 63–68.
The Ministry of Health, Labour and Welfare. A Report of The Fifth National Survey of Cardiovascular Diseases (in Japanese). Tokyo, Japan: Chuohoki Syuppan; 2003: 45–190.
National Center for Health Statistics. Health, United States, 2004 With Chartbook on Trends in the Health of Americans. Hyattsville, Md: National Center for Health Statistics; 2004: 213–244.
Tanizaki Y, Kiyohara Y, Kato I, Iwamoto H, Nakayama K, Shinohara N, Arima H, Tanaka K, Ibayashi S, Fujishima M. Incidence and risk factors for subtypes of cerebral infarction in a general population: the Hisayama study. Stroke. 2000; 31: 2616–2622.
Kimura K, Kazui S, Minematsu K, Yamaguchi T. Japan Multicenter Stroke Investigator’s Collaboration. Analysis of 16 922 patients with acute ischemic stroke and transient ischemic attack in Japan. A hospital-based prospective registration study. Cerebrovasc Dis. 2004; 18: 47–56.