Fact Sheet: Cardiovascular Disease (ICD-9 390

Volume 17, No.1 -1997

[Table of Contents]

Fact Sheet:
Cardiovascular Disease (ICD-9 390-448) and Women
Oona Hayes (Laboratory Centre for Disease Control)

Cardiovascular disease (CVD) is the major cause of death and disability among Canadian women. It is also a major cause of premature death, with mortality rates increasing significantly in postmenopausal women. During the period 1991-1993, 111,418 women died from CVD in Canada; it was responsible for 41% of all deaths among women aged 20 or older.(a)

Coronary heart disease (CHD) [ICD-9 410-414, 429.2] and stroke (ICD-9 430-438) made up the bulk of cardiovascular mortality, accounting for 76% of these deaths over the same time period. These two conditions rank first and second for all-cause mortality in women by specific disease.

As Figure 1 shows, the "other" category of cardiovascular disease constituted almost one quarter of all cardiovascular deaths among adult females between 1991 and 1993. This category includes conditions such as hypertensive disease, rheumatic fever and diseases of the arteries, arterioles and capillaries.

Social and Economic Burden

In 1991, CVD in women was responsible for more than four million hospital days, more than any other condition, including cancer, pregnancy and neurological ailments. Strokes were responsible for more than double the hospital days of coronary heart disease. Women spend more days in hospital due to stroke than do men.

In 1993, CVD in women was estimated to account for 6% (over $2.7 billion) of the total direct costs of disease to Canadian society that could be categorized by disease and sex (i.e. costs of drugs, physicians, hospitals and research), with CHD costs forming a larger proportion than those of stroke.1 This dollar value is an underestimate of the total economic burden of CVD, as it does not account for the direct economic costs that cannot be broken down by disease category and sex, nor does it include the indirect economic costs of the disease, notably the loss of future income due to premature mortality and the cost of disability.

Potential years of life lost (PYLL) is a measure of the prematurity of death. From 1991 to 1993, CVD was responsible for more than 260,000 PYLL before age 75, following all cancers and accidents, poisonings and violence in magnitude. In the same period almost 130,000 PYLL were attributable to CHD, ranking it third after breast and lung cancers. Stroke ranks 10th overall among specific diseases for PYLL before age 75, accounting for over 61,000 PYLL between 1991 and 1993 (Figure 2).

Age Differences

Both CHD and stroke mortality rates increase in women around age 45 (Figure 3). There is growing consensus that this is due to the loss of the protective effect of estrogen after menopause.2-4 There is an earlier increase in mortality among males starting at about age 35.

Time Trends

Both CHD and stroke mortality rates have decreased since 1950 in women aged 30 and over. Figure 4 depicts these rates for both sexes from 1979 to 1993.

Regional Differences CHD shows a consistent geographic trend: mortality rates for women aged 30 and over are higher in the east and then gradually decline moving west (Figure 5). Stroke rates seem to show the opposite geographic trend, though not as pronounced as for CHD, with female mortality rates for the same age group being generally higher in the west (Figure 6).

International Comparisons

Canadian women's CHD rates are average compared to those of other industrialized nations and high compared to those of developing nations.2,5 On the other hand, female stroke rates in Canada are consistently lower than those in other countries.2,6 In 1989, Canadian women had the fourth lowest stroke mortality rates of 52 industrialized and developing countries.

Risk Factors

Age is a strong risk factor for CVD overall, and especially for stroke after menopause.7 Genetics and a family history of CVD may also increase risk in women.

Smoking is the most important risk factor for CHD; the risk also shows a dose-response relationship (Table 1). For stroke, hypertension is the major risk factor. Cholesterol levels above 5.2 mmol/L are a strong risk factor for stroke in women at age 30, but are a weak risk factor at age 80. Also, diabetes seems to affect CHD and stroke rates more in women than in men.3,7,19

The following factors also contribute to the risk of CVD in women: overweight (body mass index >25),20-23 sedentary lifestyle,24,25 stress,3,20,22 menopause (either surgical or natural) and diet.20

There is a tendency for the risk factors for CVD to cluster and positively affect each other; for example, low socio-economic status is correlated with overweight, sedentary lifestyle and hypertension.26 Because of this cluster effect, it is difficult to assess the impact of individual relative risks.

Mortality rates for CVD show a sharp socio-economic gradient, with higher rates in the lower socio-economic group.26,27

(a) Unless otherwise indicated, all statistics are based on calculations performed on data provided by Statistics Canada.

TABLE 1 Relative risk (RR) of coronary heart disease (CHD) and stroke by risk factor
Risk factor	RR of CHD	RR of stroke
SMOKING
Current^3,7–10
<15 cigs/day	Low	Low
>15 cigs/day	High	Med–high
Former⁸	Low	Low
Passive^3,11	Low–med	N/A
HYPERTENSION^7,9,12	Med–high	High
DIABETES^9,13	Med–high	Med
USE OF ORAL CONTRACEPTIVES
Current^9,14	Low	Low–med
Past^9,15	Low	Low
While smoking^9,16	Very High	Low
HIGH CHOLESTEROL^9,17,18	Med–high	Low–high
RISK CATEGORIES
Low : RR = 1,0–1,9 Medium : RR = 2,0–4,0 High : RR > 4,0 Very High: RR > 20,0		+

Acknowledgements

The author would like to acknowledge gratefully the input and comments of Dr Safia Wasi of the Heart and Stroke Foundation of Canada and Dr Gregory Taylor of Health Canada's Laboratory Centre for Disease Control.

References

1. Moore R, et al. Economic burden of illness in Canada, 1993. Chronic Dis Can. In press.

2. Khaw K-T. Women, hormones and blood pressure. Proceedings of the World Conference on Hypertension Control; 1995 June 21-4; Ottawa. Can J Cardiology Suppl. In press.

3. Johansen H, Nargundkar M, Nair C, Neutel I, Wielgosz A. Women and cardiovascular disease. Chronic Dis Can 1990;11(3):41-7.

4. Barrett-Connor E, Bush TL. Estrogen and coronary heart disease in women. JAMA 1991;265(14):1861-7.

5. Promoting heart health-report of the chief medical officer of health. Toronto: Queen's Printer of Ontario, 1993.

6. Bonita R, Stewart A, Beaglehole R. International trends in stroke mortality: 1970-1985. Stroke 1990;21(7):989-92.

7. Eaker ED, Chesebro JH, Sacks FM, Wenger NK, Whisnant JP, Winston M. Cardiovascular disease in women. Circulation 1993;88(4 Pt 1):1999-2009.

8. Collishaw NE, Leahy K. Mortality attributable to tobacco use in Canada, 1989. Chronic Dis Can 1991;12(4):46-9.

9. Brezinka V, Padmos I. Coronary heart disease risk factors in women. Eur Heart J 1994;15:1571-84.

10. Kawachi I, et al. Smoking cessation and decreased risk of stroke in women. JAMA 1993;269(2):232-6.

11. Humble C, Croft J, Gerber A, Casper M, Hames CG, Tyroler HA. Passive smoking and 20-year cardiovascular disease mortality among nonsmoking wives, Evans County, Georgia. Am J Public Health 1990;80(5):599-601.

12. MacMahon S, et al. Blood pressure, stroke and coronary heart disease Part 1. Lancet 1990;335:765-74.

13. Manson JE, et al. A prospective study of maturity onset diabetes mellitus and risk of coronary heart disease and stroke in women. Arch Intern Med 1991;151(6):1141-7.

14. Hannaford PC, Croft PR, Kay CR. Oral contraception and stroke. Evidence from the Royal College of General Practitioners' Oral Contraception Study. Stroke 1994;25(5):935-42.

15. Thorogood M, Mann J, Murphy M, Vessey M. Fatal stroke and use of oral contraceptives: findings of a case control study. Am J Epidemiol 1992;136(1):35-45.

16. Wilson E. Enhancing smoke-free behaviour: prevention of stroke. Health Reports 1994;6(1):100-5. (Statistics Canada Cat 82-003).

17. Grundy SM. Cholesterol and coronary heart disease. JAMA 1986;256(20):2849-58.

18. Lindenstrøm E, Boysen G, Nyboe J. Influence of total cholesterol, high density lipoprotein cholesterol, and triglycerides on risk of cerebrovascular disease: the Copenhagen City Heart Study. Br Med J 1994;6946(309):11-5.

19. US Department of Health and Human Services. Reducing the health consequences of smoking: 25 years of progress. A report of the Surgeon General. Rockville (MD): Public Health Service, Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health; 1989; DHHS Publ No (CDC) 89-8411.

20. US Department of Health and Human Services. Heart disease and women: are you at risk? National Heart, Lung and Blood Institute, 1994.

21. National Heart, Lung and Blood Institute. The cardiovascular health of women. Heart Memo 1994; Special edition:1-26.

22. Alexander LL, Larosa JH. New dimensions in women's health. Jones and Bartlett, 1994.

23. Willett WC, et al. Weight, weight change and coronary heart disease in women. Risk within the normal weight range. JAMA 1995;273(6):461-5.

24. Blair SN, Kohl HW, Paffenbarger RS Jr, Clark DG, Cooper KH, Gibbons LW. Physical fitness and all-cause mortality. JAMA 1989;262(17):2395-401.

25. Yeager KK, Anda RF, Macera CA, Donehoo RS, Eaker ED. Sedentary lifestyle and state variation in coronary heart disease mortality. Public Health Rep 1995;110(1):100-2.

26. Millar WJ, Wigle DT. Socio-economic disparities in risk factors for cardiovascular disease. Can Med Assoc J 1986;134:127-32.

27. Diez-Roux AV, Nieto FJ, Tyroler HA, Crum LD, Szklo M. Social inequalities and atherosclerosis. The atherosclerosis risk in communities study. Am J Epidemiol 1995;141(10):960-72.

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