Incidence and prognostic implications of stable angina pectoris among women and men

Abstract

Context: Stable angina pectoris in women has often been considered a "soft" diagnosis, with less-severe prognostic implications than in men, but large-scale population studies are lacking.

Objective: To determine sex differences in the incidence and prognosis of stable angina in a large ambulatory population.

Design: Prospective cohort study using linked national registers.

Setting: All municipal primary health care centers, hospital outpatient clinics, occupational health care services, and the private sector in Finland.

Participants: Among ambulatory patients aged 45 to 89 years who had no history of coronary disease, we defined new cases of "nitrate angina" based on nitrate prescription (56,441 women and 34,885 men) or "test-positive angina" based on abnormal invasive or noninvasive test results (11,391 women and 15,806 men). Potentially eligible patients were evaluated between January 1, 1996, and December 31, 1998. Follow-up ended in December 2001.

Main outcome measures: Coronary mortality at 4 years (n = 7906 deaths) and fatal and nonfatal myocardial infarction at 1 year (n = 3129 events).

Results: The age-standardized annual incidence per 100 population of all cases of angina was 2.03 in men and 1.89 in women, with a sex ratio of 1.07 (95% confidence interval [CI], 1.06-1.09). At every age, nitrate angina in women and men was associated with a similar increase in risk of coronary mortality relative to the general population. Women with test-positive angina who were younger than 75 years had higher coronary-standardized mortality ratios than men; for example, among those aged 55 to 64 years, it was 4.69 (95% CI, 3.60-6.11) in women compared with 2.40 (95% CI, 2.11-2.73) in men (P<.001 for interaction). There was a strong, graded relationship between amount of nitrates used and event rates; women using higher doses of nitrates had prognoses comparable with those of men. Among patients with diabetes and test-positive angina, age-standardized coronary event rates were 9.9 per 100 person-years in women vs 9.3 in men (P = .69), and the fully adjusted male-female sex ratio was 1.07 (95% CI, 0.81-1.41).

Conclusions: Women have a similarly high incidence of stable angina compared with men. Furthermore, stable angina in women is associated with increased coronary mortality relative to women in the general population and, among easily identifiable clinical subgroups, has similarly high absolute rates of prognostic outcomes compared with men.