Heart disease, cancer, and stroke mortality trends and their interrelations. An international perspective

Changes in mortality from heart disease, cancer, and stroke over recent decades in many countries have received much attention. However, comprehensive and concurrent analyses of these trends and their effect on total mortality have been lacking. Moreover, the extent to which the trends for one disease may relate to those for another disease is unknown. Concordance of trends for major diseases would suggest that they have common causes and thus may be responsive to the same preventive measures.

Age-adjusted death rates for total mortality and mortality from heart disease, stroke, lung cancer, and cancer other than lung cancer were obtained for the years 1950 to 1987 in 27 countries by sex and ages 35 to 74 years from the World Health Organization statistical reports. Concordance of mortality trends was assessed for ages 35 to 74 between 1950 and 1983 through visual inspection and semiquantitative measurements of percentage change over time. The epidemic increase in heart disease mortality ended in the 1960s or 1970s in most industrialized countries; death rates often declined very steeply. Stroke mortality also changed from an increase to a decline or from a modest to a steep decline in the 1960s or 1970s. Lung cancer mortality slopes generally changed from a steep increase to either a modest increase, a flat trend, or a decline; the changes in slope are lagging behind those for heart disease and stroke. These improvements influenced trends for total mortality. Cancer other than lung cancer trends are less distinct than those for the three other causes of mortality. Yet, testing them for concordance with heart disease trends reveals that they are mostly concordant on a time-lag analysis that assumes that heart disease responds more rapidly to a change in lifestyle or environment than cancer. Trends for heart disease and lung cancer in men also tend to be concordant on time-lag analysis. Heart disease and stroke trends have become more concordant with time.

Trends for mortality from heart disease, stroke, lung cancer, and, less distinctly, cancer other than lung cancer, tend to be similar in different countries, leading to a corresponding similarity in total mortality trends. An analysis of trends for pairs of diseases within countries indicates a tendency toward concordance of trends, suggesting the existence of common causes amenable to the same preventive measures. This analysis of international mortality trends is intended to stimulate further research along these lines, as a guide to preventive and therapeutic action.