SAINTE-FOY, QUEBEC-Smoking cessation, a potent but often underused strategy, should play a larger role in primary prevention efforts to reduce mortality and morbidity due to chronic obstructive pulmonary disease (COPD). The latest results from an epidemiologic study in Canada spell out the scope of the COPD problem--consistently high prevalence rates in the population at large and an alarming rise in COPD-associated mortality among women during a 15-year period.¹

More attention should be given to a patient's smoking habits and history, according to Yves Lacasse, MD, one of the principal study investigators. In fact, smoking behavior should be considered a vital sign, accorded the same importance in the physical examination as measurement of blood pressure or pulse rate because of its long-term consequences for COPD and potentially devastating sequelae, Dr. Lacasse suggested in a recent interview with Pulmonary Reviews. "I include smoking behavior as a vital sign in my examination of any patient because I consider it so essential. A number of researchers have also recommended that this practice be followed."

It is particularly important to address the smoking behavior of teenagers, said Dr. Lacasse, because smoking cessation could have a significant impact in preventing the sequelae of COPD much later in life. Primary prevention among teenagers through strong media campaigns is essential, according to Dr. Lacasse, because that is most likely to influence trends in the epidemiology of the disease.

The National Health Survey found that 750,000 Canadians had chronic bronchitis or emphysema diagnosed by a health professional. Asthma was excluded from the analysis. When the population was divided by age-group, the following rates of chronic bronchitis or emphysema were found: 55 to 64 years, 4.6%; 65 to 74 years, 5.0%; and 75 years and older, 6.8%. Concern about the adequacy of prevention strategies is based on data for mortality related to COPD. From 1980 to 1995, the total number of deaths from COPD in Canada increased from 4,438 to 8,583 per year. These numbers, however, become more significant when gender-related differences in mortality are considered. Although the age-standardized mortality rate remained approximately the same for men (hovering around 45 per 100,000 population), that rate doubled for women, increasing from 8.3 per 100,000 in 1980 to 17.3 per 100,000 in 1995.

This difference in the mortality rates between men and women is related to their smoking practices. Given that women began smoking in the 1950s (two or three decades after men had begun) and given the lag between smoking and death from COPD, the rise in COPD mortality would be expected to show up later in women. The results from the Canadian study essentially confirmed what other studies have reported--that mortality rates had leveled off in men but had continued to rise in women. But this epidemiologic trend--noted in the late 1970s and during the 1980s in Canada--needed confirmation over a longer period.

To assess the validity of the earlier trends, Dr. Lacasse and his team analyzed data gathered by Statistics Canada in 1994-1995 for the National Population Health Survey. This survey was conducted in order to depict the health of the Canadian population. From the results of this survey, Dr. Lacasse conducted a secondary survey focusing on COPD. The researchers surveyed a total of 17,626 individuals. Prevalence rates of COPD were determined from the response to the question, "Do you have chronic bronchitis or emphysema diagnosed by a health professional?" Mortality rates were derived from information on the cause of death coded and tabulated in the Statistics Canada National Mortality Database. Morbidity statistics were based on hospital data retrieved by Statistics Canada from hospital medical records departments. These departments identified "hospital separations," each of which represented the end point of one continuous stay in the hospital: discharge, death, or transfer to another institution. Outpatient records were not examined as part of this analysis.

The researchers found that COPD has continued to affect men more than women, as demonstrated by the higher disease prevalence among men in all three of the age categories for which data were available. In addition, COPD mortality, as a percentage of all deaths, continues to rise. In 1980, for example, COPD was responsible for 2.6% of all deaths in Canada; and by 1995, it accounted for 4.1% of all-cause mortality. This rise in mortality was striking in women, among whom deaths related to COPD shot up by 241%--from 967 in 1980 to 3,295 in 1995. The total number of hospital cases in which COPD was a primary diagnosis rose by 32%--from 42,102 in 1980 to 55,785 in 1995. Once again, gender was a key factor because the analysis found a 14% increase among men and a 67% increase among women.

Cigarette smoking is undoubtedly the most important cause of COPD, Dr. Lacasse and his colleagues emphasized. Although data from 1980 to 1990 showed a decline in smoking rates among young Canadians, this trend has since reversed. The increase in the incidence of younger smokers since 1990 will likely lead to a rise in the mortality and morbidity from COPD over the next 40 years, according to the study authors.

The outlook is especially grim for older Canadians, considering that from 1984 to 1993 COPD was the fourth highest cause of mortality and hospitalization among male Canadians age 65 years and older. Furthermore, these mortality and morbidity figures do not take into account the true impact of the disease and its related sequelae--marked impairment and disability. Other factors contributing to the burden of the disease but not included in the epidemiologic data were the costs of medications, work absenteeism, early retirements, and overall quality of life.

Unfortunately, prevention campaigns have been relatively unsuccessful. The programs aimed at children and teenagers have focused on the potential long-term health consequences of smoking, but that strategy appears to be ineffective, particularly in the target population, suggested the study authors.² Instead, Dr. Lacasse and his team urge a more aggressive approach at primary prevention. Curbing cigarette smoking, they said, is critical. They also stressed secondary prevention strategies, including early detection and intervention for those at risk for the late consequences of COPD and the use of effective therapies in reducing the complications of COPD.

-Stu Chapman

References
1. Lacasse Y, Brooks D, Goldstein RS. Trends in the epidemiology of COPD in Canada, 1980 to 1995. Chest. 1999;116:306-313.
2. Goldman LK, Glantz SA. Evaluation of antismoking advertising campaigns. JAMA. 1998;279:772-777.