Risk Factors Affecting Multiple-Disease Efficacy and Effectiveness of Intervention Programs

An important issue in public health planning is the assessment of efforts to reduce the mortality, disability, and morbidity associated with chronic diseases through the modification and control of life-style, occupational, and environmental risk factors. Evaluation of the effects of a health intervention for chronic diseases, however, is complicated for two reasons. First, the simultaneous action of the health intervention with other factors such as changes in population composition, in the distribution of different risk factors, and so forth, may mask the health effects of the intervention. For example, an intervention may serve only to partially offset the negative effects of, for example, an aging population. Without proper adjustment in the analysis for these simultaneous effects, the intervention may be interpreted to actually have had negative effects on health. Second, the positive effects of the intervention may take many years before they become manifest. One reason for this lag is that the intervention must first diffuse through the population. As documented in both sociological and anthropological studies, the diffusion process may be slow, with the desired changes in population health behavior not visible for many years. This lag period is further increased because, even after the contents of the intervention program have been diffused, the resulting behavioral changes do not immediately improve the individual’s health. For example, a smoking cessation program may take years before significant numbers of individuals quit. Then, after quitting, there is still a period of time before the physiological benefits produced by smoking cessation become manifest.