Understanding Morbidity Change: Reply to Riley

Abstract

1992) for understanding morbidity change. Among the more contentious issues, Riley challenges the importance of the distinction between self-perceived morbidity and observed morbidity. He then claims that the duration of disease episodes is on average increasing. This increase is framed in terms of the epidemiological transition (Omran, 1971). According to Riley, the distinction between self-perceived and observed morbidity is false. Because self-perceived morbidity is partially informed by expert opinion, the difference between self-perceived and observed morbidity cannot be maintained. Yet, the evidence presented in our article is hard to refute. Self-reported and observed rates of various diseases do differ both in developing and developed communities. The existence of this difference was in a large part the motivation for our conceptual framework. The distinction between selfperceived and observed morbidity depends critically on the type of morbidity. We identified three types: morbidity that can be observed but not perceived, such as hypertension; morbidity that can be perceived but not observed, such as pain; and morbidity that can be observed and perceived, such as retinopathy. Clearly, the first category of morbidity can only be self-reported after contact with health services. The extensive literature on untreated and often undiagnosed hypertension in black Americans is testament to the importance of access to health services in influencing self-reported morbidity even in a high-income society. The second category of morbidity depends exclusively on self-perception. Observations of pain are essentially based on patient history. There is no battery of tests to detect the degree of pain or suffering. The often wide variance between self-reported and observed levels of the third type of morbidity requires the most explanation. Self-perceived morbidity is a complex function of observed morbidity, health expectations, contact with health services or other sources of health knowledge, and the social and cultural context. Riley appears to share our belief in the complex set of determinants of self-perceived and self-reported morbidity. His argument could be reformulated to state that over time, through exposure to expert opinion, self-perceived and