Evolution of epidemiologic methods and concepts in selected textbooks of the 20th century.

Textbooks are an expression of the state of development of a discipline at a given moment in time. By reviewing eight epidemiology textbooks published over the course of a century, we have attempted to trace the evolution of five epidemiologic concepts and methods: study design (cohort studies and case-control studies), confounding, bias, interaction and causal inference. Overall, these eight textbooks can be grouped into three generations. Greenwood (1935) and Hill (first edition 1937; version reviewed 1961)'s textbooks belong to the first generation, "early epidemiology", which comprise early definitions of bias and confounding. The second generation, "classic epidemiology", represented by the textbooks of Morris (first edition 1957; version reviewed 1964), MacMahon & Pugh (first edition 1960; version reviewed 1970), Susser (1973), and Lilienfeld & Lilienfeld (first edition 1976; version reviewed 1980), clarifies the properties of cohort and case-control study designs and the theory of disease causation. Miettinen (1985) and Rothman (1986)'s textbooks belong to a third generation, "modern epidemiology", presenting an integrated perspective on study designs and their measures of outcome, as well as distinguishing and formalizing the concepts of confounding and interaction. Our review demonstrates that epidemiology, as a scientific discipline, is in constant evolution and transformation. It is likely that new methodological tools, able to assess the complexity of the causes of human health, will be proposed in future generations of textbooks.

Impaired renal function among children in Alexandria, Egypt.

OBJECTIVE: Impairment of renal function may occur as a result of a variety of conditions. Progression to chronic renal-disease may be prevented by early detection. This epidemiologic study aimed at revealing the predisposing factors and determinants for the development of impaired renal function among Egyptian children. METHODS: This is a case-control study conducted at Alexandria University Children's Hospital, Alexandria, Egypt. All cases below 12 years of age diagnosed with impaired renal function over a total duration of 6 months (October 1999 through to March 2000) were investigated. The primary study tool was a structured questionnaire, which focused on variables suspected to play a role in the impairment of renal function. For each patient, one control matched for age and sex was selected. RESULTS: Primary renal disease tends to account for a relatively small proportion of the etiologies of renal impairment in Egyptian children. Most of the cases encountered in this study suffered functional renal impairment secondary to severe dehydration or sepsis. Presence of congenital abnormalities of the gastrointestinal tract, heart or urinary tract, increased the possibility of suffering from impaired renal function approximately 9 times. Delays in seeking medical advice increased the risk substantially. CONCLUSION: Awareness of individuals at an increased risk, along with early diagnosis and adequate management of many predisposing conditions could prevent progression to more severe renal disease which has potentially devastating effects on every aspect of a childs' life.