Contour Maps of Leading Causes of Death: an Overview of the Italian Epidemiological Transition in the XX Century
In 1971, following the unprecedented increase in life expectancy in developed countries, Abdel Omran put forward a theory describing for the first time the decrease of infectious diseases, which had gradually been replaced by chronic diseases. It was labelled “epidemiological transition” and, initially, comprised the following stages: 1) The “age of pestilence and famine”, dominated by recurrent mortality crises when life expectancy at birth was more or less 30 years (a phase indicated in the mortality transition pattern as “pre-transitional”); 2) the “age of receding pandemics”, during which some infectious diseases became less important and the sharp decline in mortality in the early years of life brought life expectancy to 50 years (start of the mortality transition); 3) the “age of degenerative diseases”, is characterized by the predominance of chronic diseases and the stabilization of mortality at a low level (end of the mortality transition period).
According to Omran, with the third age the advances in life expectancy in the mid-1960s slowed down or, in some cases, stopped, with the rise of new endemic diseases, whether degenerative (e.g. cardiovascular diseases, cancers, diabetes, metabolic disorders). France Meslé and Jaques Vallin consider Omran’s division into three ages as accurately reflecting reality up until the end of the 1960s, when he wrote his first article – a period in which the improvements in life expectancy were slowing down, particularly for men.
However, events swiftly belied Omran’s model. From the early 1970s on, life expectancy in all western countries once again began to increase for men too, driven by a clear reduction in mortality for cardiovascular diseases. Following these new behaviours and the resulting increase in survival, Jay Olshansky and Brian Ault, and Richard Rogers and Robert Hackenberg imagined a “fourth phase” of epidemiological transition. The first two authors suggested that the mortality model by cause had remained the same because the age of death had shifted forward, while the second two spoke rather of the start of a new era, where the most important advances in survival had been and would be achieved thanks to the reduction in mortality brought about by the adoption of new and healthier life styles.