offered one of the most important cause-of-death models as part of the 1990 global burden of disease study. their "cause of death" patterns sought to describe the fraction of deaths attributed to a set of mutually exclusive and collectively exhaustive causes. they divided diseases into three cause groups and made several important observations: group 1 - communicable, maternal, perinatal, and nutritional: these causes of death decline much faster than overall mortality and comprise a small fraction of deaths in wealthier countries. group 2 - non-communicable diseases: these causes of death are a major challenge for countries that have completed or nearly completed the epidemiological transition. group 3 - injuries: this cause of death is most variable within and across different countries and is less predictive of all-cause mortality. the regression approach underlying the global burden of disease received some critique in light of real-world violations of the model's "mutually exclusive and collectively exhaustive" cause attribution. building on the existing body of evidence, salomon and murray (2002), further add nuances to the traditional theory of epidemiological transition by disintegrating it based on disease categories and different age-sex groups, positing that the epidemiological transition entails a real transition in the cause composition of age-specific mortality, as opposed to just a transition in the age structure. using global burden of disease data from 1990, they disintegrate the transition across three cause groups: communicable diseases, non-communicable diseases and injuries, seeking to explain the variation in all-cause mortality as a function of cause-specific mortality in 58 countries from 1950 to 1998. this analysis validates the underlying premise of the classic epidemiological transition theory: as total mortality declines and income rises, communicable diseases cause less and less mortality compared to non-communicable diseases and injuries. decomposing this overall impact by age-sex groups, they find that for males, when overall mortality decreases, the importance of non-communicable diseases (ncds) increases relative to the other causes with an age-specific impact on the role of injuries, whereas for women, both ncds and injuries gain a more significant share with mortality decreases. for children over one year, they find that there is a gradual transition from communicable to non-communicable diseases, with injuries remaining significant in males. for young adults, the epidemiological transition is particularly different: for males, there is a shift from injuries to ncds in lower income settings, and the opposite in higher-income settings; for females, rising income also signifies a shift from ncds to injuries, but the role of injuries becomes more significant over time compared to males. finally, for both males and females over 50, there is no epidemiological transition impact on the cause composition of mortality. current evidence 25 most common gbd level 3 causes of global dalys for both sexes combined, 1990, 2005, and 2013, with age-standardised median percentage change. ranks are based on the number of dalys. 95% uis for mean rank are from 1000 draws of dalys. communicable, maternal, neonatal, and nutritional disorders causes are shown in red, non-communicable causes in blue, and injuries in green. daly=disability-adjusted life-years. gbd=global burden of disease. ui=uncertainty interval. copd=chronic obstructive pulmonary disease. the majority of the literature on the epidemiological transition that was published since these seminal papers confirms the context-specific nature of the epidemiological transition: while there is an overall all-cause mortality decline, the nature of cause-specific mortality declines differs across contexts. increasing obesity rates in high-income countries are further confirming the epidemiological transition theory as the epidemic leads to an increase in ncds. the picture is more nuanced in low- and middle-income countries, where there are signs of a protracted transition with the double burden of communicable and noncommunicable disease. a recent review of cause-specific mortality rates from 12 low- and middle-income countries in asia and sub-saharan africa by santosa and byass (2016) shows that broadly, low- and middle-income countries are rapidly transitioning to lower total mortality and lower infectious disease mortality. a more macro-level analysis from the global burden of disease data conducted by murray and others (2015) finds that while there is a global trend towards decreasing mortality and increasing ncd prevalence, this global trend is being driven by country-specific effects as opposed to a broader transition; further, there are varying patterns within and between countries, which makes it difficult to have a single unified theory of epidemiological transition. a theory of epidemiological transition aimed at explaining not just describing changes in population disease and mortality profiles would need to encompass the role in different morbid conditions of infectious diseases contracted over the life course. the concept of linear transition from infectious diseases to other conditions referred to as degenerative or non-communicable, was based on a false dichotomy as common microorganisms have now been confirmed as causal agents in several conditions recorded as the underlying cause of many deaths. a revised transition model might focus more on disease aetiology and the determinants of cause-specific mortality change, while encompassing the possibility that infectious causation may be established for other morbid conditions through the vast amount of ongoing research into associations with infectious diseases.