Mortality studies

Abstract The aim of preventive medicine is to stop the cause of illness as soon as possible. So, if the study group itself is to benefit from the results, the disease state should be in an early phase. Many published reports in occupational medicine concern mortality studies. In a follow-up study, the mortality due to a specific disease can be studied. If mortality rates among the exposed are compared with (divided by) the mortality rate for non-exposed, relative mortality rates are calculated (instead of relative morbidity rates). Often you find the term SMR (standardized mortality ratio) used in these studies, meaning that the rates are adjusted (standardized) for age-differences in the two groups compared. The SMR value gives the excess mortality in percentages. An SMR value of 130 means an excess mortality rate among the exposed of 30 percent.