Fries' hypothesis of morbidity compression asserts that the length of lifetime spent in states of chronic disease and disability is decreasing. This can be explained by improved living and working conditions and by successful primary prevention.
Using the available studies on morbidity compression it is examined whether the lengths of periods spent in states of morbidity have changed in the last decades.
For multimorbidity, chronic diseases, cognitive impairment, and for subjective health the developments are in favour of the morbidity compression hypothesis. The conclusions are nevertheless dependent on the type of health impairment considered.
There is evidence that morbidity compression has taken place in the last decades. Depending on the disease, morbidity expansion and dynamic equilibrium may also have occurred. A comprehensive assessment of the development of morbidities is only possible if more diseases are considered. In addition, there is evidence that outside of Europe and the USA morbidity patterns may also develop in other directions.