Relevance between age of onset and hospitalization characteristics of Major Depressive Disorders: A 16 years retrospective cohort study

Age of onset (AOO) influences the prognosis of many diseases and even serves as potential driver. But in Major Depressive Disorder, there is no consensus regarding the effect of AOO on the course. In this study, a total of 38,671 inpatients were surveyed over 16 years, and 6113 inpatients were eventually included in the statistical analysis after applying rigorous data criteria. Inpatients were divided into four AOO subgroups: adolescent onset, early adult onset, middle adult onset, and late adult onset. In the subset of first hospitalization (n = 4884), the differences in the length of stay between several AOO subgroups were statistically significant (F = 56.852, df1 = 3, df2 = 4880, P