World War II Effects on Prevalence and Pattern of Multimorbidity in Older Adults: Results From the KORA-Age Study

Background: While risk factors for age-related diseases may increase multimorbidity (MM), early life deprivation may also accelerate the development of chronic diseases and MM. Methods: This study explores the prevalence and pattern of MM in 65-71 year-old individuals born before, during, and after World War II in Southern Germany based on two KORA (Cooperative Health Research in the Region of Augsburg) -Age studies. MM was defined as having at least two chronic diseases, and birth periods were classified into five phases: pre-war, early war, late war, famine, and after the famine period. Logistic regression models were used to analyze the effect of the birth phases on MM with adjustment for sociodemographic and lifestyle risk factors. Furthermore, we used agglomerative hierarchical clustering to investigate the co-occurrence of diseases. Results: Participants born during the late war phase had the highest prevalence of MM (62.2%) and single chronic diseases compared to participants born during the other phases. Being born in the late war phase was significantly associated with a higher odds of MM (OR = 1.83, 95% CI: 1.15-2.91) after adjustment for sociodemographic and lifestyle factors. In women, the prevalence of joint, gastrointestinal, eye diseases, and anxiety was higher, while heart disease, stroke, and diabetes were more common in men. Moreover, three main chronic disease clusters responsible for the observed associations were identified: joint and psychosomatic, cardiometabolic and, internal organs diseases. Conclusions: Our findings imply that adverse early-life exposure may increase the risk of MM in adults aged 65-71 years. Moreover, identified disease clusters are not coincidental and require more investigation.