Accounting for psychiatric conditions when defining multimorbidity among ethno-racial groups of students in higher education

Background Multimorbidity is often overlooked in young people. More research is needed to determine how it should be defined in this population and how including psychiatric conditions affects overall and race/ethnicity-specific prevalence estimates. Methods Using data from the Healthy Minds Study (N = 96,050; September 2020–June 2021)—a weighted, nonprobability sample of students aged 18–29 years—we estimated the prevalence of multimorbidity based on 13 physical and 10 psychiatric conditions. We also used multivariable logistic regression to examine associations between race/ethnicity and physical, psychiatric, mixed, and any multimorbidity. Results The prevalence of multimorbidity was 5.3% for physical, 26.5% for psychiatric, 14.2% for mixed, and 32.2% for any multimorbidity. By unweighted co-occurrence count, the most common pair-wise co-occurences were asthma and other chronic disease for physical conditions, anxiety and depression for psychiatric conditions, and anxiety and asthma for mixed conditions. Including psychiatric conditions substantially increased the prevalence of any multimorbidity, with the largest absolute increase among American Indian/Alaska Native students and White students. Conclusion This study explored the value of integrating physical and psychiatric conditions into a working definition of multimorbidity in a large sample of young adult students in higher education in the United States. The findings show how the operational definition of multimorbidity can differentially affect prevalence estimates across racial/ethnic groups.