Norm values and psychometric properties of the brief symptom inventory-18 regarding individuals between the ages of 60 and 95

Objective: The SCL-90 and the SCL-90-R are the most applied measures regarding psychological distress. To reduce and prevent an overload to of the individuals, the Brief Symptom Inventory with 18 items (BSI-18) was developed based on the SCL-90. Since psychological disorders more frequently occur at an older age, there is a growing need for efficient instruments to measure distress in the elderly. However, the BSI-18's psychometric properties, norm values, and factorial structure have not yet been investigated in this age group. Methods: The aim of this study was to evaluate the BSI-18 in a sample of elderly people and to establish norm values for this specific population. Subsequently, demographic information and BSI-18 results were collected from a sample totaling 884 (55% female, mean age of 70.75years, SD = 7.08, age range = 60-95years). The questionnaire contains three six-item scales: somatization (SOMA), anxiety (ANX), and depression (DEPR), which form a general symptom index (GSI). Results: We found an acceptable to good model fit for a three-factor-model with a general GSI factor. The BSI-18's psychometric properties were satisfactory. Strict measurement invariance was shown for age and gender. Additionally, we found differences in psychological distress based on sociodemographic variables. Conclusions: These findings underline the growing need for preventive mechanisms for elderly people such as, e.g., (re)activating their social networks and strengthening their physical and psychological well-being.