Evaluation of the factor structure and psychometric properties of the brief symptom inventory—18 with homebound older adults

Abstract

Homebound older adults are at high risk for depression and anxiety. Systematic screening may increase identification of these difficulties and facilitate service usage. The purpose of this study was to investigate the factor structure, internal consistency, and concurrent validity of the Brief Symptom Inventory-18 (BSI-18) for use as a screening instrument for depression and anxiety with homebound older adults and to examine if the BSI-18 could be shortened further and exhibit comparable psychometric properties. A sample of 142 older adults receiving in-home aging services completed interviews that included the BSI-18 and the depression and anxiety modules of the structured clinical interview for DSM-IV. Confirmatory factor analysis showed that the theorized three-factor, second-order model of the BSI-18 fit the data well (S-B X(2) = 136.17; p = 0.36). The depression and anxiety subscales exhibited high internal consistency (alpha > 0.81), whereas the somatic subscale exhibited lower internal consistency (alpha = 0.69). Receiver operator curve (ROC) analyses suggest that the BSI-18 depression and anxiety subscales were able to predict those with DSM-IV diagnoses (Depression AUC = 0.89 p < 0.001; Anxiety AUC = 0.80, p < 0.001). The ROC results suggested adapting a cut score of T = 50 to achieve optimal sensitivity and specificity. The short three-item depression scale exhibited comparable psychometric properties to the full scale, while the three-item somatic and anxiety scales exhibited lower internal consistency and sensitivity. These findings provide initial evidence that the BSI-18 is valid for use with homebound older adults.