Progressing the Death Literacy Index: the development of a revised version (DLI-R) and a short format (DLI-9).

Background: Since the development of the Death Literacy Index (DLI) in 2019 in Australia, subsequent internationally validated versions have prompted rewording and refinement of the original survey questions. Use of the DLI in the community has also resulted in requests for a short format. Objectives: To examine and report on the psychometric properties of a revised version of the DLI-R and develop a short format DLI-9. Design: A cross-sectional national survey was conducted for the validation of the revised DLI. Methods: The DLI items were revised by the research team using the international literature. DLI data were collected from a representative online non-probability panel of 1202 Australian adults, based on age, gender, and geographical location. Confirmatory factor analysis (CFA) was conducted to ensure the revised version (DLI-R) was consistent with the original. To develop a short format version of the DLI (DLI-9), items were first removed based on face validity, followed by an exploratory factor analysis (EFA) and CFA. The internal reliability of the DLI-R and the DLI-9 was assessed using Cronbach's alpha. The intraclass correlation coefficient was calculated to examine the inter-rater reliability between the DLI-R and DLI-9. Results: Twenty-four questions in the DLI were reworded for clarity. A CFA on the 29 items of this modified version of the DLI indicated a good model fit (Tucker-Lewis Index (TLI): 0.93; Comparative Fit Index (CFI): 0.93; root mean square of approximation (RMSEA): 0.06; standardized root mean residual (SRMR): 0.06), with six latent variables and an underlying latent variable "death literacy." For the DLI-9, an EFA identified a nine-item, two-factor structure model (DLI-9). A subsequent CFA in a separate sample demonstrated a good model fit for the DLI-9 (TLI: 0.92; CFI: 0.94; RMSEA: 0.089; SRMR: 0.07). Excellent inter-rater reliability (0.98) was observed between DLI-9 and DLI-R. Cronbach's alpha coefficients for DLI-R scales and subscales and the DLI-9 all exceeded 0.8, indicating high internal consistency. Conclusion: The DLI-R and the DLI-9 were found to have acceptable psychometric properties. The development of a shorter version of the DLI provides a valid measure of overall death literacy.