Design and validation of the Disaster Health Literacy Questionnaire for diabetes patients in Iran: a mixed-methods study

TL;DR

This study created and tested a questionnaire to measure disaster health literacy among diabetic patients in Iran, showing it is reliable and valid for use in healthcare planning.

Contribution

The study introduces a validated multidimensional questionnaire for assessing disaster health literacy specifically for diabetic patients in Iran.

Findings

The DHLQ showed excellent content validity with a scale-level CVI of 1 and item-level CVI above 0.79.

MIRT analysis confirmed a three-factor structure with strong model fit (RMSEA=0.016, CFI=0.96, TLI=0.95).

Most items demonstrated moderate-to-high discrimination and medium-to-low difficulty.

Abstract

To develop and psychometrically evaluate a multidimensional Disaster Health Literacy Questionnaire (DHLQ) for diabetic patients in Iran, using advanced item response theory approaches. The questionnaire was designed in the Persian (Farsi) language.

A sequential mixed-methods study incorporating qualitative (scoping review and interviews) and quantitative (psychometric validation) phases.

Diabetes clinics and healthcare centres across Iran (2022–2023).

The study enrolled 570 patients with diabetes (56% female, mean age 45.57±16.33 years) for quantitative validation; 15 experts and 15 patients for qualitative validation.

The psychometric properties evaluated included content validity (using content validity ratio (CVR) and content validity index (CVI)), construct validity (assessed via multidimensional item response theory (MIRT)), and reliability (measured by Cronbach’s alpha and test-retest Kappa). Additionally, item parameters (multidimensional difficulty (MDIFF) and multidimensional discrimination (MDISC)) and model fit indices (RMSEA, CFI and TLI) were examined.

The final 30-item DHLQ demonstrated excellent content validity (scale-level CVI=1; item-level CVI>0.79; CVR>0.49). Cronbach’s alpha for the total scale was 0.606; test-retest reliability showed significant agreement (Kappa=0.35–1, p<0.05). MIRT confirmed a three-factor structure: Disaster Perception Risk (14 items), Medication-Nutritional Literacy (11 items), and Self-help and Emergency Literacy (five items). Model fit was excellent (RMSEA=0.016, CFI=0.96, TLI=0.95). Item analysis revealed that 73% of items had moderate-to-high discrimination (MDISC ≥0.65), and 83% had medium-to-low difficulty (MDIFF <0.5).

The DHLQ is a rigorously validated tool for assessing disaster health literacy in diabetic populations. Its multidimensional structure and strong psychometric properties support its use in clinical and emergency planning contexts to identify literacy gaps and tailor interventions.

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