Psychometric properties and validation of short health literacy screening (SHLS) to identify low health literacy

Background: The purpose of this study was to evaluate the psychometric properties and performance of the short health literacy screening (SHLS) to identify people with low health literacy among a set of Iranian adults in Mashhad and Shiraz. Methods: In this cross-sectional study, participants were 18-65 years old Iranian adults randomly selected from two major cities of Iran, encompassing inpatients, outpatients, and healthy individuals. They completed the demographic, SHLS, and Health Literacy for Iranian Adults (HELIA) questionnaires. Psychometric properties of SHLS were evaluated. We investigated the performance of screening questions for detecting inadequate and limited health literacy based on HELIA as a comparison standard. Results: SHLS had acceptable psychometric properties (Content validity index of 0.92, 0.78, 0.85, and 0.85, Spearman-Brown correlation coefficient of 0.827, 0.928, 0.581, and 0.712 for four questions, and Cronbach’s alpha of 0.713). Of 547 participants, 339 (62%) were female, and 415 (75.9%) were between 18 and 45 years old. The prevalence of inadequate and limited health literacy based on HELIA was 56 (10.2%) and 192 (35.1%), respectively. The question "How well do you understand the medical prescriptions your doctor told you?" (Comprehension of Prescriptions) showed a higher area under the receiver operating characteristic (AUROC) of 0.690 (0.620-0.759) for inadequate, and 0.666 (0.619-0.713) for limited health literacy. The combination of "How confident are you filling out forms by yourself?" and "Comprehension of Prescriptions" showed a better AUROC of 0.705 (0.638-0.773) for inadequate health literacy. All questions together had a higher AUROC of 0.683 (0.636-0.729) for limited health literacy. The response "Quite a bit" or less confident for "Comprehension of Prescriptions" increased the odds of inadequate and limited health literacy by 1.45- and 1.53-fold, respectively. Conclusion: The question "Comprehension of Prescriptions" and the four-item SHLS could identify people with low health literacy.