Development and evaluation of an oral health literacy instrument for adults

Objectives: To develop and validate an instrument to measure the functional oral health literacy of adults. Methods: For the generation of items different dental patient educational materials and text types were selected that had reading levels similar to materials used for the Test of Functional Health Literacy in Adults (TOFHLA) which was the model for our Oral Health Literacy Instrument (OHLI). The OHLI contains reading comprehension and numeracy sections. The reading comprehension section is a 38-item test with words omitted from one passage on dental caries and another on periodontal disease. The numeracy section has 19 items to test comprehension of directions for taking common prescriptions associated with dental treatment, postextraction instructions and dental appointments. We also developed a 17-item oral health knowledge test. The OHLI, the TOFHLA, the oral health knowledge test and a brief questionnaire were administered to a convenience sample of 100 patients. Internal reliability of OHLI was assessed with Cronbach's alpha. Test-retest reliability was examined by intra-class correlation coefficient (ICC). Concurrent validity was tested by comparing OHLI scores across categories of education level and frequency of dental visits. Construct validity was assessed by correlating OHLI scores with TOFHLA scores and with the oral health knowledge scores using Spearman's rho (rho) and multiple linear regression. Results: Participants averaged 39 years (SD = 12.4); 73% were female; 64% had college/university education; 40% visited a dentist every 3-6 months. Total OHLI and TOFHLA weighted mean scores were 87.2 and 91.7, respectively (possible range 0-100). The Cronbach's alpha values were high (> 0.7) for OHLI and its components. The ICC values indicated good agreement between the test and retest results for OHLI and the oral health knowledge test. Patients visiting a dentist every 3-6 months had significantly higher levels of oral health literacy than those visiting only when they felt pain. The association between OHLI and education level was not significant. OHLI scores were significantly correlated with the scores on the TOFHLA (rho = 0.613) and the test of oral health knowledge (rho = 0.573). These associations remained significant in multiple regression models. Conclusion: Initial testing of OHLI suggested that it is a valid and reliable instrument to evaluate oral health literacy among adults, although additional work is needed to investigate the instrument's predictive validity and sensitivity to change using oral health outcomes with population groups known to be at high risk of low functional oral health literacy.