Oral Health Literacy Assessment: development of an oral health literacy instrument for Spanish speakers

Objective To develop an oral health literacy instrument for Spanish-speaking adults, evaluate its psychometric properties, and determine its comparability to an English version. Methods The Oral Health Literacy Assessment in Spanish (OHLA-S) and English (OHLA-E) are designed with a word recognition section and a comprehension section using the multiple-choice format developed by an expert panel. Validation of OHLA-S and OHLA-E involved comparing the instrument with other health literacy instruments in a sample of 201 Spanish-speaking and 204 English-speaking subjects. Comparability between Spanish and English versions was assessed by testing for differential item functioning (DIF) using item response theory. Results We considered three OHLA-S scoring systems. Based on validity and reliability comparisons, 24 items were retained in the OHLA-S instrument. OHLA-S was correlated with another health literacy instrument, Spanish Test of Functional Health Literacy in Adults (P<0.05). Significant correlations were also found between OHLA-S and years of schooling, oral health knowledge, overall health, and an understanding of written health-care materials (P<0.05). OHLA-S displayed satisfactory reliability with a Cronbach Alpha of 0.70-0.80. DIF results suggested that OHLA-S and OHLA-E scores were not comparable at a given level of oral health literacy. Conclusions OHLA-S has acceptable reliability and validity. OHLA-S and OHLA-E are two different measurement tools and should not be used to compare oral health literacy between English- and Spanish-speaking populations.