Validation of Persian rapid estimate of adult literacy in dentistry.
AIM The aim of the present study was to establish the psychometric properties of the Rapid Estimate of adult Literacy in Dentistry 99 (REALD 99) in the Persian language for use in an Iranian population (IREALD 99) METHODS A total of 421 participants with a mean age of 28 years (59% male) were included in the study. Participants included those who were 18 years or older and those residing in Quazvin (a city close to Tehran) Iran. A forward backward translation process was used for the IREALD 99. The Test of Functional Health Literacy in Dentistry (TOFHLiD) was also administrated. The validity of the IREALD 99 was investigated by comparing the IREALD 99 across the categories of education and income levels. To further investigate, the correlation of IREALD 99 with TOFHLiD was computed. A principal component analysis (PCA) was performed on the data to assess unidimensionality and strong first factor. The Rasch mathematical model was used to evaluate the contribution of each item to the overall measure, and whether the data were invariant to differences in sex. Reliability was estimated with Cronbach's a and test retest correlation. RESULTS Cronbach's alpha for the IREALD 99 was 0.98, indicating strong internal consistency. The test retest correlation was 0.97. IREALD 99 scores differed by education levels. IREALD 99 scores were positively related to TOFHLiD scores (rh 0.72, P 0.01) In addition, IREALD 99 showed positive correlation with self rated oral health status (rh 0.31, P 0.01) as evidence of convergent validity. The PCA indicated a strong first component, five times the strength of the second component and nine times the third. The empirical data were a close fit with the Rasch mathematical model. There was not a significant difference in scores with respect to income level (P 0.09) and only the very lowest income level was significantly different (P 0.01) CONCLUSIONS The IREALD 99 exhibited excellent reliability on repeated administrations, as well as internal consistency. The IREALD 99 can be used for the basic screening of oral health literacy among the Iranian population.
Journal of investigative and clinical dentistry