Lee et al. BMC Public Health 2010, 10:614 http://www.biomedcentral.com/1471-2458/10/614 Table 3 Multivariate Estimation of the Association of Health Literacy with Health Status and Health Care Utilization (N = 1180) Physical Health OR (95% CI) Mental Health OR (95% CI) Outpatient clinic visit OR (95% CI) ER visit (95% CI) OR Hospitalization (95% CI) 1.02 0.82 1.00 1.32* 1.03 1.25 1.33 1.52* 0.98 1.00 0.89 (0.74-1.42) (0.50-1.33) (0.99-1.01) (1.06-1.64) (0.99-1.07) (0.91-1.73) (0.93-1.89) (1.10-2.09) (0.73-1.32) (0.72-1.40) (0.63-1.27) 1.05 0.62* 1.01* 1.08 1.02 1.21 1.50* 1.36* 0.91 0.88 0.77 (0.77-1.44) (0.39-0.99) (1.00-1.02) (0.87-1.33) (0.98-1.06) (0.88-1.65) (1.06-2.11) (1.00-1.85) (0.68-1.22) (0.64-1.23) (0.54-1.08) 0.89 0.79 1.03* 0.68* 1.03 1.12 1.15 1.22 0.94 1.32 1.60* 0.53 0.24 0.14* 0.09* 0.55 0.70 0.82 0.79 (0.61-1.29) (0.45-1.39) (1.02-1.04) (0.52-0.87) (0.98-1.08) (0.77-1.62) (0.76-1.74) (0.84-1.76) (0.67-1.31) (0.89-1.96) (1.06-2.42) (0.10-2.75) (0.05-1.21) (0.03-0.74) (0.02-0.51) (0.10-3.16) (0.12-4.02) (0.14-4.79) (0.13-4.70) Health Literacya Marginal Inadequate Age (years)b Malec Education (years)b Household Incomed 51-75% of average 76-100% of average >100% of average Residential Locatione Mid-size city Small-size city Rural/remote area Physical Healthf Poor Average Good Excellent Mental Healthf Poor Average Good Excellent * p <0.05. a “Adequate health literacy” is the comparison. b The interval form of the variable, measured in year, is used. c “Female” is the comparison. d “≤50% of average” is the comparison. e “Metropolitcan city” is the comparison. f “Very poor” is the comparison. report better physical and mental health and were less likely to be hospitalized in the last year. Adults with bet- ter physical health were less likely to use any of the health services examined in the study. To further explore the findings, step-wise logit models were conducted (results are available from the corre- sponding author upon request). The purpose of the ana- lysis was to determine which of the control variables explained the bivariate correlations between health lit- eracy and health status and health care utilization. To perform the step-wise logit models, we first entered the two dummy variables of health literacy, and then added one at a time, iteratively, each of the control variables, to see at which point the significant correlation between health literacy and health status and health care utiliza- tion became non-significant. Results indicated that edu- cational attainment accounted for the association between health literacy and physical health status. Three OR 1.15 1.08 1.01 0.97 1.02 0.96 0.85 0.0 0.88 1.01 1.05 0.38 0.26* 0.13* 0.16* 1.23 0.90 1.21 0.94 (0.70-1.91) (0.51-2.27) (0.99-1.02) (0.68-1.38) (0.96-1.09) (0.58-1.58) (0.48-1.50) (0.48-1.34) (0.54-1.43) (0.59-1.73) (0.60-1.82) (0.12-1.21) (0.08-0.83) (0.04-0.45) (0.04-0.62) (0.28-5.46) (0.20-4.12) (0.26-5.65) (0.18-4.80) 0.60 1.22 1.13* 0.94 1.09* 0.78 0.90 0.44* 1.18 1.21 1.98 0.15* 0.06* 0.06* 0.04* 4.49 4.42 2.84 4.97 Page 5 of 8 (0.27-1.32) (0.47-3.06) (1.01-1.06) (0.57-1.55) (1.00-1.18) (0.39-1.56) (0.43-1.91) (0.20-0.93) (0.57-2.46) (0.54-2.70) (0.91-4.33) (0.04-0.58) (0.01-0.22) (0.01-0.26) (0.01-0.20) (0.59-34.11) (0.55-35.56) (0.33-24.40) (0.53-47.01) covariates–age, educational attainment, and household income–together explained the correlations between health literacy and health care utilization. The multinomial logit results may be biased because of the deletion of 313 observations without household income information. To examine the potential bias, a separate set of multinomial logit models was conducted with imputed household income using linear regression estimation (covariates included age, gender, educational attainment, and residential location). The results were similar, suggesting that the deletion of those 313 obser- vations did not affect the substantive interpretation of findings (results are available upon request). Discussion In a population-based, nationally representative sample of Taiwanese adults, approximately 30% had either inadequate or marginal health literacy. By comparison,