Linking numeracy and asthma-related quality of life

Objective: To examine the correlation of numerical skills used in patients' self-management of asthma with asthma-related quality of life (AQOL). Methods: Adults with moderate-severe asthma completed the Asthma Numeracy Questionnaire (ANQ), assessments of reading comprehension and self-efficacy, and the mini-Asthma Quality of Life Questionnaire (miniAQLQ). The numeracy-AQOL relationship was evaluated in the context of potential confounders (demographic variables) and mediators (e.g. income and self-efficacy), using tests of correlation then multivariable models to assess for confounders and mediators. Results: 80 adults with moderate or severe asthma were evaluated. Mean ANQ score was 2.3 +/- 1.2 (range 0-4). ANQ was correlated with miniAQLQ (rho = 0.24, p = 0.03). This association was sustained (rho = 0.27, p = 0.02) when controlling for potential confounders significantly associated with AQOL (age, Latina ethnicity). The ANQ-miniAQLQ association was mediated by household income; the correlation was reduced by 81% when adjusting for income (rho = 0.05, p = 0.65). In contrast, self-efficacy less strongly mediated this association; the correlation was reduced by 26% when controlled for self-efficacy (rho = 0.20, p = 0.08). Conclusion: Numerical skills needed for asthma self-management influence AQOL primarily through their impact on income and, to a lesser extent, on self-efficacy. Practice implications: Adults with asthma will benefit from self-management instructions employing the simplest mathematical constructs whose understanding is confirmed by clinicians. (C) 2009 Elsevier Ireland Ltd All rights reserved.