Incorporating ‘the positive' in assessing OHQoL- is it valid?

There has been a paradigm shift within quality of life (QoL) research to assessing how ‘health' enhances QoL (the positive effects). Within dentistry the focus has been on how an oral disease (ill health) detracts from QoL (the negative effects). Recently, there has been considerable debate about the validity of assessing ‘the positive' contribution of oral health to QoL. Objective: To evaluate and compare the criterion validity of positive and negative assessments in measuring OHQoL. Methods: OHQoL was measured using OHQoL-UK from 3,000 adults in a national survey conducted in the Republic of Ireland. OHQoL-UK consists of 16 items evaluating OHQoL in 3 dimensions (physical, social, and psychological domains). OHQoL-UK ‘negative' scores were derived from responses to perceived ‘bad' effects of oral health to QoL. OHQoL-UK ‘positive' scores were derived from responses to perceived ‘good' effects of oral health to QoL. Structural Equation Modeling was applied to assess the criterion validity of the positive and negative OHQoL assessments as related to the oral health status (caries and periodontal disease). Results: For ‘physical well-being' and ‘social well-being', compared with positive assessments, negative assessments generated better model fitting for oral health status, with significantly lower χ2 (81.01 vs 223.31 for ‘physical well-being'; 106.81 vs 265.24 for ‘social well-being') and lower RMSEA values (0.037 vs 0.067 for ‘physical well-being'; 0.055 vs 0.090 for ‘social well-being') (all p<0.001). However, for ‘psychological well-being', positive assessments generated better model fitting for oral health status, with significantly lower χ2 (176.98 vs 399.73) and lower RMSEA values (0.072 vs 0.111) (both p<0.001) than those for negative assessments. Conclusion: The finding of this study supports the validity of both positive and negative assessments in measuring OHQoL. Incorporating positive assessments is particularly appropriate in assessing psychological well-being.