We determined the impact of GERD on utility scores, HRQL and work productivity in patients with moderate to severe GERD and the cross-sectional construct validity of three utility instruments (FT, SG, and HUI 3). Although the comparisons we made are indirect, the results of this study indicate that GERD causes important reductions in HRQL and utility when compared to the Canadian and US general population and to those of patients with a range of other chronic conditions. Heartburn and acid reflux were reported by our patients to have the worst impact on symptoms using the four symptoms questionnaire. The QOLRAD as well as the symptom scores improved after esomeprazole treatment although this study did not include a placebo group. In addition, our data indicate that GERD causes a considerable loss in work productivity.
The strengths of this study include the use of several utility and HRQL instruments that allow comparison to other chronic conditions. By using several quality of life instruments, we have studied GERD patients more comprehensively than previous studies [31, 32, 35]; however, our results are confined to GERD patients with moderate to severe symptoms who were participating in a clinical study. In addition, our comparison with population data is based on historical data. Despite the impressive responsive of the QOLRAD scores to esomeprazole treatment, one has to keep in mind that this study was not a randomized controlled trial. In regards to evaluation of validity, another limitation of our study is that we did not generate a priori predictions regarding correlations between the utility instruments and other measures. Had we generated such a priori predictions our conclusion about the validity of the instruments might be stronger.
Data on utility measures in GERD patients are sparse. We observed important disutility measured with the FT, SG, and HUI 3. The results suggest that the FT and HUI 3 are valid tools for the assessment of HRQL in patients with GERD. We were specifically interested in exploring the relative validity of utility instruments in patients with GERD.
In general, the correlations with other HRQL instruments were moderate. In contrast, the SG showed poor construct validity. Moreover, the FT shows better correlation with the four symptoms questionnaire than the SG and the HUI 3. Thus, our findings suggest that the FT and the HUI 3 are more appropriate indicators of HRQL impairment than the SG in these patients. Studies that use the FT, SG, HUI and SF-36 simultaneously are rare. We have previously observed a similar pattern of correlations in patients with chronic obstructive pulmonary disease (COPD) . The correlations of the FT and HUI 3 with the SF-36 were higher compared to those of the SG with the SF-36. Thus, there is external evidence that the FT and HUI 3 show greater validity for the assessment of HRQL than the SG.
The data also indicate that the disutility in patients with moderate to severe GERD is similar to that of moderate to severe COPD . The utility scores obtained with the SG are lower than what was previously reported for SG scores in patients with asthma  and comparable to those of minor stroke survivors .
We also found reductions in the SF-36 scores on all 8 domains in GERD patients. Compared to the Canadian and US general population, patients in this study had significantly reduced scores in the SF-36 MCS and PCS [33–36]. The SF-36 PCS scores are comparable to patients with clinical depression and hypertension. On the other hand, GERD patients have significantly worse SF-36 MCS scores than patients with diabetes mellitus and depression.
The QOLRAD results suggest that GERD has the greatest impact on the vitality and food/drink domains. These results are similar to those reported by Wiklund et al.  confirming the negative impact of GERD on the daily functioning of affected patients.
Health administrators and payers are interested in the magnitude of work productivity loss due to GERD . Wahlqvist et al. showed that patients with GERD symptoms report 23% reduced productivity while at work, and 30% reduced productivity while doing regular daily activities in a Swedish population . Our study supports the finding of impaired productivity in patients with moderate to severe GERD, but the estimates of work loss are somewhat lower demonstrating that about 16% of the work time is lost due to the illness. Since GERD affects approximately 9% of the Canadian population , impaired productivity has important economic consequences on society if it is not treated effectively.