This study examined the change in quality of life of adults with food allergy following OIT. The main findings of this study are that adults experience an overall significant improvement in their QoL, especially regarding the emotional and social aspects, but less so when examining food allergy related health. The most important factors impacting improvement were not having multiple food allergy and succeeding in reaching full desensitization.
Data on QoL of adult patients with food allergy is limited. One study, translating and validating the FAQLQ-AF in eight European countries, found a wide variety of QoL scores in adults between countries, attributing this to cultural differences in perception of disease severity, practices and traditions of eating and dining out, as well as differences between countries in healthcare, treatment availability and health related costs(27). Interestingly, our study demonstrates that Israeli adults, both in the study group and even more so in the control group, score worse than in all the eight European countries examined. Our population also demonstrated worse baseline scores than Dutch and American populations (28, 29), showing higher scores for the study group as well as the controls.
While limited data is available on QoL of adults with food allergy, there is no data, to the best of our knowledge, on QoL of adult patients undergoing OIT. OIT has been shown to be successful in desensitizing children (12, 30–32), and to improve both their QoL as well as the QoL of their care takers(33, 34). These patient-centered positive outcomes contributed to the acceptance of OIT as a formal treatment in FA guidelines worldwide (10, 35). Recently, we demonstrated that the adult population can succeed in achieving desensitization when treated with OIT (11). We did find, however, that adults suffer from more severe reactions throughout the process, both in clinic as well as during home treatment. Moreover, the ability to successfully desensitize patients with milk allergy decreases with age, with adults having a significantly higher failure rate. Improving patient QoL is a major goal of OIT and it is therefore extremely important to evaluate the impact of treatment on the QoL of adult patients.
Our main finding is that there is a significant clinical and statistical improvement in patient QoL following OIT in all aspects, emotional as well as dietary restriction and fear of accidental exposure, as depicted by the different questionnaire domains. This was evident both in better scores compared to controls in the second time point, and in a substantial improvement in scores between the two different time points in the study group. Only the FAH domain did not improve. This domain contains three questions dealing with the general perception of health due to FA and fear of having an additional un-diagnosed FA (22). This domain does not appear in FAQLQ questionnaires in younger ages(36), since it requires a more mature and integrated perception of health. Not surprisingly, in our cohort, adults with multiple FA demonstrated a deterioration in QoL in this domain, while adults with single FA improved. The fact that this was the only domain in which the delta in scores was not significant proves the complexity of health perception in adults, and the heavy burden carried by multiple FA, even when desensitization was achieved for one of the allergens.
We found that only multiple versus single FA and the ability to reach full or partial desensitization versus treatment failure had a significant impact on the change in QoL during OIT. While the use of epinephrine during home treatment had a significant effect on the emotional impact domain, it was not found to be influential in multivariate analysis. Other studies examining parameters influencing HRQOL in adults with food allergy showed better scores in adult onset FA versus childhood onset(37), better scores following negative oral food challenges(38, 39), worse scores correlated with a negative impact on social life(28) and tree-nut and peanut allergy(40). Yet again, our study is the first to examine the impact of OIT on the change in QoL in adults, awaiting future studies to compare these results.
It is interesting to note that male patients reported larger improvement in QoL in all domains, including the total score, albeit without statistical significance. Similarly, in a Danish study of FA related QoL differences in scores were demonstrated between genders, showing that females tend to score significantly worse on the FAQLQ questionnaires than males, is all ages (as well as adults) and in all domains(28). While gender is known to influence the perception of HRQOL(41), it was not shown to be significant in the perception of change in QoL due to OIT and might not be as influential as other parameters with respect to treatment.
This study has several limitations. First, the study group had lower (better) QoL scores at the start of treatment compared to the control group, although these differences were significant only for the FAH domain. This is similar to other studies in younger ages (8, 9) and might reflect the positive influence of a pro-active approach when beginning OIT on patients with FA. However, by analyzing the change in scores in both groups during the study, and showing that only in the study group it was significantly better, both clinically and statistically, supports to the study. Another limitation is the relatively small number of patients, both in the study as well as control groups. This reflects the low numbers of adults with food allergy (42), particularly those undergoing OIT and emphasizes the lack of data regarding the benefits of treatment in this age group, which when acquired, will allow for better publicity and acceptance of OIT as a standard treatment Finally, some adults undergoing OIT did not complete the two questionnaires and were therefore excluded. These patients had more in-clinic reactions requiring epinephrine and a higher failure rate. As the improvements in QoL scores in the study population were driven primarily by those who were fully desensitized, including additional patients who failed treatment could have affected the results. However, the main goal of the study was to show that achieving full desensitization, and not merely participating in OIT, improves patients' QoL. This finding is unlikely to be affected by inclusion of excluded patients.
In summary, this study demonstrates that OIT has a beneficial effect on the QoL of adult patients with food allergy. Considering that adults may face a variety of challenges in their personal life during OIT, improvement in QoL shows that the overall benefits of the treatment outweigh the difficulties. These findings, added to previous findings of successful desensitization in this age group, are important in promoting OIT as an effective treatment for the adult population. While the beneficial effects of OIT on QoL of younger patients increase with time (9), taking into consideration the different aspects of chronic health conditions in adults, we believe that future studies need to focus on the long-term effect on QoL in this age group.