Abstract
Background
Chemical intolerance is a condition that may result in multisystem symptoms triggered by low levels of exposure to xenobiotics such as chemicals, foods, and drugs. The prevalence of chemical intolerance is estimated to be between 8% and 33% across several countries. Clinicians and researchers require a brief, practical tool for identifying chemical intolerance.
Objectives
This 5-country, population-based study investigates the validity of a three-item screening questionnaire, the Brief Environmental Exposure and Sensitivity Inventory (BREESI), against the 50-item Quick Environmental Exposure and Sensitivity Inventory (QEESI).
Methods
One thousand individuals (n = 1,000) in each of 5 countries, the U.S., Japan, Italy, Mexico, and India responded to both the QEESI and the BREESI on a Qualtrics platform by Dyanata, a survey company that provides recruitment services for researchers. We determined performance metrics for BREESI responses comparing the number of items chosen on the BREESI with QEESI scores for chemical intolerance. We used logistic regression to determine the likelihood of chemical intolerance based on scoring 0, 1, 2 or 3 items on the BREESI. We report BREESI sensitivity and specificity, positive and negative predictive values, and positive and negative likelihood ratios.
Results
Compared to the QEESI reference standard, the BREESI had excellent sensitivity, specificity, positive and negative likelihood ratios, and positive and negative predictive values for chemical intolerance in all countries except Japan. In Japan, the BREESI had poor sensitivity and a poor negative predictive value. Logistic regression shows that in all countries, with each increase in BREESI items endorsed, there is 4- to 5-fold increase in the odds of CI. Although the samples are relatively small for estimating population prevalence, our results suggest interesting differences and overall high prevalence of chemical intolerance. Applying QEESI criteria, India appears to have very high rates of chemical intolerance—over 50% of those sampled (54.7%, 95% CI = 52–58) followed by Japan (40.3%, 95% CI = 40–77), Italy (34.3%, 95% CI = 32–37), U.S. (31.2%, 95% CI = 28–34) and Mexico (26.0%, 95% CI = 23–29).
Discussion
This study confirms the results of a two recently published validation papers in the U.S. The BREESI performs well as a screening tool for chemical intolerance. The BREESI is a practical tool for researchers, clinicians, and epidemiologists seeking to understand and address this important and prevalent condition.