Allergy, Chemical Sensitivity and ME/CFS

As noted above, allergies were the most frequent co-morbid condition in both ME/CFS groups. We had a very extensive section on the questionnaire concerning allergies and chemical sensitivities.

Long-term ME/CFS patients had a very high level of reported chemical sensitivities ranging from 24.1% sensitive to chlorine to 61.6% sensitive to tobacco smoke.

Similar results hold for the short-term group.

In the significant-other group, the highest sensitivity was 14.0% to tobacco smoke.

Since we had extensive questions concerning the types of allergens and the severity of the allergy to each, we formulated different indices for allergy severity, chemical sensitivity (pre and post ME/CFS), current or 1st year neurocognitive symptoms, and current or 1st year flu-like symptoms. We checked the correlations among each of them.

We also checked if they were related to the onset of certain types of allergic reactions (i.e., skin reactions, anaphlaxis, etc.) occurring before or after ME/CFS. A high score on this index meant the person had more types of reactions and these tended to have occurred both before and after ME/CFS started.

A correlation coefficient Pearson's r lies between zero and one (since these were positive correlations). A coefficient close to 1 is an excellent result.

For a sample of 258 subjects, an r around .22 is a modest correlation. It means that both indices being compared were generally high or low at the same time. A result is statistically significant if there is a p-value less than .05. That means there is less than a 5% chance the result could have happened randomly.

p < .0001 is extraordinarily significant. It means the result really couldn't have happened by chance. Correlations aren't causations, but they suggest the two phenomena are somehow related to each other, either directly, or via a hidden factor.

In Table 4 we show some of the more interesting significant correlations for the long-term group. The results for the short-term group were similar.

Table 4. Correlation of Illness Severity Scores in Long-term ME/CFS