Although the possibility of delayed reaction confines its use largely to hospitalized patients, inhalation challenge is occasionally the most effective means of determining the response of an asthmatic person to a suspected inhalant allergen.
"It can be used clinically to add a degree of refinement to the last of the four classical allergen indicators—history, skin test, avoidance, and provocation," Irving H. Itkin, MD, Denver, told the Section on Allergy. "Thus, it offers added opportunities of finding something better than symptomatic therapy for the more difficult asthma patients."
In assessing the possibilities and limitations of the various indicators, Dr. Itkin said the skin test is probably the least reliable of the indicators. In addition to false positive and false negative reactions, skin test reactions are often inadequately reproducible; change in reaction is extremely slow with treatment, and there may be poor correlation with the relative clinical importance of the different allergens.