USE AND SAFETY OF A SHORTENED HISTAMINE CHALLENGE TEST IN AN OCCUPATIONAL STUDY

A shortened histamine challenge test was used in a study of occupational airway disease. We evaluated the safety, defined as the absence of a decrease in forced expiratory volume in one second (FEV1) of greater than 40%. The occurrence of complaints, the repeatability of test results, and the average amount of time saved were measured.A standard protocol was used comprising 30 s tidal breathing with sequential doubling concentrations from 1 to 32 mg . ml(-1) histamine, Subjects with no indication of hyperresponsive airways started at 4 mg . ml(-1). If the decrease in FEV1 wasA total of 697 subjects performed a test. All subjects with a provocative concentration of histamine producing a 20% decrease in FEV1 (PC20) value of less than or equal to 4 mg . ml(-1) (n=16) started at the lowest concentration. Six subjects reached a greater than or equal to 20% decrease in FEV1 (range 21-24%) after a fourfold increase in concentration, Five subjects had a decrease in FEV1 of greater than 40%, and this decrease occurred after a doubling concentration, Cough, flushing, and chest tightness were noted in 18% of the subjects, In 56% of the tested subjects, the shortest provocation scheme (phosphate solution followed by 4, 16 and 32 mg . ml(-1) histamine) was applied, resulting in a time reduction of nearly 50% per test, and reducing the time needed to complete the study from 5 to 3 months. The shortened test was repeatable within one concentration difference.We conclude that, in this occupational setting, the histamine challenge test can be shortened to save time without risk of excessive falls in FEV1.