The Changing Face of Anaphylaxis

RATIONALE: Correct diagnosis of anaphylaxis is paramount for patient care, and understanding common etiologies vital in this regard. We sought to discern whether the manifestations and etiologies of anaphylaxis have changed over time when compared to previous studies in an ongoing series, dating back to 1993, of anaphylaxis cases from a private, university-affiliated allergy clinic.

METHODS: Patient charts were identified based upon ICD-9 code, 995.0, for anaphylactic shock. The same coding was used in our previous reports from this center. Charts identified were analyzed for clinical symptoms reported, comorbidities, etiology, investigative testing, and subsequent treatment. These cases were categorized as definitive, probable, or idiopathic based on history and test results.

RESULTS: We identified 281 cases, 222 met criteria for anaphylaxis. Among those 222 cases, median age was 42 years (range 9-78) and 65% were female. Regarding etiology, 88 (40%) were determined to have a definitive etiology, 58 a probable etiology (26%), and 76 (34%) were idiopathic. Interestingly, among those with a definitive cause, the most common etiology was galactose-alpha-1,3-galactose (alpha-gal), accounting for 28 cases (32%). Foods were the 2^nd leading cause, with 25 cases (28%).

CONCLUSIONS: In this follow up report on anaphylaxis etiology from a single center, the most common etiology was alpha-gal. This varies greatly from the prior report from our center, when alpha-gal had not been yet described. Interestingly, the percent of cases attributed to idiopathic anaphylaxis decreased from 59% in our past report to 34% in this report, which could largely be explained by the number of alpha-gal cases.