Recurrence rate and risk factors of recurrent anaphylaxis: A ten-year retrospective cohort study.

Background: Few studies have investigated the risk factors for recurrent anaphylaxis. Identifying these factors may help patients implement preventive measures.

Objective: To determine the rate and risk factors for recurrent anaphylaxis, assess the time to recurrence, and compare the characteristics, triggers, and clinical manifestations between recurrent and non-recurrent cases.

Methods: A retrospective cohort study was conducted at Naresuan University Hospital from March 2011 to February 2021, using medical records of patients with ICD-10-confirmed anaphylaxis. Risk factors for recurrence were analyzed using Cox proportional hazards regression model.

Results: A total of 439 anaphylactic episodes were identified in 381 patients (49 children, 332 adults). Of these, 42 patients (11.2%) experienced 58 recurrent episodes (7/49 [14.3%] children, 35/332 [10.6%] adults). Food and medications were the most and second most common triggers. The median time to recurrence was 9.9 months (IQR: 3.1-18.8), while the median follow-up duration for non-recurrent cases was 41.8 months (IQR: 23.8-61.8). The recurrent anaphylaxis rate was 4.1 events per 100 person-years. Statistically significant risk factors included a history of food, a history of insect, a history of drug allergies, chest discomfort, and severe anaphylaxis (HR [95%CI]: 3.31 [1.50-7.29], p = 0.003; 4.96 [1.47-16.82], p = 0.010; 5.87 [2.64-13.07], p < 0.001; 2.43 [1.19-4.99], p = 0.015; and 2.29 [1.07-4.88], p = 0.033, respectively). Conversely, palpitations were associated with a lower risk of recurrence (HR 0.11 [0.01-0.86], p = 0.036).

Conclusions: Identifying risk factors in anaphylaxis patients enhances medical care and aids in preventing recurrence.