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

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

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.

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.

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).

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