What is the safe FEV1 level on spirometry to start subcutaneous immunotherapy (SCIT) (allergy shots)?

What is the safe FEV1 level on spirometry to start subcutaneous immunotherapy (SCIT) (allergy shots)? At least 80% of predicted.

Dr Ledford explains below:

In the AAAAI’s survey of physician members on immunotherapy- and skin testing–induced fatal reactions and NFRs during the period of 1990-2001, 15 of the 17 fatalities occurred in patients with asthma, and in 9 patients not optimally controlled asthma was considered the susceptibility factor that contributed to the fatal outcome.The most severe NFR, respiratory failure, occurred exclusively in asthmatic patients, and 4 (57%) of 7 asthmatic patients had a baseline FEV1 of less than 70% of predicted value.

 In a prospective study of 125 asthmatic patients with mite allergy that used a 3-day rush immunotherapy protocol, FEV1 was identified as a predictor for systemic reactions. In this study 73.3% of the patients with an FEV1 of less than 80% of predicted value experienced an asthma reaction during rush immunotherapy, whereas only 12.6% of patients with an FEV1 of greater than 80% of predicted value had asthmatic reaction.The authors noted that if the patients with an FEV1 of less than 80% of predicted value had been excluded from the study, the systemic reaction rate would have been 19.7% instead of 36%. These studies suggest that labile asthma, severe asthma, or both is a risk factor for immunotherapy.

References:

https://www.aaaai.org/ask-the-expert/spirometry-immunotherapy