Women with non-eosinophilic asthma in pregnancy benefit from treatment adjustment with a FENO-guided algorithm,  according to a new analysis of the landmark Managing Asthma in Pregnancy (MAP) study.

Professor Peter Gibson’s 2011 study conducted at the Hunter Medical Research Institute in NSW showed a 50% reduction in asthma exacerbation in women whose treatment was adjusted according to an algorithm based on the fraction of exhaled nitric oxide (FENO) compared to symptom-based adjustment.

Now a new sub-analysis of the MAP study data from 200 pregnant women has shown the reduction in asthma exacerbations varied according to asthma phenotype, with a major reduction seen in the 53% of women (n = 103) classified as having non-eosinophilic asthma.

In the NEA group, treatment adjustment based on the FeNO algorithm led to an increase in long acting beta agonist (LABA)  use from 11% to 30%. The asthma exacerbation rate was 18.9% for NEA women with FeNO-guided treatment  compared to 44% in the control group who had symptom-guided treatment, of whom 14% received LABA.

In the 92 women with eosinophilic  asthma (EA), the FeNO algorithm correctly targeted inhaled corticosteroid (ICS) use to 86% of women, compared to 57% of women in the control group of symptom-guided treatment. However the rates of asthma exacerbations (38%) were similar for both algorithm groups in EA.

Writing in Respirology, study lead author Dr Vanessa Murphy said it was thought that NEA responded less well to ICS compared to EA, and therefore increasing the LABA component of treatment could theoretically be more effective in NEA patients.

But the optimal treatment strategy in NEA has not been evaluated formally, and guidelines on asthma management do not provide recommendations for treating NEA, she said.

The new sub-analysis had shown that a FENO-guided algorithm for asthma treatment adjustment in pregnancy was more effective in treating NEA compared to symptom-based treatment, resulting in greater use of LABA and fewer exacerbations.

“This was not the result of inhaled corticosteroid overtreatment, since the benefits occurred at a lower median daily ICS dose,” she noted.

The exacerbations occurred five weeks  later among women with NEA in the FENO-guided group, she noted.

In pregnancy, two to three applications of the FeNO algorithm, one month apart, would be sufficient for achieving reduced exacerbations, the authors recommended.