Summary of article Stability of Fractional Exhaled Nitric Oxide and Its Relationship With Exacerbation in Patients Aged 6 Years or Older With Uncontrolled, Moderate-to-Severe Asthma" an article from Chest June 2025 Journal

What they found

Patients with moderate-to-severe asthma (aged 6 and up), on standard treatment but not taking dupilumab, were monitored for one year. Researchers looked at:

• How steady their FeNO (fractional exhaled nitric oxide) levels stayed over time.

• Whether that stability related to how many severe asthma flare-ups they had (0, 1, 2, or 3+).

  Why FeNO

• FeNO is a quick, non-invasive breath test that shows airway inflammation.

• It reflects Type 2 inflammation, which drives many severe asthma attacks—along with IL‑4, IL‑5, IL‑13 signaling and eosinophils. High FeNO means higher flare-up risk, even if blood tests are normal. sanofi.com+10ncbi.nlm.nih.gov+10pubmed.ncbi.nlm.nih.gov+10pubmed.ncbi.nlm.nih.gov+1onlinelibrary.wiley.com+1pubmed.ncbi.nlm.nih.gov+2pmc.ncbi.nlm.nih.gov+2nejm.org+2

What they found

• FeNO stayed consistent over 52 weeks, regardless of age group (kids, teens, adults) or the number of flare-ups.

• Most patients’ FeNO fluctuated by less than 50% up or down compared to baseline.

• Between doctor visits, FeNO rarely changed more than 10–30%.

• The only groups with slightly less FeNO stability were kids who had frequent flare-ups—likely because steroid use during those episodes briefly lowered FeNO.

• Importantly, patients with more flare-ups had higher FeNO levels at baseline, even though their levels didn’t drastically change over time.

Why this matters?

• Reliable inflammation marker: FeNO doesn’t bounce around week to week, even during flares—so it's trustworthy.

• Predictive power: Higher FeNO at the start was linked to a greater risk of severe flare-ups.

• Clinical utility: Measuring FeNO can help doctors identify patients who may need stronger or more targeted therapy like dupilumab.

  Bottum line

• FeNO is a stable and meaningful test for airway inflammation in asthma patients aged 6 and above. If someone has consistently high FeNO, they’re more likely to have severe flare-ups—and should be considered for advanced treatments. This analysis reinforces FeNO’s value as a reliable, long-term monitoring tool.