Exhaled nitric oxide as a guide for asthma therapy

This article in the NEJM shows that by using exhaled nitric oxide (NO) as a guide to decreasing therapy, patients can achieve equivalent asthma control with less use of inhaled corticosteroids.

Nitric oxide is a marker of inflammation and increased exhaled levels in patients with asthma can indicate ongoing inflammation and therefore poor control of the asthma

The study is okay, but, unfortunately for them, may be underpowered. There was a noticeable, but not statistically significant drop in exacerbations in the group whose medicine use was adjusted by NO measurement compared to those managed conventionally by symptoms. A drop in exacerbations with less medicine use is much sexier than just a decrease in medicine usage.

The other weakness of the study is that it was designed using an older approach to clinical management focused primarily on titrating up the dose of inhaled steroids. Now we much more commonly add long acting beta-agonists like salmeterol (which is combined with the inhaled steroid fluticasone in Advair) especially patients already on relatively high doses of inhaled steroids like those in this study.
It remains to be seen if use of NO measurement enhances contol with less overall medicine use in patients managed according to this newer algorithm.