Asthma update: What we know we don't know (is a lot) (Review)
This is a great article by a leader in the field (William Busse), and it's free -- you should download it and save it.
His theme is "Filling in the information gaps," and there are a lot of them. Filling them in will take a lot of time, funding, and a bigger shovel than anyone's got right now. A few highlights...
Diagnosis of asthma:
Sensitivity of spirometry with bronchodilator testing to identify reversible airflow limitation in asthma: 29%; specificity, 90% (in 219 patients with a gold standard of eventual clinical diagnosis of asthma).
Bronchial hyperresponsiveness testing: A negative result may help rule out asthma; a positive result is less helpful. (BHR has more false positives in people without asthma than false negatives in people with asthma.)
Fraction of exhaled nitric oxide is elevated in many people with asthma, and represents a potentially useful tool, but its role in diagnosis and management are still unclear. (See the recent ATS statement on exhaled FENO testing.)
But the biggest and most important gaps are in our knowledge of when and how to treat asthma.
Thanks to safety concerns raised by FDA re: LABAs, there's still debate at the simplest level: how to step-up therapy for asthma uncontrolled on low-dose inhaled corticosteroid. Does one add a LABA or increase the ICS dose? Even Dr. Busse doesn't know (but his tone suggests he goes for LABAs).
The "gaps" go on and on. In fact, I daresay it's almost all gaps. There's plenty of great additional stuff here on developing phenotypes of asthma, use of Xolair/omalizumab, using combined budesonide-formoterol as both maintenance and rescue therapy (this to me is very attractive and potentially impactful, as it would simplify regimens and make adherence easy), and the new cytokine inhibitor lebrikizumab (I refuse to make any effort to spell this correctly). Dig in, but as the Brits say, mind the gap.
Busse WW. Asthma diagnosis and treatment: Filling in the information gaps. J Clin All Immunol 2011;128(4):740-750.