This summary was compiled from the tweets posted by allergists/immunologists who attended the 2013 annual meeting of the American Academy of Allergy Asthma and Immunology (AAAAI) (see the list at the end). The tweets were labeled #AAAAI. The text was edited and modified by me.
Cough is a $1B, with a "B," industry per year.
What causes cough?
Dr Canning: What causes cough? Mechanical stimulation (mucus, foreign body, tumor), capsaicin, bradykinin, citric/tartaric acid.
There are three big causes of chronic cough: rhinitis, asthma, GERD - but also chronic bronchitis, foreign body, ACEI, infection, ILD, tumor.
In multiple species, there are only two main/conserved/distinct pathways for cough: C-fibers and cough receptors. Cough receptors are essentially mechanoreceptors, they're insensitive to capsaicin but sensitive to acid.
Icatibant is approved for HAE. It's not a viable tx for cough, but bradykinin antagonism is a viable target for cough.
Dr. Brooks: Cough is a warning sign similar to pain and if we understood pain reflexes better, we might understand cough better. Cough reflex probably appeared more than 100 million years ago.
Dr. Balkissoon: Response to reflux cough can be quite lengthy and high doses (PPI BID and ranitidine qhs + lifestyle measures). Metoclopramide (Reglan) can be used for aggressive medication therapy with chronic cough due to GERD (it tightens lower esophageal sphincter). Reglan is also helpful as prokinetic agent in addition to effects on LES.
Postinfectious (post viral) cough is extremely stubborn. It can last for months.
ACEI and cough
ACEI cough mechanism probably related to substance P, bradykinin, PGs. Patients on ACEI for CHF have worse cough than those on ACEI for HTN.
ACEI cough can last for TWO MONTHS after ACEI removed.
Differential diagnosis of cough, a simple mnemonic is GREAT BAD CAT TOM. Click here to enlarge the image: (GERD (reflux), Laryngopharyngeal Reflux (LPR), Rhinitis (both allergic and non-allergic) with post-nasal drip (upper airway cough syndrome, UACS), Embolism, e.g. PE in adults, Asthma, TB (tuberculosis), Bronchitis, pneumonia, pertussis, protracted/persistent bacterial bronchitis (PBB), Aspiration, e.g foreign body in children, Drugs, e.g. ACE inhibitor, CF in children, Cardiogenic, e.g. mitral stenosis in adults, Achalasia in adults, Thyroid enlargement, e.g. goiter, "Thoughts" (psychogenic), Other causes, Malignancy, e.g. lung cancer in adults).
Treatment of chronic cough
Cough suppressing meds can be centrally-acting (opioids, dextromethorphan, diphenhydramine) or peripheral (benzonatate).
Laryngeal sensory neuropathy (neurogenic cough) can be treated with gabapentin, pregabalin, amitriptyline, nortriptyline. Treatment of refractory chronic cough with gabapentin is both effective and well tolerated (2012 study) http://buff.ly/1a2laDv
BREAK THE COUGH CYCLE! Diet, PPI, nasal steroids, benzonatate, oral steroids, exercises.
A suggested cough algorithm: chlorpheniramine 8 mg bid-qid, if no help then prednisone 40mg x 5 days then 20 mg x 5 days, if help ICS plus maybe LTRA. Then, aggressive GERD therapy, if no help, start Reglan 10 mg bid-qid, then other diagnostic studies.
How to set up a cough center in private practice
Dr. Madell Sher: A cough center is a nice way to expand your scope of practice and make a difference in your community. We have a global approach to disease and cough should be right up our alley as allergists/asthma specialists.
Set up separate phone number, branded center and acquire a website.
@MatthewBowdish: Dr Sher just mentioned our cough center at the Storms Clinic! http://bit.ly/ZxTtim
Review previous records, and include a 2-page questionnaire including Leicester cough questionnaire, physical exam with laryngeal hyperfxn on expiratory phase. VCD is often inspiratory hypofunction, but just as important to us is laryngeal hyperfxn on expiratory phase.
Leicester questionnaire evaluates social isolation, depression, anxiety and others, expressing concern.
Dr Sher’s experience with 275 pts - CRS 70%, UACS 55%, GERD 53%, Asthma 13%, Eos Bronchitis 3%, some ACEI/lung ca/bronchiectasis.
Response to PPIs in chronic cough can take months.
Dr. Sher: In the non-smoker without ACEI and a normal CXR and you've treated rhinitis/GERD/asthma, then IT'S THE COUGH REFLEX, STUPID!
Cough reflex sensitivity has variable inflammatory, neurogenic and behavioral components. All “coughers” are different and have variable expression.
Upper Airway Cough Syndrome (post-nasal drip) is probably the most common etiology.
Chlorpheniramine is the best antihistamines for chronic cough - non-sedating antihistamines do not work as well, if at all.
Diet may be more important than PPI in chronic cough.
Dr. Sher: Asthma is an uncommon cause and inhalers (especially powders such as Advair Diskus) can be irritating.
Oral steroids are very important in chronic cough, especially postinfectious cough; variable effect in acute viral cough. Longer, low-dose oral steroid therapy may be needed (similar to neurodermatitis).
Dr. Balkissoon discussed his experience in an academic cough center. A nice part about being at National Jewish is to have all specialists under the same roof (pulm, AI, ENT, GI, speech path). Speech therapy is extremely helpful in chronic cough, from respiratory retraining to vocal exercises.
Gary Stadmauer spoke on importance of rhinolaryngoscopy in chronic cough. Rhinolaryngoscopy is an extension of the physical exam via a small device. You you cannot be a true upper respiratory specialist without looking at all of the upper airway .
Reflux-cough patients do not necessarily improve on rhinolaryngoscope even though they may improve clinically after treatment with medications.
@MatthewBowdish: Everyone tweeting allows me to 'attend' multiple sessions. Don't forget to download the #AAAAI meeting app - it's great to plan your day - most evaluations can be done via the app too.
Allergists are on Twitter - follow them
Allergists increased Twitter use 470% in one year - 25 allergists reached 250,000 individuals from the 2012 #AAAAI meeting (see the references here). This summary was compiled from some of the tweets posted by the following allergists:
This is a list of the allergists who used Twitter to post updates from the 2013 #AAAAI meeting. The list is open for edit, please feel free to add your own info.
I would strongly encourage you to post updates on Twitter from the CME conferences that you are planning to attend in the future. Here is how to do it: Twitter for Physicians: How to use Twitter to keep track of the latest news and scientific meetings, and share information with colleagues and patients.
Disclaimer: The text was edited, modified, and added to by me. This is one of a series of posts that will be published during the next few weeks.
Comments from Twitter:
Farris Timimi, MD @FarrisTimimi: Gr8t overview!
Ann Wu MD MPH @Asthma3Ways: Good summary. Cough more than 8 wks in adults: chronic.
@CAREAllergy: I am glad Cough got the attention it deserves and our work did not go in vain. Thanks to all of our great speakers and attendees!
Clinical approach from the concept of cough hypersensitivity - figure: http://buff.ly/1Jej9Cq