COVID: anosmia extremely common

A recent Italian study assessed the presenting symptoms for Covid-19, finding a very large percentage had decreased smell or taste (see covid anosmia jama2020 in dropbox, or doi:10.1001/jama.2020.6771)

Details:

-- 283 patients were seen at the Treviso Regional Hospital between March 19 and March 22 and tested positive for SARS-CoV-2 (Treviso is high up in northeast Italy)

    -- 202 (71%) completed a telephone survey

-- median age 56, 48% men, never smokers 69%, no current alcohol 40%, no comorbidity 44%

-- indication for testing: exposure to confirmed contact 35%/symptomatic presentation 65%

-- they used a validated instrument called the Sino-nasal Outcome Test 22 (SNOT-22, I kid you not) to grade the severity of symptoms of the alteration of sense of smell or taste, on a scale from none (0) to as bad as it can be (5).

Results:

--presenting symptoms, per patients' recall of “during the 2 weeks preceding the swab, did you experience any of the following symptoms?”, combining results of "a little bit" plus "a lot":

    -- Felt tired: 68%

    -- altered sense of smell or taste: 65%

    -- dry cough or coughing up mucous: 60%

    -- fever: 56%

    -- loss of appetite: 55%

    -- muscle and joint pains: 45%

    -- diarrhea: 44%

    -- headache: 43%

    -- problems breathing: 41%

    -- blocked nose: 36%

    -- sore throat: 31%

    -- nausea: 20%

    -- sinonasal pain: 17%

    -- chest pain: 16%

    -- dizziness: 14%

    -- abdominal pain: 12%

    -- vomiting: 6%

-- and in terms of the SNOT-22 scores there was a decided shift to the moderate/severe/as bad as it can be spectrum

-- timing to alteration of smell or taste (the % is the overall prevalence, not just the symptomatic ones):

    -- the only symptom: 6 people (3%), but 5% of the symptomatic 130 patients having altered smell or taste

    -- prior to other symptoms: 24 (12%), 18% of symptomatics

    -- concomitant with other symptoms: 46 (23%), 35% of symptomatics

    -- after other symptoms: 54 (27%), 42% of symptomatics

-- of those reporting symptoms of altered sense of smell or taste, 45 (35%) also reported a blocked nose

-- altered sense of smell or taste was more common in women (72%)

Commentary:

-- other coronaviruses (e.g. human coronavirus OC43) have been associated with neurologic symptoms in humans, with documentation that the virus invades the central nervous system through the olfactory neuro-epithelium and propagates from within the olfactory bulb in mice (see https://jvi.asm.org/content/92/17/e00404-18 )

-- the nasal epithelial cells have the highest expression of ACE2 in the respiratory tree, and this is apparently the main entry point for SARS-CoV-2 into the body

-- in terms of combining taste and smell, a decreased sense of smell can be associated with marked changes in sense of taste (hard to differentiate, in a questionnaire)

-- of those with decreased smell/taste, it was the only or earliest symptom in almost 1/4 of the patients and at least conommitant with other inital symptoms in 60%

--limitations of this report:

    -- these data were self-reported, and subject to recall bias

    -- it was a relatively small sample

    -- it was from geographically limited to Italy and may not be generalizable to other areas

        --and, as we all know, Italians may have a different, more refined and acute senses of smell and taste, given the quality of the food there

    -- the study did not include severe Covid-19 patients

    -- no follow-up outcome data were available.

    -- there was no objective testing for olfactory function

so, this report brings up a few issues:

--we really should make sure that olfactory and taste changes are part of our routine screening for Covid-19, especially since they often seems to be a very early, and sometimes the only symptom

    --and, this was even more common than our typical first-hit screen of fever and cough

          --even in Massachusetts where there has been a significant increase in the availability of testing kits (though still not nearly enough), the state still requires symptomatic patients with fever or some signs/symptoms of at least mild respiratory illness (in those who are at higher risk of complications) or lower respiratory illness (cough, shortness of breath, pneumonia) in others, and still targets critical infrastructure employees or those in congregate settings (see https://www.mass.gov/doc/covid-19-pui-criteria/download?_ga=2.167566526.1876850177.1587412879-618943015.1540841336 )

--though i have seen anosmia as a sequela of upper respiratory viral infections (and can last a long time after the infection), it has been quite uncommon in my clinical experience. this raises a couple of issues:

    --i wonder if these anosmia cases were associated particularly with the annual regular coronavirus infections (as per the neurologic issues with mice, above)

    --and, i wonder if a change in smell/taste is actually a pretty specific finding to our current SARS-CoV-2 virus, especially in those who do not have a "blocked nose" (which was found in only 1/3 of them)

    --perhaps anosmia may be a strong, independent, and relatively specific flag for testing patients, better than waiting for fever and cough (which may not even develop in some). and, if so, testing/finding SARS-CoV-2 in these patients might lead to more isolation of them, contact testing, and decreasing viral transmission.  though we need studies to answer this question..

geoff

If you would like to be on the regular email list for upcoming blogs, please contact me at gmodest@uphams.org

to get access to all of the blogs:

1. go to http://gmodestmedblogs.blogspot.com/ to see them in reverse chronological order

2. click on 3 parallel lines top left, if you want to see blogs by category, then click on "labels" and choose a category​

3. or you can just click on the magnifying glass on top right, then  type in a name in the search box and get all the blogs with that name in them

please feel free to circulate this to others. also, if you send me their emails, i can add them to the list