Monday, February 8, 2021

Author and Editors Defend the Indefensible Stanford Study on Vaping & Covid

In August, I discussed a Stanford University study published in the Journal of Adolescent Health (JAH) claiming that young people who ever use e-cigarettes are five to seven times more likely to be diagnosed with Covid-19.  A group of harm reduction researchers subsequently wrote that the claims are implausible and the results “so suspect that any conclusions drawn from it [sic] cannot be relied upon…the paper should be retracted.”

The JAH recently published four letters to the editor regarding that study (available here).  The letters were followed by a response from only one of three original contributors: senior author Bonnie Halpern-Felsher.  One is left to wonder about why her original co-authors didn’t sign on to the reply.  Halpern-Felsher’s response did have five co-signers from four other institutions defending the article that they had not written.  Additionally, the JAH editors penned their own response – indicating that they recognized that they had problems with Halpern-Felsher’s article.

The four letters focused on a variety of issues, including these key ones.

1. Halpern-Felsher writes “We adjusted our sample to be representative of the U.S. population.”

Halpern-Felsher incorrectly claimed that her results apply to the entire U.S.  The group calling for retraction noted that the number of participants Halpern-Felsher asserts were Covid-tested would have accounted for almost half of the nation’s 10.4 million tests (here).  In fact, youth and young adults were rarely tested early in the pandemic. 

In the following table I use the 2020 National Youth Tobacco Survey and the 2019 National Health Interview Survey (the most recent available) to estimate populations of 13-17, 18-21 and 22-24 year-olds, according to whether they were ever, or never users of e-cigarettes.  I then multiply these numbers by the percentages who had a positive diagnosis for Covid-19, according to Table 1 in Halpern-Felsher’s response. 


Number of Covid Cases Among Youth and Young Adults in the U.S. On May 14, 2020, According to Dr. Bonnie Halpern-Felsher

Age Group (years)Population*Percent Covid+**Number Covid+


Never Vape13,461,2500.4763,268
Ever Vape6,022,5783.26196,336


Never Vape12,179,4150.7388,910
Ever Vape4,684,0182.68125,558

Never Vape7,682,8211.51116,011
Ever Vape4,169,2037.43309,772


*Population estimates from NYTS 2020 (13-17 years) and NHIS 2019.        **From Table 1, Halpern-Felsher et al. 

Her assertion that her numbers are nationally representative means that the total number of Covid-19 cases among youth and young adults in the U.S. when her survey ended on May 14, 2020, was 899,855.

In reality, according to the World Health Organization, the U.S. had a cumulative total of 1,361,522 Covid cases on May 14, 2020.  While it is widely acknowledged that the early epidemic in the U.S. impacted older Americans disproportionately, Halpern-Felsher’s national estimate means that 13-24 year-olds accounted for 66% of all U.S. cases.

2. Halpern-Felsher’s claims, based on tiny numbers.

In our letter, Nantaporn Plurphanswat and I used a standard epidemiologic table to estimate the numbers of cases underlying Halpern-Felsher’s five and seven times claims, as she had refused our request to publish the actual figures.   Her response confirmed that her claims were based on very small numbers.

3. Halpern-Felsher and the editors obtained questionable “independent” reviews.

In her response, Halpern-Felsher wrote, “we voluntarily decided to re-review our data set and analyses, and voluntarily asked another statistician not involved in the original study or any tobacco-related research to rerun the analyses.”  It is not clear to whom the “we” in that sentence refers, since, as noted above, the original co-authors of her article did not sign the response letter.  Further, her statement lacks substantive meaning.  Saying she “voluntarily asked another statistician” to “rerun the analyses” and later noting that “the results of the original main analyses were confirmed…by the independent analysis, and there are no changes to…the core study findings” simply means that there was no error in the analysis.  This response offers no clue as to the quality of the analytic approach, or whether the statistician thought that the whole project was worthless. 

Interestingly, the editors, in their response, also mentioned that “The independent re-analysis confirmed the original main findings” and they seemed to praise the effort by adding that “three independent scientific reviewers [were tasked] from the fields of sociology, epidemiology, and biostatistics.”

Unless the four heralded “independent” reviews are made available for scrutiny, they lend no credibility to the original work.

4. Halpern-Felsher failed to disclose conflicts of interest.

Our letter addressed the fact that Halpern-Felsher, “who is an editorial board member of the Journal of Adolescent Health, may have breached its policy on conflicts of interest” by failing to disclose that she had participated in a lawsuit against an e-cigarette manufacturer.

Halpern-Felsher responded by claiming to update her disclosure, but as of this date she had not done so.  And she reciprocated by accusing the letters’ authors of hiding conflicts themselves: “Several scientists who have raised concerns about this study receive funding from the tobacco industry, and as such, should disclose those conflicts of interest.”  She provided no evidence to support this claim.

The editors supported Halpern-Felsher’s demand, writing that “all potential conflicts of interest should be disclosed by authors… Accordingly, we have asked authors of all letters to update their disclosures.”  Importantly, the editors noted that disclosure “is a standard expectation within the scientific community.”  That is the only acknowledgment of Halpern-Felsher’s egregious disregard of the journal’s disclosure policy.

JAH editors should have better served their readers and public health by retracting the highly flawed Halpern-Felsher article.




No comments: