Covid-19 and smoking: the Pitié Salpêtrière study refuted
14 May 2020
Par: communication@cnct.fr
Dernière mise à jour: 14 May 2020
Temps de lecture: 3 minutes
In April 2020, a French study of patients at the Pitié Salpêtrière Hospital suggested that daily smokers, due to their nicotine consumption, had a much lower probability of developing symptomatic or severe COVID-19 infection, compared to the general population.
At the instigation of the High Council of Public Health, a multidisciplinary and multi-institutional working group was set up to determine whether current epidemiological data make it possible to highlight a relationship between smoking status, the risk of developing a symptomatic Covid-19 infection and its progression.
Based on an analysis of the literature on tobacco and Covid-19, an analysis of hospital data, and an ad hoc analysis of data from other AP-HP hospitals, the working group highlights that the results of the study conducted at the Pitié Salpêtrière hospital are partly biased by questionable methodological choices, ranging from a priori in favour of maximising smoking prevalence in the reference population. In other words, the study, by comparing the smoking prevalence of patients with a maximised general reference prevalence, superficially increases the gap between the latter and the prevalence of patients.
Furthermore, the choice to exclude patients admitted to intensive care leads to an underestimation of smoking among hospitalized patients. When these patients are taken into account, there is no longer a "protective" effect of smoking among hospitalized Covid-19 patients. The working group also emphasizes that the characterization of smoking status is of poor quality in medical records, leading to an underestimation of the number of smokers among the patients studied.
In this way, it is not possible to associate smoking with a reduction in the risk of developing the Coronavirus. All the data also show that smokers are more likely to develop serious forms of Covid-19, including fatal ones.
Thus, the hypothesis of underestimation of smoking prevalence is the most likely to explain why patients infected with Covid-19 almost constantly show a lower proportion of smokers among them than in the general population.
To conclude, the High Council for Public Health issues a certain number of recommendations:
- Refute this false information in all public communication
- Discourage self-prescription of nicotine products
- Strengthening anti-tobacco measures
- Encourage healthcare professionals to be extra vigilant if they detect a patient infected with Covid-19
- Improving the information and monitoring system for data relating to the patient's smoking status
- Be cautious in publicizing results
- Continue research into the links between tobacco and Covid-19
To view the notice on the link between smoking and Covid-19
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