Smoking as a mediator in the Association Between Educational Status and COVID-19 Hospitalization in COVID-19 Cases: Cross-Sectional Survey Study (Preprint)

Abstract

Educational disparities in COVID-19 outcomes have been documented in numerous studies conducted in western countries. However, evidence from China is limited, and no study has yet explored the potential role of smoking on the disparities.

To assess the association between educational status and hospitalization among cases with SARS-CoV-2 infection, as well as mediating smoking behavior.

We used data of 25 827 participants who reported positive results for SARS-CoV-2 infection through the reverse transcriptase polymerase chain reaction (RT-PCR) and/or IgM-IgG antigen test from a cross-sectional study conducted between January 28th and February 21st, 2023, shortly after a surge in the number of COVID-19 cases in Chinese mainland. The hospitalization due to COVID-19, educational status the smoking status were reported by participants in an online questionnaire. Logistic regression with and without unstable inverse probability weighting were applied to estimated odds ratios between COVID-19 hospitalization and educational status adjusting for potential confounders. Karon-Holm-Breen(KHB) method was used to estimated the percentage of mediation the smoking status contributed.

Of 25 827 participants (56.4% male; mean [SD] age, 40.9 [11.7] years),1652(6.83%) were hospitalized,9381(36.3%) had an educational status of college or above,7042(27.3%) had a smoking history. Elevated adjusted ORs for COVID-19 hospitalization were observed in participants with primary school or below (OR:1.84 [95%CI, 1.46-2.31]), junior high school (OR:1.48 [95%CI, 1.25-1.76]), high school/technical secondary school (OR:1.44 [95%CI, 1.24-1.66]) and having smoking history (OR:1.52 [95%CI, 1.35-1.70]). Mediation analysis suggested that smoking history acted as a mediator between educational status and COVID-19 hospitalization, with the proportion of mediation ranging from 7.62% to 13.34% and varied by sex.

This study found an educational gradient in COVID-19 hospitalization among people infected with SARS-CoV-2 in Chinese mainland, as well as the mediation of smoking. The findings suggest the necessity of reinforcing health promotion and smoking cessation interventions for low-educated smokers.