The impact of smoking on symptom and radiological severity at COVID-19 follow up

ABSTRACT

Background The relationship between smoking and COVID-19 disease severity is uncertain;one meta-analysis found smoking increases the risk of developing severe COVID-19 two-fold.1 No previous study has reported whether smokers have worse outcomes at follow-up. We hypothesised that smokers admitted to hospital with COVID-19 would have a greater symptom and radiological severity at follow-up. Methods We prospectively followed up swab-positive COVID-19 patients in two hospitals discharged between 03.05.20 and 19.06.20. Telephone calls were conducted 8-10 weeks post discharge. Demographics, co-morbidities, smoking history and symptom burden data were collected. Symptom burden was quantified using a numerical rating scale for breathlessness, cough and fatigue. Patients were offered a follow-up chest radiograph (CXR) if abnormal on discharge Results 782 patients were reviewed post-discharge, median (IQR) time to review 63 (54-79) days. Smoking history was obtained for 537 patients. Outcomes for 181 (34%) current/ex-smokers were compared to 356 (66%) never-smokers. Table 1 demonstrates baseline characteristics and symptom burden between groups at follow-up. Never-smokers were significantly younger (59.5±16.3 vs. 65.1±15.5 years, p<0.001) and more likely to be from ethnic minority groups (51.4% vs 34.8%, p<0.001). Ex/current smokers had significantly increased self-reported breathlessness (1 (0-3) vs 0 (0-2);p=0.037) and higher Medical Research Council (MRC) dyspnoea score (2 (1-3) vs 1(1-2);p=0.013). They were less likely to have returned to work (30% vs 51%;p=0.013). Regression analyses demonstrated no significant impact of age and ethnicity on self-reported breathlessness (p=0.317) but demonstrated a significant impact of age on the MRC score (p<0.001). There were no significant differences in CXR findings at follow-up. Conclusion In this large clinical cohort, ex/current smokers had significantly increased self-reported breathlessness at follow-up. These results should be interpreted with caution as the burden of breathlessness prior to admission is unknown. Interestingly, there were no significant differences in other symptoms, nor any differences in radiology findings. Further work is required to understand the mechanisms underlying these findings in order to mitigate the effect of COVID-19 in current/ex smokers. We should continue to routinely and optimally treat current smokers for their tobacco dependence.