Effect of the Covid-19 pandemic on hospitalizations for non-Covid-19-pneumonia and exacerbations of chronic obstructive pulmonary diseases in Switzerland: comparison of national data between 2020/2021 and 2015-2019

Background: Protective measures applied during the Covid-19 pandemic had a marked impact on the incidence of pneumonia. However, systematic data are lacking for hospitalizations for pneumonia and acute exacerbations of chronic obstructive lung diseases (AECOPD) not caused by SARS-CoV-2 in Switzerland. We aimed to compare the incidences of hospitalization for these entities between 2020/2021 and prepandemic years.

Methods: This retrospective study examined all nationwide hospitalizations for non-Covid-19-pneumonia and AECOPD listed as primary diagnoses based on ICD-10 codes between 2015 and 2021 in a publicly available hospitalization database of the Swiss Federal Statistical Office. Hospitalizations for acute coronary syndrome (ACS) and stroke were used as controls. Changes of monthly incidences of hospitalizations, length of stay (LOS) and mortality were compared between 2020/2021 and the average of 2015-2019.

Results: The incidences of hospitalizations for AECOPD and for pneumonia showed seasonal variations from 2015 to 2019 followed by significant and almost identical decreases in 2020/2021 (incidence rate ratio [IRR] 0.59, 95% CI: 0.45-0.77, p < 0.001, and IRR: 0.62, 95% CI: 0.52-0.74, p < 0.001, respectively). Hospital-mortality was slightly higher in 2020/2021 for AECOPD (2015-2019: 3.8%; 2020/2021: 4.2%, odds ratio [OR] 1.24, 95% CI: 1.07-1.44, p = 0.004) and for pneumonia (2015-2019: 4.5%, 2020/2021: 4.6%, odds ratio [OR] 1.17, 95% CI: 1.07-1.28, p < 0.001). Median LOS slightly decreased for AECOPD (2015-2019: 8 [IQR: 5-14] days; 2020/2021: 7 [IQR: 4-13] days, Wilcoxon test: p < 0.001) but slightly increased for pneumonia (2015-2019: 7 [IQR: 4-11] days; 2020/2021: 7 [IQR: 4-13] days, Wilcoxon test: p < 0.001). Throughout 2020/2021, there were no significant fluctuations observed in the incidences of ACS and stroke. (IRR: 0.98, 95% CI: 0.83-1.16, p = 0.810, IRR: 0.96, 95% CI: 0.81-1.14, p = 0.636, respectively).

Conclusion: The first two years of the Covid-19 pandemic showed a marked decrease in incidences in AECOPD and non-Covid-19 pneumonia hospitalizations in Switzerland. It is likely that this effect is associated with the society-based, at first vigorous, social distancing measures.