Hospital Admission Rates in Patients with COPD Throughout the COVID-19 Pandemic

Figures & data

Figure 1 Total monthly number of hospital admissions due to COVID-19 at Sahlgrenska University Hospital throughout the pandemic (regardless of COPD diagnosis). Five separate waves of COVID-19 admission were identified.

Figure 2 Linear graphs showing the three-month moving average number of hospital admissions according to primary diagnosis (acute exacerbations, pneumonia, influenza, or COVID-19) in patients with chronic obstructive pulmonary disease, during the prepandemic, pandemic, and post-restriction periods. A combined outcome including all of the primary diagnoses above is also shown (total COPD admissions, dashed line).

Abbreviation: AECOPD, acute exacerbation of chronic obstructive pulmonary disease.

Table 1 Average Monthly Admission Rates in COPD Patients According to Primary Diagnosis During the Pandemic, Compared with a Prepandemic Period

Primary Diagnosis	Monthly Number of Prepandemic Admissions	Monthly Number of Pandemic Admissions	Admission IRR	P^a
	Mean (95% CI)	Mean (95% CI)	(95% CI)
AECOPD	78 (75–81)	56 (53–59)	0.72 (0.67–0.77)	<0.001
Pneumonia	27 (25–28)	15 (13–16)	0.56 (0.49–0.62)	<0.001
Influenza^b	3.8 (2.5–5.5)	0.7 (0.4–1.2)	0.18 (0.10–0.30)	<0.001
COVID-19	0	15
Total COPD admissions^c	107 (103–111)	85 (81–89)	0.79 (0.75–0.84)	<0.001

Notes: ^ap-values and incidence rate ratios with 95% confidence intervals were calculated using Poisson regression. ^bMean admission rates for influenza were calculated for the winter period, as defined in the method section. ^cCombined outcome of all COPD admissions for AECOPD, pneumonia, influenza, or COVID-19.

Abbreviations: AECOPD, acute exacerbation of chronic obstructive pulmonary disease; IRR, incidence rate ratio.

Figure 3 Hospital admission incidence rate ratios for (a) acute exacerbations of chronic obstructive pulmonary disease and (b) pneumonia, from January 2020 through August 2022. An incidence rate ratio below 1.0 indicates a decrease in the rate of hospital admissions during the pandemic, compared with the prepandemic period. The incidence rate ratios for the combined outcome of total COPD admissions (acute exacerbations, pneumonia, influenza, or COVID-19) are also shown (dashed blue line). For reference, the total number of all registered COVID-19 admissions at the hospital is shown on the secondary y-axis (shaded Orange graph).

Abbreviations: AECOPD, acute exacerbation of chronic obstructive pulmonary disease; IRR, incidence rate ratio.

Table 2 Incidence Rate Ratios for Admissions of COPD Patients by Primary Diagnosis During the Different Waves of the Pandemic Compared with the Prepandemic Period

Phase^a	AECOPD Admissions		Pneumonia Admissions		Total COPD Admissions^b
	IRR (95% CI)	P^c	IRR (95% CI)	P^c	IRR (95% CI)	P^c
First wave	0.67 (0.58–0.77)	<0.001	0.61 (0.48–0.78)	<0.001	0.80 (0.71–0.89)	<0.001
Intermediate period	0.70 (0.58–0.84)	<0.001	0.47 (0.32–0.69)	<0.001	0.65 (0.56–0.77)	<0.001
Second wave	0.59 (0.52–0.68)	<0.001	0.35 (0.26–0.46)	<0.001	0.77 (0.69–0.85)	<0.001
Third wave (Alpha)	0.66 (0.55–0.79)	<0.001	0.43 (0.30–0.61)	<0.001	0.77 (0.67–0.89)	<0.001
Fourth wave (Delta)	0.90 (0.79–1.04)	0.16	0.83 (0.65–1.06)	0.15	0.89 (0.79–1.01)	0.06
Fifth wave (Omicron)	0.69 (0.60–0.80)	<0.001	0.62 (0.48–0.80)	<0.001	0.78 (0.70–0.88)	<0.001
Post-restriction period	0.95 (0.84–1.08)	0.42	0.86 (0.69–1.07)	0.17	0.98 (0.88–1.09)	0.70

Notes: Chronologically presented phases of the COVID-19 pandemic, compared to the corresponding prepandemic months. ^aDefinitions of the various phases of the pandemic are described in the methods section and Figure 1. ^bCombined outcome of all COPD admissions for AECOPD, pneumonia, influenza, or COVID-19. ^cp-values and incidence rate ratios with 95% confidence intervals were calculated using Poisson regression.

Abbreviations: AECOPD, acute exacerbation of chronic obstructive pulmonary disease; IRR, incidence rate ratio.