Table 3.
Subgroup analysis for the associations of COVID-19 fatality with environmental exposure
| Variable | Temperaturea |
PM2.5a |
PM10a |
NO2a |
SO2a |
O3a |
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| HR (95% CI) | p valueb | HR (95% CI) | p valueb | HR (95% CI) | p valueb | HR (95% CI) | p valueb | HR (95% CI) | p valueb | HR (95% CI) | p valueb | |
| Age | 0.02 | <0.01 | <0.01 | <0.01 | 0.11 | 0.58 | ||||||
| <65 | 1.00 (0.97, 1.02) | 1.06 (1.02, 1.10) | 1.05 (1.01, 1.09) | 1.11 (1.00, 1.24) | 0.89 (0.68, 1.17) | 1.07 (1.00, 1.17) | ||||||
| ≥65 | 1.04 (1.02, 1.06) | 1.14 (1.11, 1.17) | 1.13 (1.11, 1.16) | 1.34 (1.23, 1.45) | 1.16 (0.98, 1.38) | 1.10 (1.04, 1.16) | ||||||
| Sex | 0.81 | 0.64 | 0.52 | 0.15 | 0.50 | 0.32 | ||||||
| Male | 1.07 (0.98, 1.17) | 1.04 (0.96, 1.14) | 1.07 (1.00, 1.17) | 1.22 (1.13, 1.33) | 1.03 (0.86, 1.23) | 1.07 (1.01, 1.13) | ||||||
| Female | 1.09 (0.97, 1.23) | 1.07 (1.00, 1.17) | 1.12 (1.00, 1.25) | 1.35 (1.21, 1.51) | 1.14 (0.90, 1.45) | 1.12 (1.04, 1.20) | ||||||
| Severity | <0.01 | 0.09 | 0.10 | <0.01 | 0.08 | 0.39 | ||||||
| Mild | 1.13 (1.08, 1.20) | 1.18 (1.11, 1.27) | 1.16 (1.09, 1.23) | 1.62 (1.36, 1.94) | 1.91 (1.05, 3.51) | 1.18 (1.04, 1.35) | ||||||
| Severe | 1.01 (1.00, 1.03) | 1.11 (1.09, 1.13) | 1.10 (1.08, 1.12) | 1.25 (1.16, 1.34) | 1.10 (0.96, 1.27) | 1.11 (1.06, 1.17) | ||||||
| Location | <0.01 | <0.01 | <0.01 | <0.01 | 0.86 | <0.01 | ||||||
| Wuhan | 1.15 (1.12, 1.18) | 1.23 (1.19, 1.28) | 1.19 (1.15, 1.23) | 1.44 (1.33, 1.57) | 1.12 (0.69, 1.79) | 1.19 (1.11, 1.28) | ||||||
| Non-Wuhan | 1.00 (0.98, 1.02) | 1.06 (1.03, 1.09) | 1.06 (1.03, 1.09) | 1.04 (0.93, 1.16) | 1.07 (0.92, 1.25) | 1.03 (0.96, 1.09) | ||||||
| Province | <0.01 | 0.11 | 0.03 | 0.03 | <0.01 | 0.07 | ||||||
| Hubei | 1.12 (1.09, 1.15) | 1.04 (1.00, 1.05) | 1.08 (1.03, 1.13) | 1.65 (1.55, 1.76) | 1.38 (1.12, 1.71) | 1.12 (0.96, 1.32) | ||||||
| Non-Hubei | 1.02 (1.00, 1.05) | 1.09 (1.04, 1.15) | 1.02 (1.00, 1.04) | 1.33 (1.11, 1.59) | 0.71 (0.57, 0.89) | 0.96 (0.92, 1.00) | ||||||
| Lockdownc | 0.29 | 0.11 | 0.07 | 0.16 | 0.06 | <0.01 | ||||||
| After | 1.05 (1.02, 1.09) | 1.07 (1.02, 1.13) | 1.06 (1.02, 1.11) | 1.17 (1.04, 1.32) | 0.86 (0.51, 1.22) | 0.93 (0.53, 1.33) | ||||||
| Before | 1.03 (1.01, 1.04) | 1.12 (1.09, 1.14) | 1.11 (1.08, 1.14) | 1.30 (1.19, 1.42) | 1.37 (1.16, 1.62) | 1.21 (1.14, 1.29) | ||||||
Note: HR, hazard ratio; PM2.5, particulate matter with an aerodynamic diameter ≤2.5 μm; PM10, particulate matter with an aerodynamic diameter ≤10 μm; SO2, sulfur dioxide; NO2, nitrogen dioxide; O3, ozone.
All the environmental factors were estimated using exposure window I (mean exposure value from the date of symptom onset to the date of diagnosis). The effects of environmental factors were estimated using the adjusted model, adjusted for age, sex, temperature (only for the pollutants), relative humidity, occupation, residence, severity of the illness, location, transfer history, temporal trend, and lockdown.
p values were estimated using likelihood ratio test by comparing different subgroups, and p < 0.05 indicates statistical significance.
Lockdown: on January 23, 2020, the central government of China imposed a lockdown in Wuhan and other cities in Hubei.