Table 2.
Cox Proportional Hazard Regression Results for Risk of SARS-CoV-2 Infection and COVID-19 Outcomes Among KPNC Members, by Smoking Status (N = 2,427,293).
| Smoking Status | Never | Current | Former |
|---|---|---|---|
| N (row %) | 1,739,938 (71.3%) | 145,888 (6.0%) | 541,467 (22.7%) |
| SARS-CoV-2 infection | |||
| N events (row %) | 33,791 (76.3%) | 1836 (4.1%) | 8643 (19.5%) |
| Incidence rate* (95% CI) | 27.08 (27.07, 27.09) | 17.76 (17.74, 17.79) | 22.27 (22.25, 22.28) |
| Unadjusted, HR (95% CI) | 1.00 (ref) | 0.66 (0.63, 0.69) | 0.82 (0.80, 0.84) |
| Model 1, aHR (95% CI) | 1.00 (ref) | 0.67 (0.64, 0.71) | 1.03 (1.00, 1.05) |
| Model 2, aHR (95% CI) | 1.00 (ref) | 0.64 (0.61, 0.67) | 1.00 (0.98, 1.03) |
| Model 3, aHR (95% CI) | 1.00 (ref) | 0.64 (0.61, 0.67) | 0.96 (0.94, 0.99) |
| Model 4, aHR (95% CI) | 1.00 (ref) | 0.64 (0.61, 0.67) | 0.96 (0.93, 0.98) |
| Hospitalization | |||
| N events (row %) | 2540 (63.3%) | 112 (2.8%) | 1362 (33.9%) |
| Incidence rate* (95% CI) | 1.82 (1.82, 1.82) | 0.97 (0.97, 0.98) | 3.14 (3.14, 3.15) |
| Unadjusted, HR (95% CI) | 1.00 (ref) | 0.54 (0.44, 0.64) | 1.73 (1.62, 1.84) |
| Model 1, aHR (95% CI) | 1.00 (ref) | 0.53 (0.44, 0.64) | 1.31 (1.22, 1.40) |
| Model 2, aHR (95% CI) | 1.00 (ref) | 0.48 (0.40, 0.58) | 1.27 (1.18, 1.36) |
| Model 3, aHR (95% CI) | 1.00 (ref) | 0.48 (0.40, 0.58) | 1.10 (1.03, 1.18) |
| Model 4, aHR (95% CI) | 1.00 (ref) | 0.47 (0.38, 0.56) | 1.07 (1.00, 1.15) |
| ICU Admission | |||
| N events (row %) | 520 (59.8%) | 32 (3.7%) | 317 (36.5%) |
| Incidence rate* (95% CI) | 0.37 (0.37, 0.37) | 0.28 (0.27, 0.28) | 0.73 (0.73, 0.73) |
| Unadjusted, HR (95% CI) | 1.00 (ref) | 0.75 (0.51, 1.05) | 1.96 (1.71, 2.25) |
| Model 1, aHR (95% CI) | 1.00 (ref) | 0.69 (0.47, 0.97) | 1.41 (1.22, 1.63) |
| Model 2, aHR (95% CI) | 1.00 (ref) | 0.61 (0.42, 0.86) | 1.36 (1.17, 1.57) |
| Model 3, aHR (95% CI) | 1.00 (ref) | 0.62 (0.42, 0.87) | 1.11 (0.96, 1.29) |
| Model 4, aHR (95% CI) | 1.00 (ref) | 0.60 (0.41, 0.84) | 1.09 (0.94, 1.27) |
| Death | |||
| N events (row %) | 308 (50.2%) | 12 (1.9%) | 294 (47.9%) |
| Incidence rate* (95% CI) | 0.31 (0.31, 0.32) | 0.15 (0.15, 0.16) | 0.87 (0.87, 0.87) |
| Unadjusted, HR (95% CI) | 1.00 (ref) | 0.47 (0.25, 0.80) | 3.07 (2.62, 3.61) |
| Model 1, aHR (95% CI) | 1.00 (ref) | 0.60 (0.31, 1.01) | 1.57 (1.33, 1.85) |
| Model 2, aHR (95% CI) | 1.00 (ref) | 0.56 (0.30, 0.96) | 1.56 (1.32, 1.84) |
| Model 3, aHR (95% CI) | 1.00 (ref) | 0.52 (0.27, 0.89) | 1.32 (1.11, 1.56) |
| Model 4, aHR (95% CI) | 1.00 (ref) | 0.49 (0.26, 0.84) | 1.27 (1.07, 1.50) |
Notes: aHR = adjusted hazard ratio; BMI = body mass index; CI = confidence interval; HR = hazard ratio; NDI = neighborhood deprivation index; Bold = significant at p < .05 (results of 1.00 in bold are > 1 at the thousandth decimal place). Missing BMI (n = 57,551, 2.4%) was included as a category in all analyses.
Incidence rate per 1,000 person-years.
Model 1: age, sex, race, service area.
Model 2: age, sex, race, service area, Medicaid, NDI.
Model 3 (fully adjusted): age, sex, race, service area, Medicaid, NDI, BMI, hypertension, atherosclerotic cardiovascular disease, heart failure, dysrhythmias, renal disease, diabetes.
Model 4 (extended model): age, sex, race, service area, Medicaid, NDI, BMI, hypertension, atherosclerotic cardiovascular disease, heart failure, dysrhythmias, renal disease, diabetes, any respiratory condition.