Multivariable model predicting false negatives
| Population characteristic | Level | OR (95% CI) N=1065 |
| Age (years) | 1-year increase | 0.99 (0.98 to 1.00) |
| Gender | Female | 1.13 (0.84 to 1.52) |
| Comorbidity | Cardiovascular disease | 0.48 (0.20 to 1.16) |
| Chronic respiratory disease | 1.00 (0.69 to 1.45) | |
| Diabetes | 1.66 (1.13 to 2.45) | |
| Hypertension | 0.99 (0.70 to 1.40) | |
| Immunosuppression (including steroid use) | 0.62 (0.38 to 1.01) | |
| Active malignancy | 0.42 (0.15 to 1.23) | |
| Obesity | Not included | |
| Renal impairment | 0.86 (0.38 to 1.97) | |
| Smoker | 0.81 (0.58 to 1.12) | |
| Stroke | 1.99 (0.63 to 6.28) | |
| Number of drugs used | 0 | Reference |
| 1–5 | 1.13 (0.74 to 1.74) | |
| 6–10 | 0.60 (0.33 to 1.10) | |
| 11 or more | 0.38 (0.11 to 1.27) | |
| Deprivation index | 1–2 | Reference |
| 3–4 | 1.27 (0.84 to 1.93) | |
| 5–6 | 1.03 (0.66 to 1.61) | |
| 7–8 | 1.26 (0.82 to 1.93) | |
| 9–10 | 1.38 (0.88 to 2.15) | |
| Number of 111 contacts in study period | 1 | Reference |
| 2 | 1.77 (1.14 to 2.75) | |
| 3 or more | 4.03 (1.68 to 9.65) |