Table 2.
Multivariable prediction of positive test results for the development, validation and combined data set (OR, 95% CI).
| Development N = 1089 | Validation N = 719 | Combined N = 1808 | |
|---|---|---|---|
| Number of test positives (N (%)) | 202 (18.5%) | 84 (11.7%) | 286 (15.8%) |
| Predictors | OR (95% CI) | OR (95% CI) | OR (95% CI) |
| Sex (male vs female) | 1.55 (1.09–2.21) | 1.17 (0.68–2.00) | 1.44 (1.07–1.93) |
| ≥ 10 cigarettes per day (yes vs no) | 0.25 (0.13–0.50) | 0.35 (0.14–0.84) | 0.28 (0.16–0.48) |
| Taste or smell disorder (yes vs no) | 7.53 (5.14–11.04) | 11.86 (6.82–20.65) | 8.79 (6.42–12.04) |
| Close contact with confirmed COVID-19 infected person (yes vs no) | 2.02 (1.41–2.91) | 1.84 (1.00–3.40) | 2.07 (1.52–2.82) |
| Return from abroad (yes vs no) | 2.00 (1.22–3.27) | 2.40 (0.89–6.50) | 2.19 (1.41–3.41) |
| Exhaustion (yes vs no) | 1.56 (1.06–2.30) | 1.53 (0.88–2.67) | 1.56 (1.13–2.14) |
| Model performance | |||
| c-Statistic | 0.803 (0.768–0.838) | 0.821 (0.770–0.873) | 0.814 (0.786–0.843) |
| Tjur coefficienta | 0.234 | 0.217 | 0.232 |
| Mean predicted probability in test positives | 0.376 | 0.329 | 0.362 |
| Mean predicted probability in test negatives | 0.142 | 0.112 | 0.130 |
| Mean observed versus predicted | 18.5% versus 18.5% | 11.7% versus 13.7% | 15.8% versus 16.6% |
| Hosmer Lemeshow test (p value) | 0.31 | 0.02 | 0.002 |
OR: odds ratio; CI: confidence interval.
a
Mean predicted probability in test positives minus mean predicted probability in test negatives.