Comparison of model performance for predicting preterm status
| Cohort | <37 weeks GA | ≤34 weeks GA | ||||
| AUC (95% CI) | PPV 80% | p Value* | AUC (95% CI) | PPV 80% | p Value* | |
| Original validation | 0.970 (0.966 to 0.974) | – | Reference | 0.991 (0.987 to 0.995) | 80.9 | Reference |
| Validation based on immigration status in IRCC | ||||||
| New validation cohort (overall) | 0.957 (0.956 to 0.959) | 56.1 | <0.0001 | 0.981 (0.979 to 0.983) | 75.9 | <0.0001 |
| Non-immigrants | 0.958 (0.956 to 0.961) | 57.4 | <0.0001 | 0.981 (0.979 to 0.983) | 75.7 | 0.021 |
| All immigrants | 0.954 (0.95 to 0.958) | 51.7 | <0.0001 | 0.983 (0.978 to 0.987) | 74.3 | 0.0063 |
| India | 0.947 (0.936 to 0.959) | 49.3 | 0.00027 | 0.980 (0.968 to 0.993) | 61.8 | 0.240 |
| China | 0.957 (0.943 to 0.972) | 42.0 | 0.092 | 0.983 (0.966 to 1.00) | 86.3 | 0.78 |
| Pakistan | 0.949 (0.933 to 0.964) | 43.1 | 0.010 | 0.960 (0.936 to 0.985) | 77.0 | 0.103 |
| Philippines | 0.958 (0.945 to 0.971) | 57.9 | 0.082 | 0.992 (0.982 to 1.00) | 69.4 | 0.505 |
| Vietnam | 0.949 (0.916 to 0.981) | 48.9 | 0.209 | 0.991 (0.965 to 1.02) | 88.2 | 0.840 |
| Bangladesh | 0.945 (0.911 to 0.979) | 49.3 | 0.151 | 0.947 (0.888 to 1.00) | 69.6 | 0.300 |
| Somalia | 0.927 (0.880 to 0.974) | 30.9 | 0.072 | 0.974 (0.924 to 1.02) | 83.3 | 1.000 |
| Nigeria | 0.964 (0.930 to 0.998) | 51.7 | 0.733 | 0.965 (0.910 to 1.02) | 100.0 | 0.369 |
*p Value for two-sided z-test for the difference between original and subgroup AUC.
AUC, area under the receiver operating characteristic curve; GA, gestational age; IRCC, Citizenship and Immigration Canada’s Permanent Resident Database; PPV, positive predictive value.