Table 4 Estimated waxing and waning of IgA and IgG levels between diagnostic parameters
Variable | IgA | IgG |
|---|---|---|
Laboratory detection limit | 5 U/ml | 5 U/ml |
100% sensitivity level in the 46 pertussis cases | 24 U/ml | 27 U/ml |
90% specificity level in 4275 external controls | 24 U/ml | 27 U/ml |
99% specificity level in 4275 external controls | 74 U/ml | 90 U/ml |
GMC of the highest level obtained in week 9 and 12 of pertussis cases with at least 4-fold increase or decrease between week 9, 13 and 60 of the epidemic | 229 U/ml (n = 28 levels) | 406 U/ml (n = 49 levels) |
Average speed of significant increase | 16.0 U/ml/day (n = 11 level pairs) | 14.7 U/ml/day (n = 9 level pairs) |
Average speed of significant decrease | 1.0 U/ml/day (n = 18 level pairs) | 2.9 U/ml/day (n = 46 level pairs) |
Mean time to increase from detection limit to 100% sensitivity level | 1.2 days | 1.5 days |
Mean time to increase from detection limit to 99% specificity level | 4.3 days | 5.8 days |
Mean time to increase from detection limit to GMC | 14.0 days | 27.3 days |
Mean time to increase from 99% specificity level to GMC | 9.8 days | 21.5 days |
Mean time to decrease from GMC to 99% specificity level | 156.0 days | 109.0 days |
Mean time spent above 99% specificity level | 165.8 days (5.5 month) | 130.5 days (4.3 month) |
Mean time to decrease from 99% specificity level to 100% sensitivity level | 50.0 days | 21.7 days |
Total time spent going up and down between detection limit and GMC | 238.0 days | 165.6 days |
Total time spent going up and down between 100% sensitivity level and GMC | 217.8 days (7.2 months) | 156.5 days (5.1 months) |