Table S1.
Calculation of sensitivity, specificity, PPV, and NPVa
| NorPD reference standard | |||
|---|---|---|---|
| Positive (truly exposed) | Negative (truly unexposed) | ||
| MoBa questionnaire positive (exposed) | Ab (“Both”) | Bb (“MoBa only”) | “MoBa total” |
| MoBa questionnaire negative (unexposed) | Cb (“NorPD only”) | Db (“Neither”) | “Total”–“MoBa total” |
| “NorPD total” | “Total”–“NorPD total” | “Total”c | |
Notes:
Sensitivity: A/(A+C)*100, sensitivity standard error (SE_sensitivity)=((sensitivity*(1–sensitivity))/(A+C))1/2; specificity: D/(D+B)*100, specificity standard error (SE_ specificity)=((specificity*(1–specificity))/(D+B))1/2; PPV: A/(A+B)*100, PPV standard error (SE_PPV)=((PPV*(1–PPV))/(A+B))1/2; NPV: D/(D+C)*100, NPV standard error (SE_NPV)=((NPV*(1–NPV))/(D+C))1/2; given the standard error (SE), we calculate 95% CI, with Z-score (Z) of 1.96 according to (x–Z*SE, x+Z*SE), with x representing sensitivity, specificity, PPV, or NPV and SE the respective standard errors.
Table cell counts correspond to the number of consistent (ie ‘Both’, ‘Neither’) and inconsistent (ie ‘MoBa only’, ‘NorPD only’) self-reports and prescription records, and depend on THRT exposure length.
Total study population, n=56,148.
Abbreviations: MoBa, Norwegian Mother and Child Cohort Study; NorPD, Norwegian Prescription Database; NPV, negative predictive value; PPV, positive predictive value; THRT, thyroid hormone replacement therapy.