Table 3. Validity of the World Health Organization’s verbal autopsy tool for stillbirth6 as determined by comparing the cause of stillbirth of any type (direct, antecedent or underlying) diagnosed with the toola with hospital-based diagnosis, Chandigarh, India.
| Cause of stillbirth | Sensitivity |
Specificity |
PPV |
NPV |
DAb |
Area under ROC curvec |
|||
|---|---|---|---|---|---|---|---|---|---|
| VAD/HDd | % (95% CI) | VAD/HDe | % (95% CI) | % (95% CI) | % (95% CI) | % (95% CI) | Value (95% CI) | ||
| Congenital malformations | 25/27 | 92.6 (74.2–98.7) | 187/198 | 94.4 (90.0–97.1) | 69.4 (51.7–83.1) | 98.9 (95.8–99.8) | 94 (82–106) | 0.93 (0.88–0.99) | |
| Underlying maternal illnessf | 19/29 | 65.5 (45.7–81.4) | 168/196 | 85.7 (79.8–90.1) | 40.4 (26.7 −55.7) | 94.4 (89.6–97.1) | 83 (67–99) | 0.76 (0.66–0.85) | |
| Pregnancy-induced hypertension | 45/69 | 65.2 (52.7–76.0) | 131/156 | 84.0 (77.1–89.2) | 64.3 (51.9 −75.1) | 84.5 (77.6–89.6) | 78 (66–90) | 0.75 (0.68–0.81) | |
| Antepartum haemorrhage | 24/35 | 68.6 (50.6–82.6) | 159/190 | 83.7 (77.5–88.5) | 43.6 (30.6–57.6) | 93.5 (88.4–96.6) | 81 (67–95) | 0.76 (0.68–0.84) | |
| Obstetric complications | 14/19 | 73.7 (48.6–89.9) | 193/206 | 93.7 (89.2–96.5) | 51.9 (32.4–70.8) | 97.5 (93.9–99.1) | 92 (74–110) | 0.83 (0.73–0.94) | |
CI, confidence interval; DA, diagnostic accuracy; HD, hospital-based diagnosis; NPV, negative predictive value; PPV, positive predictive value; ROC, receiver operator characteristic; VAD, verbal autopsy diagnosis.
a This includes any cause of stillbirth reported by either of two reviewers as the direct, antecedent or underlying cause of death. For example, pregnancy-induced hypertension could have been designated as the underlying cause by one reviewer and as the antecedent cause by another.
c The area under the ROC curve captures the relationship between the sensitivity and specificity of a diagnostic tool or method and is therefore indicative of diagnostic performance with respect to a given condition. Because it is a probability, it takes on values between 0 and 1. A larger value generally indicates better diagnostic performance.
d Number of positives correctly diagnosed through verbal autopsy (true positives) divided by number of positives diagnosed in hospital (gold standard).
e Number of negatives correctly diagnosed through verbal autopsy (true negatives) divided by number of negatives diagnosed in hospital (gold standard).
f The main underlying chronic maternal illnesses were, in descending order of frequency, chronic hypertension, epilepsy, renal disease, liver disease and diabetes mellitus.
b ([True positives + true negatives] ÷ 225) × 100.