Table 2. Validity of the World Health Organization’s verbal autopsy tool for stillbirth6 as determined by comparing the underlying cause of stillbirth diagnosed with the toola with hospital-based diagnosis, Chandigarh, India.
| Underlying cause of stillbirtha | 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 | 23/27 | 85.2 (65.4–95.1) | 190/198 | 96.0 (91.9–98.1) | 74.2 (55.1–87.5) | 97.9 (94.5–99.3) | 95 (82–106) | 0.91 (0.83–0.97) | |
| Underlying maternal illnessf | 15/29 | 51.7 (32.9–70.1) | 192/196 | 98.0 (94.5–99.3) | 78.9 (53.9–93.0) | 93.2 (88.6–96.1) | 92 (74–109) | 0.75 (0.65–0.84) | |
| Pregnancy-induced hypertension | 42/69 | 60.9 (48.4–72.2) | 141/156 | 90.4 (84.4–94.3) | 73.7 (60.1–84.1) | 83.9 (77.3–89.0) | 81 (69–93) | 0.76 (0.69–0.81) | |
| Antepartum haemorrhage | 21/35 | 60.0 (42.2–75.6) | 173/190 | 91.1 (85.8–94.5) | 55.3 (38.5–71.0) | 92.5 (87.3–95.7) | 86 (70–102) | 0.76 (0.67–0.84) | |
| Obstetric complications | 13/19 | 68.4 (43.5–86.4) | 198/206 | 96.1 (92.2–98.2) | 61.9 (38.7–81.0) | 97.1 (93.4–98.8) | 94 (76–111) | 0.82 (0.71–0.93) | |
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 The underlying causes of stillbirth were classified in accordance with the International statistical classification of diseases and related health problems, 10th revision.16 Diseases or conditions that occur early in the chronology of events are placed higher in the order.
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 divided by number of positives diagnosed in hospital (gold standard).
e Number of negatives correctly diagnosed through verbal autopsy 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.