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Table 3 Validity of the Western Australia Antenatal Influenza Vaccination Database (WAAIVD) for capturing antenatal vaccinations (n = 563), by patient characteristics

From: Surveillance of antenatal influenza vaccination: validity of current systems and recommendations for improvement

Subgroup Recorded Vaccinationsa True Vaccinationsb Sensitivity PPVc Specificity NPVd
  n N % (95 % CI) % (95 % CI) % (95 % CI) % (95 % CI)
Total 145 144 45.7 (40.1–51.4) 99.3 (96.2–99.9) 99.6 (97.8–99.9) 59.1 (54.3–63.7)
Maternal age (years)
 18–29 49 107 44.9 (35.8–54.3) 97.9 (89.3–99.6) 99.0 (94.7–99.8) 63.3 (55.7–70.4)
 30–39 85 187 45.5 (38.5–52.6) 100 (95.7–100) 100 (97.3–100) 57.1 (50.8–63.3)
 40–45 11 21 52.4 (32.4–71.7) 100 (74.1–100) 100 (70.1–100) 47.4 (27.3–68.3)
Socioeconomic status (SEIFA score)e
 Quintile 1 (Most disadvantaged) 3 12 25.0 (5.5–57.2) 100 (43.9–100) 100 (56.6–100) 35.7 (16.3–61.2)
 Quintile 2 17 32 53.1 (34.7–70.9) 100 (81.6–100) 100 (83.9–100) 57.1 (40.9–72.0)
 Quintile 3 32 69 44.9 (32.9–57.4) 96.9 (84.3–99.4) 96.9 (83.8–99.4) 44.1 (32.9–55.9)
 Quintile 4 31 56 55.4 (42.4–67.6) 100 (88.8–100) 100 (93.0–100) 67.1 (55.9–76.6)
 Quintile 5 (Least disadvantaged) 56 138 40.6 (32.7–48.9) 100 (93.6–100) 100 (97.1–100) 61.1 (54.4–67.5)
Existing medical conditions
 Has ≥1 chronic medical condition 22 46 47.8 (34.1–61.9) 100 (85.1–100) 100 (91.8–100) 64.2 (52.2–74.6)
 No chronic medical condition 123 269 45.3 (39.5–51.3) 99.2 (95.5–99.9) 99.5 (97.3–99.9) 58.1 (52.9–63.2)
Antenatal (AN) care providerf
 Public hospital AN clinic 67 117 56.4 (47.4–65.1) 98.5 (92.0–99.7) 99.2 (95.8–99.9) 71.7 (64.7–77.7)
 General practice clinic 30 57 52.6 (39.9–65.0) 100 (88.6–100) 100 (91.0–100) 59.1 (47.0–70.1)
 Private obstetrician 46 137 33.6 (26.2–41.8)§§ 100 (92.3–100) 100 (94.9–100) 44.2 (36.8–51.8)g
  1. aRecorded vaccinations were defined as vaccination events identified in the state’s antenatal influenza vaccination database, based on provider-reported vaccination information
  2. bTrue vaccinations were defined as vaccination events self-reported by the woman during telephone interview
  3. cPPV, positive predictive value
  4. dNPV, negative predictive value
  5. eSEIFA, Socioeconomic indexes for areas
  6. fAntenatal care provider was defined as the healthcare professional who provided the majority of antenatal care as self-reported at the time of telephone interview
  7. gSignifiant at p < .05