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Table 4 Operating characteristics of the acetaminophen overdose algorithm according to the development of hepatotoxicity

From: Validation of ICD-9-CM/ICD-10 coding algorithms for the identification of patients with acetaminophen overdose and hepatotoxicity using administrative data

  Sensitivity (95% CI) Specificity (95% CI) PPV (95% CI) NPV (95% CI) C-statistic (95% CI)
No hepatotoxicity (n = 112)      
   Overall 94% (86–98%) (66/70) 83% (69–93%) (35/42) 90% (81–96%) (66/73) 90% (76–97%) (35/39) 0.89 (0.82–0.95)
   ICD-9-CM 94% (82–99%) (44/47) 81% (61–93%) (21/26) 90% (78–97%) (44/49) 88% (68–97%) (21/24) 0.87 (0.79–0.96)
   ICD-10 96% (78–100%) (22/23) 88% (62–98%) (14/16) 92% (73–99%) (22/24) 93% (68–100%) (14/15) 0.92 (0.82–1.00)
Hepatotoxicity (n = 69) *      
   Overall 86% (75–93%) (59/69) N/A 100% (NA) (59/59) 0% (NA) (0/10) N/A
   ICD-9-CM 88% (74–96%) (37/42) N/A 100% (NA) (37/37) 0% (NA) (0/5) N/A
   ICD-10 81% (62–94%) (22/27) N/A 100% (NA) (22/22) 0% (NA) (0/5) N/A
  1. * Hepatotoxicity as defined by the following diagnostic codes: hepatic necrosis (570, K71.1), toxic hepatitis (573.3, K71.2, K71.6, K71.9), and hepatic encephalopathy (572.2, K72.0, K72.9). Because hepatotoxicity cases had acetaminophen overdose by definition, the PPV of the overdose algorithm is 100% in these cases. For the same reason, the specificities and c-statistics cannot be calculated, and the NPVs are 0%.
  2. CI, confidence interval; NPV, negative predictive value; NA, not applicable; PPV, positive predictive value.