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Table 2 Operating characteristics of diagnostic coding algorithms for the identification of acetaminophen overdose

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

      C-statistic (95% CI)
Diagnostic Algorithm Sensitivity (95% CI) Specificity (95% CI) PPV (95% CI) NPV (95% CI) All years 1994–2001 (ICD-9-CM era) 2002–2004 (ICD-10 era)
All ICD-9-CM and ICD-10 codes * 100% (97–100%)(139/139) 0% (0–8%)(0/42) 77% (70–83%)(139/181) 0% (0/0) -- -- --
Principal codes (965.4, T39.1) 90% (84–94%) (125/139) 83% (69–93%) (35/42) 95% (89–98%) (125/132) 71% (57–83%) (35/49) 0.87 (0.80–0.93) 0.86 (0.78–0.94) 0.88 (0.78–0.97)
Specific codes (965.4, T39.1, E850.4, E935.4, Y45.5) 96% (91–98%) (133/139) 55% (39–70%) (23/42) 88% (81–92%) (133/152) 79% (60–92%) (23/29) 0.75 (0.67–0.83) 0.71 (0.61–0.81) 0.81 (0.69–0.94)
  1. * See Table 1.
  2. Non-specific codes (ie potentially including overdoses due to medications other than acetaminophen) excluded.
  3. P < 0.005 vs. the algorithm limited to specific codes.
  4. CI, confidence interval; NPV, negative predictive value; PPV, positive predictive value.