The use of international classification of diseases codes to identify hospital admissions linked with adverse drug events: Validation study

AimsSeveral methods exist to identify hospital admissions related to adverse drug events (ADEs). Clinical adjudication by healthcare professionals is the gold standard but is labour-intensive. Spontaneous reporting and routinely collected healthcare data using a set of International Classification of Diseases (ICD) codes often underestimate the prevalence of ADE-related admissions. Expanding the set of ICD codes could improve detection; however, validation is limited. The objective was to describe the agreement between ADE-related ICD-10 codes and clinically adjudicated ADE-related admissions in 2 settings.MethodsThis study analysed 2 datasets: 1102 readmissions from a hospital in the Netherlands (180 ADE-related) and 1228 admissions from a hospital in the Czech Republic (195 ADE-related). Clinical adjudication involved expert review including causality assessment to identify ADE-related hospital admissions. The sensitivities and specificities were calculated for a narrow code set (higher drug-likelihood codes containing words like drug-induced) and a broad code set of ICD-10 codes (including codes very likely, likely and possibly ADE-related).ResultsThe narrow ICD-10 set showed a sensitivity of 3% (95% confidence interval [CI] 2-6%) and a specificity of 99.6% (95% CI 99-100%). The broad set increased sensitivity to 27% (95% CI 23-32%), with specificity decreasing slightly to 92% (95% CI 91-94%). Preventable ADEs were identified less frequently with both ICD-10 code sets.ConclusionsOnly 3% of ADE-related admissions were detected by the narrow ICD-code set and 27% by the broad code set without a significant drop in the specificity. ADE-related ICD codes seem to serve as triggers for 1 in 4 ADE-related hospital admissions.