Validation of the Diagnostic Accuracy Levels of International Classification of Diseases, 10th Revision Codes for Diabetic Ketoacidosis: A Multicentre, Cross-sectional Study of Adults

International Classification of Diseases (ICD) codes are commonly used to identify cases of diabetic ketoacidosis (DKA) in health services research, but they have not been validated. Our aim in this study was to assess the accuracy of ICD, 10th revision (ICD-10) diagnosis codes for DKA. We conducted a multicentre, cross-sectional study using data from 5 hospitals in Ontario, Canada. Each hospitalization event has a single most responsible diagnosis code. We identified all hospitalizations assigned diagnosis codes for DKA. A true case of DKA was defined using laboratory values (serum bicarbonate ≤18 mmol/L, arterial pH ≤7.3, anion gap ≥14 mEq/L, and presence of ketones in urine or blood). Chart review was conducted to validate DKA if laboratory values were missing or the diagnosis of DKA was unclear. Outcome measures included positive predictive value (PPV), negative predictive value (NPV), sensitivity, and specificity of ICD-10 codes in patients with laboratory-defined DKA. We identified 316,517 hospitalizations. Among these, 312,948 did not have an ICD-10 diagnosis code for DKA and 3,569 had an ICD-10 diagnosis code for DKA. Using a combination of laboratory and chart review, we identified that the overall PPV was 67.0%, the NPV was 99.7%, specificity was 99.6%, and sensitivity was 74.9%. When we restricted our analysis to hospitalizations in which DKA was the most responsible discharge diagnosis (n=3,374 [94.5%]), the test characteristics were PPV 69.8%, NPV 99.7%, specificity 99.7%, and sensitivity 71.9%. ICD-10 codes can identify patients with DKA among those admitted to general internal medicine. Les codes de la Classification internationale des maladies (CIM) sont fréquemment utilisés dans la recherche sur les services de santé pour répertorier les cas d’acidocétose diabétique (ACD), mais ils n’ont pas fait l’objet d’une validation. Évaluer l’exactitude des codes de diagnostic de la CIM-10 (10e révision) sur l’ACD. Nous avons réalisé une étude transversale multicentrique à partir des données de 5 hôpitaux de l’Ontario, au Canada. Chaque hospitalisation a un code de diagnostic principal unique. Nous avons relevé toutes les hospitalisations dont les codes de diagnostic attribués étaient l’ACD. Nous avons défini un véritable cas d’ACD à l’aide des valeurs de laboratoire (bicarbonate sérique ≤ 18, pH artériel ≤ 7,3, trou anionique > 14, et présence de cétones dans l’urine ou le sang). Nous avons réalisé une revue de dossiers pour valider l’ACD dans les c