Positive predictive value and sensitivity of cancer-associated venous thromboembolism diagnoses in the Danish National Patient Register

• Published in: Thrombosis research Vol. 241; p. 109074
• Main Authors: Overvad, Thure Filskov, Severinsen, Marianne Tang, Johnsen, Søren Paaske, Madsen, Susanne Storm, Kannik, Karina, Stenfeldt, Louise Gundel, Larsen, Torben Bjerregaard, Nielsen, Peter Brønnum
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01-09-2024
• Subjects: Adult; Aged; Cancer; Denmark - epidemiology; Diagnosis; Female; Humans; ICD-10; International Classification of Diseases; Male; Middle Aged; Neoplasms - complications; Neoplasms - epidemiology; Predictive Value of Tests; Register-based studies: Validity; Registries; Sensitivity and Specificity; Venous thromboembolism; Venous Thromboembolism - diagnosis; Venous Thromboembolism - epidemiology; Denmark; Register-based studies: Validity; ICD-10; Diagnosis; Venous thromboembolism; Cancer
• ISSN: 0049-3848; 1879-2472; 1879-2472
• DOI: 10.1016/j.thromres.2024.109074

Hospital discharge diagnoses from administrative registries are frequently used in studies of cancer-associated venous thromboembolism, but the validity of International Classification of Diseases (ICD) codes for identifying such events is unknown.
Using patient samples from the Danish National Patient Register, we calculated positive predictive values (PPV), i.e., the proportion of registered ICD codes, which could be confirmed after manual search of the electronic health record. Sensitivity was estimated in a sample of patients with imaging-verified venous thromboembolism but without prior knowledge about their ICD coding status. Sensitivity was calculated as the proportion of these patients, who were discharged with an ICD code for venous thromboembolism.
The overall PPV of an ICD-10 diagnosis of cancer-associated venous thromboembolism was 75.9 % (95 % confidence interval 71.3–80.0). In subgroups, the PPV was particularly low for recurrent venous thromboembolism (44.2 %), diagnoses in a secondary position (55.7 %), outpatient diagnoses (65.3 %), and diagnoses given at surgical (66.7 %), emergency wards (48.4 %), or via hospices/palliative teams (0 %).
The overall sensitivity was 68 %, meaning 32 % of patients with cancer diagnosed in hospital with venous thromboembolism were discharged without any registered ICD code for venous thromboembolism.
The positive predictive value of an ICD diagnosis of cancer-associated venous thromboembolism in the Danish Patient Register was overall adequate for research purposes, but with notable variation across subgroups. Sensitivity was limited, as 1/3 of patients with venous thromboembolism were discharged without any relevant ICD code. Cautious interpretation of incidence of cancer-associated venous thromboembolism based on administrative register-based data is warranted.
•Venous thromboembolism is common among patients with cancer.•The quality of ICD-10 diagnoses for identifying such events is unknown.•The positive predictive value in the Danish National Patient Register was 75.9 %.•Sensitivity was limited, with 1/3 patients discharged without a relevant ICD code.•Administrative discharge diagnoses for cancer-associated thromboembolism venous should be used with caution.