Venous thromboembolism discharge diagnoses in the Danish National Patient Registry should be used with caution.
OBJECTIVE
We validated discharge diagnoses of venous thromboembolism (VTE) in the Danish National Patient Registry.


METHODS
We identified all first-time VTE discharge diagnoses in the Danish National Patient Registry among participants of the Danish cohort study "Diet, Cancer, and Health", in the period from 1994 to 2006. Medical records were retrieved and VTE diagnoses were verified by one of the authors using a standard protocol. The positive predictive value (PPV) of a discharge diagnosis of VTE was calculated as percent of registry diagnoses with the corresponding true diagnosis in the chart among all registry diagnoses.


RESULTS
We retrieved medical records from 1,100 of 1,135 participants (96.9%) registered with a discharge diagnosis of VTE; 626 diagnoses were confirmed and 17 were considered probable. The PPV of diagnoses coded at wards was 75.0% (95% confidence interval: 71.9, 77.9). Diagnoses from emergency departments were not valid. The PPV varied by type of VTE (deep venous thrombosis and pulmonary embolism), type of diagnosis (primary or secondary), and sex.


CONCLUSIONS
Data on VTE obtained from administrative registries are a valuable source of information but should be used with caution in medical research.
Severinsen
Marianne Tang
MT
Department of Clinical Biochemistry, Center for Cardiovascular Research, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark. m.severinsen@rn.dk
Kristensen
Søren Risom
SR
Overvad
Kim
K
Dethlefsen
Claus
C
Tjønneland
Anne
A
Johnsen
Søren Paaske
SP
D003718:Denmark / Q000453:epidemiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006748:Hospital Departments / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge / Q000706:statistics & numerical data*; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000453:epidemiology; D012042:Registries; D012737:Sex Factors; D054556:Venous Thromboembolism / Q000175:diagnosis* / Q000453:epidemiology; D020246:Venous Thrombosis / Q000175:diagnosis / Q000453:epidemiology