64
· DOS Abstracts
Can hip surgeons code periprosthetic joint infection?
A cross-sectional study of data validity in the Danish
National Patient Registry.
Jeppe Lange, Alma B. Pedersen, Anders Troelsen, Kjeld Søballe
Lundbeckfoundation Centre for Fast-track Hip and Knee Surgery, Tage-
Hansens Gade 2, 8000 Aarhus, Den, Department of Orthopaedic Surgery,
Aarhus University Hospital, Tage-Hansens Gade 2, 8000 Aarhus, Den;
Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes
Allé 43-45, 8200 Aarhus, Denmark; Department of Orthopaedic Surgery,
Copenhagen University Hospital Hvidovre, Kettegaard Allé 30, 2650 Hvidovre
Denmark
Background:
The Danish National Patient Registry (DNPR) collects data for all
patients in Denmark. The DNPR is a potential high quality research database,
however, validity of data on prosthetic joint infection (PJI) is unknown.
Purpose / Aim of Study:
To evaluate the positive predictive value (PPV) of
diagnosis and procedure codes associated with hip PJI.
Materials and Methods:
We identified patients in the DNPR from 2003-2008
in Aarhus, Aalborg, Silkeborg, Viborg, Hvidovre, Vejle, Gentofte, Hørsholm,
Hillerød, Helsingør, and Frederikssund with a primary and secondary ICD10
discharge diagnosis of T84.5. As we aim to validate only hip joint affections,
we combined T84.5 with a hip joint noninfectious-specific (NIS) or infectious-
specific (IS) procedure code. Medical records of all identified patients (n= 236)
were reviewed by one of the authors.
Findings / Results:
190 of the 236 patients were confirmed as having a hip
PJI according to a priori defined criteria, corresponding to an overall PPV of 81%.
This means that the T84.5 diagnosis code truly correlates with hip PJI in 81% of
the patients coded with the investigated combination in the DNRP. The PPV of
the T84.5 diagnosis code in combination alone with a hip NIS procedure code
was 69%, while T84.5 in combination alone with a hip IS procedure codes was
87%.
Conclusions:
T84.5 is the sole discharge diagnosis regarding PJI. The PPV of
T84.5 in the DNRP is currently not satisfactory. Data on PJI obtained from ad-
ministrative registries are a valuable source of information, but should be used
with caution in medical research. We urge hip surgeons to be meticulous in their
onward coding practice, to increase the PPV of the T84.5 code to enable valid
research in a field where absolute number of PJI is low, making clinical epidemio-
logic research on register data a valuable source of future knowledge.
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