INTRODUCTION: The aim was to evaluate the validity and the degree of completeness of the cholesteatoma diagnosis in the Danish National Hospital Register (DNHR).

MATERIAL AND METHODS:

VALIDITY: A random sample of 286 patients with a cholesteatoma diagnosis who had been admitted to an ear-nose-throat department on Funen between 1977 and 2007 were selected from the DNHR for validation. The diagnosis was verified on the basis of surgical chart review. Completeness: The DNHR was compared with the local Ear-database at Odense University Hospital (EDOUH) covering the 1996-2007 period.

RESULTS:

VALIDITY: A total of 273 patients had 422 registrations of a cholesteatoma diagnosis combined with relevant surgery (CWRS). The remaining 13 of the initially 286 selected patients had a cholesteatoma diagnosis, but without relevant surgery. Surgical charts could be retrieved for 262 patients with 401 registrations. The positive predictive value (PPV) of the CWRS in the DNHR was 85.8%. When only the first-time patients with CWRS were recorded, the PPV was 89.3%. Completeness: A total of 329 cases of surgery were recorded in the DNHR, the EDOUH or both. Surgical charts could be retrieved for 322. The diagnosis was confirmed for 277. Based on the confirmed cases, the degree of completeness of the CWRS in the DNHR was estimated to 91.0%. When only the first-time patients were included, the degree of completeness was estimated to 89.3%.

CONCLUSION: Misclassification of the first CWRS in the NHR was close to 10%, and the DNHR may be considered a useful tool for epidemiological research on cholesteatoma.