Validity of the hospital discharge diagnosis in epidemiologic studies of biliopancreatic pathology

Background: The aim was to analyse the magnitude, direction and predictors of change in the main hospital discharge diagnosis (HDD) after a clinical e xpert review, among patients included in a multicentre molecular epidemiolo gic study of biliopancreatic diseases. Methods: A total of 602 patients wit h a suspicion diagnosis of pancreas cancer (PC), cancer of the extrahepatic biliary system (CEBS) or benign biliopancreatic pathologies (BPP) were pro spectively recruited at five general hospitals. A structured form was used to collect information from medical records. A panel of experts revised all diagnostic information and established the main clinico-pathological diagn osis (CPD) by consensus. Results: Of the 204 cases with a HDD of PC, 176 (8 6%) were deemed to have a CPD of PC, eight of CEBS, twelve a neoplasm of di fferent origin, four BPP and four syndromic diagnoses. Thus, 28 cases (14%) were false positives. Of the 129 patients with a HDD of CEBS, 15 (12%) wer e false positives. Nine of the 396 cases with a HDD of non-PC (2%) had a CP D of PC (false negatives), whilst 14 of 471 patients with a HDD of non-CEBS (3%) were deemed to have CEBS. Overall, sensitivity and specificity of HDD for PC were, respectively, 95 and 93%, and for CEBS, 89 and 97%. Cytohisto logical confirmation and laparotomy were independent predictors of diagnost ic change. Conclusions: Validity of the HDD was high, but its association w ith some clinical variables suggests that sole reliance on HDD can signific antly bias results, and highlights the need to review all HDDs. Alternative ly, only patients at high risk of misdiagnosis could be reviewed: primarily , those lacking a cytohistological diagnosis or a laparotomy. No exclusions appear warranted solely on the basis of age, gender or tumour spread.