Identification of diverticular disease in Swedish healthcare registers: a validation study.

Purpose: The Swedish National Patient Register (SNPR) is frequently used in studies of colonic diverticular disease (DD). Despite this, the validity of the coding for this specific disease in the register has not been studied.

Methods: From SNPR, 650 admissions were randomly identified encoded with ICD 10, K572-K579. From the years 2002 and 2010, 323 and 327 patients respectively were included in the validation study. Patients were excluded prior to, or up to 2 years after a diagnosis with IBD, Celiac disease, IBS, all forms of colorectal cancer (primary and secondary), and anal cancer. Medical records were collected and data on clinical findings with assessments, X-ray examinations, endoscopies and laboratory results were reviewed. The basis of coding was compared with internationally accepted definitions for colonic diverticular disease. Positive predictive values (PPV) were calculated.

Results: The overall PPV for all diagnoses and both years was 95% (95% CI: 93-96). The PPV for the year 2010 was slightly higher 98% (95% CI: 95-99) than in the year 2002, 91% (95% CI: (87-94) which may be due to the increasing use of computed tomography (CT).

Conclusion: The validity of DD in SNPR is high, making the SNPR a good source for population-based studies on DD.