A Validation of the Swedish Colorectal Cancer Register - With Focus on Histopathology, Complications and Recurrences

There is an urgent need to evaluate the quality of healthcare systems to improve and deliver high-quality care. Clinical registries have become important platforms for performance measurements, improvements, and clinical research. Hence, the quality of data in registries is crucial. This study aimed to assess the validity of data in the Swedish Colorectal Cancer Register (SCRCR). Seven hundred patients from 12 hospitals were randomly selected and proportionally distributed among three different hospital categories in Sweden using two-stage cluster sampling. Validity was assessed by re-abstracting data from the medical files of patients reported to the SCRCR in 2015. Data on histopathology, postoperative complications, and a 3-year follow-up were selected for validation. Re-abstracted data were defined as source data, and validity was defined as the proportion of cases in the SRCRC dataset that agreed with the source data. Validity was expressed as the percentage of exact agreement of non-missing data in both data sets, and Cohen´s kappa coefficient (κ) was used to measure the strength of the agreement. The median agreement of the categorical histopathology variables was 93.4% (κ = 0.83). The general postoperative complication variable showed substantial agreement (84.3%, κ = 0.61). Likewise, the variable for overall cancer recurrence showed an almost perfect agreement (95.7%, κ = 0.86), whereas specific variables for local recurrence and distant recurrence displayed only moderate and fair agreement (85.9% and 89.1%, κ = 0.58 and 0.34, respectively). Validation of the SCRCR data showed high validity of pathology data and recurrence rates, whereas detailed data on recurrence were not as good. Data on postoperative complications were less reliable, although the incidence and Clavien-Dindo grading of severe complications (grade 3b or higher) were reliable.