|Abstract / Summary
Several nationally implemented registers makes Denmark a phenomenal arena for register-based, epidemiological studies. Established in 1977, the Danish National Patient Registry gathers prospective data on all hospital discharges in Denmark. The Danish Fracture Database gathered nationwide data on patients surgically treated for fractures between 2015 and 2020. Combined, these two registers offer a great source of data for evaluating the risk of secondary procedures such as reoperations in patients surgically treated for fractures; however, evaluation of data quality for both registers is strongly warranted.
The Ph.D. thesis consisted of three separate studies:
Study 1 – “The Danish Fracture Database: Completeness and validity”: The aim was to evaluate the Danish Fracture Database for completeness and validity. Completeness was calculated as sensitivity by comparing occurrence in the Danish Fracture Database with occurrence in the Danish National Patient Registry. Validity was calculated as the positive predictive value for individually assessed variables in the Danish Fracture Database by comparison to patient medical records. The study found a completeness of 55% and validity of individual variables ranging from 81 – 100%.
Study 2 – “Positive predictive values of diagnosis and surgical procedure codes for fracture-related surgery in the Danish National Patient Registry” The aim was to evaluate the validity of the Danish National Patient Registry by calculating the positive predictive values for transfer of diagnosis and surgical procedure codes from patient medical records to the Danish National Patient Registry for patients having undergone primary, fracture-related surgery at a Danish hospital in 2016. The gold standard was patient medical records. For diagnosis codes, validity ranged from 79 – 97%. For surgical procedure codes, validity ranged from 97 – 99%.
Study 3 – “Risk of reoperation following surgical treatment of fractures in adults” The aim was to estimate the absolute risk of secondary procedures following primary fracture-related surgery in adults within 2 years of receiving primary surgery at a Danish hospital in 2016. Absolute risk was calculated by using the cumulative incidence function using death as a competing event and emigration as censoring. We estimated absolute risk of secondary procedures overall and stratified on anatomical regions by the surgical procedure codes for primary surgery. Secondary procedures were divided into any secondary, musculoskeletal surgery, reoperations and major reoperations. The overall risk of secondary musculoskeletal surgery was 20%, for reoperations it was 19% and for major reoperations it was 8%.