The completeness and accuracy of the Norwegian Female Incontinence Registry

Medical quality registries have gained popularity as tools for monitoring the quality of medical treatments and they serve as data sources for research. The Norwegian Female Incontinence Registry (NFIR) was established in 1998 to monitor and improve the quality of surgery for women with stress and mixed urinary incontinence in Norway and to collect data for research. This study aimed to assess the completeness and accuracy of the Norwegian Female Incontinence Registry, and potential differences in data accuracy over time and according to surgical volume of the reporting hospitals.

A random selection of 300 women from a total of 20 610 operated for urinary incontinence between 1998 and 2016 reported to the Norwegian Female Incontinence Registry from 28 public hospitals were selected for validation. The database completeness was estimated for 2008-2017 by comparing surgical procedures registered both in the Norwegian Female Incontinence Registry and the Norwegian National Patient Registry. Historical data recorded in the Registry for 10 selected key variables were extracted and compared with the patients' individual medical records at the reporting hospitals as reference. The reviewers were blinded to the previously stored information. The intraclass correlation coefficient for continuous variables and Cohen's kappa for categorical variables were calculated.

Primary source data on 285 of the 300 women selected from Norwegian Female Incontinence Registry were successfully retrieved. The completeness of the registry has increased from 61% in 2008 to 99% in 2017. The national coverage has increased from 12 reporting departments in 1998 to all 38 public departments performing female incontinence surgery in 2017. Excellent accuracy was found for both continuous variables (intraclass correlation coefficient >0.94) and categorical variables (Cohen's kappa >0.86). No differences in data accuracy were found comparing high-volume hospitals with low-volume hospitals, or when comparing data accuracy over time.

The Norwegian Female Incontinence Registry is a reliable tool for quality assessment of incontinence surgery and research. The registry completeness has improved over time and now contains data on nearly all women undergoing incontinence surgery in Norway.