Registration rate in the Norwegian Cruciate Ligament Register Large-volume hospitals perform better

Background and purpose The Norwegian Cruciate Ligament Register (NCLR) was founded in 2004. The purpose of the NCLR is to provide representative and reliable data for future research. In this study we evaluated the development of the registration rate in the NCLR. Methods The Norwegian Patient Register (NPR) and the electronic patient charts (EPCs) were used as reference data for public and private hospitals, respectively. Data were retrieved for all primary and revision anterior cruciate ligament (ACL) surgery during 2008-2009 in public hospitals and during 2008 in private hospitals. The NOMESCO classification of surgical procedures was used for identification of ACL surgeries. Public hospitals were divided into subgroups according to the annual number of operations in the NPR: small hospitals (< 30 operations) and large hospitals (>= 30 operations). Results For the 2-year data extracted from public hospitals, 2,781 and 2,393 operations met the inclusion criteria according to the NPR and the NCLR, respectively, giving an average registration rate of 86% (95% CI: 0.85-0.87). The registration rate for small public hospitals was 69% (CI: 0.65-0.73), which was significantly less than for large public hospitals (89%, CI: 0.88-0.90; p < 0.001). In 2008, private hospitals reported 548 operations to the NCLR while 637 were found in the EPCs, giving a registration rate of 86% (CI: 0.83-0.89). In that year, the registration rate for public hospitals was 86%, which was similar to that for private hospitals. Interpretation The NCLR registration rate for the period 2008-09 was similar in both 2008 and 2009, and is satisfactory for research. There is room for improvement of registration rates, particularly in hospitals with a small volume of ACL operations.