There are no actual validation studies of the Finnish Arthroplasty Register (FAR), and only a few studies about the accuracy of self-reported hip and knee arthroplasty exist. Therefore, we examine how reliably total hip (THA) and knee (TKA) arthroplasties can be identified from multiple data sources, including self-reports, the hospital discharge register, the arthroplasty register, and medical records.
Data from the FAR and from the Finnish Hospital Discharge Register (FHDR) during the years 1980-2010 were cross-checked to identify all THA and TKA events for the Kuopio Osteoporosis Risk Factor and Prevention Study cohort (n = 14,220). Unclear events were further checked from the medical records. After establishing a gold standard, by referring to confirmed THAs and TKAs, we examined the validity of self-reports in identifying the prevalent population with THA/TKA and in identifying incident THA/TKA.
Completeness of 2820 total arthroplasty events was 96.1% in FAR and 98.3% in FHDR. The self-reports had 95.1% sensitivity and 92.9% positive predictive value (PPV) to identify population with THA and for TKA sensitivity was 94.6% and PPV 95.2%. Self-reports’ sensitivity of finding the actual surgery events was 65.3% and PPV 85.4% for THA and for TKA sensitivity was 62.9% and PPV 83.4%.
The best way to identify THAs and TKAs in Finland is to combine data from the FAR and the FHDR. Self-reports can be considered as suitable to identify the prevalent population with THA/TKA, and they do not work as well to identify the actual surgery events.