Patient reported outcomes in hip arthroplasty registries.

PROs are used increasingly in orthopedics and in joint registries, but still many aspects of use in this area have not been examined in depth. To be able to introduce PROs in the DHR in a scientific fashion, my studies were warranted; the feasibility of four often used PROs (OHS, HOOS, EQ-5D and SF-12) was examined in a registry context. Having the PROs in the target language is an absolute necessity, so I translated, cross-culturally adapted and validated a Danish language version of an often used PRO (OHS), since this PRO had no properly developed Danish language version. To minimize data loss and to maximize the data quality I validated our data capture procedure, an up to date AFP system, by comparing scannable, paper-based PROs, with manual single-key- and double-key entered data. To help further registry-PRO studies, I calculated the number of patients needed to discriminate between subgroups of age, sex, diagnosis, and prosthesis type for each of four often used PROs (OHS, HOOS, EQ-5D and SF-12), and to simplify the clinical interpretation of PRO scores and PRO change scores in PRO studies, I estimated MCII and PASS for two often used PROs (EQ-5D and HOOS). The feasibility study included 5,747 THA patients registered in the DHR, and I found only minor differences between the disease-specific and the generic PROs regarding ceiling and floor effects as well as discarded items. The HOOS, the OHS, the SF-12, and the EQ-5D are all appropriate PROs for administration in a hip registry. I found that group sizes from 51 to 1,566 were needed for subgroup analysis, depending on descriptive factors and choice of PRO. The AFP study included 200 THA patients (398 PROs, 4,875 items and 21,887 data fields), and gave excellent results provided use of highly structured questionnaires. OMR performed equally as well as manual double-key entering, and better than single-key entering. The PRO translation and validation study included 2,278 patients (and 212 patients for the test-retest). I found that the translated PRO had good feasibility, an excellent response rate, no floor effect, but a high ceiling effect (as was expected with our postoperative patients) and few patients missed too many items to calculate a sum score. The translated PRO had high test-retest reliability and very high internal consistency, and appears to be a valid and reliable tool for outcome studies on THA patients in a hip registry setting. The MCII and PASS study included 1,335 patients, and I estimated that one year after THA, an improvement of 38-55% from mean baseline PRO score and absolute follow-up scores of 57-91% of the maximum score correspond to a minimal important improvement and acceptable symptom state, respectively.