Objective: To assess the comparative usefulness of the Short Form-36 (SF-36) and the Sickness Impact Profile, (SIP) as generic health status measures in total hip arthroplasty.
Methods: Analysis of preoperative and 3-month data of 54 consecutive patients undergoing total hip replacement for osteoarthritis or rheumatoid arthritis. Instruments were mailed to patients preoperatively and 3 months postoperatively.
Results: In 10 of the 12 SIP subscales, but just 1 of the 8 SF-36 subscales, more than 40% of the patients had scores of zero. On a 100-point scale, the median global SIP was 12 (range 0-40) whereas the median global SF-36 was 50 (range 10-85). This indicates that many items of the SIP were not germane to patients undergoing joint arthroplasty. The global and, particularly, the physical dimensions of the SF-36 were more responsive than their SIP counterparts, as measured both by the standardized response mean (1.26 and 0.88, respectively) and the correlation with self-perceived improvement in quality of life (r = 0.37 and 0.26, respectively). The SF-36, but not the SIP, discriminated between patients with relatively good physical performance at 3 months with respect to their ability to work, to play sports, or to garden.
Conclusion: The SF-36 is briefer, more relevant, and more responsive than the SIP and is preferable as a generic health status measure in patients undergoing elective hip arthroplasty. The SF-36 should be tested in other populations as well as other conditions to determine whether it is a superior generic health status instrument for evaluative research in orthopedic surgery.