ABSTRACT
BACKGROUND:
Hip arthroplasty (HA) and
knee arthroplasty (KA) are high-volume
procedures. However, there is a debate about the quality of indication; that is, whether
surgery is truly indicated in all
patients.
Patient-reported outcome measures (PROMs) may be used to determine preoperative thresholds to differentiate
patients who will likely benefit from
surgery from those
who will not. QUESTIONS/
PURPOSES:
(1) What were the minimum clinically important differences (MCIDs) for three commonly used PROMs in a large
population of
patients undergoing HA or KA treated in a general orthopaedic practice? (2) Do
patients who reach the MCID differ in important ways from those
who do not? (3) What preoperative PROM score thresholds best distinguish
patients who achieve a meaningful improvement 12 months postsurgery from those
who do not? (4) Do
patients with preoperative PROM scores below thresholds still experience gains after
surgery?
METHODS:
Between October 1, 2019, and December 31, 2020, 4182
patients undergoing HA and 3645
patients undergoing KA agreed to be part of the PROMoting Quality study and were hence included by study
nurses in one of nine participating German
hospitals. From a selected group of 1843
patients with HA and 1546 with KA, we derived MCIDs using the anchor-based change difference
method to determine meaningful improvements. Second, we estimated which preoperative PROM score thresholds best distinguish
patients who achieve an MCID from those
who do not, using the preoperative PROM scores that maximized the Youden index. PROMs were
Hip Disability and
Osteoarthritis Outcome Score-Physical Function short form (HOOS-PS) (scored 0 to 100 points; lower indicates better
health),
Knee Injury and
Osteoarthritis Outcome Score-Physical Function short form (KOOS-PS) (scored 0 to 100 points; lower indicates better
health), EuroQol 5-Dimension 5-level (EQ-5D-5L) (scored -0.661 to 1 points; higher indicates better
health), and a 10-point VAS for
pain (perceived
pain in the
joint under consideration for
surgery within the past 7 days) (scored 0 to 10 points; lower indicates better
health). The performance of derived thresholds is reported using the Youden index,
sensitivity,
specificity, F1 score, geometric mean as a
measure of central tendency, and area under the
receiver operating characteristic curve.
RESULTS:
MCIDs for the EQ-5D-5L were 0.2 for HA and 0.2 for KA, with a maximum of 1 point, where higher values represented better
health-related quality of life. For the
pain scale, they were -0.9 for HA and -0.7 for KA, of 10 points (maximum), where lower scores represent lower
pain. For the HOOS-PS, the MCID was -10, and for the KOOS-PS it was -5 of 100 points, where lower scores represent better functioning.
Patients who reached the MCID differed from
patients who did not reach the MCID with
respect to baseline PROM scores across the evaluated PROMs and for both HA and KA.
Patients who reached an MCID versus those
who did not also differed regarding other aspects including
education and comorbidities, but this was not consistent across PROMs and
arthroplasty type. Preoperative PROM score thresholds for HA were 0.7 for EQ-5D-5L (Youden index 0.55), 42 for HOOS-PS (Youden index 0.27), and 3.5 for the
pain scale (Youden index 0.47). For KA, the thresholds were 0.6 for EQ-5D-5L (Youden index 0.57), 39 for KOOS-PS (Youden index 0.25), and 6.5 for the
pain scale (Youden index 0.40). A higher Youden index for EQ-5D-5L than for the other PROMs indicates that the thresholds for EQ-5D-5L were better for distinguishing
patients who reached a meaningful improvement from those
who did not.
Patients who did not reach the thresholds could still achieve MCIDs, especially for functionality and the
pain scale.
CONCLUSION:
We found that
patients who experienced meaningful improvements (MCIDs) mainly differed from those
who did not regarding their preoperative PROM scores. We further identified that
patients undergoing HA or KA with a score above 0.7 or 0.6, respectively, on the EQ-5D-5L, below 42 or 39 on the HOOS-PS or KOOS-PS, or below 3.5 or 6.5 on a 10-point
joint-specific
pain scale presurgery had no meaningful benefit from
surgery. The thresholds can support
clinical decision-making. For example, when thresholds indicate that a meaningful improvement is not likely to be achieved after
surgery, other
treatment options may be prioritized. Although the thresholds can be used as support,
patient preferences and medical expertise must supplement the
decision.
Future studies might evaluate the utility of using these thresholds in practice, examine how different thresholds can be combined as a multidimensional
decision tool, and derive presurgery thresholds based on additional PROMs used in practice.
CLINICAL RELEVANCE Preoperative PROM score thresholds in this study
will support clinicians in
decision-making through objective
measures that can improve the quality of the recommendation for
surgery.