Defining Clinically Meaningful Thresholds for Patient-Reported Outcomes in Knee Arthroplasty

Systematic review reveals that EQ-5D minimally important differences vary with treatment type and may decrease with increasing baseline score

OBJECTIVES

To provide an updated summary of published anchor-based Minimally Important Difference (MID) estimates for the EQ-5D index and EQ visual analog scale (EQ VAS) scores and identify factors influencing those estimates.

STUDY DESIGN AND SETTING

We systematically searched eight electronic databases from January 1990 to March 2023. We examined the association of baseline score, type of score change (improvement/worsening), data source, value set, disease/condition, treatment type (surgical/non-surgical), and type of anchor (clinical vs. self-rated) with MID estimates for the EQ-5D-3L and EQ-5D-5L indices, and EQ VAS. Significant variables were used to develop prediction formulas for MID by testing both linear and nonlinear regression models.

RESULTS

Of 6786 records reviewed, 47 articles were included for analysis. MID ranges for improved scores were -0.13 to 0.68 (EQ-5D-3L), 0.01-0.41 (EQ-5D-5L), and 0.42-23.0 (EQ VAS). Surgical intervention and lower baseline scores were associated with higher MIDs for both the EQ indices but not for EQ VAS. The nonlinear polynomial model outperformed the linear model in predicting the MIDs. MIDs based on deteriorated scores were insufficient for quantitative synthesis (mean: -0.02 for EQ-5D-3L; -0.04 for EQ-5D-5L; and -6.5 for EQ VAS).

CONCLUSION

This review revealed that the MID of EQ-5D index scores varies with baseline score and treatment type, indicating that use of a uniform MID may not be appropriate. We recommend using baseline score-adjusted and treatment type-specific EQ-5D MIDs, and call for more MID research, particularly in the context of assessing deterioration in health using this widely used generic health-status instrument.

Inadequate Classification of Poor Response After Total Knee Arthroplasty: A Comparative Analysis of 15 Definitions Using Data From the Dutch Arthroplasty Register and the Osteoarthritis Initiative Database

BACKGROUND

Variations in defining poor response to total knee arthroplasty (TKA) impede comparisons of response after TKA over time and across hospitals. This study aimed to compare the prevalence, overlap, and discriminative accuracy of 15 definitions of poor response after TKA using 2 databases.

METHODS

Data of patients one year after primary TKA from the Dutch Arthroplasty Register (n = 12,275) and the Osteoarthritis Initiative database (n = 204) were used to examine the prevalence, overlap (estimated by Cohen's kappa), and discriminative accuracy (sensitivity, specificity, positive predictive value, negative predictive value, and Youden index) of 15 different definitions of poor response after TKA. In the absence of a gold standard for measuring poor response to TKA, the numeric rating scale satisfaction (≤ 6 'poor responder') and the global assessment of knee impact (dichotomized: ≥ 4 'poor responder') were used as anchors for assessing discriminative accuracy for the Dutch Arthroplasty Register and Osteoarthritis Initiative dataset, respectively. These anchors were chosen based on a prior qualitative study that identified (dis)satisfaction as a central theme of poor responses to TKA by patients and knee specialists.

RESULTS

The median (25th to 75th percentile) prevalence of poor responders in the examined definitions was 18.5% (14.0 to 25.5%), and the median Cohen's kappa for the overlap between pairs of definitions was 0.41 (0.32 to 0.59). Median (25th to 75th percentile) sensitivity was 0.45 (0.39 to 0.54), specificity was 0.86 (0.82 to 0.94), positive predictive value was 0.45 (0.34 to 0.62), negative predictive value was 0.89 (0.87 to 0.89), and the Youden index was 0.36 (0.20 to 0.43).

CONCLUSIONS

This study found a lack of overlap between different definitions of poor response to TKA. None of the examined definitions adequately classified poor responders to TKA. In contrast, the absence of a poor response could be classified with confidence.

Socioeconomic Status Affects Patient-Reported Outcome Measures in Total Hip and Knee Arthroplasty: A Retrospective Dutch Registry Study

BACKGROUND

To determine the association between socioeconomic status (SES) and patient-reported outcome measures in a Dutch cohort who have undergone total hip arthroplasty (THA) or total knee arthroplasty (TKA).

METHODS

A retrospective national registry study of all patients who underwent primary THA or TKA between 2014 and 2020 in the Netherlands was performed. Linear mixed effects regression models were used to assess the association between SES and patient-reported outcome measures for THA and TKA patients separately. The following measures were collected: numeric rating scale for pain, Oxford Hip/Knee Score, Hip/Knee disability and Osteoarthritis Outcome Score, and the EuroQol 5-Dimensions questionnaire. Sex, age, body mass index, American Society of Anesthesiologists classification, Charnley classification, and smoking status were considered as covariates in the models.

RESULTS

THA patients (n = 97,443) were on average 70 years old with a body mass index of 27.4 kg/m2, and TKA patients (n = 78,811) were on average 69 years old with a body mass index of 29.7 kg/m2. Preoperatively, patients with a lower SES undergoing THA or TKA reported more severe symptoms and lower health-related quality of life. At 1-year follow-up, they also reported lower scores and less improvement over time compared to patients with a higher SES.

CONCLUSIONS

Patients with lower SES report worse symptoms when admitted for surgery and less improvement after surgery. Future research must address potentially mediating factors of the association between SES and symptom reporting such as access to surgery and rehabilitation, subjectivity in reporting, and patient expectation for THA and TKA outcomes.

Anxiety and depression prior to total knee arthroplasty are associated with worse pain and subjective function: A prospective comparative study

PURPOSE

The aim of this study was to investigate the influence of preoperative anxiety and depression on subjective function, pain and revision rates following total knee arthroplasty (TKA).

METHODS

A prospective comparative study was conducted, including 349 patients undergoing TKA surgery between January 2019 and April 2021. Patients completed the Hospital Anxiety and Depression Scale (HADS) questionnaire preoperatively, and a set of Patient-Reported Outcome Measures (PROMs) preoperatively and at 6, 12 and 24 months postoperatively. Patients were categorized into anxiety and depression groups based on HADS scores. PROMs included the Knee injury and Osteoarthritis Outcome Score-Physical Function Shortform (KOOS-PS), Oxford Knee Score (OKS) and NRS-Pain. Differences in PROM scores between the anxiety/depression group and, respectively, nonanxiety/nondepression group were assessed, as well as differences in minimal clinical important difference (MCID) and attainment of Patient Acceptable Symptom State (PASS). Lastly, revision rates were compared.

RESULTS

Anxiety and depression groups exhibited inferior subjective function preoperatively and postoperatively compared to nonanxiety and nondepression groups (all p < 0.05), experienced more pain preoperatively (p < 0.001) and also postoperatively for depression patients (all p < 0.05). Significantly fewer patients with anxiety and depression reached the PASS for KOOS-PS, OKS and NRS-Pain (all p < 0.05). There were no differences in the proportion of patients reaching the MCID for all PROMs (all p > 0.060), and revision rates did not differ between groups (both p > 0.96).

CONCLUSION

Preoperative anxiety and depression negatively influence subjective function and pain preoperatively and up to 2-year follow-up in patients undergoing TKA. Revision rates did not differ between groups, and there were no relevant differences in clinical improvement of subjective function and pain.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

The mind matters: Psychological factors influence subjective outcomes following unicompartmental knee arthroplasty-A prospective study

PURPOSE

This study aimed to investigate how psychological factors, including pain catastrophizing (PC), anxiety and depression affect preoperative and postoperative subjective outcomes in patients undergoing unicompartmental knee arthroplasty (UKA).

METHODS

A prospective comparative study was performed among 150 patients undergoing medial or lateral UKA for isolated unicompartmental osteoarthritis. Patients were categorized based on their preoperative PC and Hospital Anxiety and Depression Scale, stratifying them into groups with PC, anxiety or depression, and those without these psychological factors. Patient-reported outcomes, including the Knee Injury and Osteoarthritis Outcome Score-Physical function Short form (KOOS-PS), 5-level EQ5D Visual Analogue Scale (EQ5D-VAS), Forgotten Joint Score (FJS) and Numeric Rating Scale for pain (NRS-pain) were compared between groups preoperatively and at 6-, 12-, and 24-month follow-up.

RESULTS

At 24 months, PC patients had inferior outcomes in KOOS-PS (66.9 ± 16.5 vs. 77.6 ± 14.7, p = .008), EQ5D-VAS (63.5 ± 19.9 vs. 78.9 ± 20.1, p = .003) and FJS (73.7 ± 14.3 vs. 84.6 ± 13.8, p = .003). Anxiety was associated with inferior KOOS-PS (65.4 ± 15.2 vs. 78.2 ± 14.5, p = <.001), EQ5D-VAS (64.2 ± 23.2 vs. 79.3 ± 19.4, p = .002), FJS (75.7 ± 16.8 vs. 84.6 ± 13.4, p = .008) and NRS-pain (27.4 ± 24.6 vs. 13.7 ± 19.3, p = .023) at 24 months. Depression consistently resulted in inferior outcomes in KOOS-PS, EQ5D-VAS, FJS and NRS-pain across all follow-up assessments (p = <.05). Additionally, patients with anxiety and depression experienced longer length of hospital stay compared to those without these psychological factors (anxiety: 2.3 ± 2.3 vs. 0.8 ± 0.8 days, p = .006; depression: 2.3 ± 2.4 vs. 0.8 ± 0.8 days, p = .017).

CONCLUSIONS

Preoperative PC, anxiety and depression are associated with inferior subjective outcomes both prior to and following UKA. Among these factors, depression seemed to exert the most substantial adverse impact on outcomes following UKA. Patients with anxiety and depression had an extended duration of hospitalization lasting over twice as long as patients without these psychological factors. It seems that inferior outcomes primarily stem from the suboptimal preoperative condition rather than an inherent inability to benefit from UKA.

LEVEL OF EVIDENCE

Level II, prospective study.

Establishing patient-centered metrics for the knee injury and osteoarthritis outcome score following medial unicompartmental knee arthropalsty

BACKGROUND

This study aimed to determine the minimal clinically important difference (MCID) and the patient acceptable symptoms state (PASS) threshold for the knee injury and osteoarthritis outcome score (KOOS) pain subscore, KOOS physical short form (PS), and KOOS joint replacement (JR) following medial unicompartmental knee arthroplasty (mUKA).

METHODS

Prospectively collected data from 743 patients undergoing mUKA from a single academic institution from April 2015 through March 2020 were analyzed. Patient-reported outcome measures (PROMs) were collected both pre-operatively and 1-year post-operatively. Distribution-based and anchored-based approaches were used to estimate MCIDs and PASS, respectively. The optimal cut-off point and the percentage of patients who achieved PASS were also calculated.

RESULTS

MCID for KOOS-pain, KOOS-PS, and KOOS-JR following mUKA were calculated to be 7.6, 7.3, and 6.2, respectively. The PASS threshold for KOOS pain, PS, and JR were 77.8, 70.3, and 70.7, with 68%, 66%, and 64% of patients achieving satisfactory outcomes, respectively. Cut-off values for delta KOOS pain, PS, and JR were found to be 25.7, 14.3, and 20.7 with 73%, 69%, and 68% of patients achieving satisfactory outcomes, respectively.

CONCLUSION

The current study identified useful values for the MCID and PASS thresholds at 1 year following medial UKA of KOOS pain, KOOS PS, and KOOS JR scores. These values may be used as targets for surgeons when evaluating PROMS using KOOS to determine whether patients have achieved successful outcomes after their surgical intervention. Potential uses include the integration of these values into predictive models to enhance shared decision-making and guide more informed decisions to optimize patient outcomes.

LEVEL OF EVIDENCE

III.

Effect of Patient Characteristics on the Minimal Clinically Important Difference and Patient Acceptable Symptom State Thresholds After Arthroscopic Bankart Repair

BACKGROUND

There is scarce literature on clinically significant values after arthroscopic Bankart repair (ABR).

PURPOSE

To determine the minimal clinically important difference (MCID) and the patient acceptable symptom state (PASS) thresholds at 1 year for the Rowe and Athletic Shoulder Outcome Scoring System (ASOSS) scores after ABR and to determine the effect of patient characteristics on these metrics after ABR.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A retrospective review of patients undergoing ABR from a single institution between January 2017 and January 2020 was performed. Patients with at least 1 episode of instability and a minimum follow-up of 12 months were included. The exclusion criteria were as follows: bony defects of >20% on the anteroinferior portion of the glenoid based on a preoperative computed tomography scan; engaging Hill-Sachs lesions at 90° of abduction and 90° of external rotation based on an arthroscopic examination; previous surgery on the same shoulder; multidirectional instability or concomitant repair of full-thickness rotator cuff tears; superior labral anterior to posterior lesions; posterior labral tears; or humeral avulsion of the glenohumeral ligament lesions. Patient-reported outcome measures were collected both preoperatively and 1-year postoperatively. Delta was defined as the change between preoperative and 1-year postoperative scores. Distribution-based (one-half the standard deviation of the difference between pre- and postoperative outcome scores) and anchored-based approaches (response to a satisfaction question at 1 year) were used to estimate the MCID and the PASS, respectively. The optimal cutoff point, where sensitivity and specificity were maximized, and the percentage of patients achieving those thresholds were also calculated.

RESULTS

Overall, 190 patients were included. The distribution-based MCID for the Rowe and ASOSS scores were calculated to be 8.2 and 8.7, respectively. The rate of patients who achieved MCID thresholds was 96% for the Rowe and 96% for ASOSS scores. The PASS threshold for the Rowe and ASOSS scores were ≥80 and ≥90, respectively. The rate of patients who achieved PASS scores after ABR were 86% and 83%, respectively. The MCID and PASS values showed great variability based on sex (men: 8.5 and ≥85 for Rowe / 8.9 and ≥90 for ASOSS, respectively, vs women: 6.7 and ≥73 for Rowe / 8.1 and ≥75 for ASOSS), age (≥21: 8.4 and ≥80 / 9.2 and ≥90 vs <21: 7.8 and ≥75 / 7.7 and ≥85), sports participation (sports: 8.8 and ≥85 / 9.5 and ≥90 vs no sports: 8.1 and ≥75 / 8.6 and ≥80), and type of athlete (competitive: 8.4 and ≥85 / 8.9 and ≥87 vs recreational: 7.5 and ≥73 / 8.1 and ≥68).

CONCLUSION

This study identified the MCID and PASS thresholds for the Rowe and ASOSS scores at 1 year after ABR. However, these values showed great variability when accounting for different patient characteristics such as sex, age, sports participation, and type of athlete, highlighting the importance of considering individual patient-specific characteristics for optimal treatment decision-making and ensuring treatment success tailored to each patient's unique needs and expectations.

How Much Perioperative Pain and Dysfunction Underlie the HOOS JR and KOOS JR?

BACKGROUND

The Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS JR) and Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS JR) scores represent pain and dysfunction as a single number ranging from 0 (extreme pain and dysfunction) to 100 (no pain or functional limitations). However, scores between 0 and 100 lack a simple interpretation because they reflect varying combinations of pain levels and dysfunction. Given that most adverse events and improvement occur within the first 90 days after surgery, a deeper understanding of the level of pain and dysfunction may reveal missed opportunities for patient care.

QUESTIONS/PURPOSES

(1) What does a given preoperative or postoperative HOOS JR and KOOS JR score indicate about pain and ability to perform daily activities? (2) How much of a change in score (that is, delta) is needed to indicate significant improvement in pain control and daily functioning?

METHODS

The Michigan Arthroplasty Registry Collaborative Quality Initiative contains more than 95% of THAs and TKAs performed in Michigan. Between January 2017 and March 2019, 84,175 people in the registry underwent primary THA or TKA and were potentially eligible for this retrospective, comparative study of the first 90 postoperative days. Eighty-four percent (70,608 of 84,175) were excluded because their surgeons did not attain a target survey collection proportion of 70% and another 6% (5042) were missing covariate information or surveys, leaving 10% (8525) for analysis. The mean age and percentage of women were 65 ± 11 years and 55% (2060 of 3716), respectively, for patients undergoing THA and 67 ± 9 years and 61% (2936 of 4809), respectively, for those undergoing TKA. There were no clinically meaningful differences between patients who were analyzed and those who were excluded except for lower representation of non-White patients in the analyzed group. For interpretation, patient responses to Question 7 (pain) and Question 6 (function) from the Patient-Reported Outcomes Measurement Information System global items (PROMIS-10) were dichotomized into "much pain" (rating of pain 4 to 10 of 10) versus "less pain" (rating of ≤ 3) and "good function" (able to perform most activities) versus "poor function" (not able to perform most activities) and combined into four pain-function categories. We examined the mean preoperative and postoperative HOOS JR and KOOS JR scores for each pain-function category, adjusted for patient characteristics. We calculated the size of the delta associated with an increase to a more favorable category postoperatively (versus staying in the same or worse category) via multivariable logistic regression that controlled for patient characteristics.

RESULTS

Patients in the least favorable "much pain, poor function" category preoperatively had adjusted mean scores of 40 (95% confidence interval 39 to 41) for both the HOOS JR and KOOS JR. Those with mixed levels of pain and function had mean scores between 46 and 55. Those in the most favorable "less pain, good function" category had means of 60 (95% CI 58 to 62) and 59 (95% CI 58 to 61) for the HOOS JR and KOOS JR, respectively. The adjusted delta to achieve a pain level of ≤ 3 or the ability to perform most activities was 30 (95% CI 26 to 36) on the HOOS JR and 27 (95% CI 22 to 29) on the KOOS JR scales.

CONCLUSION

These adjusted means of the HOOS JR and KOOS JR provide context for understanding the levels of pain and dysfunction for individuals as well for patients reported in other studies. Potential quality improvement efforts could include tracking the proportion of patients with THA or TKA who achieved a sufficient delta to attain pain levels of ≤ 3 or the ability to perform most activities. Future studies are needed to understand pain and function represented by the HOOS JR and KOOS JR at 1 to 2 years, how these may differ by patient subgroups, and whether scores can be improved through quality improvement efforts.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Response rates in clinical quality registries and databases that collect patient reported outcome measures: a scoping review

BACKGROUND

Patient Reported Outcome Measures (PROMs) are being increasingly introduced in clinical registries, providing a personal perspective on the expectations and impact of treatment. The aim of this study was to describe response rates (RR) to PROMs in clinical registries and databases and to examine the trends over time, and how they change with the registry type, region and disease or condition captured.

METHODS

We conducted a scoping literature review of MEDLINE and EMBASE databases, in addition to Google Scholar and grey literature. All English studies on clinical registries capturing PROMs at one or more time points were included. Follow up time points were defined as follows: baseline (if available), < 1 year, 1 to < 2 years, 2 to < 5 years, 5 to < 10 years and 10 + years. Registries were grouped according to regions of the world and health conditions. Subgroup analyses were conducted to identify trends in RRs over time. These included calculating average RRs, standard deviation and change in RRs according to total follow up time.

RESULTS

The search strategy yielded 1,767 publications. Combined with 20 reports and four websites, a total of 141 sources were used in the data extraction and analysis process. Following the data extraction, 121 registries capturing PROMs were identified. The overall average RR at baseline started at 71% and decreased to 56% at 10 + year at follow up. The highest average baseline RR of 99% was observed in Asian registries and in registries capturing data on chronic conditions (85%). Overall, the average RR declined as follow up time increased.

CONCLUSION

A large variation and downward trend in PROMs RRs was observed in most of the registries identified in our review. Formal recommendations are required for consistent collection, follow up and reporting of PROMs data in a registry setting to improve patient care and clinical practice. Further research studies are needed to determine acceptable RRs for PROMs captured in clinical registries.

Discordance Abounds in Minimum Clinically Important Differences in THA: A Systematic Review

BACKGROUND

The minimum clinically important difference (MCID) is intended to detect a change in a patient-reported outcome measure (PROM) large enough for a patient to appreciate. Their growing use in orthopaedic research stems from the necessity to identify a metric, other than the p value, to better assess the effect size of an outcome. Yet, given that MCIDs are population-specific and that there are multiple calculation methods, there is concern about inconsistencies. Given the increasing use of MCIDs in total hip arthroplasty (THA) research, a systematic review of calculated MCID values and their respective ranges, as well as an assessment of their applications, is important to guide and encourage their use as a critical measure of effect size in THA outcomes research.

QUESTIONS/PURPOSES

We systematically reviewed MCID calculations and reporting in current THA research to answer the following: (1) What are the most-reported PROM MCIDs in THA, and what is their range of values? (2) What proportion of studies report anchor-based versus distribution-based MCID values? (3) What are the most common methods by which anchor-based MCID values are derived? (4) What are the most common derivation methods for distribution-based MCID values? (5) How do the reported medians and corresponding ranges compare between calculation methods for each PROM?

METHODS

The EMBASE, MEDLINE, and PubMed databases were systematically reviewed from inception through March 2022 for THA studies reporting an MCID value for any PROMs. Two independent authors reviewed articles for inclusion. All articles calculating new PROM MCID scores after primary THA were included for data extraction and analysis. MCID values for each PROM, MCID calculation method, number of patients, and study demographics were extracted from each article. In total, 30 articles were included. There were 45 unique PROMs for which 242 MCIDs were reported. These studies had a total of 1,000,874 patients with a median age of 64 years and median BMI of 28.7 kg/m 2 . Women made up 55% of patients in the total study population, and the median follow-up period was 12 months (range 0 to 77 months). The overall risk of bias was assessed as moderate using the modified Methodological Index for Nonrandomized Studies criteria for comparative studies (the mean score for comparative papers in this review was 18 of 24, with higher scores representing better study quality) and noncomparative studies (for these, the mean score was 10 of a possible 16 points, with higher scores representing higher study quality). Calculated values were classified as anchor-based, distribution-based, or not reported. MCID values for each PROM, MCID calculation method, number of patients, and study demographics were extracted from each study. Anchor-based and distribution-based MCIDs were compared for each unique PROM using a Wilcoxon rank sum test, given the non-normal distribution of values.

RESULTS

The Oxford Hip Score (OHS) and the Hip Injury and Osteoarthritis Score (HOOS) Pain and Quality of Life subscore MCIDs were the most frequently reported, comprising 12% (29 of 242), 8% (20 of 242), and 8% (20 of 242), respectively. The EuroQol VAS (EQ-VAS) was the next-most frequently reported (7% [17 of 242]) followed by the EuroQol 5D (EQ-5D) (7% [16 of 242]). The median anchor-based value for the OHS was 9 (IQR 8 to 11), while the median distribution-based value was 6 (IQR 5 to 6). The median anchor-based MCID values for HOOS Pain and Quality of Life were 33 (IQR 28 to 35) and 25 (14 to 27), respectively; the median distribution-based values were 10 (IQR 9 to 10) and 13 (IQR 10 to 14), respectively. Thirty percent (nine of 30) of studies used an anchor-based method to calculate a new MCID, while 40% (12 of 30) used a distribution-based technique. Thirty percent of studies (nine of 30) calculated MCID values using both methods. For studies reporting an anchor-based calculation method, a question assessing pain relief, satisfaction, or quality of life on a five-point Likert scale was the most commonly used anchor (30% [eight of 27]), followed by a receiver operating characteristic curve estimation (22% [six of 27]). For studies using distribution-based calculations, the most common method was one-half the standard deviation of the difference between preoperative and postoperative PROM scores (46% [12 of 26]). Most reported median MCID values (nine of 14) did not differ by calculation method for each unique PROM (p > 0.05). The OHS, HOOS JR, and HOOS Function, Symptoms, and Activities of Daily Living subscores all varied by calculation method, because each anchor-based value was larger than its respective distribution-based value.

CONCLUSION

We found that MCIDs do not vary very much by calculation method across most outcome measurement tools. Additionally, there are consistencies in MCID calculation methods, because most authors used an anchor question with a Likert scale for the anchor-based approach or used one-half the standard deviation of preoperative and postoperative PROM score differences for the distribution-based approach. For some of the most frequently reported MCIDs, however, anchor-based values tend to be larger than distribution-based values for their respective PROMs.

CLINICAL RELEVANCE

We recommend using a 9-point increase as the MCID for the OHS, consistent with the median reported anchor-based value derived from several high-quality studies with large patient groups that used anchor-based approaches for MCID calculations, which we believe are most appropriate for most applications in clinical research. Likewise, we recommend using the anchor-based 33-point and 25-point MCIDs for the HOOS Pain and Quality of Life subscores, respectively. We encourage using anchor-based MCID values of WOMAC Pain, Function, and Stiffness subscores, which were 29, 26, and 30, respectively.

Patient appropriateness for total knee arthroplasty and predicted probability of a good outcome

OBJECTIVES

One-fifth of total knee arthroplasty (TKA) recipients experience a suboptimal outcome. Incorporation of patients' preferences in TKA assessment may improve outcomes. We determined the discriminant ability of preoperative measures of TKA need, readiness/willingness and expectations for a good TKA outcome.

METHODS

In patients with knee osteoarthritis (OA) undergoing primary TKA, we preoperatively assessed TKA need (Western Ontario-McMaster Universities OA Index (WOMAC) Pain Score and Knee injury and Osteoarthritis Outcome Score (KOOS) function, arthritis coping), health status, readiness (Patient Acceptable Symptom State, depressive symptoms), willingness (definitely yes-yes/no) and expectations (outcomes deemed 'very important'). A good outcome was defined as symptom improvement (met Outcome Measures in Rheumatology and Osteoarthritis Research Society International (OMERACT-OARSI) responder criteria) and satisfaction with results 1 year post TKA. Using logistic regression, we assessed independent outcome predictors, model discrimination (area under the receiver operating characteristic curve, AUC) and the predicted probability of a good outcome for different need, readiness/willingness and expectations scenarios.

RESULTS

Of 1,053 TKA recipients (mean age 66.9 years (SD 8.8); 58.6% women), 78.1% achieved a good outcome. With TKA need alone (WOMAC pain subscale, KOOS physical function short-form), model discrimination was good (AUC 0.67, 95% CI 0.63 to 0.71). Inclusion of readiness/willingness, depressive symptoms and expectations regarding kneeling, stair climbing, well-being and performing recreational activities improved discrimination (p=0.01; optimism corrected AUC 0.70, 0.66-0.74). The predicted probability of a good outcome ranged from 44.4% (33.9-55.5) to 92.4% (88.4-95.1) depending on level of TKA need, readiness/willingness, depressive symptoms and surgical expectations.

CONCLUSIONS

Although external validation is required, our findings suggest that incorporation of patients' TKA readiness, willingness and expectations in TKA decision-making may improve the proportion of recipients that experience a good outcome.

Preoperative Pain Catastrophizing Prior to Total Knee Arthroplasty is Associated With Worse Preoperative Symptoms and More Clinical Improvement: A Prospective Comparative Study

BACKGROUND

Total knee arthroplasty (TKA) is a reliable procedure for end-stage osteoarthritis with excellent long-term survivorship, but approximately 15% of patients are not satisfied. Pain catastrophizing (PC) has been proposed as a potential cause but current evidence is limited to smaller studies with short-term follow-up. Our goal was to assess outcomes following TKA in a large cohort with and without PC.

METHODS

A prospective comparative study was performed with patients undergoing unilateral primary TKA between 2019 and 2021 with 2-year follow-up. All patients completed a PC Scale questionnaire preoperatively and a score of minimum 30 was considered PC. Outcomes consisted of Knee injury and Osteoarthritis Outcome Score-Physical Function Shortform (KOOS-PS), Oxford Knee Score (OKS), numeric rating scale Pain, and aseptic revisions. Ultimately, 301 patients were included (mean age 69 years [range, 30-92 years], with 60.8% women). Forty four patients (14.6%) had PC.

RESULTS

Preoperatively, PC patients had inferior KOOS-PS, inferior OKS, and more pain than non-PC patients (all P < .001). PC patients had more improvement from preoperatively to 6 months postoperatively for KOOS-PS, OKS, and pain (all P < .05) and to 12 months for KOOS-PS and OKS (both P < .005). Similarly, PC patients had more improvement from preoperative to 24 months for OKS (P = .003). At 24 months, however, PC patients reported more pain than non-PC patients. There was no difference in revision rates (P = .192).

CONCLUSION

Patients who had PC reported worse function and pain preoperatively but had more improvement to 6 months and 12 months postoperatively. At 24 months, similar subjective function was noted, although PC patients reported more pain.

There are Considerable Inconsistencies Among Minimum Clinically Important Differences in TKA: A Systematic Review

BACKGROUND

Patient-reported outcome measures (PROMs) are frequently used to assess the impact of total knee arthroplasty (TKA) on patients. However, mere statistical comparison of PROMs is not sufficient to assess the value of TKA to the patient, especially given the risk profile of arthroplasty. Evaluation of treatment effect sizes is important to support the use of an intervention; this is often quantified with the minimum clinically important difference (MCID). MCIDs are unique to specific PROMs, as they vary by calculation methodology and study population. Therefore, a systematic review of calculated MCID values, their respective ranges, and assessment of their applications is important to guide and encourage their use as a critical measure of effect size in TKA outcomes research.

QUESTIONS/PURPOSES

In this systematic review of MCID calculations and reporting in primary TKA, we asked: (1) What are the most frequently reported PROM MCIDs and their reported ranges in TKA? (2) What proportion of studies report distribution- versus anchor-based MCID values? (3) What are the most common methods by which these MCID values are derived for anchor-based values? (4) What are the most common derivation methods for distribution-based values? (5) How do the reported medians and corresponding interquartile ranges (IQR) compare between calculation methods for each PROM?

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review was conducted using the PubMed, EMBASE, and MEDLINE databases from inception through March 2022 for TKA articles reporting an MCID value for any PROMs. Two independent reviewers screened articles for eligibility, including any article that calculated new MCID values for PROMs after primary TKA, and extracted these data for analysis. Overall, 576 articles were identified, 38 of which were included in the final analysis. These studies had a total of 710,128 patients with a median age of 67.7 years and median BMI of 30.9 kg/m 2 . Women made up more than 50% of patients in most studies, and the median follow-up period was 17 months (range 0.25 to 72 months). The overall risk of bias was assessed as moderate using the Jadad criteria for one randomized controlled trial (3 of 5 ideal global score) and the modified Methodological Index for Non-randomized Studies criteria for comparative studies (mean 17.2 ± 1.8) and noncomparative studies (mean 9.6 ± 1.3). There were 49 unique PROMs for which 233 MCIDs were reported. Calculated values were classified as anchor-based, distribution-based, or not reported. MCID values for each PROM, MCID calculation method, number of patients, and study demographics were extracted from each study. Anchor-based and distribution-based MCIDs were compared for each unique PROM using a Wilcoxon rank sum test given non-normal distribution of values.

RESULTS

The WOMAC Function and Pain subscores were the most frequently reported MCID value, comprising 9% (22 of 233) and 9% (22 of 233), respectively. The composite Oxford Knee Score (OKS) was the next most frequently reported (9% [21 of 233]), followed by the WOMAC composite score (6% [13 of 233]). The median anchor-based values for WOMAC Function and Pain subscores were 23 (IQR 16 to 33) and 25 (IQR 14 to 31), while the median distribution-based values were 11 (IQR 10.8 to 11) and 22 (IQR 17 to 23), respectively. The median anchor-based MCID value for the OKS was 6 (IQR 4 to 7), while the distribution-based value was 7 (IQR 5 to 10). Thirty-nine percent (15 of 38) used an anchor-based method to calculate a new MCID, while 32% (12 of 38) used a distribution-based technique. Twenty-nine percent of studies (11 of 38) calculated MCID values using both methods. For studies reporting an anchor-based calculation method, a question assessing patient satisfaction, pain relief, or quality of life along a five-point Likert scale was the most commonly used anchor (40% [16 of 40]), followed by a receiver operating characteristic curve estimation (25% [10 of 40]). For studies using distribution-based calculations, all articles used a measure of study population variance in their derivation of the MCID, with the most common method reported as one-half the standard deviation of the difference between preoperative and postoperative PROM scores (45% [14 of 31]). Most reported median MCID values (15 of 19) did not differ by calculation method for each unique PROM (p > 0.05) apart from the WOMAC Function component score and the Knee Injury and Osteoarthritis Outcome Score Pain and Activities of Daily Living subscores.

CONCLUSION

Despite variability of MCIDs for each PROM, there is consistency in the methodology by which MCID values have been derived in published studies. Additionally, there is a consensus about MCID values regardless of calculation method across most of the PROMs we evaluated.

CLINICAL RELEVANCE

Given their importance to treatment selection and patient safety, authors and journals should report MCID values with greater consistency. We recommend using a 7-point increase as the MCID for the OKS, consistent with the median reported anchor-based value derived from several high-quality studies with large patient groups that used anchor-based approaches for MCID calculation, which we believe are most appropriate for most applications in clinical research. Likewise, we recommend using a 10-point to 15-point increase for the MCID of composite WOMAC, as the median value was 12 (IQR 10 to 17) with no difference between calculation methods. We recommend use of median reported values for WOMAC function and pain subscores: 21 (IQR 15 to 33) and 23 (IQR 13 to 29), respectively.

How do Patient-reported Outcome Scores in International Hip and Knee Arthroplasty Registries Compare?

BACKGROUND

Patient-reported outcome measures (PROMs) are the only systematic approach through which the patient's perspective can be considered by surgeons (in determining a procedure's efficacy or appropriateness) or healthcare systems (in the context of value-based healthcare). PROMs in registries enable international comparison of patient-centered outcomes after total joint arthroplasty, but the extent to which those scores may vary between different registry populations has not been clearly defined.

QUESTIONS/PURPOSES

(1) To what degree do mean change in general and joint-specific PROM scores vary across arthroplasty registries, and to what degree is the proportion of missing PROM scores in an individual registry associated with differences in the mean reported change scores? (2) Do PROM scores vary with patient BMI across registries? (3) Are comorbidity levels comparable across registries, and are they associated with differences in PROM scores?

METHODS

Thirteen national, regional, or institutional registries from nine countries reported aggregate PROM scores for patients who had completed PROMs preoperatively and 6 and/or 12 months postoperatively. The requested aggregate PROM scores were the EuroQol-5 Dimension Questionnaire (EQ-5D) index values, on which score 1 reflects "full health" and 0 reflects "as bad as death." Joint-specific PROMs were the Oxford Knee Score (OKS) and the Oxford Hip Score (OHS), with total scores ranging from 0 to 48 (worst-best), and the Hip Disability and Osteoarthritis Outcome Score-Physical Function shortform (HOOS-PS) and the Knee Injury and Osteoarthritis Outcome Score-Physical Function shortform (KOOS-PS) values, scored 0 to 100 (worst-best). Eligible patients underwent primary unilateral THA or TKA for osteoarthritis between 2016 and 2019. Registries were asked to exclude patients with subsequent revisions within their PROM collection period. Raw aggregated PROM scores and scores adjusted for age, gender, and baseline values were inspected descriptively. Across all registries and PROMs, the reported percentage of missing PROM data varied from 9% (119 of 1354) to 97% (5305 of 5445). We therefore graphically explored whether PROM scores were associated with the level of data completeness. For each PROM cohort, chi-square tests were performed for BMI distributions across registries and 12 predefined PROM strata (men versus women; age 20 to 64 years, 65 to 74 years, and older than 75 years; and high or low preoperative PROM scores). Comorbidity distributions were evaluated descriptively by comparing proportions with American Society of Anesthesiologists (ASA) physical status classification of 3 or higher across registries for each PROM cohort.

RESULTS

The mean improvement in EQ-5D index values (10 registries) ranged from 0.16 to 0.33 for hip registries and 0.12 to 0.25 for knee registries. The mean improvement in the OHS (seven registries) ranged from 18 to 24, and for the HOOS-PS (three registries) it ranged from 29 to 35. The mean improvement in the OKS (six registries) ranged from 15 to 20, and for the KOOS-PS (four registries) it ranged from 19 to 23. For all PROMs, variation was smaller when adjusting the scores for differences in age, gender, and baseline values. After we compared the registries, there did not seem to be any association between the level of missing PROM data and the mean change in PROM scores. The proportions of patients with BMI 30 kg/m 2 or higher ranged from 16% to 43% (11 hip registries) and from 35% to 62% (10 knee registries). Distributions of patients across six BMI categories differed across hip and knee registries. Further, for all PROMs, distributions also differed across 12 predefined PROM strata. For the EQ-5D, patients in the younger age groups (20 to 64 years and 65 to 74 years) had higher proportions of BMI measurements greater than 30 kg/m 2 than older patients, and patients with the lowest baseline scores had higher proportions of BMI measurements more than 30 kg/m 2 compared with patients with higher baseline scores. These associations were similar for the OHS and OKS cohorts. The proportions of patients with ASA Class at least 3 ranged across registries from 6% to 35% (eight hip registries) and from 9% to 42% (nine knee registries).

CONCLUSION

Improvements in PROM scores varied among international registries, which may be partially explained by differences in age, gender, and preoperative scores. Higher BMI tended to be associated with lower preoperative PROM scores across registries. Large variation in BMI and comorbidity distributions across registries suggest that future international studies should consider the effect of adjusting for these factors. Although we were not able to evaluate its effect specifically, missing PROM data is a recurring challenge for registries. Demonstrating generalizability of results and evaluating the degree of response bias is crucial in using registry-based PROMs data to evaluate differences in outcome. Comparability between registries in terms of specific PROMs collection, postoperative timepoints, and demographic factors to enable confounder adjustment is necessary to use comparison between registries to inform and improve arthroplasty care internationally.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Interpretation threshold values for the Oxford Knee Score in patients undergoing unicompartmental knee arthroplasty

BACKGROUND AND PURPOSE

Developing meaningful thresholds for the Oxford Knee Score (OKS) advances its clinical use. We determined the minimal important change (MIC), patient acceptable symptom state (PASS), and treatment failure (TF) values as meaningful thresholds for the OKS at 3-, 12-, and 24-month follow-up in patients undergoing unicompartmental knee arthroplasty (UKA).

PATIENTS AND METHODS

This is a cohort study with data from patients undergoing UKA collected at a hospital in Denmark between February 2016 and September 2021. The OKS was completed preoperatively and at 3, 12, and 24 months postoperatively. Interpretation threshold values were calculated with the anchor-based adjusted predictive modeling method. Non-parametric bootstrapping was used to derive 95% confidence intervals (CI).

RESULTS

Complete 3-, 12-, and 24-month postoperative data was obtained for 331 of 423 (78%), 340 of 479 (71%), and 235 of 338 (70%) patients, median age of 68-69 years (58-59% females). Adjusted OKS MIC values were 4.7 (CI 3.3-6.0), 7.1 (CI 5.2-8.6), and 5.4 (CI 3.4- 7.3), adjusted OKS PASS values were 28.9 (CI 27.6-30.3), 32.7 (CI 31.5-33.9), and 31.3 (CI 29.1-33.3), and adjusted OKS TF values were 24.4 (CI 20.7-27.4), 29.3 (CI 27.3-31.1), and 28.5 (CI 26.0-30.5) at 3, 12, and 24 months postoperatively, respectively. All values statistically significantly increased from 3 to 12 months but not from 12 to 24 months.

INTERPRETATION

The UKA-specific measurement properties and clinical thresholds for the OKS can improve the interpretation of UKA outcome and assist quality assessment in institutional and national registries.