30 years with the Knee injury and Osteoarthritis Outcome Score (KOOS).

This narrative review describes the development and use of patient-reported outcomes over 30 years, focusing on the Knee injury and Osteoarthritis Outcome Score (KOOS). KOOS is a five-subscale patient-reported instrument intended for use from the time of knee injury to the development of osteoarthritis. Numerous studies have confirmed that the psychometric properties of the KOOS and its short-form KOOS-12 are acceptable. More recent research has focused on the use and interpretation of KOOS scores in clinical trials using thresholds, such as minimal important differences, patient-acceptable symptom states, and treatment failure. As an indication of KOOS's popularity, the total 3854 PubMed results for KOOS have increased exponentially since the first KOOS paper was published 25 years ago and now seem to have plateaued at around 650 annually. The selected articles are not based on a systematic search, but on the author's own publications, reading, and literature search that grew organically from that.

Patient acceptable symptom state and treatment failure threshold values for work productivity and activity Impairment and EQ-5D-5L in osteoarthritis.

OBJECTIVE: To estimate patient acceptable symptom state (PASS) and treatment failure (TF) threshold values for Work Productivity and Activity Impairment (WPAI) measure and EQ-5D-5L among people with hip or knee osteoarthritis (OA) 3 and 12 months following participation in a digital self-management intervention (Joint Academy®). METHODS: Among the participants, we computed work and activity impairments scores (both 0-100, with a higher value reflecting higher impairment) and the Swedish hypothetical- (range: - 0.314 to 1) and experience-based (range: 0.243-0.976) EQ-5D-5L index scores (a higher score indicates better health status) at 3- (n = 14,607) and 12-month (n = 2707) follow-ups. Threshold values for PASS and TF were calculated using anchor-based adjusted predictive modeling. We also explored the baseline dependency of threshold values according to pain severity at baseline. RESULTS: Around 42.0% and 48.3% of the participants rated their current state as acceptable, while 4.2% and 2.8% considered the treatment had failed at 3 and 12 months, respectively. The 3-month PASS/TF thresholds were 16/29 (work impairment), 26/50 (activity impairment), 0.92/0.77 (hypothetical EQ-5D-5L), and 0.87/0.77 (the experience-based EQ-5D-5L). The thresholds at 12 months were generally comparable to those estimated at 3 months. There were baseline dependencies in PASS/TF thresholds with participants with more severe baseline pain considering poorer (more severe) level of WPAI/EQ-5D-5L as satisfactory. CONCLUSION: PASS and TF threshold values for WPAI and EQ-5D-5L might be useful for meaningful interpretation of these measures among people with OA. The observed baseline dependency of estimated thresholds limits their generalizability and values should be applied with great caution in other settings/populations.

The attainment of a patient acceptable symptom state in patients undergoing revision spine fusion.

INTRODUCTION: Revision lumbar fusion is most commonly due to nonunion, adjacent segment disease (ASD), or recurrent stenosis, but it is unclear if diagnosis affects patient outcomes. The primary aim of this study was to assess whether patients achieved the patient acceptable symptom state (PASS) or minimal clinically important difference (MCID) after revision lumbar fusion and assess whether this was influenced by the indication for revision. METHODS: We retrospectively identified all 1-3 level revision lumbar fusions at a single institution. Oswestry Disability Index (ODI) was collected at preoperative, three-month postoperative, and one-year postoperative time points. The MCID was calculated using a distribution-based method at each postoperative time point. PASS was set at the threshold of ≤ 22. RESULTS: We identified 197 patients: 56% with ASD, 28% with recurrent stenosis, and 15% with pseudarthrosis. The MCID for ODI was 10.05 and 10.23 at three months and one year, respectively. In total, 61% of patients with ASD, 52% of patients with nonunion, and 65% of patients with recurrent stenosis achieved our cohort-specific MCID at one year postoperatively with ASD (p = 0.78). At one year postoperatively, 33.8% of ASD patients, 47.8% of nonunion patients, and 37% of patients with recurrent stenosis achieved PASS without any difference between indication (p = 0.47). CONCLUSIONS: The majority of patients undergoing revision spine fusion experience significant postoperative improvements regardless of the indication for revision. However, a large proportion of these patients do not achieve the patient acceptable symptom state. While revision spine surgery may offer substantial benefits, these results underscore the need to manage patient expectations.

Effect of age and gender in rates of achieving minimal clinically important difference and patient-acceptable symptom state 2 years after arthroscopic superior capsular reconstruction.

PURPOSE: This study aimed to evaluate patient-reported outcome measures (PROMs) and the effects of gender and age on achieving clinically significant outcomes in patients undergoing arthroscopic superior capsular reconstruction (ASCR) with a minimum 2-year follow-up. METHODS: Patients undergoing ASCR for irreparable rotator cuff tear between 2013 and 2020 were reviewed. Preoperative and minimum 2-year postoperative PROMs were collected, including American Shoulder and Elbow Surgeons (ASES), Constant, single assessment numeric evaluation (SANE), and visual analog scale (VAS) scores. Minimal clinically important difference (MCID) and patient-acceptable symptomatic state (PASS) were calculated for each functional score and analyzed according to age and gender. The percentages of patients achieving MCID and PASS were recorded. RESULTS: The study included 83 patients, with a mean follow-up of 3.5 ± 1.4 years. Significant improvements were found in ASES, Constant, SANE, and VAS for all groups based on gender and age. Based on receiver-operating characteristic curves, all scores had acceptable areas under the curve for PASS. Values for PASS and MCID were 81.5 and 10.3 for ASES; 61.5 and 6.2 for Constant; 82.5 and 11.5 for SANE and 1.5 and 1.1 for VAS, respectively. Analysis of achieving MCID and PASS showed no difference between the groups in the majority of outcome measures. However, female patients achieved the SANE thresholds for PASS at significantly higher rates than male patients. Patients ≥65 years old achieved ASES and Constant thresholds for MCID at significantly higher rates than patients ˂65 years old. CONCLUSION: Most patients achieved MCID and PASS at a 2-year follow-up. Patients showed comparable rates of MCID and PASS achievement on most outcome tools based on age and gender. Female patients achieved PASS on SANE at significantly higher rates than male patients and older patients achieved MCID on ASES and Constant at higher rates than young patients. Thus, age is a stronger factor for achieving MCID than gender. LEVEL OF EVIDENCE: Level II.

Unicompartmental knee arthroplasty improves mental health in patients with single compartment knee osteoarthritis.

PURPOSE: The purpose of this study was to determine if preoperative mental health status improves following unicompartmental knee arthroplasty (UKA) in patients with single compartment knee osteoarthritis (OA). METHODS: A total of 163 patients underwent UKA [115 (71%) medial, 48 (29%) lateral] (mean age = 65 ± 11) completed preoperative and minimum 2-year postoperative veterans RAND 12 item health survey (VR-12) mental component score (MCS). VR-12 MCS was the primary outcome measure. Secondary measures included VR-12 physical component summary score (PCS), knee osteoarthritis outcome score (KOOS) and KOOS patient acceptable symptom state at the final follow-up. RESULTS: The median VR-12 MCS improved from 50.5 [interquartile range (IQR): 43.7-56.8] to 55.0 [IQR: 52.3-57.0] (p < 0.001) at a mean follow-up of 9.5 ± 4 years (range 2-19 years) following UKA. Preoperative VR-12 MCS was significantly correlated with patients postoperative VR-12 PCS (ρ = 0.294, p < 0.01), KOOS pain (ρ = 0.201, p = 0.012), KOOS ADL (ρ = 0.243, p = 0.002) and KOOS quality of life (ρ = 0.233, p < 0.01). Sixty-three (39%) patients improved from low VR-12 MCS (<50) to normal VR-12 MCS (≥50). One hundred forty-two (87%) achieved a normal VR-12 MCS score (≥50) postoperatively. CONCLUSION: At a mean of 10-year follow-up, patients who underwent UKA for single compartment osteoarthritic knee pain demonstrated significant improvement in mental health scores. UKA resulted in normal mental health in a majority of patients (87%). The resultant improved mental health scores were associated with improved patient pain and activities of daily living. LEVEL OF EVIDENCE: Level III retrospective cohort study.

The Delaware-Oslo ACL Cohort treatment algorithm yields superior outcomes to usual care 9-12 years after anterior cruciate ligament reconstruction.

PURPOSE: Patient-reported outcomes were compared between participants who followed the treatment algorithm of the Delaware-Oslo ACL Cohort, consisting of progressive preoperative and postoperative rehabilitation, patient education, clinical testing and shared decision-making about treatment choice, and those who followed usual care 9-12 years after anterior cruciate ligament reconstruction (ACLR). METHODS: Participants with primary ACLR were included from the Norwegian arm of the Delaware-Oslo ACL Cohort and the Norwegian Knee Ligament Registry (usual care). The Knee Injury and Osteoarthritis Outcome Score (KOOS) subscale scores and the International Knee Documentation Committee-Subjective Knee Form (IKDC-SKF) scores were compared. KOOS scores for the usual care group were converted to IKDC-SKF scores with recently published validated crosswalk. The percentages of participants with scores above predefined thresholds for patient acceptable symptom state (PASS) were also calculated. RESULTS: Eighty of 100 (80%) participants from the Delaware-Oslo ACL Cohort and 1588 of 3248 (49%) from the usual care group participated in the follow-up. Participants from the Delaware-Oslo ACL Cohort had higher KOOS subscale (p < 0.001) and IKDC-SKF scores (p < 0.001), and a higher percentage reached PASS (84%-96% vs. 62%-76%, p ≤ 0.002) for KOOS Pain, symptoms, activities of daily living and sports compared to the usual care group. No significant differences were found for KOOS quality of life scores (not significant [n.s.]) or PASS percentages (80% vs. 74%, n.s.). CONCLUSION: Participants with ACLR who followed the Delaware-Oslo ACL Cohort treatment algorithm had reduced knee symptoms, superior function and higher percentages of satisfactory outcomes than participants who followed usual care. LEVEL OF EVIDENCE: Level II.

Should We Wait for Bone-on-Bone Arthritis? Equivalent Clinical Outcomes in Patients Requiring Advanced Imaging Before Primary Total Hip Arthroplasty.

BACKGROUND: Plain radiographs remain the standard for diagnosing osteoarthritis (OA). Total hip arthroplasty (THA) is generally offered only for advanced OA by plain radiographs. Advanced imaging is used as an adjunct to assess OA severity in cases of progressive symptoms with less advanced OA by plain radiographs. The objective of this study was to compare outcomes following THA in patients who have advanced OA visualized by plain radiographs to patients who have less severe OA visualized by plain radiographs. METHODS: From February 2016 to February 2020, 93 patients who had Kellgren-Lawrence (KL) grade 0 to 2 OA and underwent THA were identified. The median age was 65 years, and 55% were women. They were matched 1:3 to patients who underwent THA for KL 4 OA based on age, sex, body mass index, and Charlson Comorbidity Index. The primary outcome was achievement of the Hip Injury and Osteoarthritis Outcome Score for Joint Replacement (HOOS JR) minimum clinically important difference, substantial clinical benefit, and patient-acceptable symptom state at 1 year postoperatively. RESULTS: There was no difference between the KL 0 to 2 and KL 4 cohorts in the achievement of HOOS JR minimum clinically important difference (86 versus 85.6%, P = .922), substantial clinical benefit (81.7 versus 80.2%, P = .751), or patient-acceptable symptom state (89.2 versus 85.6%, P = .374). The KL 0 to 2 cohort had a similar improvement in their 2-year HOOS JR (42.5 versus 38.6, P = .019). CONCLUSIONS: In this series, there was no difference in outcomes following primary THA between patients who have severe OA on plain radiographs (KL 4) compared to those who have less severe OA (KL 0 to 2). In the setting of severe symptoms and the absence of advanced OA on radiographs, advanced imaging can be used to guide treatment and select patients who could benefit from THA.

What Are the Diagnosis-Specific Thresholds of Minimal Clinically Important Difference and Patient Acceptable Symptom State in Hip Disability and Osteoarthritis Outcome Score After Primary Total Hip Arthroplasty?

BACKGROUND: This study aimed to determine the minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) thresholds for Hip Disability and Osteoarthritis Outcome Score (HOOS) pain, physical short form (PS), and joint replacement (JR) 1 year after primary total hip arthroplasty stratified by preoperative diagnosis of osteoarthritis (OA) versus non-OA. METHODS: A prospective institutional cohort of 5,887 patients who underwent primary total hip arthroplasty (January 2016 to December 2018) was included. There were 4,184 patients (77.0%) who completed a one-year follow-up. Demographics, comorbidities, and baseline and one-year HOOS pain, PS, and JR scores were recorded. Patients were stratified by preoperative diagnosis: OA or non-OA. Minimal detectable change (MDC) and MCIDs were estimated using a distribution-based approach. The PASS values were estimated using an anchor-based approach, which corresponded to a response to a satisfaction question at one year post surgery. RESULTS: The MCID thresholds were slightly higher in the non-OA cohort versus OA patients. (HOOS-Pain: OA: 8.35 versus non-OA: 8.85 points; HOOS-PS: OA: 9.47 versus non-OA: 9.90 points; and HOOS-JR: OA: 7.76 versus non-OA: 8.46 points). Similarly, all MDC thresholds were consistently higher in the non-OA cohort compared to OA patients. The OA cohort exhibited similar or higher PASS thresholds compared to the non-OA cohort for HOOS-Pain (OA: ≥80.6 versus non-OA: ≥77.5 points), HOOS-PS (OA: ≥83.6 versus non-OA: ≥83.6 points), and HOOS-JR (OA: ≥76.8 versus non-OA: ≥73.5 points). A similar percentage of patients achieved MCID and PASS thresholds regardless of preoperative diagnosis. CONCLUSIONS: While MCID and MDC thresholds for all HOOS subdomains were slightly higher among non-OA than OA patients, PASS thresholds for HOOS pain and JR were slightly higher in the OA group. The absolute magnitude of the difference in these thresholds may not be sufficient to cause major clinical differences. However, these subtle differences may have a significant impact when used as indicators of operative success in a population setting.

Establishing minimal clinically important differences and patient acceptable symptom state thresholds following birmingham hip resurfacing.

INTRODUCTION: Birmingham Hip Resurfacing (BHR) has emerged as a compelling and innovative alternative to total hip arthroplasty (THA), especially among young, active patients. However, the Minimal Clinically Important Difference (MCID) and the Patient Acceptable Symptom State (PASS) thresholds have not yet been determined for patients undergoing BHR. Therefore, the current study aimed to (1) determine the MCID and PASS thresholds for both the Hip disability and Osteoarthritis Outcome Score (HOOS)-Pain and HOOS physical function shortform (PS), for patients who underwent BHR; and (2) identify factors influencing the achievement of MCID and PASS for HOOS-Pain and HOOS-PS. METHODS: Prospectively collected data from patients undergoing BHR was analyzed. Patients with osteoarthritis and completed preoperative and 1-year postoperative PROMs were included. Distribution-based and anchored-based approaches were used to estimate MCID and PASS, respectively. The optimal cut-off point for PASS thresholds was calculated using the Youden index. RESULTS: MCID for HOOS-Pain and PS were calculated to be 9.2 and 9.3, respectively. The PASS threshold for HOOS-Pain and PS were ≥ 77.7 and ≥ 87.3, respectively. The current study identified several factors affecting postoperative achievement of thresholds. Baseline Mental Component Summary (MCS) scores were a predictor for achieving MCID for postoperative HOOS-Pain, achieving MCID for postoperative HOOS-PS, achieving PASS for postoperative HOOS-Pain, and achieving PASS for postoperative HOOS-PS. Furthermore, baseline HOOS-Pain was a significant predictor for achieving MCID for postoperative HOOS-PS, achieving PASS for postoperative HOOS-Pain, and achieving PASS for postoperative HOOS-PS. CONCLUSIONS: MCID and PASS thresholds were established for HOOS-Pain and PS domains following BHR with most patients achieving these clinically meaningful benchmarks. Additionally, several factors affecting achievement of MCID and PASS were identified, including modifiable risk factors that may allow clinicians to implement optimization strategies and further improve outcomes.

Harmonising knee pain patient-reported outcomes: a systematic literature review and meta-analysis of Patient Acceptable Symptom State (PASS) and individual participant data (IPD).

OBJECTIVE: In order to facilitate data pooling between studies, we explored harmonisation of patient-reported outcome measures (PROMs) in people with knee pain due to osteoarthritis or knee trauma, using the Patient Acceptable Symptom State scores (PASS) as a criterion. METHODS: We undertook a systematic literature review (SLR) of PASS scores, and performed individual participant data (IPD) analysis of score distributions from concurrently completed PROM pairs. Numerical rating scales (NRS), visual analogue scales, KOOS and WOMAC pain questionnaires were standardised to 0 to 100 (worst) scales. Meta-regression explored associations of PASS. Bland Altman plots compared PROM scores within individuals using IPD from WebEx, KICK, MenTOR and NEKO studies. RESULTS: SLR identified 18 studies reporting PASS in people with knee pain. Pooled standardised PASS was 27 (95% CI: 21 to 35; n = 6,339). PASS was statistically similar for each standardised PROM. Lower PASS was associated with lower baseline pain (ß = 0.49, P = 0.01) and longer time from treatment initiation (Q = 6.35, P = 0.04). PASS scores were lowest in ligament rupture (12, 95% CI: 11 to 13), but similar between knee osteoarthritis (31, 95% CI: 26 to 36) and meniscal tear (27, 95% CI: 20 to 35). In IPD, standardised PROMs each revealed similar group mean scores, but scores within individuals diverged between PROMs (LoA between -7 to -38 and +25 to 52). CONCLUSION: Different standardised PROMs give similar PASS thresholds in group data. PASS thresholds may be affected more by patient and treatment characteristics than between PROMs. However, different PROMs give divergent scores within individuals, possibly reflecting different experiences of pain.

Patient acceptable symptom state (PASS): thresholds for the EQ-5D-5L and Oxford hip and knee scores for patients with total hip and knee replacement.

PURPOSE: To define patient acceptable symptom state (PASS) cut-off values for the EQ-5D-5L and Oxford hip (OHS) and knee (OKS) scores 6 and 12 months after total hip (THR) or knee (TKR) replacement. To compare PASS cut-off values for the EQ-5D-5L scored using: (1) the Canadian value set, (2) the crosswalk value set, and (3) the equal weighted Level Sum Score (LSS). METHODS: We mailed questionnaires to consecutive patients following surgeon referral for primary THR or TKR and at 6 and 12 months post-surgery. Patient reported outcome measures (PROMs) were the EQ-5D-5L, the OHS, and OKS. We assessed PASS cut-off values for PROMs using percentile and ROC methods, with the Youden Index. RESULTS: Five hundred forty-two surgical patients (mean age, 64 years, 57% female, 49% THR) completed baseline and 12-month questionnaires. 89% of THR and 81% of TKR patients rated PASS as acceptable at 12 months. PASS cut-off values for THR for the EQ-5D-5L (Canadian) were 0.85 (percentile) and 0.84 (Youden) at 12 months. Cut-off values were similar for the LSS (0.85 and 0.85) and lower for the crosswalk value set (0.74 and 0.73), respectively. EQ-5D-5L cut-off values for TKR were Canadian, 0.77 (Percentile) and 0.78 (Youden), LSS, 0.75 and 0.80, and crosswalk, 0.67 and 0.74, respectively. Cut-off values 6 and 12 months post-surgery ranged from 38 to 39 for the OHS, and 28 to 36 for the OKS (range 0 worst to 48 best). CONCLUSION: PASS cut-off values for the EQ-5D-5L and Oxford scores varied, not only between methods and timing of assessment, but also by different EQ-5D-5L value sets, which vary between countries. Because of this variation, PASS cut-off values are not necessarily generalizable to other populations of TJR patients. We advise caution in interpreting PROMs when using EQ-5D-5L PASS cut-off values developed in different countries. A standardization of methods is needed before published cut-off values can be used with confidence in other populations.

Estimating meaningful thresholds for multi-item questionnaires using item response theory.

PURPOSE: Meaningful thresholds are needed to interpret patient-reported outcome measure (PROM) results. This paper introduces a new method, based on item response theory (IRT), to estimate such thresholds. The performance of the method is examined in simulated datasets and two real datasets, and compared with other methods. METHODS: The IRT method involves fitting an IRT model to the PROM items and an anchor item indicating the criterion state of interest. The difficulty parameter of the anchor item represents the meaningful threshold on the latent trait. The latent threshold is then linked to the corresponding expected PROM score. We simulated 4500 item response datasets to a 10-item PROM, and an anchor item. The datasets varied with respect to the mean and standard deviation of the latent trait, and the reliability of the anchor item. The real datasets consisted of a depression scale with a clinical depression diagnosis as anchor variable and a pain scale with a patient acceptable symptom state (PASS) question as anchor variable. RESULTS: The new IRT method recovered the true thresholds accurately across the simulated datasets. The other methods, except one, produced biased threshold estimates if the state prevalence was smaller or greater than 0.5. The adjusted predictive modeling method matched the new IRT method (also in the real datasets) but showed some residual bias if the prevalence was smaller than 0.3 or greater than 0.7. CONCLUSIONS: The new IRT method perfectly recovers meaningful (interpretational) thresholds for multi-item questionnaires, provided that the data satisfy the assumptions for IRT analysis.

Values derived from patient reported outcomes in spine surgery: a systematic review of the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptom state.

PURPOSE: While patient reported outcome measures (PROMs) define value in spine surgery, several values such as minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptom state (PASS) help guide the interpretation of PROMs and identify thresholds of clinical significance. Significant variation exists in reported values and their calculation, so the primary objective of this study was to systematically review the spine surgery literature for metrics of clinical significance derived from PROMs. METHODS: We conducted a query of PubMed/MEDLINE and Scopus databases from inception to January 1, 2023, for studies that derived quantitative metrics (e.g., SCB, MCID, PASS) from PROMs in the setting of spine surgery with minimum 1-year follow-up. Details regarding the specific PROMs were collected including which PROM was measured, whether anchor- or distribution-based methods were utilized, the specific calculations, and the recommended value for a given PROM based on all evaluated calculations. RESULTS: Thirty-seven studies of 21,780 patients were included. The most commonly evaluated PROM-derived value was the MCID (n = 28), followed by PASS (n = 6) and SCB (n = 4). Twenty-one studies only utilized anchor-based calculations, 15 utilized both anchor-based and distribution-based methods, and one only utilized distribution-based calculations. The most commonly evaluated legacy PROMs were the Oswestry Disability Index (ODI) (N = 11, MCID range 4-20) and visual analog scale back pain (N = 5, MCID range 0.5-4.6). All 10 studies that derived SCB or PASS utilized the receiver operating characteristic methods. Among the six studies deriving a PASS value, four only evaluated ODI, identifying PASS ranging from 5 to 22. CONCLUSION: While calculated measures of clinical significance such as MCID, PASS, and SCB exist, significant heterogeneity exists in the current literature. Current shortcomings include a wide variability of reported value thresholds across the literature, and limited applicability to more heterogenous patient populations than the targeted cohorts included in published investigations. Continued investigations that apply these methods to heterogenous, large-scale populations can help increase generalizability and validity of these measures. LEVEL OF EVIDENCE: III.

Preoperative factors associated with failure to reach the patient acceptable symptom state after anterior cruciate ligament reconstruction in patients aged 40 and older.

PURPOSE: To perform a predictive analysis to identify preoperative patient factors associated with failure to achieve a newly defined patient acceptable symptom state (PASS) for the International Knee Documentation Committee (IKDC) Score after anterior cruciate ligament reconstruction (ACLR) in patients aged ≥ 40 years with a minimum of 2-year follow-up. METHODS: This was a secondary analysis of a retrospective review of all patients aged 40 years or older receiving a primary allograft ACLR at a single institution between the years of 2005 and 2016, with 2-year minimum follow-up. Using an updated PASS threshold of 66.7 for the International Knee Documentation Committee (IKDC) score previously established for this patient cohort, a univariate and multivariate analysis was performed to identify preoperative patient characteristics predictive of failure to achieve PASS. RESULTS: A total of 197 patients with a mean follow-up of 6.2 ± 2.1 years (range 2.7 - 11.2) were included in the analysis (48.5 ± 5.6 years, 51.8% female, Body Mass Index (BMI) 25.9 ± 4.4). PASS was achieved by 162 patients (82.2%). Patients who failed to achieve PASS more often had lateral compartment cartilage defects (P = 0.001) and lateral meniscus tears (P = 0.004), higher BMIs (P = 0.004), and Workers' Compensation status (P = 0.043) on univariable analysis. Factors predictive of failure to achieve PASS on multivariable analysis included BMI and lateral compartment cartilage defect (OR 1.12 [1.03-1.23], P = 0.013; OR 5.1 [1.87-13.9], P = 0.001). CONCLUSION: Among patients ≥ 40 years who receive a primary allograft ACLR, patients who fail to achieve PASS more often had lateral compartment cartilage defects and higher BMIs. LEVEL OF EVIDENCE: Level IV.

MCID and PASS in Knee Surgeries. Theoretical Aspects and Clinical Relevance References.

The application and interpretation of patient-reported outcome measures (PROM), following knee injuries, pathologies, and interventions, can be challenging. In recent years, the literature has been enriched with metrics to facilitate our understanding and interpretation of these outcome measures. Two commonly utilized tools include the minimal clinically important difference (MCID) and the patient acceptable symptoms state (PASS). These measures have demonstrated clinical value, however, they have often been under- or mis-reported. It is paramount to use them to understand the clinical significance of any statistically significant results. Still, it remains important to know their caveats and limitations. In this focused report on MCID and PASS, their definitions, methods of calculations, clinical relevance, interpretations, and limitations are reviewed and presented in a simple approach.

The patient acceptable symptom state for the knee society score, oxford knee score and short form-36 following unicompartmental knee arthroplasty.

PURPOSE: The patient acceptable symptom state (PASS) is a target value on a patient-reported outcome measures (PROM) scale beyond which patients deem themselves to have attained an acceptable outcome. This study aimed to define the PASS thresholds for generic and knee-specific PROMs at 2 years after unicompartmental knee arthroplasty (UKA). METHODS: Prospectively collected data of 955 patients who underwent UKA for medial osteoarthritis at a single institution was reviewed. Patients were assessed preoperatively and 2 years postoperatively using the Knee Society Knee Score (KSKS), Function Score (KSFS), Oxford Knee Score (OKS), SF-36 Physical Component Score (PCS) and Mental Component Score (MCS). Responses to an anchor question assessing patients' overall rating of treatment results were dichotomized and used to determine if PASS was achieved. PASS thresholds for each PROM were selected based on the Youden index on a receiver operating characteristics (ROC) curve. Sensitivity analyses were performed for different subgroups (by age, gender, BMI), baseline score tertiles and an alternate definition of PASS. RESULTS: In total, 92.7% reported their current state as acceptable. The areas under the curve (AUC) for ROCs were 0.72-0.83, except for the SF-36 PCS (AUC 0.64), indicating good discriminative accuracy of the other PROMs. PASS thresholds were 85.5 for KSKS, 77.5 for KSFS, 41.5 for OKS, 49.9 for SF-36 PCS and 54.6 for SF-36 MCS. Sensitivity analyses revealed that the thresholds were robust. Patients who attained a PASS were at least 4-5 times more likely to be satisfied and have expectations fulfilled. CONCLUSION: PASS thresholds can be used to define treatment success in future outcome studies. At the individual level, they provide clinically relevant benchmarks for surgeons when assessing postoperative recovery. LEVEL OF EVIDENCE: III.

Custom total knee arthroplasty combined with personalised alignment grants 94% patient satisfaction at minimum follow-up of 2 years.

PURPOSE: The purpose was to report detailed patient-reported outcome measures (PROMs) and satisfaction rates for computed tomography (CT)-based custom TKA at minimum follow-up of 2 years. The hypothesis was that custom TKA combined with 'personalised alignment' would yield equivalent or better PROMs compared to values reported in systematic reviews and meta-analyses on off-the-shelf (OTS) TKA. METHODS: Of an initial cohort of 150 custom TKAs, four died (unrelated to surgery), one required a revision, and five refused participation, leaving 140 patients for analysis. Patients completed pre- and post-operative PROMs (Oxford Knee Score (OKS), Forgotten Joint Score (FJS), Knee injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster osteoarthritis index (WOMAC)) as well as overall level of satisfaction. Proportions that attained a patient acceptable symptom state (PASS) were calculated for OKS and FJS. Clinical findings were compared to the average scores reported for PROMs in recent systematic reviews and/or meta-analyses on OTS TKA. Descriptive statistics were used to summarise the clinical findings as means, standard deviations (SD) and ranges, or numbers and percentages. RESULTS: At mean follow-up 33.5 ± 4.5 months, 94% (135/143) were either satisfied or very satisfied. Proportions that achieved PASS were 89% for OKS (120/135), and 85% for FJS (118/139). Median OKS, WOMAC and KOOS Symptoms and Pain scores were all within the 4th quartile of medians reported in systematic reviews and/or meta-analyses. CONCLUSIONS: At a minimum follow-up of two years following custom TKA combined with 'personalised alignment', 94% of patients were either satisfied or very satisfied, and the PASS criteria were achieved in 89% for OKS and 85% for FJS, all of which compare favourably to published outcomes of OTS TKA. Direct comparisons to the literature may not be appropriate, however, considering the heterogeneity of patient demographics and alignment techniques. Randomised controlled trials with sufficient statistical power are needed to corroborate these findings and generalise them to unselected TKA patients. LEVEL OF EVIDENCE: IV, retrospective cohort study.

Patients aged 50-75 years take longer to achieve the patient acceptable symptom state than patients aged 20-34 years following primary hip arthroscopy for femoroacetabular impingement syndrome.

PURPOSE: Though an increasing number of adults older than 50 years are undergoing hip arthroscopy for treatment of Femoroacetabular Impingement Syndrome (FAIS), it is unclear how their timeline for functional outcome improvement compares to that of younger patients. The purpose of this study was to assess the impact of age on time to achieving the Minimum Clinically Important Difference (MCID), Substantial Clinical Benefit (SCB), and Patient Acceptable Symptom State (PASS) following primary hip arthroscopy for FAIS. METHODS: A retrospective comparative single-surgeon cohort study of primary hip arthroscopy patients with minimum 2-year follow-up was conducted. Age categories were 20-34 years, 35-49 years, and 50-75 years. All subjects completed the modified Harris Hip Score (mHHS) prior to surgery and at 6-month, 1-year, and 2-year follow-up. MCID and SCB cutoffs were defined as pre-to-postoperative increases in mHHS by ≥ 8.2 and ≥ 19.8, respectively. PASS cutoff was set at postoperative mHHS ≥ 74. Time to achievement of each milestone was compared using interval-censored survival analysis. The effect of age was adjusted for Body Mass Index (BMI), sex, and labral repair technique using an interval-censored proportional hazards model. RESULTS: Two hundred eighty-five patients were included in the analysis with 115 (40.4%) aged 20-34 years, 92 (32.3%) aged 35-49 years, and 78 (27.4%) aged 50-75 years. There were no significant differences between groups in time to achievement for the MCID (n.s.) or SCB (n.s.). However, patients in the oldest group had significantly longer time to PASS than those in the youngest group, both in the unadjusted analysis (p = 0.02) and after adjusting for BMI, sex, and labral repair technique (HR 0.68, 95% CI 0.48-0.96, p = 0.03). CONCLUSION: Achievement of the PASS, but not the MCID or SCB, is delayed among FAIS patients aged 50-75 years who undergo primary hip arthroscopy compared to those aged 20-34 years. Older FAIS patients should be counseled appropriately about their longer timeline to achieving hip function comparable to their younger counterparts. LEVEL OF EVIDENCE: III.

Identifying Aseptic Revision Total Knee Arthroplasty Diagnoses That Achieve Minimal Clinically Important Difference and Patient Acceptable Symptom State.

BACKGROUND: Minimal clinically important difference (MCID) defines a meaningful clinical change in patient-reported outcome measures. Patient acceptable symptom state (PASS) provides a patient-reported outcome measures threshold value to indicate a satisfactory clinical state. MCID and PASS for revision total knee arthroplasty (rTKA) are ill-defined. Moreover, it is unknown whether diagnosis influences the likelihood of achieving MCID or PASS. The purpose of this study was to calculate MCID for aseptic rTKA and compare the percentage of patients achieving MCID and PASS per diagnosis. METHODS: An institutional registry of rTKA was used. First-time aseptic rTKA were included. Demographics, revision diagnosis, preoperative Knee Injury and Osteoarthritis Outcome Score, Jr (KOOS Jr), and 1-year postoperative KOOS Jr were recorded. The 1-year postoperative KOOS Jr PASS score was available. MCID was calculated using distribution-based methods. Three hundred fifty eight first-time aseptic rTKAs were analyzed. The 3 most common diagnoses were aseptic loosening (n = 156), instability (n = 109), and stiffness (n = 37). RESULTS: The mean KOOS Jr 1-year postoperative MCID for rTKA was 10.3. Overall, 75.4% achieved MCID and 56.9% achieved PASS. The percentage of patients per diagnosis achieving MCID and PASS, respectively, were periprosthetic fracture (100, 44), aseptic loosening (94, 60), implant fracture (88, 63), stiffness (60, 38), instability (59, 61), polyethylene wear/osteolysis (57, 57), and metal allergy (44, 33). CONCLUSION: Aseptic rTKA MCID is 10.3 for KOOS Jr at 1 year postoperatively. rTKA outcomes vary depending on preoperative diagnosis. Even in diagnoses with a high proportion of MCID achieved, less than 2/3 of patients achieved PASS, suggesting rTKA provides noticeable improvement but may not return patients to a satisfactory state.

Metrics of Clinically Important Changes in Total Hip Arthroplasty: A Systematic Review.

BACKGROUND: Although patient-reported outcome measures (PROMs) have become a regularly used metric, there is little consensus on the methodology used to determine clinically relevant postoperative outcomes. We systematically reviewed the literature for studies that have identified metrics of clinical efficacy after total hip arthroplasty (THA) including minimal clinically important difference (MCID), patient acceptable symptom state (PASS), minimal detectable change (MDC), and substantial clinical benefit (SCB). METHODS: A systematic review examining quantitative metrics for assessing clinical improvement with PROMs following THA was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the MEDLINE database from 2008 to 2020. Inclusion criteria included full texts, English language, primary THA with minimum 1-year follow-up, use of metrics for assessing clinical outcomes with PROMs, and primary derivations of those metrics. Sixteen studies (24,487 THA patients) met inclusion criteria and 11 different PROMs were reported. RESULTS: MCIDs were calculated using distribution methods in 7 studies (44%), anchor methods in 2 studies (13%), and both methods in 2 studies (13%). MDC was calculated in 2 studies, PASS was reported in 1 study using anchor-based method, and SCB was calculated in 1 study using anchor-based method. CONCLUSION: There is a lack of consistency in the literature regarding the use and interpretation of PROMs to assess patient satisfaction. MCID was the most frequently reported measure, while MDC, SCB, and PASS were used relatively infrequently. Method of derivation varied based on the PROM used; distribution method was more frequently used for MCID.