Gender Differences in Pain, Function, and Quality of Life Five Years Following Primary Total Knee Arthroplasty.

BACKGROUND: Multiple authors have sought to determine what patient characteristics influence outcomes after total knee arthroplasty (TKA). The impact of gender on outcomes after TKA remains controversial. Previous studies had less than 5 years of follow-up after TKA. The aim of this evaluation was to determine what differences in pain, function, and quality of life (QoL) exist between female and male patients 5 years after primary TKA. METHODS: A prospective, multicenter cohort of 11,602 unilateral primary TKA patients (7,284 females and 4,318 males) was prospectively evaluated. All patients were enrolled in the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement. Demographic data, musculoskeletal and medical comorbid conditions, and patient-reported outcome measures, including the Knee Injury and Osteoarthritis Outcome (KOOS) and Short-Form (36-item) Health Survey mental component score (MCS) and physical component score (PCS) were collected preoperatively and at 5 years after TKA. Descriptive statistics were generated, and stratified by gender, and differences in pain, function, and QoL between female and male patients were evaluated. Multivariate regression models with a 95% confidence interval (CI) were used to assess the role of patient gender as a predictive factor for KOOS pain and function in daily living (ADL) scores reported 5 years after primary TKA, while adjusting for other variables. RESULTS: Prior to surgery, female patients reported worse pain (KOOS pain 46 versus 52), function (KOOS ADL 53 versus 59), and QoL (KOOS QoL 26 versus 29) than male patients. The differences in preoperative scores ranged from 2.70 (KOOS QoL) to 6.12 (KOOS ADL). At 5 years after TKA, female patients reported slightly worse pain (87 versus 89), function (85 versus 87), and QoL (74 versus 75) when compared to male patients. The differences in the mean 5-year postoperative KOOS scores (range, 0.99 to 2.73), although statistically significant (P < .001), were clinically negligible. Female patients achieved greater improvement in pain (41 versus 37), function (32 versus 29), and QoL (48 versus 46) scores in comparison to male patients. Female patients also reported lower preoperative PCS global function (33 versus 35) scores, 5-year postoperative PCS scores (45 versus 46), and MCS global mental function scores (52 versus 54). Similarly, the differences in the 5-year postoperative Short-Form (36-item) Health Survey MCS and PCS scores were clinically negligible. Multivariate regression analysis showed that female gender was not independently predictive for either pain (ß = -1.08; 95% CI [-1.25 to 1.03] [P = .85]) or function (ß = 0.64; 95% CI [-0.51 to 1.79] [P = .28]) 5 years after surgery. CONCLUSIONS: There are no clinically significant gender differences in pain, function, or QoL 5 years after TKA. Female patients typically have worse symptoms prior to surgery, improve more than male patients, and end up with pain, function, and QoL scores clinically equal to male patients. These data can enhance the shared decision-making process between female patients and surgeons and assist in setting appropriate patient expectations prior to TKA.

Predictive Factors of Pain and Functional Outcome 5 Years Following Total Hip Arthroplasty: A Prospective Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement Cohort Study.

BACKGROUND: Previous reports have identified a number of potential predictors of pain and function after total hip arthroplasty (THA). However, the results of these studies were conflicting, and most had a short follow-up after THA. The purpose of this study was to identify factors predictive of pain and function 5 years after THA. METHODS: A multicenter cohort of 7,934 primary unilateral THA patients was prospectively enrolled in the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement consortium. Demographic data, comorbidities, and patient-reported outcome measures were collected preoperatively and postoperatively at 5 years, including the Hip Disability and OSteoarthritis Outcome Score (HOOS) pain and activities of daily living (ADL) scores. Multivariate logistic regression models with 95% confidence interval were used to identify independent predictors of pain and function at 5 years. RESULTS: The patient dissatisfaction percentage was 8.2% at 5 years after THA. The multivariate regression identified the following predictive factors for the HOOS pain score at 5 years: age, educational level, insurance, smoking, race, Charlson Comorbidity Index, back pain severity, number of other lower extremity painful joints, the Knee Injury and Osteoarthritis Outcome Score pain severity of the ipsilateral knee, preoperative Short-Form Health Survey 36-item (SF-36) mental component summary score, and HOOS pain scores. The multivariate regression identified the following predictor factors for HOOS ADL score at 5 years: body mass index, insurance, smoking, race, back pain severity, number of other lower extremity painful joints, Knee Injury and Osteoarthritis Outcome Score pain severity of ipsilateral knee, preop HOOS ADL, and preoperative SF-36 mental component summary score and SF-36 physical component summary score. CONCLUSIONS: Overall, 8.2% of patients were dissatisfied 5 years after primary THA. We have identified a number of factors that predict less improvement in pain and function 5 years after THA. These potentially modifiable factors can be targeted with preoperative patient optimization programs to improve patient outcomes and satisfaction after primary THA. Knowledge of these factors that predict less improvement in pain and function can assist the surgeon and patient during shared decision-making, and in setting appropriate patient expectations preoperatively.

Strengthening Quality Measurement to Predict Success for Total Knee Arthroplasty: Results from a Nationally Representative Total Knee Arthroplasty Cohort.

BACKGROUND: When performed well on appropriate patients, total knee arthroplasty (TKA) can dramatically improve quality of life. Patient-reported outcome measures (PROMs) are increasingly used to measure outcome following TKA. Accurate prediction of improvement in PROMs after TKA potentially plays an important role in judging the surgical quality of the health-care institutions as well as informing preoperative shared decision-making. Starting in 2027, the U.S. Centers for Medicare & Medicaid Services (CMS) will begin mandating PROM reporting to assess the quality of TKAs. METHODS: Using data from a national cohort of patients undergoing primary unilateral TKA, we developed an original model that closely followed a CMS-proposed measure to predict success, defined as achieving substantial clinical benefit, specifically at least a 20-point improvement on the Knee injury and Osteoarthritis Outcome Score, Joint Arthroplasty (KOOS, JR) at 1 year, and an enhanced model with just 1 additional predictor: the baseline KOOS, JR. We evaluated each model's performance using the area under the receiver operator characteristic curve (AUC) and the ratio of observed to expected (model-predicted) outcomes (O:E ratio). RESULTS: We studied 5,958 patients with a mean age of 67 years; 63% were women, 93% were White, and 87% were overweight or obese. Adding the baseline KOOS, JR improved the AUC from 0.58 to 0.73. Ninety-four percent of those in the top decile of predicted probability of success under the enhanced model achieved success, compared with 34% in its bottom decile. Analogous numbers for the original model were less discriminating: 77% compared with 57%. Only the enhanced model predicted success accurately across the spectrum of baseline scores. The findings were virtually identical when we replicated these analyses on only patients ≥65 years of age. CONCLUSIONS: Adding a baseline knee-specific PROM score to a quality measurement model in a nationally representative cohort dramatically improved its predictive power, eliminating ceiling and floor effects and mispredictions for readily identifiable patient subgroups. The enhanced model neither favors nor discourages care for those with greater knee dysfunction and requires no new data collection. LEVEL OF EVIDENCE: Prognostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Enhancing phase I dose-finding trials design through dynamic borrowing information and handling late-onset toxicity.

Introduction: In recent years, there has been a growing trend among regulatory agencies to consider the use of historical controls in clinical trials as a means of improving the efficiency of trial design. In this paper, to enhance the statistical operating characteristic of Phase I dose-finding trials, we propose a novel model-assisted design method named "MEM-Keyboard". Methods: The proposed design is based on the multisource exchangeability models (MEMs) that allows for dynamic borrowing of information from multiple supplemental data sources, including historical trial data, to inform the dose-escalation process. Furthermore, with the frequent occurrence of delayed toxicity in novel anti-cancer drugs, we extended our proposed method to handle late-onset toxicity by incorporating historical data. This extended method is referred to as "MEM-TITE-Keyboard" and aims to improve the efficiency of early clinical trials. Results: Simulation studies have indicated that the proposed methods can improve the probability of correctly selecting the maximum tolerated dose (MTD) with an acceptable level of risk, compared to designs that do not account for information borrowing and late-onset toxicity. Discussion: The MEM-Keyboard and MEM-TITE-Keyboard, easy to implement in practice, provide a useful tool for identifying MTD and accelerating drug development.

Selective CO2 reduction to CH3OH over atomic dual-metal sites embedded in a metal-organic framework with high-energy radiation.

The efficient use of renewable X/γ-rays or accelerated electrons for chemical transformation of CO2 and water to fuels holds promise for a carbon-neutral economy; however, such processes are challenging to implement and require the assistance of catalysts capable of sensitizing secondary electron scattering and providing active metal sites to bind intermediates. Here we show atomic Cu-Ni dual-metal sites embedded in a metal-organic framework enable efficient and selective CH3OH production (~98%) over multiple irradiated cycles. The usage of practical electron-beam irradiation (200 keV; 40 kGy min-1) with a cost-effective hydroxyl radical scavenger promotes CH3OH production rate to 0.27 mmol g-1 min-1. Moreover, time-resolved experiments with calculations reveal the direct generation of CO2•‒ radical anions via aqueous electrons attachment occurred on nanosecond timescale, and cascade hydrogenation steps. Our study highlights a radiolytic route to produce CH3OH with CO2 feedstock and introduces a desirable atomic structure to improve performance.

Age-Related Differences in Pain, Function, and Quality of Life Following Primary Total Knee Arthroplasty: Results From a FORCE-TJR (Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement) Cohort.

BACKGROUND: The impact of age on patient outcomes after total knee arthroplasty (TKA) remains controversial. Age has shown no effect on outcome in some studies, while others have reported better or worse outcome in younger patients. The aims of this study were to determine the differences in pain, function, and quality of life (QoL) reported 1 year after TKA across different age groups. METHODS: A prospective, multicenter cohort of 11,602 unilateral primary TKA patients was evaluated. Demographic data, comorbid conditions, and patient-reported outcome measures including the knee injury and osteoarthritis outcome score (KOOS), KOOS-12, KOOS Joint Replacement, and Short-Form health survey (12-item) were collected preoperatively and at 1-year postoperatively. Descriptive statistics were generated, stratified by age [<55 years (younger adult), 55 to 64 years (older adult), 65 to 74 years (early elder), and ≥ 75 years (late elder)], and differences in pain, function, and QoL among the 4 age groups were evaluated using Chi-square and Kruskal-Wallis tests. Multivariate regression models with 95% confidence interval were performed to determine if age was predictive for KOOS pain and function scores. RESULTS: Prior to surgery, younger patients (<55 years) reported worse KOOS pain (39), function (50), and QoL (18) scores with poor mental health score (47) than other older patient groups. The mean preoperative score differences across the age groups in the KOOS total score (9.37), KOOS pain (11.61), KOOS-12 pain (10.14), and KOOS/KOOS-12 QoL (12.60) reached the calculated minimal clinically important difference. At 1 year after TKA, younger patients (<55 years) reported lower KOOS pain, function, and QoL scores when compared to older patients (≥ 75 years). The differences in 1-year postop scores among the 4 age groups (ranging from 4.0 to 12.2) reached the minimal clinically important difference for pain (10.4) and QoL (12.2). Younger patients (<55 years) achieved higher baseline to 1-year pain (36.8 points), function (30.3 points), and QoL (40.7 points) score changes when compared to older patients aged ≥ 75 years. Although statistically significant, the differences in score changes among the age groups were clinically irrelevant. The multivariate regression analyses showed that age was a significant predictor for pain, but not for function at 1 year where KOOS pain score was predicted to be higher (less pain) (ß = 6.17; 95% confidence interval 4.12- 8.22) (P < .001) in older patients (≥ 75 years) when compared to younger patients (<55 years). CONCLUSION: A TKA provides a dramatic improvement in pain, function, and QoL in all age groups. However, there are age-related clinically significant differences in preoperative pain, QoL, and mental health and in final postoperative pain and QoL scores with younger patients (<55 years) reporting more pain, less QoL, and worse preoperative mental health. The patient-reported outcome measure data presented here can be used clinically to improve shared decision-making and patient expectations prior to TKA.

How Back Pain Affects Patient Satisfaction After Primary Total Knee Arthroplasty.

BACKGROUND: Although back pain (BP) has been shown to be a predictor of dissatisfaction after total knee arthroplasty (TKA) in some reports, these studies did not use a scale to quantify the degree of pain. The purpose of this study was to quantify the effect of BP intensity on patient satisfaction reported at 1 year after TKA. METHODS: A multicenter prospective cohort was taken in which 9,057 patients undergoing primary unilateral TKA were enrolled in FORCE-TJR and demographic and clinical data were collected. Back pain (BP) intensity was assessed using the Oswestry back disability index (ODI) pain intensity questionnaire. Patients were classified into 4 categories based on the severity of BP. Patient-reported outcomes (PROs) were collected preoperatively and postoperatively after 1 year including the Knee injury and Osteoarthritis Outcome Score (KOOS) (total score, pain, Activities of Daily Living (ADL), and Quality of Life (QOL), Short-Form health survey 36-item (SF-36) Physical Component Score (PCS), and Mental Component Score (MCS)). We used a validated 5-point Likert satisfaction scale. Univariate analyses of the difference between the satisfied and dissatisfied patients' groups was performed. Multivariate logistic regression models with 95% confidence interval (CI) were used to quantify the effect of BP intensity on patient dissatisfaction at 1 year. Receiver operating characteristic (ROC) analyses were performed with measurement of area under curve (AUC). RESULTS: At 1 year, a total of 1,657 TKA patients (18.3%) were dissatisfied. A total of 4,765 patients (52.6%) reported back pain at the time of surgery, including mild BP in 2,264 patients (24.9%), moderate BP in 1,844 patients (20.3%), and severe BP in 657 patients (7.2%). Severe back pain was significantly associated with patient dissatisfaction at 1 year after TKA (P = .0006). The multivariate regressions showed that patients who had severe BP were 1.6 times more likely to be dissatisfied when compared to patients who had no BP [odds ratio (OR) 1.63; 95% confidence interval (CI) (1.23-2.16), P = .0006]. While patients who had mild BP [OR 0.98; 95% CI (0.82-1.17), P = .87] or moderate BP [OR 0.97; 95% CI (0.80-1.18), P = .78] were not associated with an increased likelihood of dissatisfaction. Other predictive variables for dissatisfaction, include age [OR for younger patients <65 years versus older patients ≥65 years, 0.74; 95% CI (0.59-0.92)], educational level [OR for post high school versus less, 0.83; 95% CI (0.71, 0.97)], smoking [OR for nonsmoker versus current smoker, 0.63; 95% CI (0.45, 0.87)], and Charlson comorbidity index [OR for CCI ≥2 versus 0, 1.25; 95% CI (1.05, 1.49)]. CONCLUSION: Increased BP intensity was associated with increased risk of dissatisfaction 1 year after TKA. Only patients who had severe BP were 1.6 times more likely to be dissatisfied. The data presented here can help to improve shared decision-making and patient counseling before surgery. Surgeons should consider a spine evaluation in patients who have severe BP prior to TKA.

Metabolism-associated molecular classification of gastric adenocarcinoma.

Most gastric cancers (GC) are adenocarcinomas, whereas GC is a highly heterogeneous disease due to its molecular heterogeneity. However, traditional morphology-based classification systems, including the WHO classification and Lauren's classification, have limited utility in guiding clinical treatment. We performed nonnegative matrix factorization (NMF) clustering based on 2752 metabolism-associated genes. We characterized each of the subclasses from multiple angles, including subclass-associated metabolism signatures, immune cell infiltration, clinic10al characteristics, drug sensitivity, and pathway enrichment. As a result, four subtypes were identified: immune suppressed, metabolic, mesenchymal/immune exhausted and hypermutated. The subtypes exhibited significant prognostic differences, which suggests that the metabolism-related classification has clinical significance. Metabolic and hypermutated subtypes have better overall survival, and the hypermutated subtype is likely to be sensitive to anti-PD-1 immunotherapy. In addition, our work showed a strong connection with previously established classifications, especially Lei's subtype, to which we provided an interpretation based on the immune cell infiltration perspective, deepening the understanding of GC heterogeneity. Finally, a 120-gene classifier was generated to determine the GC classification, and a 10-gene prognostic model was developed for survival time prediction.

Do Patient Outcomes Vary by Patient Age Following Primary Total Hip Arthroplasty?

BACKGROUND: Multiple authors have sought to determine what patient characteristics influence outcome after total hip arthroplasty (THA). Age has shown no effect on outcome in some evaluations, while others have reported higher functional improvement in younger patients. The aim of this study was to determine if outcome after THA varies based on patient age. METHODS: A prospective, multicenter cohort of 7,934 unilateral primary THA patients from the FORCE-TJR comparative effectiveness consortium was evaluated. Demographic data, comorbid conditions, and Patient-Reported Outcome Measures, including (HOOS), HOOS-12, HOOS JR, and SF-36 (PCS) and (MCS), were collected preop and at 1-year postop. Descriptive statistics were generated, stratified by age (<55 years [younger adult], 55-64 years [older adult], 65-74 years [early elder], and ≥75 years [late elder]), and differences in pain, function, and quality of life among the 4 age groups were evaluated. A multivariate regression model with 95% confidence interval (CI) was used to assess the role of patient age as a predictive factor for HOOS pain and function scores reported 1 year after primary THA. RESULTS: Prior to surgery, younger patients (<55 years) reported worse pain, function, and quality of life than the other 3 patient groups. At 1 year after THA, younger patients (<55 years) reported slightly worse pain and quality of life but better function scores than the 3 older patients' groups. Younger patients (<55 years) achieved higher baseline to 1-year pain, and function score changes when compared to the older patients' groups. The quality of life score changes was not different among the 4 age groups. The differences in 1-year postop scores (ranging from 2.74 to 8.46) and the magnitude of score changes from baseline to 1 year (ranging from 1.9 to 5.85), although statistically significant (P < .001), did not reach the minimal clinically important difference (MCID). The multivariate regression analysis shows that age is a significant predictor for pain at 1 year but not for function. Although HOOS pain score is predicted to be higher by 4.38 points (less pain) 1 year after THA in older patients (≥75), when compared to younger patients (<55 years), again the difference is well below the MCID and is clinically insignificant. CONCLUSION: Although there are statistically significant differences in pain relief, functional improvement, and quality of life between younger and older patients among different patients' age groups, there is no clinically significant difference. THA provides an improvement in quality of life by decreasing pain and increasing function in all 4 age groups, with large improvements in Patient-Reported Outcome Measures scores (>2 standard deviations) without clinically significant age-related differences in THA outcome at 1 year.

The Prevalence and Predictors of Patient Dissatisfaction 5-years Following Primary Total Knee Arthroplasty.

BACKGROUND: Previous studies have evaluated patient dissatisfaction after total knee arthroplasty (TKA) at 1 year, but there is no data about the prevalence of dissatisfaction among TKA patients after prolonged follow-up. The purpose of this study is to determine patient dissatisfaction 5-years after TKA and to identify patient factors predictive of dissatisfaction. METHODS: Demographic and clinical data on 4402 patients undergoing primary unilateral TKA between 2012 and 2015 were collected prospectively through the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) comparative effectiveness consortium including diverse community and academic practices distributed across 23 states in the United States. Data collected at 1 year preoperatively and 5 years postoperatively included patient satisfaction (using a 5-point Likert satisfaction scale) and patient-reported outcome measures (PROMs) including the Knee injury and Osteoarthritis Outcome Score (KOOS) and Short-Form health survey (36-item). A univariate analysis of the difference between the satisfied and dissatisfied patients' groups was performed. A multivariate logistic regression model with 95% confidence interval (CI) was used to identify independent predictors of dissatisfaction at 5 years. The regression model was performed after adjusting the following variables: age, gender, body mass index (BMI), Charlson Comorbidity Index (CCI), marital status, smoking, education, and insurance type. The Receiver Operating Characteristic (ROC) analysis was performed with the measurement of area under curve (AUC). Hosmer-Lemeshow goodness of fit test was performed to evaluate the validity of the model. RESULTS: A total of 12.7% patients (559/4402) reported dissatisfaction 5-years after TKA. Increased BMI, higher CCI, higher Oswestry disability index, and increased number of other painful lower extremities (LE) joints were significantly associated with dissatisfaction. Higher rates of dissatisfaction were present in young patients, patients with less education, and non-White patients. Patient dissatisfaction was significantly associated with poor preoperative and 5-year postoperative PROMs scores and less score improvement from baseline to 5 years (P < .001). The multivariate regression analysis showed that an increased number of other painful LE joints (OR = 1.81; 95% CI (1.14-2.88) (P = .01), increased Oswestry back disability index (OR = 1.40; 95% CI (1.07-1.82) (P = .01), non-White patients (OR = 1.74; 95% CI (1.26-2.40) (P = .001), and minimal preoperative functional disability with KOOS function in daily living (ADL) score ≥70 (OR = 0.64; 95% CI (0.43-0.95) (P = .02) were independent predictive factors for dissatisfaction at 5 years. CONCLUSION: A total of 12.7% patients reported dissatisfaction 5-years after TKA. Clinical profiles of the satisfied and dissatisfied patients were captured 5-years after TKA with differences in the preoperative demographic and clinical characteristic variables identified. Risk factors for long-term patient dissatisfaction after TKA have been identified and should be considered during shared decision making while planning for TKA. Surgeons should use these identified risk factors to set realistic expectations for patients at an increased risk for dissatisfaction aiming to optimize their outcomes and increase their long-term satisfaction after TKA.

Association of Early Postoperative Pain Trajectories With Longer-term Pain Outcome After Primary Total Knee Arthroplasty.

Importance: Studies to date have not comprehensively examined pain experience after total knee arthroplasty (TKA). Discrete patterns of pain in this period might be associated with pain outcomes at 6 to 12 months after TKA. Objectives: To examine patterns of individual post-TKA pain trajectories and to assess their independent associations with longer-term pain outcome after TKA. Design, Setting, and Participants: This prospective cohort study combined data from a national US TKA cohort with ancillary pain severity data at 2 weeks and 8 weeks after the index TKA using a numeric rating scale. All participants received primary, unilateral TKA within the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) national network of community sites in 22 states or at the lead site (University of Massachusetts Medical School). Participants had a date of surgery between May 1, 2013, and December 1, 2014. The data analysis was performed between January 13, 2015, and July 5, 2016. Exposures: Pain trajectories in the postoperative period (8 weeks). Main Outcomes and Measures: Index knee pain at 6 months after TKA using the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain scale. Group-based trajectory methods examined the presence of pain trajectories in the postoperative period (8 weeks) and assessed whether trajectories were independently associated with longer-term pain (6 months). Results: The cohort included 659 patients who underwent primary TKA with complete data at 4 points (preoperative, 2 weeks, 8 weeks, and 26 weeks). Their mean (SD) age was 67.1 (8.0) years, 64.5% (425 of 659) were female, the mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) was 30.77 (5.66), 94.5% (613 of 649) were white, and the mean (SD) preoperative 36-Item Short Form Health Survey physical component summary and mental component summary scores were 34.1 (8.2) and 53.8 (11.4), respectively. Two pain trajectory subgroups were identified at 8 weeks after TKA: patients who experienced fast pain relief in the first 8 weeks after TKA (fast pain responders, composing 72.4% [477 of 659] of the sample) and patients who did not (slow pain responders, composing 27.6% [182 of 659] of the sample). After adjusting for patient factors, the pain trajectory at 8 weeks after TKA was independently associated with the mean KOOS pain score at 6 months, with a between-trajectory difference of -11.3 (95% CI, -13.9 to -8.7). Conclusions and Relevance: The trajectory among slow pain responders at 8 weeks after surgery was independently associated with improved but greater persistent index knee pain at 6 months after TKA compared with that among fast pain responders. Early identification of patients with a trajectory of slow pain response at 8 weeks after TKA may offer an opportunity for interventions in the perioperative period to potentially improve the long-term pain outcomes after TKA.

A Web-Based Treatment Decision Support Tool for Patients With Advanced Knee Arthritis: Evaluation of User Interface and Content Design.

BACKGROUND: Data-driven surgical decisions will ensure proper use and timing of surgical care. We developed a Web-based patient-centered treatment decision and assessment tool to guide treatment decisions among patients with advanced knee osteoarthritis who are considering total knee replacement surgery. OBJECTIVE: The aim of this study was to examine user experience and acceptance of the Web-based treatment decision support tool among older adults. METHODS: User-centered formative and summative evaluations were conducted for the tool. A sample of 28 patients who were considering total knee replacement participated in the study. Participants' responses to the user interface design, the clarity of information, as well as usefulness, satisfaction, and acceptance of the tool were collected through qualitative (ie, individual patient interviews) and quantitative (ie, standardized Computer System Usability Questionnaire) methods. RESULTS: Participants were older adults with a mean age of 63 (SD 11) years. Three-quarters of them had no technical questions using the tool. User interface design recommendations included larger fonts, bigger buttons, less colors, simpler navigation without extra "next page" click, less mouse movement, and clearer illustrations with simple graphs. Color-coded bar charts and outcome-specific graphs with positive action were easiest for them to understand the outcomes data. Questionnaire data revealed high satisfaction with the tool usefulness and interface quality, and also showed ease of use of the tool, regardless of age or educational status. CONCLUSIONS: We evaluated the usability of a patient-centered decision support tool designed for advanced knee arthritis patients to facilitate their knee osteoarthritis treatment decision making. The lessons learned can inform other decision support tools to improve interface and content design for older patients' use.