Mental health in paediatric and adult myositis-related diseases: current state of research, interventions, and future steps from the MIHRA Psychological Impact Scientific Working Group.

Psychological and emotional well-being are critical aspects of overall health for individuals with chronic rheumatologic conditions. Mental health-related literature, however, predominantly focuses on systemic lupus erythematosus or rheumatoid arthritis, with limited emphasis on idiopathic inflammatory myopathies (IIMs). High proportions of those with juvenile myositis report psychological distress at levels warranting mental health referral. Adults with dermatomyositis diagnosed with depression or anxiety do not receive adequate mental health care. Mental health symptoms in those with IIMs are associated with worse health-related quality of life, medication adherence, and disease outcomes. Despite demonstrated high rates of mental health burden, access to mental health care remains severely lacking.Data related to mental health burden is limited by small sample size, limited generalisability, variable methods of assessment, and inconsistent diagnosis codes to define mental health conditions. Additional research is needed to validate current screening tools in myositis populations. Other relevant measurable factors include disease severity, non-health- and health-related trauma exposure, loneliness, isolation, loss of control, sleep difficulties, fatigue, pain, self-esteem, body image, sexual health, and health inequities. Studiesare needed investigating the efficacy of therapeutic and pharmacologic interventions among patients with myositis who experience depression and anxiety. Currently, knowledge and resources are limited around mental health burden and potential intervention for those living with IIMs. The Myositis International Health & Research Collaborative Alliance (MIHRA) Psychological Impact Scientific Working Group offers a preliminary road map to characterise and prioritise the work ahead to understand baseline mental health burden and compare avenues for intervention.

Collaborative research in myositis-related disorders: MIHRA, a global shared community model.

Myositis International Health and Research Collaborative Alliance (MIHRA) is a newly formed purpose-built non-profit charitable research organization dedicated to accelerating international clinical trial readiness, global professional and lay education, career development and rare disease advocacy in IIM-related disorders. In its long form, the name expresses the community's scope of engagement and intent. In its abbreviation, MIHRA, conveys linguistic roots across many languages, that reflects the IIM community's spirit with meanings such as kindness, community, goodness, and peace. MIHRA unites the global multi-disciplinary community of adult and pediatric healthcare professionals, researchers, patient advisors and networks focused on conducting research in and providing care for pediatric and adult IIM-related disorders to ultimately find a cure. MIHRA serves as a resourced platform for collaborative efforts in investigator-initiated projects, consensus guidelines for IIM assessment and treatment, and IIM-specific career development through connecting research networks.MIHRA's infrastructure, mission, programming and operations are designed to address challenges unique to rare disease communities and aspires to contribute toward transformative models of rare disease research such as global expansion and inclusivity, utilization of community resources, streamlining ethics and data-sharing policies to facilitate collaborative research. Herein, summarises MIHRA operational cores, missions, vision, programming and provision of community resources to sustain, accelerate and grow global collaborative research in myositis-related disorders.

Comparing the hta core model with a national health technology assessment report.

OBJECTIVES: The HTA Core Model is a framework for producing health technology assessments (HTAs) in a structured format. The Model splits the content of a HTA into assessment elements. The objective is to explore the adaptability of these assessment elements in national report production in a pilot case study comparing a national HTA report and the HTA Core Model. METHODS: An on-going Dutch HTA report on endovascular repair of abdominal aortic aneurysm (EVAR) was chosen as a typical representative of a national report on medical interventions. The author of the EVAR report assessed the relevance and comprehensiveness of the assessment elements of the HTA Core Model for her work. Another researcher annotated the Core Model specific content in the EVAR report. Matching and missing content, as well as the distribution of information in the EVAR report were tabulated and analysed in joint deliberations. RESULTS: Forty percent of the assessment elements of the Core Model were considered relevant for the EVAR report. Some issues relevant for EVAR but missing from the Core Model were identified: they were about re-interventions, secondary prevention, subpopulations that benefit most, and the length of the hospital stay. The distribution of information differed substantially between the Code Model and the national report. CONCLUSIONS: The assessment elements of the HTA Core Model covered most relevant questions of the national report. In order to facilitate easy adaptation of information, the distribution of information should be more consistent in the national report and the Core model.

Patient-Reported Outcome Measures in Neuromuscular Diseases: A Scoping Review.

 Patient-reported outcome measures (PROMs) are valuable in comprehensively understanding patients' health experiences and informing healthcare decisions in research and clinical care without clinicians' input. Until now, no central resource containing information on all PROMS in neuromuscular diseases (NMD) is available, hindering the comparison and choice of PROMs used to monitor NMDs and appropriately reflect the patient's voice. This scoping review aimed to present a comprehensive assessment of the existing literature on using PROMs in children and adults with NMD. A scoping methodology was followed using Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidelines to assess the literature on PROMs in NMDs. Eligibility criteria encompassed articles describing psychometric development or evaluation of generic or disease-specific PROM-based instruments for adults and children with specific NMDs. The data charting process involved extracting measurement properties of included PROMs, comprising validity, reliability, responsiveness, and interpretability information. The review identified 190 PROMs evaluated across 247 studies in individuals with NMDs. The majority of PROMs were disease specific. The physical functioning domain was most assessed. Validity was the most frequently investigated measurement property, with a limited number of PROMs sufficiently evaluated for a range of psychometric characteristics. There is a strong need for further research on the responsiveness and interpretability of PROMs and the development of PROMs on social functioning in NMD.

The impact of pain on daily activities in patients with idiopathic inflammatory myopathies: Report from the OMERACT myositis working group.

BACKGROUND: International focus groups with patients with idiopathic inflammatory myopathies (IIM) conducted by the OMERACT Myositis Working Group over the years demonstrated the pain as an important symptom experienced by these patients. In this study, we aimed to examine the frequency and degree of pain interference, the aspects of daily life impacted by pain, and the factors associated with pain interference in adults with IIM. METHODS: This was a prospective observational study with two visits. The patients who fulfilled the probable/definite IIM (ACR/EULAR Myositis Classification Criteria) were enrolled. Pain interference was assessed with PROMIS pain interference form (6a). Myositis core set measures and PROMIS fatigue (7a) and physical function (8b) were obtained at both visits. Logistic regression and linear mixed models were performed to assess the association between pain interference and other parameters. RESULTS: A total of 129 patients with IIM (60 % females) were recruited from U.S., South Korea, Netherlands, Sweden, and Australia. Approximately 71 % reported pain interference. The patients in the greater pain interference group were more likely to be female, had significantly worse patient/physician global disease activity, fatigue, and physical function than those in the lower pain interference group. The most commonly impacted life aspect was household chores. Manual muscle testing, patient/physician global disease activity, fatigue, and physical function were all significantly associated with pain interference score >60. CONCLUSION: The majority of the patients with IIM experience the impact of pain on their daily activities, particularly household chores. Myositis disease activity, duration, and subtype could be associated with greater pain interference.

Patient outcomes in longitudinal observational studies (POLOS) of rheumatoid arthritis: Determining the OMERACT core domain set.

OBJECTIVE: To define and select rheumatoid arthritis (RA)-specific core domain set for Longitudinal Observational Studies (LOS) within the Outcome Measures in Rheumatology (OMERACT) framework. METHODS: A three-round online Delphi exercise, including patient research partners (PRPs) and other community partners in healthcare, was conducted. Domains scored 7-9 (i.e., critically important to include) by ≥ 70 % of participants in both groups were included. Items were consolidated in a subsequent dedicated meeting. RESULTS: Nineteen domains scored ≥ 70 % consensus in both groups. The focus group refined these into a list of twelve domains. CONCLUSION: The achieved consensus will inform the next steps of developing the core domain set for LOS in RA.

Difference in quality of life, fatigue and societal participation between living and deceased donor kidney transplant recipients.

Purpose of this study was to assess whether living (LD) and deceased donor (DD) kidney transplant recipients differ in health-related quality of life (HRQoL), fatigue and societal participation, depending on time since transplantation and after adjustment for clinical and demographic variables. A questionnaire study was performed among 309 LD and 226 DD recipients (response rate 74% and 61%) transplanted between 1997 and 2009. After adjustment for age, sex, and education, LD recipients transplanted less than or equal to five yr ago experienced better HRQoL than DD recipients on the domains' role limitations due to physical problems, general health perception, and on the physical component summary score (all p < 0.05) and a better societal participation (all subscales, p < 0.05). No differences were found in the mental health domains. The LD recipients also had better renal clearance than DD recipients (62.1 vs. 55.9 mL/min, p = 0.01). After additional adjustment for renal clearance, the differences in HRQoL and societal participation between LD and DD recipients remained. No differences were found in recipients transplanted more than five yr ago. We conclude that LD recipients on average have better HRQoL and societal participation than DD recipients, in the first years after transplantation.

Reliability and validity of PROMIS physical function, pain interference, and fatigue as patient reported outcome measures in adult idiopathic inflammatory myopathies: International study from the OMERACT myositis working group.

OBJECTIVE: Pain interference, fatigue, and impaired physical function are common features of idiopathic inflammatory myopathies (IIM). The objective of this study was to evaluate the construct validity and test-retest reliability of the Patient Reported Outcome Information System (PROMIS) Pain Interference 6av1.0, Fatigue 7av1.0, and Physical Function 8bv2.0 instruments. METHODS: Patient-Reported Outcome Measures (PROMs) were deployed to adult IIM patients from OMERACT Myositis Working Group (MWG) international clinic sites via two online surveys (2019, 2021). Internal consistency of each PROM was analyzed by Cronbach's α. Construct validity was determined by a priori hypotheses generated by the MWG with >75% agreement for each hypothesis and calculated with Pearson correlations. Test-retest reliability was assessed using intraclass correlation coefficient with PROMIS instruments administered at time zero and 7 days. RESULTS: Surveys were sent to 368 participants in total; participants who completed each questionnaire varied (n=65 to 263). For construct validity, 10 out of 13 a priori hypotheses were met supporting construct validity of PROMIS instruments (Pain Interference 3/4, fatigue 4/4, and Physical Function 3/5). Test-retest reliability was strong for all PROMIS instruments. All PROMIS instruments demonstrated excellent internal consistency. None of the measures demonstrated any ceiling or floor effects except for a ceiling effect in the Pain Interference instrument. CONCLUSIONS: This study presents test-retest reliability and construct validity evidence supporting PROMIS Pain Interference (6a v1.0), Fatigue (7a v1.0), and Physical Function (8b v2.0) using a large international cohort of patients with IIM. Internal consistency of these instruments was excellent. A ceiling effect was noted in the Pain Interference instrument.

Reduced quality of life in living kidney donors: association with fatigue, societal participation and pre-donation variables.

Health related quality of life (HRQoL) of living kidney donors on average is good, but some donors experience a low HRQoL after donation. This study assessed the prevalence of reduced HRQoL and explored associations with pre- and post-donation variables. 316 donors (response rate 74%) who donated a kidney between 1997 and 2009 filled in a questionnaire. HRQoL was measured using the Short-Form 36; fatigue using the Multidimensional Fatigue Inventory; societal participation using the Utrecht Scale for Evaluation of Rehabilitation-Participation. Donors on average had better HRQoL than the general population. However, 12% had a reduced physical (PCS) and 18% a reduced mental (MCS) HRQoL. Donors with reduced HRQoL reported greater fatigue (P < 0.01), lower societal participation (P < 0.01) and showed a trend towards statistical significance in experiencing more donor-recipient relationship changes (P = 0.07). Prior to donation, donors with reduced PCS had a higher BMI (P < 0.05) and more often smoked (P < 0.05). Donors with reduced MCS had higher expectations (P < 0.05). Reduced HRQoL is associated with higher BMI, smoking and higher expectations prior to donation. These results may be used to develop a screening instrument to select donors at high risk for reduced HRQoL.

Decision making around living and deceased donor kidney transplantation: a qualitative study exploring the importance of expected relationship changes.

BACKGROUND: Limited data exist on the impact of living kidney donation on the donor-recipient relationship. Purpose of this study was to explore motivations to donate or accept a (living donor) kidney, whether expected relationship changes influence decision making and whether relationship changes are actually experienced. METHODS: We conducted 6 focus groups in 47 of 114 invited individuals (41%), asking retrospectively about motivations and decision making around transplantation. We used qualitative and quantitative methods to analyze the focus group transcripts. RESULTS: Most deceased donor kidney recipients had a potential living donor available which they refused or did not want. They mostly waited for a deceased donor because of concern for the donor's health (75%). They more often expected negative relationship changes than living donor kidney recipients (75% vs. 27%, p = 0.01) who also expected positive changes. Living donor kidney recipients mostly accepted the kidney to improve their own quality of life (47%). Donors mostly donated a kidney because transplantation would make the recipient less dependent (25%). After transplantation both positive and negative relationship changes are experienced. CONCLUSION: Expected relationship changes and concerns about the donor's health lead some kidney patients to wait for a deceased donor, despite having a potential living donor available. Further research is needed to assess whether this concerns a selected group.

Is the impact of hospital performance data greater in patients who have compared hospitals?

BACKGROUND: Public information on average has limited impact on patients' hospital choice. However, the impact may be greater in consumers who have compared hospitals prior to their hospital choice. We therefore assessed whether patients who have compared hospitals based their hospital choice mainly on public information, rather than e.g. advice of their general practitioner and consider other information important than patients who have not compared hospitals. METHODS: 337 new surgical patients completed an internet-based questionnaire. They were asked whether they had compared hospitals prior to their hospital choice and which factors influenced their choice. They were also asked to select between four and ten items of hospital information (total: 41 items) relevant for their future hospital choice. These were subsequently used in a hospital choice experiment in which participants were asked to compare hospitals in an Adaptive Choice-Based Conjoint analysis to estimate which of the hospital characteristics had the highest Relative Importance (RI). RESULTS: Patients who have compared hospitals more often used public information for their hospital choice than patients who have not compared hospitals (12.7% vs. 1.5%, p < 0.001). However, they still mostly relied on their own (47.9%) and other people's experiences (31%) rather than to base their decision on public information. Both groups valued physician's expertise (RI 20.2 [16.6-24.8] in patients comparing hospitals vs. 16.5 [14.2-18.8] in patients not comparing hospitals) and waiting time (RI 15.1 [10.7-19.6] vs. 15.6 [13.2-17.9] respectively) as most important public information. Patients who have compared hospitals assigned greater importance to information on wound infections (p = 0.010) and respect for patients (p = 0.022), but lower importance to hospital distance (p = 0.041). CONCLUSION: Public information has limited impact on patient's hospital choice, even in patients who have actually compared hospitals prior to hospital choice.

Clinical Relevance of Epidural Steroid Injections on Lumbosacral Radicular Syndrome-related Synptoms: Systematic Review and Meta-Analysis.

OBJECTIVES: Epidural steroid injections (ESIs) can be used to reduce lumbosacral radicular syndrome (LRS) related pain. The clinical relevance of ESIs are currently unknown. This systematic review and meta-analyses aims to assess whether ESIs are clinically relevant for patients with LRS. MATERIALS AND METHODS: Comprehensive literature searches for randomized controlled trials regarding steroid injections for LRS were conducted in PudMed, EMBASE, CINAHL, and CENTRAL from their inception to September 2018 (December 2019 for PubMed). For each homogenous comparison, the outcomes function, pain intensity and health-related quality of life at different follow-up intervals were pooled separately. The GRADE approach was used to determine the overall certainty of the evidence. RESULTS: Seventeen studies were included. Two different homogenous comparisons were identified for which the randomized controlled trials could be pooled. In 36 of the 40 analyses no clinically relevant effect was found. The certainty of evidence varied between very low to high. Four analyses found a clinically relevant effect, all on pain intensity and health-related quality of life, but the certainty of the evidence was either low or very low. Two of the 33 subgroup analyses showed a clinically relevant effect. However, according to the GRADE approach the certainty of these findings are low to very low. DISCUSSION: On the basis of the analyses we conclude there is insufficient evidence that ESIs for patients with LRS are clinically relevant at any follow-up moment. High-quality studies utilizing a predefined clinical success are necessary to identify potential clinically relevant effects of ESIs. Until the results of these studies are available, there is reason to consider whether the current daily practice of ESIs for patients with LRS should continue.

Functional capacity and actual daily activity do not contribute to patient satisfaction after total knee arthroplasty.

BACKGROUND: After total knee arthroplasty (TKA) only 75-89% of patients are satisfied. Because patient satisfaction is a prime goal of all orthopaedic procedures, optimization of patient satisfaction is of major importance. Factors related to patient satisfaction after TKA have been explored, but no studies have included two potentially relevant factors, i.e. the functional capacity of daily activities and actual daily activity. This present prospective study examines whether functional capacity and actual daily activity (in addition to an extensive set of potential factors) contribute to patient satisfaction six months after TKA. METHODS: A total of 44 patients were extensively examined preoperatively and six months post surgery. Functional capacity was measured with three capacity tests, focusing on walking, stair climbing, and chair rising. Actual daily activity was measured in the patient's home situation by means of a 48-hour measurement with an Activity Monitor. To establish which factors were related to patient satisfaction six months post surgery, logistic regression analyses were used to calculate odds ratios. RESULTS: Preoperative and postoperative functional capacity and actual daily activity had no relation with patient satisfaction. Preoperatively, only self-reported mental functioning was positively related to patient satisfaction. Postoperatively, based on multivariate analysis, only fulfilled expectations regarding pain and experienced pain six months post surgery were related to patient satisfaction. CONCLUSIONS: Functional capacity and actual daily activity do not contribute to patient satisfaction after TKA. Patients with a better preoperative self-reported mental functioning, and patients who experienced less pain and had fulfilled expectations regarding pain postoperatively, were more often satisfied.

Responders to Exercise Therapy in Patients with Osteoarthritis of the Hip: A Systematic Review and Meta-Analysis.

The Outcome Measures in Rheumatology workgroup (OMERACT), together with the Osteoarthritis Research Society International (OARSI) developed the OMERACT-OARSI responder criteria. These criteria are used to determine if a patient with osteoarthritis (OA) 'responds' to therapy, meaning experiences a clinically relevant effect of therapy. Recently, more clinical OA trials report on this outcome and most OA trials have data to calculate the number of responders according to these criteria. A systematic review and meta-analysis were performed on the response to exercise therapy, compared to no or minimal intervention in patients with hip OA using the OMERACT-OARSI responder criteria. The literature was searched for relevant randomized trials. If a trial fit the inclusion criteria, but number of responders was not reported, the first author was contacted. This way the numbers of responders of 14 trials were collected and a meta-analysis on short term (directly after treatment, 12 trials n = 1178) and long term (6-8 months after treatment, six trials n = 519) outcomes was performed. At short term, the risk difference (RD) was 0.14 (95% confidence interval (CI) 0.06-0.22) and number needed to treat (NNT) 7.1 (95% CI 4.5-17); at long term RD was 0.14 (95% CI 0.07-0.20) and NNT 7.1 (95% CI 5.0-14.3). Quality of evidence was moderate for the short term and high for the long term. In conclusion, 14% more hip OA patients responded to exercise therapy than to no therapy.

Assessing the content validity of patient-reported outcome measures in adult myositis: A report from the OMERACT myositis working group.

OBJECTIVE: To investigate the content validity of several patient-reported outcome measures (PROMs) in patients with idiopathic inflammatory myopathies (IIM). METHODS: Seven individual PROM instruments were selected by the Outcome Measures in Rheumatology (OMERACT) Myositis Working Group relating to the following domains: pain, fatigue, physical function and physical activity. Twenty patients from the Johns Hopkins Myositis Center were selected for one-on-one face-to-face or phone interviews for cognitive interviewing of individual PROMs to assess comprehension and content validity. Additionally, patients were asked if they thought muscle symptoms, an area originally identified in qualitative studies, were encapsulated by the other four domains. RESULTS: The majority of patients (>70%) felt that each of the instruments was clear, easy to read and understand, and could be used for assessment of its domain. Two-thirds (66%) of patients felt that 'muscle symptoms' were captured by the other domains. CONCLUSIONS: We provided evidence to support adequate content validity for several PROMs. Further research is needed to determine whether 'muscle symptoms' warrant a separate domain.

Perceptions of Patients, Caregivers, and Healthcare Providers of Idiopathic Inflammatory Myopathies: An International OMERACT Study.

OBJECTIVE: Patient-reported outcome measures (PROM) that incorporate the patient perspective have not been well established in idiopathic inflammatory myopathies (IIM). As part of our goal to develop IIM-specific PROM, the Outcome Measures in Rheumatology (OMERACT) Myositis special interest group sought to determine which aspects of disease and its effects are important to patients and healthcare providers (HCP). METHODS: Based on a prior qualitative content analysis of focus groups, an initial list of 24 candidate domains was constructed. We subsequently conducted an international survey to identify the importance of each of the 24 domains to be assessed in clinical research. Patients with IIM, their caregivers, and HCP treating IIM completed the survey. RESULTS: In this survey, a total of 638 respondents completed the survey, consisting of 510 patients, 101 HCP, and 27 caregivers from 48 countries. Overall, patients were more likely to rank "fatigue," "cognitive impact," and "difficulty sleeping" higher compared with HCP, who ranked "joint symptoms," "lung symptoms," and "dysphagia" higher. Both patients and providers rated muscle symptoms as their top domain. In general, patients from different countries were in agreement on which domains were most important. One notable exception was that patients from Sweden and the Netherlands ranked lung symptoms significantly higher compared to other countries including the United States and Australia (mean weighted rankings of 2.86 and 2.04 vs 0.76 and 0.80, respectively; p < 0.0001). CONCLUSION: Substantial differences exist in how IIM is perceived by patients compared to HCP, with different domains prioritized. In contrast, patients' ratings across the world were largely similar.

OMERACT 2018 Modified Patient-reported Outcome Domain Core Set in the Life Impact Area for Adult Idiopathic Inflammatory Myopathies.

OBJECTIVE: To present and vote on a myositis modified patient-reported outcome core domain set in the life impact area at the Outcome Measures in Rheumatology (OMERACT) 2018. METHODS: Based on results from international focus groups and Delphi surveys, a draft core set was developed. RESULTS: Domains muscle symptoms, fatigue, level of physical activity, and pain reached ≥ 70% consensus and were mandatory to assess in all trials. Domains lung, joint, and skin symptoms were mandatory in specific circumstances. This core set was endorsed by > 85% at OMERACT 2018. CONCLUSION: We propose a life impact core set for patients with idiopathic inflammatory myopathies and will proceed with instrument selections.

The Dutch version of the Knee Injury and Osteoarthritis Outcome Score: a validation study.

BACKGROUND: The Knee Injury and Osteoarthritis Outcome Score (KOOS) was constructed in Sweden. This questionnaire has proved to be valid for several orthopedic interventions of the knee. It has been formally translated and validated in several languages, but not yet in Dutch. The purpose of the present study was to evaluate the clinimetric properties of the Dutch version of the KOOS questionnaire in knee patients with various stages of osteoarthritis (OA). METHODS: The Swedish version of the KOOS questionnaire was first translated into Dutch according to a standardized procedure and second tested for clinimetric quality. The study population consisted of patients with different stages of OA (mild, moderate and severe) and of patients after primary TKA, and after a revision of the TKA. All patients filled in the Dutch KOOS questionnaire, as well as the SF-36 and a Visual Analogue Scale for pain. The following analyses were performed to evaluate the clinimetric quality of the KOOS: Cronbach's alpha (internal consistency), principal component analyses (factor analysis), intraclass correlation coefficients (reliability), spearman's correlation coefficient (construct validity), and floor and ceiling effects. RESULTS: For all patients groups Cronbach's alpha was for all subscales above 0.70. The ICCs, assessed for the patient groups with mild and moderate OA and after revision of the TKA patients, were above 0.70 for all subscales. Of the predefined hypotheses 60% or more could be confirmed for the patients with mild and moderate OA and for the TKA patients. For the other patient groups less than 45% could be confirmed. Ceiling effects were present in the mild OA group for the subscales Pain, Symptoms and ADL and for the subscale Sport/Recreation in the severe OA group. Floor effects were found for the subscales Sport/Recreation and Qol in the severe OA and revision TKA groups. CONCLUSION: Based on these different clinimetric properties within the present study we conclude that the KOOS questionnaire seems to be suitable for patients with mild and moderate OA and for patients with a primary TKA. The Dutch version of the KOOS had a lower construct validity for patients with severe OA on a waiting list for TKA and patients after revision of a TKA. Further validation studies on the Dutch version of the KOOS should also include a knee specific questionnaire for assessing the construct validity.

Small increase of actual physical activity 6 months after total hip or knee arthroplasty.

UNLABELLED: Limitation in daily physical activity is one of the reasons for total hip arthroplasty (THA) or total knee arthroplasty (TKA). However, studies of the effects of THA or TKA generally do not determine actual daily activity as part of physical functioning. We determined the effect of THA or TKA on patients' actual physical activity and body function (pain, stiffness), capacity to perform tasks, and self-reported physical functioning. We also assessed whether there are differences in the effect of the surgery between patients undergoing THA or TKA and whether the improvements vary between these different outcome measures. We recruited patients with long-standing end-stage osteoarthritis of the hip or knee awaiting THA or TKA. Measurements were performed before surgery and 3 and 6 months after surgery. Actual physical activity improved by 0.7%. Patients' body function, capacity, and self-reported physical functioning also improved. The effects of the surgery on these aspects of physical functioning were similar for THA and TKA. The effect on actual physical activity (8%) was smaller than on body function (80%-167%), capacity (19%-36%), and self-reported physical functioning (87%-112%). Therefore, in contrast to the large effect on pain and stiffness, patients' capacity, and their self-reported physical functioning, the improvement in actual physical activity of our patients was less than expected 6 months after surgery. LEVEL OF EVIDENCE: Level I, prospective study. See the Guidelines for Authors for a complete description of levels of evidence.