Sustainability, spread, and scale in trials using audit and feedback: a theory-informed, secondary analysis of a systematic review.

BACKGROUND: Audit and feedback (A&F) is a widely used implementation strategy to influence health professionals' behavior that is often tested in implementation trials. This study examines how A&F trials describe sustainability, spread, and scale. METHODS: This is a theory-informed, descriptive, secondary analysis of an update of the Cochrane systematic review of A&F trials, including all trials published since 2011. Keyword searches related to sustainability, spread, and scale were conducted. Trials with at least one keyword, and those identified from a forward citation search, were extracted to examine how they described sustainability, spread, and scale. Results were qualitatively analyzed using the Integrated Sustainability Framework (ISF) and the Framework for Going to Full Scale (FGFS). RESULTS: From the larger review, n = 161 studies met eligibility criteria. Seventy-eight percent (n = 126) of trials included at least one keyword on sustainability, and 49% (n = 62) of those studies (39% overall) frequently mentioned sustainability based on inclusion of relevant text in multiple sections of the paper. For spread/scale, 62% (n = 100) of trials included at least one relevant keyword and 51% (n = 51) of those studies (31% overall) frequently mentioned spread/scale. A total of n = 38 studies from the forward citation search were included in the qualitative analysis. Although many studies mentioned the need to consider sustainability, there was limited detail on how this was planned, implemented, or assessed. The most frequent sustainability period duration was 12 months. Qualitative results mapped to the ISF, but not all determinants were represented. Strong alignment was found with the FGFS for phases of scale-up and support systems (infrastructure), but not for adoption mechanisms. New spread/scale themes included (1) aligning affordability and scalability; (2) balancing fidelity and scalability; and (3) balancing effect size and scalability. CONCLUSION: A&F trials should plan for sustainability, spread, and scale so that if the trial is effective, the benefits can continue. A deeper empirical understanding of the factors impacting A&F sustainability is needed. Scalability planning should go beyond cost and infrastructure to consider other adoption mechanisms, such as leadership, policy, and communication, that may support further scalability. TRIAL REGISTRATION: Registered with Prospero in May 2022. CRD42022332606.

The effectiveness of a multifaceted, group-facilitated audit and feedback intervention to increase tranexamic acid use during total joint arthroplasty.

PURPOSE: Intraoperative tranexamic acid (TXA) is used to reduce blood loss and the need for transfusions following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Despite evidence in literature and local practice protocols supporting TXA as a part of standard of care for joint arthroplasty, TXA administration is underutilized. We aimed to use group-facilitated audit and feedback as the foundation of a knowledge translation strategy to increase TXA use for THA and TKA procedures. METHODS: Anesthesiologists consented to receive two data reports summarizing their individual rates of TXA use and postoperative blood transfusions compared with site peers. Variables collected included patient demographics, TXA usage, and the frequency and volume of red blood cell transfusions administered in the 72-hr postoperative period. The facilitated feedback session discussed report findings and focused on factors contributing to local practice patterns and opportunities for change. RESULTS: Tranexamic acid use increased for THA procedures at the intervention site from 66.6 to 74.4% (absolute change, 7.9%; 95% confidence interval [CI], 2.4 to 13.3). Likewise, TXA use for TKA procedures increased from 62.4 to 82.3% (absolute change, 19.9%; 95% CI 15.0 to 25.0). CONCLUSIONS: Physicians and their teams were able to review their practice data on TXA utilization, reflect on differences compared with evidence-based guidelines, discuss findings with peers, and identify opportunities for improvement. The intervention increased the use of TXA for both TKA and THA and shifted the dosage to better align with evidence-based practice guidelines.

RéSUMé: OBJECTIF : L'acide tranexamique (ATX) peropératoire est utilisé pour réduire les pertes sanguines et les besoins transfusionnels après les arthroplasties totales de la hanche (ATH) et du genou (ATG). Malgré les données probantes et les protocoles de pratique locaux appuyant l'utilisation d'ATX dans le cadre de la norme de soins en cas d'arthroplastie, l'administration de cet agent est sous-utilisée. Notre objectif était d'utiliser l'audit et la rétroaction facilités par le groupe comme base d'une stratégie d'application des connaissances afin d'accroître l'utilisation de l'ATX lors des ATH et ATG. MéTHODE: Les anesthésiologistes ont consenti à recevoir deux rapports de données résumant leurs taux individuels d'utilisation d'ATX et de transfusions sanguines postopératoires par rapport à leurs pairs au sein du même établissement. Les variables recueillies comprenaient les données démographiques des patients, l'utilisation d'ATX et la fréquence et le volume des transfusions d'érythrocytes administrées au cours d'une période postopératoire de 72 heures. La séance de rétroaction facilitée a porté sur les conclusions du rapport et s'est concentrée sur les facteurs contribuant aux habitudes de pratique locales et aux possibilités de changement. RéSULTATS: L'utilisation d'acide tranexamique a augmenté pour les procédures d'ATH au site d'intervention, passant de 66,6 % à 74,4 % (variation absolue, 7,9 %; intervalle de confiance [IC] à 95 %, 2,4 à 13,3). De même, l'utilisation d'ATX pour les procédures d'ATG est passée de 62,4 % à 82,3 % (variation absolue, 19,9 %; IC 95 %, 15,0 à 25,0). CONCLUSION: Les médecins et leurs équipes ont pu passer en revue leurs données de pratique sur l'utilisation d'ATX, réfléchir aux différences par rapport aux lignes directrices fondées sur des données probantes, discuter des résultats avec leurs pairs et identifier les possibilités d'amélioration. L'intervention a augmenté l'utilisation d'ATX pour l'ATG et l'ATH et a modifié la posologie pour mieux s'aligner sur les lignes directrices de pratique fondées sur des données probantes.

The Impact of Comorbidities on Calgary Hospital Utilization in Patients With Chronic Obstructive Pulmonary Disease and Heart Failure.

Background Chronic obstructive pulmonary disease (COPD) and heart failure (HF) are chronic conditions with high acute care utilization. Disease-specific order sets were developed for patients with COPD or HF in Calgary to reduce total days in hospital for this population of patients. However, many patients have comorbidities which may contribute to hospital utilization; thus, disease-specific order sets may not be an optimal solution to reduce overall acute care utilization. Methods Inpatient data on Calgary hospitalizations for COPD or HF between April 1, 2017 - March 31, 2019 and associated diagnoses were identified. Outcomes included total days in hospital and length of stay for COPD and HF patients stratified by number of comorbidities. Results Total days in hospital increased with the number of comorbidities for both conditions. During the study period, 131 patients with COPD and no comorbidities had a median length of stay of three days (IQR: 3) compared to 3,911 COPD patients with one to five comorbidities with a median length of stay of seven days (IQR: 9). There were 47 patients with HF and no comorbidities with a median length of stay of four days (IQR: 5) compared to 6,273 HF patients with one to five comorbidities with a median length of stay of nine days (IQR: 12). Common comorbidities included hypertension, type 2 diabetes, and acute renal failure. COPD and HF are frequently comorbid.  Conclusions Total days in hospital for patients with COPD or HF is positively correlated with the number of comorbidities. COPD or HF patients with between one to five comorbidities (compared to those with no comorbidities, and those with more than five comorbidities) represent the majority of total days in hospital, and the majority of patients. This highlights the importance of focusing on patients with comorbidities in efforts to reduce hospital utilization, and suggests that concurrent management of commonly occurring comorbidities for HF and COPD patients may be necessary to achieve this goal.

The effect of different methods to identify, and scenarios used to address energy intake misestimation on dietary patterns derived by cluster analysis.

BACKGROUND: All self-reported dietary intake data are characterized by measurement error, and validation studies indicate that the estimation of energy intake (EI) is particularly affected. METHODS: Using self-reported food frequency and physical activity data from Alberta's Tomorrow Project participants (n = 9847 men 16,241 women), we compared the revised-Goldberg and the predicted total energy expenditure methods in their ability to identify misreporters of EI. We also compared dietary patterns derived by k-means clustering under different scenarios where misreporters are included in the cluster analysis (Inclusion); excluded prior to completing the cluster analysis (ExBefore); excluded after completing the cluster analysis (ExAfter); and finally, excluded before the cluster analysis but added to the ExBefore cluster solution using the nearest neighbor method (InclusionNN). RESULTS: The predicted total energy expenditure method identified a significantly higher proportion of participants as EI misreporters compared to the revised-Goldberg method (50% vs. 47%, p < 0.0001). k-means cluster analysis identified 3 dietary patterns: Healthy, Meats/Pizza and Sweets/Dairy. Among both men and women, participants assigned to dietary patterns changed substantially between ExBefore and ExAfter and also between the Inclusion and InclusionNN scenarios (Hubert and Arabie's adjusted Rand Index, Kappa and Cramer's V statistics < 0.8). CONCLUSIONS: Different scenarios used to account for EI misreporters influenced cluster analysis and hence the composition of the dietary patterns. Continued efforts are needed to explore and validate methods and their ability to identify and mitigate the impact of EI misestimation in nutritional epidemiology.

Administering a combination of online dietary assessment tools, the Automated Self-Administered 24-Hour Dietary Assessment Tool, and Diet History Questionnaire II, in a cohort of adults in Alberta's Tomorrow Project.

BACKGROUND: Evidence suggests that combining tools that gather short- and long-term dietary data may be the optimal approach for the assessment of diet-disease associations in epidemiologic studies. Online technology can reduce the associated burdens for researchers and participants, but feasibility must be demonstrated in real-world settings before wide-scale implementation. OBJECTIVE: The objective of this study was to determine the feasibility and acceptability of combining web-based tools (the Automated Self-Administered 24-hour Dietary Assessment Tool [ASA24-2016] and the past-year Diet History Questionnaire II [DHQ-II]) in a subset of participants in Alberta's Tomorrow Project, a prospective cohort. DESIGN: For this feasibility study, invitations were mailed to 550 randomly selected individuals enrolled in Alberta's Tomorrow Project. Consented participants (n = 331) were asked to complete a brief sociodemographic and health questionnaire, four ASA24-2016 recalls, the DHQ-II, and an evaluation survey. PARTICIPANTS/SETTING: The study was conducted from March 2016 to December 2016 in Alberta, Canada. The majority of participants, mean age (SD) = 57.4 (9.8) years, were women (70.7%), urban residents (85.5%), and nonsmokers (95.7%). MAIN OUTCOME MEASURES: Primary outcomes were number of ASA24-2016 recalls completed, response rate of DHQ-II completion, and time to complete each assessment. STATISTICAL ANALYSES: The Wilcoxon signed rank sum test was used to assess differences in completion time. RESULTS: One-third (n = 102) of consenting participants did not complete any ASA24-2016 recalls. The primary reason to withdraw from the feasibility study was a lack of time. Among consenting participants, 51.9% (n = 172), 41.1% (n = 136), and 36.5% (n = 121) completed at least two ASA24-2016 recalls, the DHQ-II, and at least two ASA24-2016 recalls plus the DHQ-II, respectively. Median (25th to 75th percentile) completion times for participants who completed all recalls were 39 minutes (25 to 53 minutes) for the first ASA24-2016 recall and 60 minutes (40 to 90 minutes) for the DHQ-II. CONCLUSIONS: Findings indicate combining multiple ASA24-2016 recalls and the DHQ-II is feasible in this subset of Alberta's Tomorrow Project participants. However, optimal response rates may be contingent on providing participant support. Completion may also be sensitive to timing and frequency of recall administration.

Implementation and Evaluation of Audit and Feedback for Monitoring Treat-to-Target (T2T) Strategies in Rheumatoid Arthritis Using Performance Measures.

INTRODUCTION: In collaboration with the Alberta Medical Association's Physician Learning Program we developed individualized physician reports and held a group feedback session on rheumatoid arthritis (RA) performance measures (PM) to facilitate treat-to-target (T2T) strategies and evaluated physician experiences with this process. METHODS: 5 PMs addressing T2T concepts from an established Canadian quality framework were operationalized for physician practice reports at 2 university-affiliated rheumatology clinics. Rheum4U, a quality improvement and research platform, was the data source. The audit results were reviewed in a facilitated group feedback session. Rheumatologists provided experiential feedback on the process through survey and/or an interview. Transcripts from interviews were analyzed using a 6-step thematic analysis. RESULTS: 11 of 12 eligible rheumatologists consented to receive practice reports and provided feedback through surveys (n = 5) and interviews (n = 6). The practice reports from Rheum4U (n = 448 patients) revealed high rates of yearly follow-up (> 85%, PM1) and 100% performance on documentation of disease activity at ≥ 50% of visits (PM2). Only 34% of patients were seen within 3 months if not in remission (PM3) with 62% (2017) and 69% (2018) of those with active RA achieving a LDA state within 6 months (PM4). Approximately 70% of patients were in remission at any time point (PM5). All survey respondents agreed or strongly agreed comparison to peers was valuable and helped them reflect on their practice. Several strategies for improvement were identified, including but not limited to, leveraging of electronic records for future audit and feedback reports, providing additional granularity of results, additional stratification of results, and using high-performing peers as the comparator rather than the group mean. CONCLUSIONS: Audit and feedback was perceived by clinicians as a useful strategy for evaluating T2T efforts in RA. Future work will focus on longitudinal evaluation of the clinical impact of this quality improvement initiative.

Group-facilitated audit and feedback to improve bronchiolitis care in the emergency department.

OBJECTIVE: Despite strong evidence recommending supportive care as the mainstay of management for most infants with bronchiolitis, prior studies show that patients still receive low-value care (e.g., respiratory viral testing, salbutamol, chest radiography). Our objective was to decrease low-value care by delivering individual physician reports, in addition to group-facilitated feedback sessions to pediatric emergency physicians. METHODS: Our cohort included 3,883 patients ≤ 12 months old who presented to pediatric emergency departments in Calgary, Alberta, with a diagnosis of bronchiolitis from April 1, 2013, to April 30, 2018. Using administrative data, we captured baseline characteristics and therapeutic interventions. Consenting pediatric emergency physicians received two audit and feedback reports, which included their individual data and peer comparators. A multidisciplinary group-facilitated feedback session presented data and identified barriers and enablers of reducing low-value care. The primary outcome was the proportion of patients who received any low-value intervention and was analysed using statistical process control charts. RESULTS: Seventy-eight percent of emergency physicians consented to receive their audit and feedback reports. Patient characteristics were similar in the baseline and intervention period. Following the baseline physician reports and the group feedback session, low-value care decreased from 42.6% to 27.1% (absolute difference: -15.5%; 95% CI: -19.8% to -11.2%) and 78.9% to 64.4% (absolute difference: -14.5%; 95% CI: -21.9% to -7.2%) in patients who were not admitted and admitted, respectively. Balancing measures, such as intensive care unit admission and emergency department revisit, were unchanged. CONCLUSION: The combination of audit and feedback and a group-facilitated feedback session reduced low-value care for patients with bronchiolitis.

Strategies to Address Misestimation of Energy Intake Based on Self-Report Dietary Consumption in Examining Associations Between Dietary Patterns and Cancer Risk.

The objective of this study was to determine the influence of strategies of handling misestimation of energy intake (EI) on observed associations between dietary patterns and cancer risk. Data from Alberta's Tomorrow Project participants (n = 9,847 men and 16,241 women) were linked to the Alberta Cancer Registry. The revised-Goldberg method was used to characterize EI misestimation. Four strategies assessed the influence of EI misestimation: Retaining individuals with EI misestimation in the cluster analysis (Inclusion), excluding before (ExBefore) or after cluster analysis (ExAfter), or reassigning into ExBefore clusters using the nearest neighbor method (InclusionNN). Misestimation of EI affected approximately 50% of participants. Cluster analysis identified three patterns: Healthy, Meats/Pizza and Sweets/Dairy. Cox proportional hazard regression models assessed associations between the risk of cancer and dietary patterns. Among men, no significant associations (based on an often-used threshold of p < 0.05) between dietary patterns and cancer risk were observed. In women, significant associations were observed between the Sweets/Dairy and Meats/Pizza patterns and all cancer risk in the ExBefore (HR (95% CI): 1.28 (1.04-1.58)) and InclusionNN (HR (95% CI): 1.14 (1.00-1.30)), respectively. Thus, strategies to address misestimation of EI can influence associations between dietary patterns and disease outcomes. Identifying optimal approaches for addressing EI misestimation, for example, by leveraging biomarker-based studies could improve our ability to characterize diet-disease associations.

Patterns and predictors of adherence to colorectal cancer screening recommendations in Alberta's Tomorrow Project participants stratified by risk.

BACKGROUND: Colorectal cancer (CRC) screening is an important modifiable behaviour for cancer control. Regular screening, following recommendations for the type, timing and frequency based on personal CRC risk, contributes to earlier detection and increases likelihood of successful treatment. METHODS: To determine adherence to screening recommendations in a large provincial cohort of adults, participants in Alberta's Tomorrow Project (n = 9641) were stratified based on increasing level of CRC risk: age (Age-only), family history of CRC (FamilyHx), personal history of bowel conditions (PersonalHx), or both (Family/PersonalHx) using self-reported information from questionnaires. Provincial and national guidelines for timing and frequency of screening tests were used to determine if participants were up-to-date based on their CRC risk. Screening status was compared between enrollment (2000-2006) and follow-up (2008) to determine screening pattern over time. RESULTS: The majority of participants (77%) fell into the average risk Age-only strata. Only a third of this strata were up-to-date for screening at baseline, but the proportion increased across the higher risk strata, with > 90% of the highest risk Family/PersonalHx strata up-to-date at baseline. There was also a lower proportion (< 25%) of the Age-only group who were regular screeners over time compared to the higher risk strata, though age, higher income and uptake of other screening tests (e.g. mammography) were associated with a greater likelihood of regular screening in multinomial logistic regression. CONCLUSIONS: The low (< 50%) adherence to regular CRC screening in average and moderate risk strata highlights the need to further explore barriers to uptake of screening across different risk profiles.

Diet quality is associated with reduced incidence of cancer and self-reported chronic disease: Observations from Alberta's Tomorrow Project.

The objective of this study was to assess diet quality using the Healthy Eating Index-2005 Canada (HEI-2005-Canada) and its association with risk of cancer and chronic disease in a sample of Alberta's Tomorrow Project (ATP) participants. Food frequency questionnaires completed by 25,169 participants (38% men; mean age 50.3 (9.2)) enrolled between 2000 and 2008 were used to calculate HEI-2005-Canada scores. Data from a subset of participants (n=10,735) who reported no chronic disease at enrollment were used to investigate the association between HEI-2005-Canada score and development of self-reported chronic disease at follow-up (2008). Participants were divided into HEI-2005-Canada score quartiles. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for cancer and chronic disease incidence. In this cohort, mean HEI-2005-Canada scores for men and women were 50.9 and 55.5 (maximum range 0-100), respectively. In men, higher HEI-2005-Canada score (Q4 vs. Q1) was associated with lower cancer risk (HR (95% CI) 0.63 (0.49-0.83)) over the course of follow-up (mean (SD)=10.4 (2.3) years); the same was not observed in women. In contrast, higher overall HEI-2005-Canada score (Q4 vs. Q1) was associated with lower risk of self-reported chronic disease (0.85 (0.75-0.97)) in both men and women over follow-up (4.2 (2.3) years). In conclusion, in this cohort better diet quality was associated with a lower risk of cancer in men and lower risk of chronic disease in both sexes. Future studies with longer follow-up and repeated measures of diet may be helpful to elucidate sex-specific associations between dietary quality and disease outcomes.

Lessons from Studies to Evaluate an Online 24-Hour Recall for Use with Children and Adults in Canada.

With technological innovation, comprehensive dietary intake data can be collected in a wide range of studies and settings. The Automated Self-Administered 24-hour (ASA24) Dietary Assessment Tool is a web-based system that guides respondents through 24-h recalls. The purpose of this paper is to describe lessons learned from five studies that assessed the feasibility and validity of ASA24 for capturing recall data among several population subgroups in Canada. These studies were conducted within a childcare setting (preschool children with reporting by parents), in public schools (children in grades 5-8; aged 10-13 years), and with community-based samples drawn from existing cohorts of adults and older adults. Themes emerged across studies regarding receptivity to completing ASA24, user experiences with the interface, and practical considerations for different populations. Overall, we found high acceptance of ASA24 among these diverse samples. However, the ASA24 interface was not intuitive for some participants, particularly young children and older adults. As well, technological challenges were encountered. These observations underscore the importance of piloting protocols using online tools, as well as consideration of the potential need for tailored resources to support study participants. Lessons gleaned can inform the effective use of technology-enabled dietary assessment tools in research.

Design, methods and demographics from phase I of Alberta's Tomorrow Project cohort: a prospective cohort profile.

BACKGROUND: Prospective cohorts have the potential to support multifactorial, health-related research, particularly if they are drawn from the general population, incorporate active and passive follow-up and permission is obtained to allow access by researchers to data repositories. This paper describes Phase I of the Alberta's Tomorrow Project cohort, a broad-based research platform designed to support investigations into factors that influence cancer and chronic disease risk. METHODS: Adults aged 35-69 years living in Alberta, Canada, with no previous cancer diagnosis other than nonmelanoma skin cancer were recruited to the project by telephone-based random digit dialling. Participants were enrolled if they returned a Health and Lifestyle Questionnaire. Past year diet and physical activity questionnaires were mailed 3 months after enrolment. Consent was sought for active follow-up and linkage with administrative databases. Depending on enrolment date, participants were invited to complete up to 2 follow-up questionnaires (2004 and 2008). RESULTS: Between 2001 and 2009, 31 072 (39% men) participants (mean age 50.2 [± 9.2] yr) were enrolled and 99% consented to linkage with administrative databases. Participants reported a wide range of educational attainment and household income. Compared with provincial surveillance data from the Canadian Community Health Survey, Alberta's Tomorrow Project participants had higher body mass index, lower prevalence of smoking and similar distribution of chronic health conditions. Follow-up questionnaires were completed by 83% and 72% of participants in 2004 and 2008, respectively. Robust quality control measures resulted in low frequencies of missing data. INTERPRETATION: Alberta's Tomorrow Project provides a robust platform, based on a prospective cohort design, to support research into risk factors for cancer and chronic disease.

The infrapatellar fat pad is affected by injury induced inflammation in the rabbit knee: use of dexamethasone to mitigate damage.

OBJECTIVE AND DESIGN: The health of the infrapatellar fat pad (IFP) has been linked to pain, joint inflammation, and the onset of post-traumatic osteoarthritis. Thus, early inflammation effects on the IFP could have long term sequelae on joint integrity. This study was designed to characterize the natural history of the IFP in a model of surgically induced knee injury and inflammation, and to test the efficacy of one intra-articular (IA) administration of dexamethasone (DEX) immediately following surgery. METHODS: An IA bone drill hole injury to the rabbit knee was conducted and immediately treated with DEX (n = 12). Early and late post-surgical time-points were investigated (48 h and 9 weeks) and the outcome measures were analysis of IFP histology, mRNA levels for relevant molecules, and protein levels for a subset of cytokines. Data were analyzed against a surgical control (injury without treatment; n = 12), a surgical sham (capsular incision only; n = 12), and normal control (n = 6). TREATMENT: Single IA injection of DEX (0.5 mg/kg), administered at the completion of surgery. RESULTS: IFPs from injured joints exhibited significantly increased cellularity and early fibrosis at 48 h post surgery. While the histological inflammation from a capsular incision alone resolved, knee injured animals progressed to a significantly more fibrotic IFP by 9 weeks. DEX significantly lowered histological scores at 48 h, but not at the 9 weeks. DEX did not influence mRNA levels for IL-1ß, 6, and 8, however, protein analysis indicated that IL-8 levels were lower in DEX treated joints. DEX resulted in significantly elevated expression of mRNA for MCP-1, leptin, and VEGF. CONCLUSION: One IA administration of a glucocorticoid appears to mitigate the initial inflammation within the joint, but is not sufficient to protect the joint to 9 weeks post-surgery.

Alterations in Hoffa's fat pad induced by an inflammatory response following idealized anterior cruciate ligament surgery.

OBJECTIVE: To determine whether inflammation following anterior cruciate ligament (ACL) reconstruction leads to long-term pathological changes in the infrapatellar fat pad (IPFP or Hoffa's fat pad) which could compromise the integrity of the knee joint. MATERIALS AND METHODS: Sixteen mature sheep underwent anatomic idealized ACL reconstruction surgery (ACL-R) and were sacrificed at 2 weeks (n = 9) and 20 weeks (n = 7) post-ACL-R. Five additional animals served as unoperated controls. A histological grading protocol was developed to quantify the changes in the IPFP post-injury. mRNA expression levels for key markers of inflammation, angiogenesis and tissue regeneration were assessed by qPCR. RESULTS: The IPFP exhibited altered cellularity and fibrosis at 2 and 20 weeks post-ACL-R. Immunohistochemistry detected macrophage-like cells in the IPFP which were increased at 20 weeks. Specific pro-inflammatory cytokines and IPFP specific adipokines exhibited changes indicating early inflammation mediated alterations. Elevations in CD105 mRNA levels at 2 weeks corroborated the increases in neovascularization observed in the IPFP following injury. CONCLUSIONS: Sustained long-term pathological changes stemming from inflammation are present in IPFP tissue after ACL-R surgery and may compromise the long-term integrity of the knee joint.

Severe atrophy of slow myofibers in aging muscle is concealed by myosin heavy chain co-expression.

Although slow myofibers are considered less susceptible to atrophy with aging, slow fiber atrophy may have been underestimated previously. First, the marked atrophy of the aging rat soleus (Sol) muscle cannot be explained by the atrophy of only the fast fibers, due to their low abundance. Second, the increase in small fibers co-expressing both fast and slow myosin heavy chains (MHC) in the aging rat Sol is proportional to a decline in pure MHC slow fibers (Snow et al., 2005), suggesting that these MHC co-expressing fibers represent formerly pure slow fibers. Thus, we examined the size and proportion of MHC slow, MHC fast, and MHC fast-slow co-expressing fibers in the Sol and mixed region of the gastrocnemius (Gas) muscle in young adult (YA) and senescent (SEN) rats. Our results suggest that formerly pure MHC slow fibers are the source of MHC co-expressing fibers with aging in both muscle regions. Accounting for the atrophy of these fibers in calculating MHC slow fiber atrophy with aging revealed that MHC slow fibers atrophy on average by 40% in the Sol and by 38% in the mixed Gas, values which are similar to the 60% and 31% atrophy of pure MHC fast fibers in the Sol and mixed Gas, respectively. Probing for the atrophy-dependent ubiquitin ligase, MAFbx (atrogin 1), it was suggested that former slow fibers acquire atrophy potential via the up-regulation of MAFbx coincident with the co-expression of fast MHC. These results redefine the impact of aging on slow fiber atrophy, and emphasize the necessity of addressing the atrophy of fast and slow fibers in seeking treatments for aging muscle atrophy.

Denervation causes fiber atrophy and myosin heavy chain co-expression in senescent skeletal muscle.

Although denervation has long been implicated in aging muscle, the degree to which it is causes the fiber atrophy seen in aging muscle is unknown. To address this question, we quantified motoneuron soma counts in the lumbar spinal cord using choline acetyl transferase immunhistochemistry and quantified the size of denervated versus innervated muscle fibers in the gastrocnemius muscle using the in situ expression of the denervation-specific sodium channel, Nav1.5, in young adult (YA) and senescent (SEN) rats. To gain insights into the mechanisms driving myofiber atrophy, we also examined the myofiber expression of the two primary ubiquitin ligases necessary for muscle atrophy (MAFbx, MuRF1). MN soma number in lumbar spinal cord declined 27% between YA (638±34 MNs×mm⁻¹) and SEN (469±13 MNs×mm⁻¹). Nav1.5 positive fibers (1548±70 µm²) were 35% smaller than Nav1.5 negative fibers (2367±78 µm²; P<0.05) in SEN muscle, whereas Nav1.5 negative fibers in SEN were only 7% smaller than fibers in YA (2553±33 µm²; P<0.05) where no Nav1.5 labeling was seen, suggesting denervation is the primary cause of aging myofiber atrophy. Nav1.5 positive fibers had higher levels of MAFbx and MuRF1 (P<0.05), consistent with involvement of the proteasome proteolytic pathway in the atrophy of denervated muscle fibers in aging muscle. In summary, our study provides the first quantitative assessment of the contribution of denervation to myofiber atrophy in aging muscle, suggesting it explains the majority of the atrophy we observed. This striking result suggests a renewed focus should be placed on denervation in seeking understanding of the causes of and treatments for aging muscle atrophy.

Accumulation of severely atrophic myofibers marks the acceleration of sarcopenia in slow and fast twitch muscles.

The age-related decline in muscle mass, known as sarcopenia, exhibits a marked acceleration in advanced age. Although many studies have remarked upon the accumulation of very small myofibers, particularly at advanced stages of sarcopenia, the significance of this phenomenon in the acceleration of sarcopenia has never been examined. Furthermore, although mitochondrial dysfunction characterized by a lack of cytochrome oxidase (COX) activity has been implicated in myofiber atrophy in sarcopenia, the contribution of this phenotype to the accumulation of severely atrophied fibers in aged muscles has never been determined. To this end, we examined the fiber size distribution in the slow twitch soleus (Sol) and fast twitch gastrocnemius (Gas) muscles between young adulthood (YA) and senescence (SEN). We also quantified the abundance of COX deficient myocytes and their size attributes to gain insight into the contribution of this phenotype to myofiber atrophy with aging. Our data showed that the progression of muscle atrophy, particularly its striking acceleration between late middle age and SEN, was paralleled by an accumulation of severely atrophic myofibers (≤ 1000 µm(2) in size) in both Sol and Gas. On the other hand, we observed no COX deficient myofibers in Sol, despite nearly 20% of the myofibers being severely atrophic. Similarly, only 0.17 ± 0.06% of all fibers in Gas were COX deficient, and their size was generally larger (2375 ± 319 µm(2)) than the severely atrophied myofibers noted above. Collectively, our results suggest that similar processes likely contribute to the acceleration of sarcopenia in both slow twitch and fast twitch muscles, and that COX deficiency is not a major contributor to this phenomenon.