Changes in the Workforce Characteristics of Providers Who Care for Adult Patients With Rheumatologic and Musculoskeletal Disease in the United States.

OBJECTIVE: The aim of this study was to describe the adult rheumatology workforce in the United States, assess change in rheumatology providers over time, and identify variation in rheumatology practice characteristics. METHODS: Using national Medicare claims data from 2006 to 2020, clinically active rheumatology physicians and advanced practice providers (APPs) were identified. Each calendar year was used for inclusion, exclusion, and analysis, and providers were determined to be entering, exiting, or stable based upon presence or absence in the prior or subsequent years of data. Characteristics (age, gender, practice type, rural, and region) of rheumatologists were determined for 2019 and in mutually exclusive study periods from 2009 to 2011, 2012 to 2015, and 2016 to 2019. The location of rheumatology practice was determined by billing tax identification and mapped. Demographics of physicians exiting or entering the rheumatology workforce were compared separately to those stable by logistic regression. RESULTS: The clinically active adult rheumatology workforce identified in US Medicare in 2019 was 5,667 rheumatologists and 379 APPs. From 2009 to 2020, the number of rheumatologists increased 23% and the number of APPs increased 141%. There was an increase in female rheumatologists over time, rising to 43% in 2019. Women and those employed by a health care system were more likely to exit, and those in a small practice or in the South were less likely to exit. CONCLUSION: The overall number of clinically active rheumatology providers grew more than 20% over the last decade to a high of 6,036 in 2020, although this rate of growth appears to be flattening off in later years.

Assessment of antibody levels to SARS-CoV-2 in patients with idiopathic inflammatory myopathies receiving treatment with intravenous immunoglobulin.

Antibodies to Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) have been reported in pooled healthy donor plasma and intravenous immunoglobulin products (IVIG). It is not known whether administration of IVIG increases circulating anti-SARS-CoV-2 antibodies (COVID ab) in IVIG recipients. COVID ab against the receptor binding domain of the spike protein were analyzed using a chemiluminescent microparticle immunoassay in patients with idiopathic inflammatory myopathies (IIM) both receiving and not receiving IVIG (IVIG and non-IVIG group, respectively). No significant differences in COVID ab levels were noted between IVIG and non-IVIG groups (417 [67-1342] AU/mL in IVIG vs 5086 [43-40,442] AU/mL in non-IVIG, p = 0.11). In linear regression models including all post-vaccination patient samples, higher number of vaccine doses was strongly associated with higher COVID ab levels (2.85 [1.21, 4.48] log AU/mL, regression coefficient [Formula: see text] [95% CI], p = 0.001), while use of RTX was associated with lower ab levels (2.73 [- 4.53, - 0.93] log AU/mL, [Formula: see text][95%CI], p = 0.004). In the IVIG group, higher total monthly doses of IVIG were associated with slightly higher COVID ab levels (0.02 [0.002-0.05] log AU/mL, p = 0.04). While patients on IVIG did not have higher COVID ab levels compared to the non-IVIG group, higher monthly doses of IVIG were associated with higher circulating levels of COVID ab in patients receiving IVIG, particularly in patients concomitantly receiving RTX. Our findings suggest that IIM patients, especially those at increased risk of COVID infection and worse COVID outcomes due to RTX therapy may have protective benefits when on concurrent IVIG treatment.

Calcium pyrophosphate crystal size and characteristics.

OBJECTIVE: To describe the characteristics of calcium pyrophosphate (CPP) crystal size and morphology under compensated polarized light microscopy (CPLM). Secondarily, to describe CPP crystals seen only with digital enhancement of CPLM images, confirmed with advanced imaging techniques. METHODS: Clinical lab-identified CPP-positive synovial fluid samples were collected from 16 joint aspirates. Four raters used a standardized protocol to describe crystal shape, birefringence strength and color. A crystal expert confirmed CPLM-visualized crystal identification. For crystal measurement, a high-pass linear light filter was used to enhance resolution and line discrimination of digital images. This process identified additional enhanced crystals not seen by raters under CPLM. Single-shot computational polarized light microscopy (SCPLM) provided further confirmation of the enhanced crystals' presence. RESULTS: Of 932 suspected crystals identified by CPLM, 569 met our inclusion criteria, and 293 (51%) were confirmed as CPP crystals. Of 175 unique confirmed crystals, 118 (67%) were rods (median area 3.6 µm2 [range, 1.0-22.9 µm2]), and 57 (33%) were rhomboids (median area 4.8 µm2 [range, 0.9-16.7 µm2]). Crystals visualized only after digital image enhancement were smaller and less birefringent than CPLM-identified crystals. CONCLUSIONS: CPP crystals that are smaller and weakly birefringent are more difficult to identify. There is likely a population of smaller, less birefringent CPP crystals that routinely goes undetected by CPLM. Describing the characteristics of poorly visible crystals may be of use for future development of novel crystal identification methods.

Limitations of dual-energy CT in the detection of monosodium urate deposition in dense liquid tophi and calcified tophi.

OBJECTIVE: Dual-energy CT (DECT) detection of monosodium urate (MSU) crystal deposition has demonstrated good sensitivity and specificity in patients with established gout. However, limitations have been reported with early disease and with low urate burden. We aimed to study the performance of DECT in the detection and quantification of MSU deposition in solid and liquid tophi. MATERIALS AND METHODS: Patient-derived solid and liquid tophi, suspensions of commercial synthetic, and in-house synthetic MSU crystals were prepared at varying concentrations. DECT was performed at 80 kVp and 150 kVp, and post-processed using Syngo Via gout software (Siemens) that color-coded urate and cortical bone as green and purple, respectively. DECT findings were correlated with ultrasound and microscopic findings. The protocol was reviewed by IRB and considered a non-human subject research. RESULTS: DECT did not detect urate deposition in either patient-derived liquid tophi or in-house synthetic crystals at any concentration. Lowering the post-processing minimum threshold increased the detection of in-house synthetic crystals but did not change the detection of patient-derived liquid tophi. Areas of calcium-rich purple color-coded regions, masking detection of urate, within the solid tophi and surrounding liquid tophi were noted on DECT. Histology showed co-presence of calcium along with MSU deposition in these. CONCLUSION: This study illustrates important limitations of DECT for liquid tophi due to subthreshold CT attenuation and for calcified tophi due to the obscuration of urate by calcium. Urate may be either undetectable or underestimated by DECT when these conditions are present.

Efficacy and Safety of Pharmacologic Interventions in Patients Experiencing a Gout Flare: A Systematic Review and Network Meta-Analysis.

OBJECTIVE: To compare the relative efficacy and safety of pharmacologic antiinflammatory interventions for gout flares. METHODS: We searched Ovid Medline, Embase, and Cochrane library for randomized controlled trials (RCTs) that compared pharmacologic antiinflammatory treatment of gout flares. We conducted a network meta-analysis (NMA) using a frequentist framework and assessed the certainty of evidence and made conclusions using the Grading of Recommendations Assessment, Development, and Evaluation for NMA. RESULTS: In the 30 eligible RCTs, canakinumab provided the highest pain reduction at day 2 and at longest follow-up (mean difference relative to acetic acid derivative nonsteroidal antiinflammatory drugs [NSAIDs] -41.12 [95% confidence interval (95% CI) -53.36, -29.11] on a 0-100 scale at day 2, and mean difference -12.84 [95% CI -20.76, -4.91] at longest follow-up; both moderate certainty; minimum important difference -19). Intravenous or intramuscular corticosteroids were inferior to canakinumab but may be better than the other commonly used interventions (low to very low certainty). For joint tenderness, canakinumab may be the most effective intervention at day 2. Acetic acid derivative NSAIDs improved joint swelling better than ibuprofen NSAIDs at day 2 (mean difference -0.29 [95% CI -0.56, -0.02] on a 0-4 scale; moderate certainty) and improved patient global assessment (PtGA) greater than ibuprofen NSAIDs at the longest follow-up (mean difference -0.44 [95% CI -0.86, -0.02]; moderate). CONCLUSION: Canakinumab may be superior to other alternatives and intravenous or intramuscular corticosteroids may be the second best in pain reduction. Acetic acid derivative NSAIDs may be superior to ibuprofen NSAIDs in improving joint swelling and PtGA.

Patient Perspectives on Gout and Gout Treatments: A Patient Panel Discussion That Informed the 2020 American College of Rheumatology Treatment Guideline.

OBJECTIVE: The objective of this study was to understand patient perspectives to inform the voting process for the 2020 American College of Rheumatology (ACR) gout treatment guideline. METHODS: We conducted a panel meeting of eight patients with gout in Birmingham, Alabama. Patients were referred to the project by private and academic rheumatologists in the Birmingham area. All participants received orientation related to the guideline development process and evidence rating at the beginning of the meeting. With the help of a physician moderator, the patient panel reviewed nine key clinical scenarios and the supporting evidence and discussed their views and perspectives related to each. They also provided their preference for one of the two treatment options for each clinical scenario. RESULTS: The patient panel included eight men with gout. Of these eight participants, seven received their gout care from a rheumatologist and one from a primary care physician. Patients favored more active urate-lowering therapy (ULT) management and interventional management of gout flares to achieve desired clinical outcomes, resulting in unanimous consensus on choices related to six clinical scenarios: ULT initiation in gout, treat-to-target management strategy, use of pegloticase for refractory gout, starting ULT during a gout flare, using injectable treatments (over oral) for acute gout flares, and use of febuxostat in people with cardiovascular disease. CONCLUSION: Knowledge of patient preferences and values is valuable and was influential for the development of the 2020 ACR gout treatment guideline.

2020 American College of Rheumatology Guideline for the Management of Gout.

OBJECTIVE: To provide guidance for the management of gout, including indications for and optimal use of urate-lowering therapy (ULT), treatment of gout flares, and lifestyle and other medication recommendations. METHODS: Fifty-seven population, intervention, comparator, and outcomes questions were developed, followed by a systematic literature review, including network meta-analyses with ratings of the available evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and patient input. A group consensus process was used to compose the final recommendations and grade their strength as strong or conditional. RESULTS: Forty-two recommendations (including 16 strong recommendations) were generated. Strong recommendations included initiation of ULT for all patients with tophaceous gout, radiographic damage due to gout, or frequent gout flares; allopurinol as the preferred first-line ULT, including for those with moderate-to-severe chronic kidney disease (CKD; stage >3); using a low starting dose of allopurinol (≤100 mg/day, and lower in CKD) or febuxostat (<40 mg/day); and a treat-to-target management strategy with ULT dose titration guided by serial serum urate (SU) measurements, with an SU target of <6 mg/dl. When initiating ULT, concomitant antiinflammatory prophylaxis therapy for a duration of at least 3-6 months was strongly recommended. For management of gout flares, colchicine, nonsteroidal antiinflammatory drugs, or glucocorticoids (oral, intraarticular, or intramuscular) were strongly recommended. CONCLUSION: Using GRADE methodology and informed by a consensus process based on evidence from the current literature and patient preferences, this guideline provides direction for clinicians and patients making decisions on the management of gout.

2020 American College of Rheumatology Guideline for the Management of Gout.

OBJECTIVE: To provide guidance for the management of gout, including indications for and optimal use of urate-lowering therapy (ULT), treatment of gout flares, and lifestyle and other medication recommendations. METHODS: Fifty-seven population, intervention, comparator, and outcomes questions were developed, followed by a systematic literature review, including network meta-analyses with ratings of the available evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and patient input. A group consensus process was used to compose the final recommendations and grade their strength as strong or conditional. RESULTS: Forty-two recommendations (including 16 strong recommendations) were generated. Strong recommendations included initiation of ULT for all patients with tophaceous gout, radiographic damage due to gout, or frequent gout flares; allopurinol as the preferred first-line ULT, including for those with moderate-to-severe chronic kidney disease (CKD; stage >3); using a low starting dose of allopurinol (≤100 mg/day, and lower in CKD) or febuxostat (<40 mg/day); and a treat-to-target management strategy with ULT dose titration guided by serial serum urate (SU) measurements, with an SU target of <6 mg/dl. When initiating ULT, concomitant antiinflammatory prophylaxis therapy for a duration of at least 3-6 months was strongly recommended. For management of gout flares, colchicine, nonsteroidal antiinflammatory drugs, or glucocorticoids (oral, intraarticular, or intramuscular) were strongly recommended. CONCLUSION: Using GRADE methodology and informed by a consensus process based on evidence from the current literature and patient preferences, this guideline provides direction for clinicians and patients making decisions on the management of gout.

Ultrasound detects synovitis in replaced and other surgically operated joints in rheumatoid arthritis patients.

BACKGROUND: Joint replacements continue to occur during a rheumatoid arthritis (RA) patient's lifetime despite significant advances in available treatment options. The purpose of this study was to examine and quantify synovitis in surgically operated joints by ultrasound (US) in RA patients starting a new therapeutic agent. METHODS: RA subjects were enrolled in either tocilizumab or tofacitinib open-label, investigator-initiated trials and were assessed by ultrasound. In a subset of RA patients with joint replacements and/or operations of joint areas (OJA; e.g. joint arthroscopies, fusions, and synovectomies), joint-level scores of synovitis were compared between replaced joints, OJAs, and native joints. Joint-level synovitis was measured by grayscale (GSUS (0-3)) and power Doppler (PDUS (0-3)) at baseline and follow-up (3-6 months). McNemar's test or Wilcoxon signed rank test utilized the mixed effects ordinal logistic regression models. RESULTS: Twenty RA patients had a total of 25 replaced joints and 24 OJA. All replaced joints had GSUS> 1 and 92% had PDUS> 1 at baseline, while OJA and native joints had lower evidence of GSUS> 1 (37.5, 38% respectively) and PDUS> 1 (45.8, 62% respectively). GSUS and PDUS semiquantitative scores improved significantly with treatment in replaced joints (p = 0.01, p = 0.007), and native joints (p < 0.001 both), but not OJA. CONCLUSIONS: In RA, joint replacement does not eliminate or prevent ultrasound measured synovitis, where all replaced joints have some evidence of US synovitis. US can also act as a potential marker of response to therapy in replaced joints. Scoring US synovitis in replaced joints should be considered in ultrasound RA clinical trials. TRIAL REGISTRATION: ClinicalTrials.gov NCT01717859 (registered 10/31/2012); ClinicalTrials.gov NCT02321930 (registered 12/22/2014).

Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) consensus statement regarding labels and definitions of disease states of gout.

OBJECTIVE: There is a lack of standardisation in the terminology used to describe gout. The aim of this project was to develop a consensus statement describing the recommended nomenclature for disease states of gout. METHODS: A content analysis of gout-related articles from rheumatology and general internal medicine journals published over a 5-year period identified potential disease states and the labels commonly assigned to them. Based on these findings, experts in gout were invited to participate in a Delphi exercise and face-to-face consensus meeting to reach agreement on disease state labels and definitions. RESULTS: The content analysis identified 13 unique disease states and a total of 63 unique labels. The Delphi exercise (n=76 respondents) and face-to-face meeting (n=35 attendees) established consensus agreement for eight disease state labels and definitions. The agreed labels were as follows: 'asymptomatic hyperuricaemia', 'asymptomatic monosodium urate crystal deposition', 'asymptomatic hyperuricaemia with monosodium urate crystal deposition', 'gout', 'tophaceous gout', 'erosive gout', 'first gout flare' and 'recurrent gout flares'. There was consensus agreement that the label 'gout' should be restricted to current or prior clinically evident disease caused by monosodium urate crystal deposition (gout flare, chronic gouty arthritis or subcutaneous tophus). CONCLUSION: Consensus agreement has been established for the labels and definitions of eight gout disease states, including 'gout' itself. The Gout, Hyperuricaemia and Crystal-Associated Disease Network recommends the use of these labels when describing disease states of gout in research and clinical practice.

Development of the American College of Rheumatology Electronic Clinical Quality Measures for Gout.

OBJECTIVE: Electronic clinical quality measures (eCQMs) are increasingly used by health registries and third parties to evaluate and improve the quality of health care. To complete these eCQMs, data are extracted from electronic health records (EHRs). The treatment of gout has been an area identified with gaps in quality of care. On behalf of the American College of Rheumatology (ACR), we sought to develop and test eCQMs to evaluate gout care. METHODS: Drawing from the 2012 ACR gout guidelines, a working group developed candidate gout process measures that were evaluated by an interdisciplinary panel of health care stakeholders, the ACR Quality Measures Subcommittee (QMS), and ultimately the ACR Board of Directors for formal validity testing. For each of the selected gout eCQMs, 3 clinical sites using different EHR systems tested the scientific feasibility and validity of the measures. Measures appropriate for accountability were presented for national endorsement. RESULTS: Of the 10 proposed eCQMs, 4 were endorsed by the ACR QMS, 3 were incorporated into the ACR's Rheumatology Informatics System for Effectiveness (RISE) Registry, and 2 were endorsed by the National Quality Forum. The 3 eCQMs incorporated into RISE (evaluating indications for urate-lowering therapy [ULT]), monitoring serum urate, and treat-to-target outcome) demonstrated high validity and reliability. Proportions of patients passing these 3 eCQMs in RISE and at the 3 clinical testing sites ranged between 32% and 58%, indicating significant room for improvement in care. CONCLUSION: Three eCQMs have been validated and implemented into RISE. Two of these measures (evaluating indications for ULT and monitoring serum urate) are available for use in federal quality reporting programs. Performance on these measures suggests there is significant room for improvement in the management of gout.

2015 American College of Rheumatology Workforce Study: Supply and Demand Projections of Adult Rheumatology Workforce, 2015-2030.

OBJECTIVE: To describe the character and composition of the 2015 US adult rheumatology workforce, evaluate workforce trends, and project supply and demand for clinical rheumatology care for 2015-2030. METHODS: The 2015 Workforce Study of Rheumatology Specialists in the US used primary and secondary data sources to estimate the baseline adult rheumatology workforce and determine demographic and geographic factors relevant to workforce modeling. Supply and demand was projected through 2030, utilizing data-driven estimations regarding the proportion and clinical full-time equivalent (FTE) of academic versus nonacademic practitioners. RESULTS: The 2015 adult workforce (physicians, nurse practitioners, and physician assistants) was estimated to be 6,013 providers (5,415 clinical FTE). At baseline, the estimated demand exceeded the supply of clinical FTE by 700 (12.9%). By 2030, the supply of rheumatology clinical providers is projected to fall to 4,882 providers, or 4,051 clinical FTE (a 25.2% decrease in supply from 2015 baseline levels). Demand in 2030 is projected to exceed supply by 4,133 clinical FTE (102%). CONCLUSION: The adult rheumatology workforce projections reflect a major demographic and geographic shift that will significantly impact the supply of the future workforce by 2030. These shifts include baby-boomer retirements, a millennial predominance, and an increase of female and part-time providers, in parallel with an increased demand for adult rheumatology care due to the growing and aging US population. Regional and innovative strategies will be necessary to manage access to care and reduce barriers to care for rheumatology patients.

Treatment approaches and adherence to urate-lowering therapy for patients with gout.

Gout is the most common inflammatory arthritis characterized by painful disabling acute attacks. It is caused by hyperuricemia and deposition of urate crystals in and around the joints. Long-standing untreated hyperuricemia can lead to chronic arthritis with joint damage, tophi formation and urate nephropathy. Gout is associated with significant morbidity and health care associated cost. The goal of long-term therapy is to lower the serum urate level to promote dissolution of urate crystals, reduce recurrent acute gout flares, resolve tophi and prevent joint damage. Despite the presence of established gout treatment guidelines and effective medications to manage gout, patient outcomes are often poor. Etiology for these shortcomings is multifactorial including both physician and patient characteristics. Poor adherence to urate-lowering therapy (ULT) is prevalent and is a significant contributor to poor patient outcomes. This article reviews the treatment strategies for the management of hyperuricemia in chronic gout, gaps in quality of care in gout management, factors contributing to poor adherence to ULT and discusses potential interventions to achieve improved gout-related outcomes. These interventions include initiation of prophylactic anti-inflammatory medication when starting ULT, frequent follow-ups, regular serum urate monitoring and improved patient education, which can be achieved through pharmacist- or nurse-assisted programs. Interventions such as these could improve adherence to ULT and, ultimately, result in optimal gout-related outcomes.

Management of Gout: A Systematic Review in Support of an American College of Physicians Clinical Practice Guideline.

BACKGROUND: Gout is a common type of inflammatory arthritis in patients seen by primary care physicians. PURPOSE: To review evidence about treatment of acute gout attacks, management of hyperuricemia to prevent attacks, and discontinuation of medications for chronic gout in adults. DATA SOURCES: Multiple electronic databases from January 2010 to March 2016, reference mining, and pharmaceutical manufacturers. STUDY SELECTION: Studies of drugs approved by the U.S. Food and Drug Administration and commonly prescribed by primary care physicians, randomized trials for effectiveness, and trials and observational studies for adverse events. DATA EXTRACTION: Data extraction was performed by one reviewer and checked by a second reviewer. Study quality was assessed by 2 independent reviewers. Strength-of-evidence assessment was done by group discussion. DATA SYNTHESIS: High-strength evidence from 28 trials (only 3 of which were placebo-controlled) shows that colchicine, nonsteroidal anti-inflammatory drugs (NSAIDs), and corticosteroids reduce pain in patients with acute gout. Moderate-strength evidence suggests that low-dose colchicine is as effective as high-dose colchicine and causes fewer gastrointestinal adverse events. Moderate-strength evidence suggests that urate-lowering therapy (allopurinol or febuxostat) reduces long-term risk for acute gout attacks after 1 year or more. High-strength evidence shows that prophylaxis with daily colchicine or NSAIDs reduces the risk for acute gout attacks by at least half in patients starting urate-lowering therapy, and moderate-strength evidence indicates that duration of prophylaxis should be longer than 8 weeks. Although lower urate levels reduce risk for recurrent acute attacks, treatment to a specific target level has not been tested. LIMITATION: Few studies of acute gout treatments, no placebo-controlled trials of management of hyperuricemia lasting longer than 6 months, and few studies in primary care populations. CONCLUSION: Colchicine, NSAIDs, and corticosteroids relieve pain in adults with acute gout. Urate-lowering therapy decreases serum urate levels and reduces risk for acute gout attacks. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality. (Protocol registration: http://effectivehealth-care.ahrq.gov/ehc/products/564/1992/Gout-managment-protocol-141103.pdf).

Diagnosis of Gout: A Systematic Review in Support of an American College of Physicians Clinical Practice Guideline.

BACKGROUND: Alternative strategies exist for diagnosing gout that do not rely solely on the documentation of monosodium urate (MSU) crystals. PURPOSE: To summarize evidence regarding the accuracy of clinical tests and classification algorithms compared with that of a reference standard of MSU crystals in joint aspirate for diagnosing gout. DATA SOURCES: Several electronic databases from inception to 29 February 2016. STUDY SELECTION: 21 prospective cohort, cross-sectional, and case-control studies including participants with joint inflammation and no previous definitive gout diagnosis who had MSU analysis of joint aspirate. DATA EXTRACTION: Data extraction and risk-of-bias assessment by 2 reviewers independently; overall strength of evidence (SOE) judgment by group. DATA SYNTHESIS: Recently developed algorithms including clinical, laboratory, and imaging criteria demonstrated good sensitivity (up to 88%) and fair to good specificity (up to 96%) for diagnosing gout (moderate SOE). Three studies of dual-energy computed tomography (DECT) showed sensitivities of 85% to 100% and specificities of 83% to 92% for diagnosing gout (low SOE). Six studies of ultrasonography showed sensitivities of 37% to 100% and specificities of 68% to 97%, depending on the ultrasonography signs assessed (pooled sensitivity and specificity for the double contour sign: 74% [95% CI, 52% to 88%] and 88% [CI, 68% to 96%], respectively [low SOE]). LIMITATION: Important study heterogeneity and selection bias; scant evidence in primary and urgent care settings and in patients with conditions that may be confused with or occur with gout. CONCLUSION: Multidimensional algorithms, which must be validated in primary and urgent care settings, may help clinicians make a provisional diagnosis of gout. Although DECT and ultrasonography also show promise for gout diagnosis, accessibility to these methods may be limited. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality. (Protocol registration: https://effectivehealthcare.ahrq.gov/ehc/products/564/1937/gout-protocol-140716.pdf).

Hyaluronic acid injection therapy for osteoarthritis of the knee: concordant efficacy and conflicting serious adverse events in two systematic reviews.

BACKGROUND: The prevalence of knee osteoarthritis (OA)/degenerative joint disease (DJD) is increasing in the USA. Systematic reviews of treatment efficacy and adverse events (AEs) of hyaluronic acid (HA) injections report conflicting evidence about the balance of benefits and harms. We review evidence on efficacy and AEs of intraarticular viscosupplementation with HA in older individuals with knee osteoarthritis and account for differences in these conclusions from another systematic review. METHODS: We searched PubMed and eight other databases and gray literature sources from 1990 to December 12, 2014. Double-blind placebo-controlled randomized controlled trials (RCTs) reporting functional outcomes or quality-of-life; RCTs and observational studies on delay/avoidance of arthroplasty; RCTs, case reports, and large cohort studies and case series assessing safety; and systematic reviews reporting on knee pain were considered for inclusion. A standardized, pre-defined protocol was applied by two independent reviewers to screen titles and abstracts, review full text, and extract details on study design, interventions, outcomes, and quality. We compared our results with those of a prior systematic review and found them to be discrepant; our analysis of why this discrepancy occurred is the focus of this manuscript. RESULTS: Eighteen RCTs reported functional outcomes: pooled analysis of ten placebo-controlled, blinded trials showed a standardized mean difference of -0.23 (95 % confidence interval (CI) -0.45 to -0.01) favoring HA at 6 months. Studies reported few serious adverse events (SAEs) and no significant differences in non-serious adverse events (NSAEs) (relative risk (RR) [95 % CI] 1.03 [0.93-1.15] or SAEs (RR [95 % CI] 1.39 [0.78-2.47]). A recent prior systematic review reported similar functional outcomes, but significant SAE risk. Differences in SAE inclusion and synthesis accounted for the disparate conclusions. CONCLUSIONS: Trials show a small but significant effect of HA on function on which recent systematic reviews agree, but lack of AE synthesis standardization leads to opposite conclusions about the balance of benefits and harms. A limitation of the re-analysis of the prior systematic review is that it required imputation of missing data.