The impact of rheumatoid arthritis on the risk of adverse events following joint replacement: a real-world cohort study

Comprehensive insights into rheumatoid arthritis: Pathophysiology, current therapies and herbal alternatives for effective disease management

Rheumatoid arthritis is a chronic autoimmune inflammatory disease characterized by immune response overexpression, causing pain and swelling in the synovial joints. This condition is caused by auto-reactive antibodies that attack self-antigens due to their incapacity to distinguish between self and foreign molecules. Dysregulated activity within numerous signalling and immunological pathways supports the disease's development and progression, elevating its complexity. While current treatments provide some alleviation, their effectiveness is accompanied by a variety of adverse effects that are inherent in conventional medications. As a result, there is a deep-rooted necessity to investigate alternate therapeutic strategies capable of neutralizing these disadvantages. Medicinal herbs display a variety of potent bioactive phytochemicals that are effective in the complementary management of disease, thus generating an enormous potency for the researchers to delve deep into the development of novel phytomedicine against autoimmune diseases, although additional evidence and understanding are required in terms of their efficacy and pharmacodynamic mechanisms. This literature-based review highlights the dysregulation of immune tolerance in rheumatoid arthritis, analyses the pathophysiology, elucidates relevant signalling pathways involved, evaluates present and future therapy options and underscores the therapeutic attributes of a diverse array of medicinal herbs in addressing this severe disease.

Rheumatoid Arthritis Is Not a Contraindication to Unicompartmental Knee Arthroplasty

BACKGROUND

Rheumatoid arthritis (RA) has historically been considered a contraindication for unicompartmental knee arthroplasty (UKA). However, the widespread use of disease-modifying antirheumatic drugs has substantially improved the management of RA and prevented disease progression. The objective of this study was to ascertain whether RA impacts UKA revision-free survivorship.

METHODS

Patients undergoing UKA from 2010 to 2021 were identified in an administrative claims database (n = 105,937) using Current Procedural Terminology code 27446. All patients who underwent UKA who had a diagnosis of RA with a minimum of 2-year follow-up (n = 1,422) were propensity score matched based on age, sex, and Elixhauser Comorbidity Index to those who did not have RA (n = 1,422). Laterality was identified using the 10th Revision of International Classification of Diseases codes. The primary outcome was ipsilateral revision to total knee arthroplasty (TKA) within 2 years, and the secondary outcome was ipsilateral revision at any time.

RESULTS

Among the 1,422 patients who had a UKA and a diagnosis of RA, 37 patients (2.6%) underwent conversion to TKA within 2 years, and 48 patients (3.4%) underwent conversion to TKA at any point. In comparison, 28 patients (2.0%) in the propensity-matched control group underwent conversion to TKA within 2 years, and 40 patients (2.8%) underwent conversion to TKA at any point. Statistical analysis revealed no significant difference in conversion to TKA between patients who had and did not have RA, either within 2 years (P = .31) or anytime (P = .45).

CONCLUSIONS

Patients who had RA and underwent UKA did not have an increased risk of revision to TKA compared to those who did not have RA. This may indicate that modern management of RA could allow for expanded UKA indications for RA patients.

Rheumatoid arthritis patients are at increased risk for adverse events following lumbar discectomy

BACKGROUND CONTEXT

Lumbar discectomy is a common procedure for which patients with rheumatoid arthritis (RA) may be considered. RA is an autoinflammatory disease that may predispose patients to postoperative adverse outcomes.

PURPOSE

To assess the relative odds of adverse events after lumbar discectomy for those with versus without RA in a large, national, administrative dataset.

STUDY DESIGN/SETTING

Retrospective cohort study using the 2010 to 2020 MSpine PearlDiver dataset.

PATIENT SAMPLE

After exclusion of patients under 18 years old, those with any trauma, neoplasm, or infection diagnosis within the month before lumbar discectomy, and any patients who had any alternative lumbar spinal surgery performed on the same day as lumbar discectomy, we identified 36,479 lumbar discectomy patients. 2,937 (8.1%) of these patients had a prior diagnosis of RA. After matching 4:1 by patient age, sex, and Elixhauser Comorbidity Index (ECI, a longitudinal measure of patient comorbidity burden generated via ICD-9 and 10 diagnosis codes), 8,485 lumbar discectomy patients without RA and 2,149 with RA were included.

OUTCOME MEASURES

Incidence of severe and minor adverse events in the 90-days following lumbar discectomy, predictive factors for adverse events within 90-days of lumbar discectomy, risk of adverse events within 90-days of lumbar discectomy stratified by patient medication regimen, 5-year survival to reoperation following lumbar discectomy.

METHODS

Patients undergoing lumbar discectomy were identified from the PearlDiver MSpine dataset. The subset of those with versus without RA were identified and matched 1:4 based on patient age, sex, and ECI scores. The incidence of 90-day adverse events in the two groups was determined and compared by univariate and multivariate analyses. Subgroup analysis was performed based on RA medications being taken.

RESULTS

Matched lumbar discectomy patients with RA (n=2,149) and without RA (n=8,485) were identified. Controlling for patient age, sex, and ECI, those with RA were at significantly higher odds of any (odds ratio [OR] 3.30), severe (OR 2.78), and minor (OR 3.30) adverse events (p<.0001 for all). Stratifying by medications being taken (and relative to those without RA), there was increasing odds of all adverse events (AAE) based on potency of medications (no biologic or disease modifying antirheumatic drugs [DMARDs] OR 2.33, DMARDs only OR 3.86, biologic±DMARDs OR 5.69 (p<.0001 for all). Despite this, no statistically significant difference in 5-year survival from subsequent lumbar surgery was found between those with versus without RA (p=.1000).

CONCLUSIONS

Lumbar discectomy patients with RA were found to be at significantly higher risk for 90-day adverse events following lumbar discectomy, and this was incrementally greater for those on increasingly suppressive medications. Lumbar discectomy patients with RA bear specific consideration and perioperative monitoring when considered for lumbar discectomy.

A systematic review and meta-analysis comparing outcomes following total knee arthroplasty for rheumatoid arthritis versus for osteoarthritis

PURPOSE

Total knee arthroplasty (TKA) in patients with osteoarthritis (OA) are considered to be a successful procedure, but with little being known about outcomes in patients with rheumatoid arthritis (RA). The aim of this study was to compare the outcomes of TKA in patients with RA versus OA.

METHODS

Data were obtained from PubMed, Cochrane Library, EBSCO and Scopus for all available studies comparing the outcomes of THA in RA and OA patients (From January 1, 2000 to October 15, 2022). Outcomes of interest included infection, revision, venous thromboembolism (VTE), mortality, periprosthetic fractures, prosthetic loosening, length of stay, and satisfaction. Two reviewers independently assessed each study for quality and extracted data. The quality of the studies was scored using the Newcastle-Ottawa scale (NOS).

RESULTS

Twenty-four articles with a total 8,033,554 patients were included in this review. The results found strong evidence for increased risk of overall infection (OR = 1.61, 95% CI, 1.24-2.07; P = 0.0003), deep infection (OR = 2.06, 95% CI, 1.37-3.09; P = 0.0005), VTE (OR = 0.76, 95% CI, 0.61-0.93; P = 0.008), pulmonary embolism (PE) (OR = 0.84, 95% CI, 0.78-0.90; P<0.00001), periprosthetic fractures (OR = 1.87, 95% CI, 1.60-2.17; P<0.00001); and reasonable evidence for increased risk of deep venous thrombosis (DVT) (OR = 0.74, 95% CI, 0.54-0.99; P = 0.05), and length of stay (OR = 0.07, 95% CI, 0.01-0.14; P = 0.03) after TKA in patients with RA versus OA. There were no significant differences in superficial site infection (OR = 0.84,95% CI, 0.47-1.52; P = 0.57), revision (OR = 1.33,95% CI, 0.79-2.23; P = 0.28), mortality (OR = 1.16,95% CI, 0.87-1.55; P = 0.32), and prosthetic loosening (OR = 1.75, 95% CI, 0.56-5.48; P = 0.34) between the groups.

CONCLUSION

Our study demonstrated that patients with RA have a higher risk of postoperative infection, VTE, periprosthetic fracture, and lengths of stay, but did not increase revision rate, prosthetic loosening and mortality compared to patients with OA following TKA. In conclusion, despite RA increased incidence of postoperative complications, TKA should continue to be presented as an effective surgical procedure for patients whose conditions are intractable to conservative and medical management of RA.

Clinical and Histological Features of Prosthetic Joint Infections May Differ in Patients With Inflammatory Arthritis and Osteoarthritis

Background: Patients with inflammatory arthritis are at increased risk of prosthetic joint infections (PJIs), but diagnosis in these patients can be challenging because active inflammatory arthritis produces elevated inflammatory markers that may mimic those seen in PJI. Purpose: In this pilot study, we sought to identify the clinical, microbiologic, and histopathologic features of culture-positive and culture-negative PJI in patients with inflammatory arthritis who underwent total hip arthroplasty (THA) or total knee arthroplasty (TKA). We also sought to obtain preliminary data to support a definitive study of optimal methods for PJI diagnosis in patients with inflammatory arthritis. Methods: We performed a retrospective analysis of TKA and THA patients treated for PJI from 2009 to 2018 at a single tertiary care orthopedic institution. Data were extracted from a longitudinally maintained hospital infection database. We reviewed hematoxylin and eosin slides of osteoarthritis and inflammatory arthritis PJI cases matched 3:1, respectively, by age, sex, and culture status. Clinical characteristics were evaluated using the Fisher exact test, χ² test, Student t test, and Mann-Whitney U test where appropriate. Results: A total of 807 PJI cases were identified (36 inflammatory arthritis and 771 osteoarthritis cases). Patients with inflammatory arthritis presented younger, had a higher Charlson Comorbidity Index, more frequently used glucocorticoids, were more likely women, and had a higher proportion of culture-negative PJI compared with osteoarthritis patients. Of the 88 inflammatory arthritis cases reviewed for histopathology, a higher proportion of culture-positive than culture-negative PJI cases had >10 polymorphonuclear leucocytes per high-power field and met Musculoskeletal Infection Society criteria but presented with less chronic inflammation. Conclusions: This retrospective prognostic study suggests that culture-negative PJI may be more frequent in patients with inflammatory arthritis than in those with osteoarthritis. Chronic infections, antibiotic use, or misdiagnosis may be contributing factors to unclear PJI diagnoses among culture-negative cases. This preliminary work supports the need for further studies to assess the differences in clinical features between culture-negative and culture-positive PJI in patients with inflammatory arthritis and the ability of biological diagnostic markers to discriminate between them in this population.

Association between outpatient follow-up and incidence of revision after knee and hip replacements: a population-based cohort study

BACKGROUND

Follow-up visits 5 or 7 years after surgery were recommended for people having primary hip or knee replacement. The benefits of this practice to patients and the healthcare system, however, have not yet been specifically examined. The aim of this study was to investigate the association between long-term follow-up outpatient hospital visits and revision rates for patients who undergo primary knee or hip replacement surgery.

METHODS

Cohorts were identified for patients undergoing knee or hip replacement surgery using medical records from primary care practices within the UK Clinical Practice Research Datalink (CPRD) GOLD dataset linked to hospital records from the English Hospital Episodes Statistics (HES) data. Two groups of patients were compared in terms of revision and mortality rates: those with at least one long-term (between five and 10 years since primary surgery) follow-up visit at the orthopaedic department ('Follow-up' group), and those without ('No follow-up' group).

RESULTS

A total of 9856 (4349 in the Follow-up group) patients with knee replacement and 10,837 (4870 in the Follow-up group) with hip replacement were included in the analysis. For knee replacement, the incidence of revision was 3.6% for those followed-up and 0.6% for those not followed-up. An adjusted regression model confirmed the difference in the hazard ratio (HR) for revision was statistically significant (HR: 5.65 [95% CI 3.62 to 8.81]). Mortality at 4 years was lower for the Follow-up (17%) compared to the No follow-up group (21%), but this difference was not statistically significant (HR: 0.95 [0.84 to 1.07]). For hip replacement, the incidence of revision rates were 3.2 and 1.4% for the follow-up and not follow-up groups, respectively, the difference being statistically significant (HR: 2.34 [1.71 to 3.20]). Mortality was lower for the Follow-up (15%) compared to the No follow-up group (21%), but the difference was not statistically significant (HR: 0.91 [0.81 to 1.02]).

CONCLUSION

Patients attending follow-up orthopaedic consultations show a higher risk of revision surgery compared to those who are not followed-up. A cause for this difference could not be identified in this study but a likely explanation is that surgeons play an effective role as ultimate arbitrators when identifying patients to be included in long-term follow-up lists.

Total Hip Replacement in Patients with Rheumatoid Arthritis: Trends in Incidence and Complication Rates Over 35 Years

INTRODUCTION

Advances in rheumatoid arthritis (RA) management have made disease remission achievable. We evaluated trends in total hip replacement (THR) and postoperative outcomes in patients with RA in Western Australia (WA) over more than three decades.

METHODS

This was a retrospective analysis of routinely collected prospective data from a state-wide registry containing longitudinally linked administrative health data based on International Classification of Diseases (ICD) diagnostic and procedural codes. We included patients with two or more diagnostic codes for RA (between 1980 and 2015) and studied THR incidence rates (THR IR) and complication rates (revision, peri-prosthetic fracture, infection, venous thrombosis, and mechanical loosening). Survival rates were estimated by Kaplan-Meier method and predictors analyzed by Cox regression.

RESULTS

We followed 9201 RA patients over 111,625 person-years, during which 1560 patients (16.9%) underwent THR. From 1985 to 2015, THR IR (per 1000 RA patient-years) decreased from 20.8 (95% CI 20.1-21.5) to 7.3 (95% CI 7.2-7.5), and 5-year THR-free survival increased from 84.3 to 95.3% (1980-2015). Ten-year prosthetic survival was 91.2%. Complication rates in the first 5 years post-THR decreased significantly from 13.1 to 3.7% (p < 0.001). Mechanical complications such as loosening and periprosthetic fracture rates decreased significantly (> 35%, P < 0.05), while infection and revision did not change over the observation period (p > 0.05).

CONCLUSIONS

Over the last 30 years in RA patients, THR IR and mechanical complication rates decreased significantly, but the medical complication of infection has not changed significantly.

Unicompartmental compared with total knee replacement for patients with multimorbidities: a cohort study using propensity score stratification and inverse probability weighting

BACKGROUND

Although routine NHS data potentially include all patients, confounding limits their use for causal inference. Methods to minimise confounding in observational studies of implantable devices are required to enable the evaluation of patients with severe systemic morbidity who are excluded from many randomised controlled trials.

OBJECTIVES

Stage 1 - replicate the Total or Partial Knee Arthroplasty Trial (TOPKAT), a surgical randomised controlled trial comparing unicompartmental knee replacement with total knee replacement using propensity score and instrumental variable methods. Stage 2 - compare the risk benefits and cost-effectiveness of unicompartmental knee replacement with total knee replacement surgery in patients with severe systemic morbidity who would have been ineligible for TOPKAT using the validated methods from stage 1.

DESIGN

This was a cohort study.

SETTING

Data were obtained from the National Joint Registry database and linked to hospital inpatient (Hospital Episode Statistics) and patient-reported outcome data.

PARTICIPANTS

Stage 1 - people undergoing unicompartmental knee replacement surgery or total knee replacement surgery who met the TOPKAT eligibility criteria. Stage 2 - participants with an American Society of Anesthesiologists grade of ≥ 3.

INTERVENTION

The patients were exposed to either unicompartmental knee replacement surgery or total knee replacement surgery.

MAIN OUTCOME MEASURES

The primary outcome measure was the postoperative Oxford Knee Score. The secondary outcome measures were 90-day postoperative complications (venous thromboembolism, myocardial infarction and prosthetic joint infection) and 5-year revision risk and mortality. The main outcome measures for the health economic analysis were health-related quality of life (EuroQol-5 Dimensions) and NHS hospital costs.

RESULTS

In stage 1, propensity score stratification and inverse probability weighting replicated the results of TOPKAT. Propensity score adjustment, propensity score matching and instrumental variables did not. Stage 2 included 2256 unicompartmental knee replacement patients and 57,682 total knee replacement patients who had severe comorbidities, of whom 145 and 23,344 had linked Oxford Knee Scores, respectively. A statistically significant but clinically irrelevant difference favouring unicompartmental knee replacement was observed, with a mean postoperative Oxford Knee Score difference of < 2 points using propensity score stratification; no significant difference was observed using inverse probability weighting. Unicompartmental knee replacement more than halved the risk of venous thromboembolism [relative risk 0.33 (95% confidence interval 0.15 to 0.74) using propensity score stratification; relative risk 0.39 (95% confidence interval 0.16 to 0.96) using inverse probability weighting]. Unicompartmental knee replacement was not associated with myocardial infarction or prosthetic joint infection using either method. In the long term, unicompartmental knee replacement had double the revision risk of total knee replacement [hazard ratio 2.70 (95% confidence interval 2.15 to 3.38) using propensity score stratification; hazard ratio 2.60 (95% confidence interval 1.94 to 3.47) using inverse probability weighting], but half of the mortality [hazard ratio 0.52 (95% confidence interval 0.36 to 0.74) using propensity score stratification; insignificant effect using inverse probability weighting]. Unicompartmental knee replacement had lower costs and higher quality-adjusted life-year gains than total knee replacement for stage 2 participants.

LIMITATIONS

Although some propensity score methods successfully replicated TOPKAT, unresolved confounding may have affected stage 2. Missing Oxford Knee Scores may have led to information bias.

CONCLUSIONS

Propensity score stratification and inverse probability weighting successfully replicated TOPKAT, implying that some (but not all) propensity score methods can be used to evaluate surgical innovations and implantable medical devices using routine NHS data. Unicompartmental knee replacement was safer and more cost-effective than total knee replacement for patients with severe comorbidity and should be considered the first option for suitable patients.

FUTURE WORK

Further research is required to understand the performance of propensity score methods for evaluating surgical innovations and implantable devices.

TRIAL REGISTRATION

This trial is registered as EUPAS17435.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 66. See the NIHR Journals Library website for further project information.

Patients' risk factors for periprosthetic joint infection in primary total hip arthroplasty: a meta-analysis of 40 studies

BACKGROUND

Periprosthetic joint infection (PJI) is a catastrophic complication after total hip arthroplasty (THA). Our meta-analysis aimed to identify the individual-related risk factors that predispose patients to PJI following primary THA.

METHODS

Comprehensive literature retrieval from Pubmed, Web of Science, and the Cochrane Library was performed from inception to Feb 20th, 2021. Patient-related risk factors were compared as per the modifiable factors (BMI, smoke and alcohol abuse), non-modifiable factors (gender, age), and medical history characteristics, such as diabetes mellitus (DM), avascular necrosis (AVN) of femoral head, femoral neck fracture, rheumatoid arthritis (RA), cardiovascular disease (CVD), and osteoarthritis (OA) etc. The meta-analysis was applied by using risk ratios with 95% corresponding intervals. Sensitivity analysis and publication bias were performed to further assess the credibility of the results.

RESULTS

Overall, 40 studies with 3,561,446 hips were enrolled in our study. By implementing cumulative meta-analysis, higher BMI was found associated with markedly increased PJI risk after primary THA [2.40 (2.01-2.85)]. Meanwhile, medical characteristics including DM [1.64 (1.25-2.21)], AVN [1.65 (1.07-2.56)], femoral neck fracture [1.75 (1.39-2.20)], RA [1.37 (1.23-1.54)], CVD [1.34 (1.03-1.74)], chronic pulmonary disease (CPD) [1.22 (1.08-1.37)], neurological disease [1.19 (1.05-1.35)], opioid use [1.53 (1.35-1.73)] and iron-deficiency anemia (IDA) [1.15 (1.13-1.17)] were also significantly correlated with higher rate of PJI. Conversely, dysplasia or dislocation [0.65 (0.45-0.93)], and OA [0.70 (0.62-0.79)] were protective factors. Of Note, female gender was protective for PJI only after longer follow-up. Besides, age, smoking, alcohol abuse, previous joint surgery, renal disease, hypertension, cancer, steroid use and liver disease were not closely related with PJI risk.

CONCLUSION

Our finding suggested that the individual-related risk factors for PJI after primary THA included high BMI, DM, AVN, femoral neck fracture, RA, CVD, CPD, neurological disease, opioid use and IDA, while protective factors were female gender, dysplasia/ dislocation and OA.

Incidence and Complication Rates for Total Hip Arthroplasty in Rheumatoid Arthritis: A Systematic Review and Meta-Analysis Across Four Decades

INTRODUCTION

Over the past several decades, management of rheumatoid arthritis (RA) has evolved significantly, but few studies have examined the real-world impact of these changes on orthopaedic surgery in patients with RA. This systematic review assessed total hip arthroplasty (THA) incidence and postoperative complication rates across the past four decades.

METHODS

This is a systematic literature review sourcing data on THA in patients with RA from the electronic databases MEDLINE, EMBASE, Scopus, and Cochrane between January 1, 1980 and December 31, 2019.

RESULTS

The search retrieved 1715 articles of which 44 were included for quantitative synthesis. The rate for THA decreased by almost 40% from 11/1000 patient years (PY) in the 2000s to 7/1000 PY in the 2010s, while the overall complication rate decreased from 9.9% in the 1990s to 5.3% in the 2010s. Throughout the duration of the study, THA incidence and overall complication rate decreased. However, not all individual complication rates decreased. For example, revision and periprosthetic fracture decreased, infection and aseptic loosening remained constant, and dislocation increased.

CONCLUSION

Medical management of patients with RA has reduced the need for THA, while postoperative medical and surgical management has improved some postoperative outcomes. Nevertheless, there remains room for further improvement to postoperative outcomes through RA-specific management.

Impact of TNF inhibitor therapy on joint replacement rates in rheumatoid arthritis: a matched cohort analysis of BSRBR-RA UK registry data

OBJECTIVES

Previous ecological data suggest a decline in the need for joint replacements in RA patients following the introduction of TNF inhibitor (TNFi) therapy, although patient-level data are lacking. Our primary aim was to estimate the association between TNFi use and subsequent incidence of total hip replacement (THR) and total knee replacement.

METHODS

A propensity score matched cohort was analysed using the British Society for Rheumatology Biologics Registry (2001-2016) for RA data. Propensity score estimates were used to match TNFi users to similar conventional synthetic DMARD users (with replacement) using a 1:1 ratio. Weighted multivariable Cox regression was used to estimate the impact of TNFi on study outcomes. Effect modification by baseline age and disease severity were investigated. Joint replacement at other sites was also analysed. An instrumental variable sensitivity analysis was also performed.

RESULTS

The matched analysis contained a total of 19 116 patient records. Overall, there was no significant association between TNFi use vs conventional synthetic DMARD on rates of THR (hazard ratios = 0.86 [95% CI: 0.60, 1.22]) although there was significant effect modification by age (P < 0.001). TNFi was associated with a reduction in THR among those >60 years old (hazard ratio = 0.60 [CI: 0.41, 0.87]) but not in younger patients. No significant associations were found for total knee replacement or other joint replacement.

CONCLUSION

Overall, no association was found between the use of TNFi and subsequent incidence of joint replacement. However, TNFi was associated with a 40% relative reduction in THR rates among older patients.

Cardiac and vascular complications in rheumatoid arthritis

Rheumatoid arthritis (RA) is an independent risk factor for the development of a variety of cardiovascular diseases, with a 1.5-factor increase in risk. This literature review aims to provide a global overview of the pathogenesis, effects of anti-rheumatoid treatment on cardiovascular risk, a description of the cardiovascular complications associated with RA, and current opinion on cardiovascular risk assessment and management in patients with RA. Author conducted a literature search in PubMed, Scopus, Web of Science and Embase regarding RA and associated cardiovascular complications. The mechanism of increased risk of cardiovascular disease in patients with RA is complex. There are specific genetic factors associated with both diseases, and traditional cardiovascular risk factors may be more prevalent in patients with RA. Most anti-rheumatic drugs decrease cardiovascular risk, and general recommendations focus on reduction of disease activity and strict management of cardiovascular risk as per the general population.

Efficacy and safety of gyejigachulbutang (Gui-Zhi-Jia-Shu-Fu-Tang, Keishikajutsubuto, TJ-18) for knee pain in patients with degenerative knee osteoarthritis: a randomized, placebo-controlled, patient and assessor blinded clinical trial

Background

Degenerative knee osteoarthritis is a leading cause of disability in the elderly. If patients do not respond to pharmacological or nonpharmacological intervention, total knee replacement surgery is recommended. However, owing to the contraindications and adverse effects of surgery, the need for a new treatment strategy is emerging. Traditional herbal medicine is a widely used intervention in east Asia to treat knee osteoarthritis. Gyejigachulbutang is one of the frequently prescribed herbal formulae. The aim of our study is to evaluate the efficacy and safety of gyejigachulbutang for knee osteoarthritis.

Methods

This study is a randomized, placebo-controlled, patient and assessor blinded, superiority clinical trial. A total of 80 patients with knee osteoarthritis will be enrolled. The participants will be randomly assigned to the gyejigachulbutang or placebo group in a 1:1 ratio in two Korean medical hospitals. Every participant will take gyejigachulbutang or placebo at a dose of 2.5 g three times a day for 4 weeks. Additional follow-up will be conducted 4 weeks after treatment completion. Any concomitant treatment to relive knee pain will not be allowed except for rescue medicine (acetaminophen). The primary outcome will be a comparison of the change in the visual analogue scale score for knee pain from baseline to visit 3 (week 4) for both the treatment and placebo groups. Secondary outcomes include clinical relevance, minimal clinically important difference, disability, quality of life, and safety.

Discussion

This protocol presents a research methodology for clinical trials of gyejigachulbutang for knee osteoarthritis. Various secondary outcomes make this trial more informative. Our trial will provide fundamental evidence for knee osteoarthritis management via herbal medicine treatment.

Trial registration

Clinical Research Information Service (CRIS), KCT0003024. Registered on 25 July 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3234-6) contains supplementary material, which is available to authorized users.