Development and validation of a machine learning-supported strategy of patient selection for osteoarthritis clinical trials: the IMI-APPROACH study

Objectives

To efficiently assess the disease-modifying potential of new osteoarthritis treatments, clinical trials need progression-enriched patient populations. To assess whether the application of machine learning results in patient selection enrichment, we developed a machine learning recruitment strategy targeting progressive patients and validated it in the IMI-APPROACH knee osteoarthritis prospective study.

Design

We designed a two-stage recruitment process supported by machine learning models trained to rank candidates by the likelihood of progression. First stage models used data from pre-existing cohorts to select patients for a screening visit. The second stage model used screening data to inform the final inclusion. The effectiveness of this process was evaluated using the actual 24-month progression.

Results

From 3500 candidate patients, 433 with knee osteoarthritis were screened, 297 were enrolled, and 247 completed the 2-year follow-up visit. We observed progression related to pain (P, 30%), structure (S, 13%), and combined pain and structure (P ​+ ​S, 5%), and a proportion of non-progressors (N, 52%) ∼15% lower vs an unenriched population. Our model predicted these outcomes with AUC of 0.86 [95% CI, 0.81-0.90] for pain-related progression and AUC of 0.61 [95% CI, 0.52-0.70] for structure-related progression. Progressors were ranked higher than non-progressors for P ​+ ​S (median rank 65 vs 143, AUC = 0.75), P (median rank 77 vs 143, AUC = 0.71), and S patients (median rank 107 vs 143, AUC = 0.57).

Conclusions

The machine learning-supported recruitment resulted in enriched selection of progressive patients. Further research is needed to improve structural progression prediction and assess this strategy in an interventional trial.

Machine-learning predicted and actual 2-year structural progression in the IMI-APPROACH cohort

In the Innovative Medicine's Initiative Applied Public-Private Research enabling OsteoArthritis Clinical Headway (IMI-APPROACH) knee osteoarthritis (OA) study, machine learning models were trained to predict the probability of structural progression (s-score), predefined as >0.3 mm/year joint space width (JSW) decrease and used as inclusion criterion. The current objective was to evaluate predicted and observed structural progression over 2 years according to different radiographic and magnetic resonance imaging (MRI)-based structural parameters. Radiographs and MRI scans were acquired at baseline and 2-year follow-up. Radiographic (JSW, subchondral bone density, osteophytes), MRI quantitative (cartilage thickness), and MRI semiquantitative [SQ; cartilage damage, bone marrow lesions (BMLs), osteophytes] measurements were obtained. The number of progressors was calculated based on a change exceeding the smallest detectable change (SDC) for quantitative measures or a full SQ-score increase in any feature. Prediction of structural progression based on baseline s-scores and Kellgren-Lawrence (KL) grades was analyzed using logistic regression. Among 237 participants, around 1 in 6 participants was a structural progressor based on the predefined JSW-threshold. The highest progression rate was seen for radiographic bone density (39%), MRI cartilage thickness (38%), and radiographic osteophyte size (35%). Baseline s-scores could only predict JSW progression parameters (most P>0.05), while KL grades could predict progression of most MRI-based and radiographic parameters (P<0.05). In conclusion, between 1/6 and 1/3 of participants showed structural progression during 2-year follow-up. KL scores were observed to outperform the machine-learning-based s-scores as progression predictor. The large amount of data collected, and the wide range of disease stage, can be used for further development of more sensitive and successful (whole joint) prediction models. Trial Registration: Clinicaltrials.gov number NCT03883568.

The association of the lipid profile with knee and hand osteoarthritis severity: the IMI-APPROACH cohort

OBJECTIVE

To investigate the association of the lipidomic profile with osteoarthritis (OA) severity, considering the outcomes radiographic knee and hand OA, pain and function.

DESIGN

We used baseline data from the Applied Public-Private Research enabling OsteoArthritis Clinical Headway (APPROACH) cohort, comprising persons with knee OA fulfilling the clinical American College of Rheumatology classification criteria. Radiographic knee and hand OA severity was quantified with Kellgren-Lawrence sum scores. Knee and hand pain and function were assessed with validated questionnaires. We quantified fasted plasma higher order lipids and oxylipins with liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based platforms. Using penalised linear regression, we assessed the variance in OA severity explained by lipidomics, with adjustment for clinical covariates (age, sex, body mass index (BMI) and lipid lowering medication), measurement batch and clinical centre.

RESULTS

In 216 participants (mean age 66 years, mean BMI 27.3 kg/m², 75% women) we quantified 603 higher order lipids (triacylglycerols, diacylglycerols, cholesteryl esters, ceramides, free fatty acids, sphingomyelins, phospholipids) and 28 oxylipins. Lipidomics explained 3% and 2% of the variance in radiographic knee and hand OA severity, respectively. Lipids were not associated with knee pain or function. Lipidomics accounted for 12% and 6% of variance in hand pain and function, respectively. The investigated OA severity outcomes were associated with the lipidomic fraction of bound and free arachidonic acid, bound palmitoleic acid, oleic acid, linoleic acid and docosapentaenoic acid.

CONCLUSIONS

Within the APPROACH cohort lipidomics explained a minor portion of the variation in OA severity, which was most evident for the outcome hand pain. Our results suggest that eicosanoids may be involved in OA severity.

Neuropathic pain in the IMI-APPROACH knee osteoarthritis cohort: prevalence and phenotyping

Objectives

Osteoarthritis (OA) patients with a neuropathic pain (NP) component may represent a specific phenotype. This study compares joint damage, pain and functional disability between knee OA patients with a likely NP component, and those without a likely NP component.

Methods

Baseline data from the Innovative Medicines Initiative Applied Public-Private Research enabling OsteoArthritis Clinical Headway knee OA cohort study were used. Patients with a painDETECT score ≥19 (with likely NP component, n=24) were matched on a 1:2 ratio to patients with a painDETECT score ≤12 (without likely NP component), and similar knee and general pain (Knee Injury and Osteoarthritis Outcome Score pain and Short Form 36 pain). Pain, physical function and radiographic joint damage of multiple joints were determined and compared between OA patients with and without a likely NP component.

Results

OA patients with painDETECT scores ≥19 had statistically significant less radiographic joint damage (p≤0.04 for Knee Images Digital Analysis parameters and Kellgren and Lawrence grade), but an impaired physical function (p<0.003 for all tests) compared with patients with a painDETECT score ≤12. In addition, more severe pain was found in joints other than the index knee (p≤0.001 for hips and hands), while joint damage throughout the body was not different.

Conclusions

OA patients with a likely NP component, as determined with the painDETECT questionnaire, may represent a specific OA phenotype, where local and overall joint damage is not the main cause of pain and disability. Patients with this NP component will likely not benefit from general pain medication and/or disease-modifying OA drug (DMOAD) therapy. Reserved inclusion of these patients in DMOAD trials is advised in the quest for successful OA treatments.

Trial registration number

The study is registered under clinicaltrials.gov nr: NCT03883568.

The association of clinical and structural knee osteoarthritis with physical activity in the middle-aged population: the NEO study

OBJECTIVE

To investigate if knee osteoarthritis (OA) is associated with lower physical activity in the general middle-aged Dutch population, and if physical activity is associated with patient-reported outcomes in knee OA.

DESIGN

Clinical knee OA was defined in the Netherlands Epidemiology of Obesity population using the ACR criteria, and structural knee OA on MRI. We assessed knee pain and function with the Knee Injury and Osteoarthritis Score (KOOS), health-related quality of life (HRQoL) with the Short Form-36, and physical activity (in Metabolic Equivalent of Task (MET) hours) with the Short Questionnaire to Assess Health-enhancing physical activity. We analysed the associations of knee OA with physical activity, and of physical activity with knee pain, function, and HRQoL in knee OA with linear regression adjusted for potential confounders.

RESULTS

Clinical knee OA was present in 14% of 6,212 participants, (mean age 56 years, mean BMI 27 kg/m², 55% women, 24% having any comorbidity) and structural knee OA in 12%. Clinical knee OA was associated with 9.60 (95% CI 3.70; 15.50) MET hours per week more physical activity, vs no clinical knee OA. Structural knee OA was associated with 3.97 (-7.82; 15.76) MET hours per week more physical activity, vs no structural knee OA. In clinical knee OA, physical activity was not associated with knee pain, function or HRQoL.

CONCLUSIONS

Knee OA was not associated with lower physical activity, and in knee OA physical activity was not associated with patient-reported outcomes. Future research should indicate the optimal treatment advice regarding physical activity for individual knee OA patients.

Relationship between motion, using the GaitSmartTM system, and radiographic knee osteoarthritis: an explorative analysis in the IMI-APPROACH cohort

Objectives

To assess underlying domains measured by GaitSmart^TMparameters and whether these are additional to established OA markers including patient reported outcome measures (PROMs) and radiographic parameters, and to evaluate if GaitSmart analysis is related to the presence and severity of radiographic knee OA.

Methods

GaitSmart analysis was performed during baseline visits of participants of the APPROACH cohort (n = 297). Principal component analyses (PCA) were performed to explore structure in relationships between GaitSmart parameters alone and in addition to radiographic parameters and PROMs. Logistic and linear regression analyses were performed to analyse the relationship of GaitSmart with the presence (Kellgren and Lawrence grade ≥2 in at least one knee) and severity of radiographic OA (ROA).

Results

Two hundred and eighty-four successful GaitSmart analyses were performed. The PCA identified five underlying GaitSmart domains. Radiographic parameters and PROMs formed additional domains indicating that GaitSmart largely measures separate concepts. Several GaitSmart domains were related to the presence of ROA as well as the severity of joint damage in addition to demographics and PROMs with an area under the receiver operating characteristic curve of 0.724 and explained variances (adjusted R²) of 0.107, 0.132 and 0.147 for minimum joint space width, osteophyte area and mean subchondral bone density, respectively.

Conclusions

GaitSmart analysis provides additional information over established OA outcomes. GaitSmart parameters are also associated with the presence of ROA and extent of radiographic severity over demographics and PROMS. These results indicate that Gaitsmart^TM may be an additional outcome measure for the evaluation of OA.

Mediation of the association between obesity and osteoarthritis by blood pressure, vessel wall stiffness and subclinical atherosclerosis

Objective

We investigated the role of blood pressure, vessel wall stiffness [pulse wave velocity (PWV)] and subclinical atherosclerosis markers [carotid intima-media thickness (cIMT), popliteal vessel wall thickness (pVWT)] as mediators of the association of obesity with OA.

Methods

We used cross-sectional data from a subset of the population-based NEO study (n = 6334). We classified clinical hand and knee OA by the ACR criteria, and structural knee OA, effusion and bone marrow lesions on MRI (n = 1285). cIMT was assessed with ultrasonography. pVWT was estimated on knee MRI (n = 1285), and PWV by abdominal velocity-encoded MRIs (n = 2580), in subpopulations. Associations between BMI and OA were assessed with logistic regression analyses, adjusted for age, sex and education. Blood pressure, cIMT, pVWT and PWV were added to the model to estimate mediation.

Results

The population consisted of 55% women, with a mean (s.d.) age of 56(6) years. Clinical hand OA was present in 8%, clinical knee OA in 10%, and structural knee OA in 12% of participants. BMI was positively associated with all OA outcomes. cIMT partially mediated the association of BMI with clinical hand OA [10.6 (6.2; 30.5)%], structural knee OA [3.1 (1.9; 7.3)%] and effusion [10.8 (6.0; 37.6)%]. Diastolic blood pressure [2.1 (1.6; 3.0)%] minimally mediated the association between BMI and clinical knee OA. PWV and pVWT did not mediate the association between BMI and OA.

Conclusions

cIMT and diastolic blood pressure minimally mediated the association of BMI with OA. This suggests that such mediation is trivial in the middle-aged population.

POS1431 THE ASSOCIATION OF CLINICAL AND STRUCTURAL KNEE OSTEOARTHRITIS WITH PHYSICAL ACTIVITY IN THE MIDDLE-AGED POPULATION: THE NEO STUDY

Background:

Lack of physical activity in individuals with knee OA has shown to be associated with increased cardiovascular risk and mortality. Consequently, physical activity is a potential target for interventions in knee OA. However, most of the available studies concerning physical activity in individuals with knee OA were performed in relatively old populations with an inactive lifestyle. It is unclear how previous results can be generalized to other populations with different lifestyle and physical activity habits.

Objectives:

To investigate if knee OA is associated with lower physical activity in a general middle-aged Dutch population. Furthermore, to investigate the association of physical activity with patient reported outcomes such as knee pain and function, and health-related quality of life in individuals with knee OA.

Methods:

We used cross-sectional data from the Netherlands Epidemiology of Obesity (NEO) study, in which participants aged 45-65 years were included. Clinical knee OA was defined using the ACR criteria. Structural knee OA was defined on MRI using the modified criteria by Hunter et al. in a random subset of 1,285 individuals of our study population.

We assessed knee pain and function with the Knee injury and Osteoarthritis Score (KOOS), and health-related quality of life (HRQoL) with the Short Form (SF)-36. Physical activity (in Metabolic Equivalent of Task (MET) hours per week) was assessed using the Short Questionnaire to Assess Health-enhancing physical activity (SQUASH).

We used linear regression analyses to investigate 1) the association of knee OA with physical activity, and 2) of physical activity with knee pain, function, and HRQoL in participants with clinical knee OA. All analyses were adjusted for age, sex, body mass index (BMI), ethnicity, educational level and comorbidities. To account for possible information bias, we performed a sensitivity analysis to assess the association between clinical knee OA and physical activity measured by an accelerometer in a random subset of 15% of the study population.

Results:

Of 6,212 participants, we observed clinical knee OA in 14%, and structural knee OA in 12%. The general population characteristics and median physical activity of our study population are presented in Table 1. In comparison to participants without knee OA, participants with clinical knee OA had on average 9.60 (95% CI 3.70;15.50) MET hours per week more total physical activity (Figure 1). Structural knee OA was associated with 3.97 (-7.82; 15.76) MET hours per week more physical activity, compared with no structural knee OA.

Sensitivity analysis showed a weak positive association of clinical knee OA with physical activity measured by an accelerometer: 2.37 (-6.05; 10.80) MET hours per week more physical activity in participants with clinical knee OA, compared with participants without clinical knee OA.

In the subpopulation of participants with clinical knee OA, physical activity was not associated with knee pain, function or HRQoL.

Conclusion:

Knee OA was not associated with lower physical activity in this middle-aged Dutch population. This contrasts previous findings and warrants caution when generalizing physical activity outcomes to other populations. Furthermore, it stresses the need of more insight in the barriers and facilitators of physical activity in the middle-aged population.

Table 1.

Characteristics of the NEO study population

Alln = 6,214No clinical knee OA86%Clinical knee OA14%General population characteristics Age (year)55.7 (6.0)55.4 (6.1)57.5 (5.0) Sex (% women)555467 BMI (kg/m2)26.3 (4.4)26.1 (4.3)27.6 (5.1) Comorbidities (% present)242332Physical activity Total^ (MET-hours per week)118.8 (76.8;155.0)118.4 (76.6;154.4)123.5 (77.8;157.2)

Numbers represent mean (SD) or percentages. ^median (25th, 75th percentiles). Abbreviations: OA = osteoarthritis. BMI = Body Mass Index. MET = Metabolic Equivalent of Task.

Disclosure of Interests:

None declared

POS1087 USING LIPIDOMICS TO PREDICT PREDNISOLONE TREATMENT RESPONSE IN PATIENTS WITH INFLAMMATORY HAND OSTEOARTHRITIS: THE HOPE STUDY

Background:

Lipidomics analysis has become a valuable technology for understanding patho-physiological mechanisms and may aid the identification of biomarkers of therapeutic responsiveness.

Objectives:

To explore the use of lipidomics for prediction of prednisolone treatment response in patients with inflammatory hand osteoarthritis.

Methods:

The Hand Osteoarthritis Prednisolone Efficacy (HOPE) study is a blinded, randomized placebo-controlled trial, that investigated the effect of prednisolone treatment in patients with painful, inflammatory hand OA, fulfilling the American College of Rheumatology criteria. The present analyses comprised only patients randomized to daily 10 mg prednisolone treatment for six weeks. Response to prednisolone treatment was defined according to the OARSI-OMERACT responder criteria at six weeks. Baseline blood samples were obtained non-fasted. Lipid species were quantified in erythrocytes with the LipidyzerTM platform (Sciex). After pre-processing of the data, 286 lipids species were available for further analyses (nmol/mL). In addition, we used an in-house LC-MS/MS platform to analyse oxylipins in plasma, identifying 25 oxylipins (area ratios). Elastic net regularized regression was used to predict prednisolone treatment response. A 10-fold cross-validation (CV) was performed for selection of the optimal tuning parameters based on the smallest CV mean prediction error. First, a model was fit with commonly assessed patient characteristics and patient reported outcomes, measured at baseline (model 1). Second, we fitted model 2 by adding the LipidyzerTM platform lipids to model 1. Third, we fitted model 3 by adding the oxylipins to model 1. The discriminatory accuracy of the model was estimated by receiver operating characteristic (ROC) analyses. The area under the curve (AUC) and corresponding 95% confidence intervals (CI) were calculated using 1,000 bootstrap replications.

Results:

Among the 40 patients included, 31 (78%) fulfilled the OARSI-OMERACT responder criteria. From the included general patient characteristics (Table 1), elastic net selected baseline hand function as only predictor of treatment response, with an AUC of 0.78 (95% CI 0.60;0.96) (Figure 1). In model 2, we added the 286 LipidyzerTM platform variables to model 1. In addition to hand function, two lipids were selected: diacylglycerol(DAG)(16:0/16:0) and phosphatidylethanolamine(PE)(O-18:0/20:4), which improved the discriminatory accuracy to an AUC of 0.92 (0.83;1.02). Lastly, model 3 was fit with patient characteristics as well as oxylipins, resulting in selection of AUSCAN function and three oxylipin predictors: 9-hydroxy-octadecatrienoic acid (HOTrE), 5-hydroxy-eicosapentaenoic acid (HEPE) and 10-hydroxy-docosahexaenoic acid (HDHA), with an AUC of 0.85 (0.69;1.02).

Conclusion:

The patients’ lipid profile improved the discriminative accuracy of the prediction of prednisolone treatment response in patients with inflammatory hand osteoarthritis compared to prediction by commonly measured patient characteristics alone. This exploratory study suggests that lipidomics is a promising field for biomarker discovery for prediction of anti-inflammatory treatment response.

Table 1.

Baseline characteristics

All prednisolone treatedn = 40Respondersn = 31 (78%)Non-respondersn = 9 (23%)General characteristicsAge, year62.4 (9.3)62.9 (9.4)60.8 (9.4)Sex, % women858489BMI, kg/m227.4 (4.4)27.8 (4.2)26.2 (5.0)Education, % high464256Disease duration6.7 (7.1)7.2 (7.4)4.9 (5.8)Erosive OA, %717456Kellgren-Lawrence sum score, 0-12035.1 (16.4)34.1 (16.5)37.5 (14.7)Ultrasound synovitis sum score, 0-9016.2 (6.6)15.5 (6.4)18.7 (7.2)VAS global assessment, 0-10052.3 (20.6)54.2 (16.8)45.6 (30.8)AUSCAN pain, 0-2011.0 (3.3)11.3 (2.4)10 (5.4)AUSCAN function, 0-3617.7 (7.6)19.6 (6.6)11 (7.5)

Numbers represent mean (SD) unless otherwise specified. AUSCAN = Australian/Canadian Hand Osteoarthritis Index, BMI = body mass index, VAS = visual analogue scale

Disclosure of Interests:

Marieke Loef: None declared, Tariq Faquih: None declared, Johannes von Hegedus: None declared, Mohan Ghorasaini: None declared, Andreea Ioan-Facsinay: None declared, Féline Kroon: None declared, Martin Giera Shareholder of: Pfizer, Consultant of: Boehringer Ingelheim Pharma, Margreet Kloppenburg: None declared.

POS0371 BIOLOGICAL REPRODUCIBILITY OF TARGETED LIPIDOME ANALYSES IN PLASMA AND ERYTHROCYTES OVER A 6-WEEK PERIOD

Background:

Lipidomics analysis has become a valuable technology for understanding patho-physiological mechanisms and the identification of candidate biomarkers in rheumatic musculoskeletal disorders. Variability in within-subject repeated measurements may lead to bias towards the null when estimating the association between biomarkers and a disease or treatment. Hence, information regarding the stability of the metabolite levels over time is essential.

Objectives:

We aimed to assess the lipid composition and biological reproducibility of lipid measurements in plasma and erythrocytes.

Methods:

Plasma and erythrocyte samples from 42 osteoarthritis patients (77% women, mean age 65 years, mean BMI 27 kg/m2), obtained non-fasted at baseline and six weeks, were used for the quantitative measurement of up to 1000 lipid species across 13 lipid classes with the LipidyzerTM platform in nmol/mL. Data was processed based on the relative standard deviation of quality controls, taking batch effects into account. Intraclass correlation coefficients (ICCs) and corresponding 95% confidence intervals (CI) were calculated to investigate the variability of the lipid concentrations between timepoints. The ICC distribution of lipid metabolites in plasma and erythrocytes were compared using two-sided paired Wilcoxon tests.

Results:

We measured 778 lipids in plasma, compared to 916 lipids in erythrocytes. After data processing, the analyses included 630 lipids in plasma, and 286 in erythrocytes. From these, 243 lipids overlapped between sample types. Major differences were observed between the sample types in the number of lipids per lipid class and the total concentration of the lipids within a class. Triacylglycerols (TAG) and cholesteryl esters (CE) were more abundant in plasma. Conversely, phosphatidylethanolamines (PE), sphingomyelins (SM) and ceramides (CER) were less abundant in plasma compared to erythrocytes (table 1). In plasma 78% of lipid measurements were good to excellently reproduced, with an overall median ICC 0.69. Compared to plasma, a considerably lower amount (35%) of lipids were well reproduced in erythrocytes. Median reproducibility of lipids in erythrocytes was 0.51. Figure 1 shows the ICC score distribution in plasma with erythrocytes, with a significantly better reproducibility in plasma (p-value<0.001). However, while overall reproducibility was better in plasma, this was not observed for all lipid classes. At class-level, reproducibility in plasma was superior for TAGs and CEs, while CERs, DAGs, (L)PEs and SMs showed better reproducibility in erythrocytes.

Table 1.

Number of individual lipids per class and class concentrations in plasma and erythrocytes

PlasmaErythrocytesNumber of lipid speciesClass concentration (nmol/mL)Number of lipid speciesClass concentration (nmol/mL)Triacylglycerols4821579.4 (1064.9-3195.2)1346.5 (5.6-9.4)Diacylglycerols913.3 (8.4-22.2)105.8 (4.7-6.2)Free fatty acids20745.3 (552.0-1202.9)20486.9 (379.2-669.2)Cholesteryl esters244571.6 (4065.1-5521.3)51.2 (0.9-1.7)Phosphatidylcholines314013.7 (3203.1-4661.6)423899.2 (3723.0-4296.6)Phosphatidylethanolamines26156.2 (120.9-180.3)423954.6 (3721.9-4323.3)Lysophosphatidylcholines9385.9 (335.6-442.9)7119.8 (109.7-168.9)Lysophosphatidylethanolamines24.2 (3.5-4.9)48.6 (6.8-9.7)Sphingomyelins121204.6 (1037.0-1351.9)82695.8 (2434.8-2815.6)Ceramides614.1 (11.9-17.4)7163.0 (133.3-186.4)Dihydroceramides21.0 (0.8-1.3)11.8 (1.4-2.1)Hexosylceramides55.1 (4.7-5.9)45.6 (5.0-7.4)Lactosylceramides23.4 (2.7-3.8)223.8 (20.6-33.5)

Numbers represent median (interquartile range) unless otherwise specified. Data represents baseline measurements.

Conclusion:

In plasma biological reproducibility was good for most lipid measurements. Although overall reproducibility was better in plasma compared to erythrocytes, notable differences were observed at individual- and lipid class-level that may favour the use of a particular sample type.

Disclosure of Interests:

Marieke Loef: None declared, Johannes von Hegedus: None declared, Mohan Ghorasaini: None declared, Féline Kroon: None declared, Martin Giera Shareholder of: Pfizer, Consultant of: Boehringer Ingelheim Pharma, Andreea Ioan-Facsinay: None declared, Margreet Kloppenburg: None declared

Percentile curves for the knee injury and osteoarthritis outcome score in the middle-aged Dutch population

OBJECTIVE

To improve the interpretation of the Knee injury and Osteoarthritis Outcome Score (KOOS) in individual patients, we explored associations with age, sex, BMI, history of knee injury and presence of clinical knee osteoarthritis, and developed percentile curves.

METHODS

We used cross-sectional data of middle-aged individuals from the population-based Netherlands Epidemiology of Obesity (NEO) study. Clinical knee osteoarthritis was defined using the ACR classification criteria. KOOS scores were handled according to the manual (zero = extreme problems, 100 = no problems). Patient characteristics associated with KOOS were explored using ordered logistic regression, and sex and body mass index (BMI)-specific percentile curves were developed using quantile regression with fractional polynomials. The curves were applied as a benchmark for comparison of KOOS scores of participants with knee osteoarthritis and comorbidities.

RESULTS

The population consisted of 6,643 participants (56% women, mean (SD) age 56(6) years). Population-based KOOS subscale scores (median; interquartile range) near optimum: pain (100;94-100), symptoms (96;86-100), ADL function (100;96-100), sport/recreation function (100;80-100), quality of life (100;75-100). Worse KOOS scores were observed in women and in participants with higher BMI. Clinical knee osteoarthritis was defined in 15% of participants, and was, in comparison to other patient characteristics, associated with the highest odds of worse KOOS scores. Furthermore, presence of any comorbidity and cardiovascular disease specifically, was associated with worse KOOS scores, particularly in women.

CONCLUSIONS

In the middle-aged Dutch population KOOS scores were generally good, but worse in women and with higher BMI. These percentile curves may be used as benchmarks in research and clinical practice.

Cohort profile: The Applied Public-Private Research enabling OsteoArthritis Clinical Headway (IMI-APPROACH) study: a 2-year, European, cohort study to describe, validate and predict phenotypes of osteoarthritis using clinical, imaging and biochemical markers

PURPOSE

The Applied Public-Private Research enabling OsteoArthritis Clinical Headway (APPROACH) consortium intends to prospectively describe in detail, preselected patients with knee osteoarthritis (OA), using conventional and novel clinical, imaging, and biochemical markers, to support OA drug development.

PARTICIPANTS

APPROACH is a prospective cohort study including 297 patients with tibiofemoral OA, according to the American College of Rheumatology classification criteria. Patients were (pre)selected from existing cohorts using machine learning models, developed on data from the CHECK cohort, to display a high likelihood of radiographic joint space width (JSW) loss and/or knee pain progression.

FINDINGS TO DATE

Selection appeared logistically feasible and baseline characteristics of the cohort demonstrated an OA population with more severe disease: age 66.5 (SD 7.1) vs 68.1 (7.7) years, min-JSW 2.5 (1.3) vs 2.1 (1.0) mm and Knee injury and Osteoarthritis Outcome Score pain 31.3 (19.7) vs 17.7 (14.6), except for age, all: p<0.001, for selected versus excluded patients, respectively. Based on the selection model, this cohort has a predicted higher chance of progression.

FUTURE PLANS

Patients will visit the hospital again at 6, 12 and 24 months for physical examination, pain and general health questionnaires, collection of blood and urine, MRI scans, radiographs of knees and hands, CT scan of the knee, low radiation whole-body CT, HandScan, motion analysis and performance-based tests.After two years, data will show whether those patients with the highest probabilities for progression experienced disease progression as compared to those wit lower probabilities (model validation) and whether phenotypes/endotypes can be identified and predicted to facilitate targeted drug therapy.

TRIAL REGISTRATION NUMBER

NCT03883568.

FRI0413 THE ASSOCIATION OF OBESITY WITH OSTEOARTHRITIS IS LIMITEDLY MEDIATED BY HYPERTENSION AND SUBCLINICAL ATHEROSCLEROSIS

Background:

Obesity-related metabolic dysregulation may lead to atherosclerotic vascular changes. It has been hypothesized that a compromised blood flow may cause detrimental changes to the subchondral bone and decrease nutrient supply to the cartilage. To which extent atherosclerosis may explain the association between obesity and OA has not been investigated.

Objectives:

To investigate the role of hypertension and subclinical atherosclerosis (carotid intima-media thickness (IMT), popliteal vessel wall thickness (VWT), aortic pulse wave velocity (PWV)) as mediators of the association of obesity with hand and knee OA.

Methods:

We used cross-sectional data from the population-based NEO study, excluding participants with concomitant rheumatic diseases (n = 323), resulting in 6,334 participants. Clinical hand and knee OA were defined by the ACR classification criteria. Popliteal VWT was assessed on MR images in a subpopulation (n = 1,095), using VesselMASS for semi-automated detection of the vessel wall boundaries. Aortic PWV was estimated on abdominal velocity-encoded MR images in a subpopulation (n = 2,580). Carotid IMT was assessed by ultrasonography. Hypertension was defined as a systolic blood pressure ≥ 130 mmHg or a diastolic blood pressure ≥ 85 mmHg, or using antihypertensive medication. Continuous variables were standardized (mean 0, standard deviation 1). Associations between BMI and OA were assessed with logistic regression analyses, adjusted for age, sex and education. Subsequently, possible mediators were added to the model and the percentage mediation was calculated.

Results:

The population consisted of 55% women, with a mean (SD) age of 56 (6) years and BMI of 26 (4) kg/m2. Hand OA was present in 8% and knee OA in 10% of participants. Hypertension was present in 61.6% of participants. Mean (SD) carotid IMT was 0.62 (0.09) mm, popliteal VWT was 0.53 (0.05) mm, and aortic PWV was 6.56 (1.30) m/s. BMI was associated with the presence of hand OA and knee OA (table 1). BMI was positively associated with hypertension and carotid IMT, but not with popliteal VWT and aortic PWV. The association between BMI and hand OA was partially mediated by hypertension (5.9%) and carotid IMT (10.6%). Hypertension (4.9%) showed a weak mediating effect for the association between BMI and knee OA.

Table 1.

Mediation of the association of BMI with OA by hypertension and atherosclerosis

Hand OAOR (95% CI)MediatorOR/β (95% CI)Hand OAOR (95% CI)Mediation% (95% CI)BMI1.21 (1.08; 1.36)1.72 (1.56; 1.90)1.20 (1.06; 1.36)5.9 (3.4; 17.4)Hypertension1.15 (0.82; 1.60)BMI1.21 (1.08; 1.36)0.23 (0.19; 0.27)1.19 (1.05; 1.34)10.6 (6.2; 30.5)Carotid IMT1.09 (0.94; 1.25)BMI1.56 (1.17; 2.08)0.01 (-0.06; 0.09)1.55 (1.16; 2.07)0.5 (0.3; 1.7)Popliteal VWT1.14 (0.84; 1.55)BMI1.41 (1.15; 1.73)0.05 (-0.01; 0.11)1.41 (1.15; 1.73)0.7 (0.4; 2.0)Aorta PWV1.04 (0.81; 1.33)Knee OAOR (95% CI)MediatorOR/β (95% CI)Knee OAOR (95% CI)BMI1.46 (1.32; 1.62)1.70 (1.55; 1.87)1.43 (1.29; 1.59)4.9 (3.7; 7.0)Hypertension1.25 (0.93; 1.67)BMI1.46 (1.32; 1.62)0.24 (0.20; 0.27)1.47 (1.33; 1.62)-1.6 (-2.4; -1.2)Carotid IMT0.97 (0.86; 1.09)BMI1.20 (0.88; 1.64)0.03 (-0.04; 0.11)1.21 (0.89; 1.64)-0.5 (-7.4; 13.3)Popliteal VWT0.95 (0.74; 1.24)BMI1.37 (1.12; 1.67)0.05 (-0.00; 0.11)1.37 (1.12; 1.67)-0.5 (-1.8; -0.3)Aorta PWV0.96 (0.76; 1.21)

Results are based on analyses weighted towards the BMI distribution of the general population (n = 6,334). Analysis regarding popliteal VWT (n = 1,095) and aorta PWV (n = 2,580) were assessed in a subpopulation Continuous variables were standardized (mean 0, SD 1), SD BMI = 4.41, SD carotid IMT = 0.09, SD popliteal VWT = 0.05, SD aorta PWV = 1.30.

Conclusion:

We assessed whether the association between BMI and OA was mediated by hypertension and atherosclerosis. Our results imply that either such mediation is absent or trivial, or that the atherosclerosis measures were too weak.

Disclosure of Interests:

None declared

The association of plasma fatty acids with hand and knee osteoarthritis: the NEO study

OBJECTIVE

To investigate the association of postprandial and fasting plasma saturated fatty acid (SFAs), monounsaturated fatty acid (MUFAs) and polyunsaturated fatty acid (PUFAs) concentrations with hand and knee osteoarthritis (OA).

DESIGN

In the population-based NEO study clinical hand and knee OA were defined by the ACR classification criteria. Structural knee OA was defined on MRI. Hand and knee pain was determined by Australian/Canadian Hand Osteoarthritis Index (AUSCAN) and KOOS, respectively. Plasma was sampled fasted and 150 min after a standardized meal, and subsequently analysed using a nuclear magnetic resonance platform. Logistic regression analyses were used to investigate the association of total fatty acid, SFA, MUFA, total PUFA, omega-3 PUFA and omega-6 PUFA concentrations with clinical hand and knee OA, structural knee OA and hand and knee pain. Fatty acid concentrations were standardized (mean 0, SD 1). Analyses were stratified by sex and corrected for age, education, ethnicity and total body fat percentage.

RESULTS

Of the 5,328 participants (mean age 56 years, 58% women) 7% was classified with hand OA, 10% with knee OA and 4% with concurrent hand and knee OA. In men, postprandial SFAs (OR (95% CI)) 1.23 (1.00; 1.50), total PUFAs 1.26 (1.00; 1.58) and omega-3 PUFAs 1.24 (1.01; 1.52) were associated with hand OA. SFAs and PUFAs were associated with structural, but not clinical knee OA. Association of fasting fatty acid concentrations were weaker than postprandial concentrations.

CONCLUSION

Plasma postprandial SFA and PUFA levels were positively associated with clinical hand and structural knee OA in men, but not in women.

Health-related Quality of Life in Patients with Hand Osteoarthritis from the General Population and the Outpatient Clinic

Objective.

To investigate the association of hand osteoarthritis (OA) and concurrent hand and knee OA with health-related quality of life (HRQOL) in the general population, and in patients consulting a rheumatology outpatient clinic.

Methods.

In the population-based Netherlands Epidemiology of Obesity (NEO) study, participants were recruited from the greater area of Leiden, the Netherlands. In the Hand OSTeoArthritis in Secondary care (HOSTAS) study, patients with a rheumatologist’s diagnosis of hand OA were recruited from a Leiden-based hospital. In both cohorts, hand and knee OA were defined by the American College of Rheumatology clinical criteria. In NEO, self-reported hospital-based specialist consultation for OA was recorded. Physical and mental HRQOL was assessed with normalized Medical Outcomes Study Short Form-36 scores. Associations were analyzed using linear regression, adjusted for age, sex, education, ethnicity, and body mass index.

Results.

Hand OA alone and concurrent hand and knee OA was present in 8% and 4% of 6334 NEO participants, and in 57% and 32% of 538 HOSTAS patients. In NEO, hand OA alone, and concurrent hand and knee OA, were associated with lower physical component summary (PCS) scores [mean difference −2.4 (95% CI −3.6, −1.3) and −7.7 (95% CI −9.3, −6.2), respectively] compared with no OA. Consulting a specialist was associated with worse PCS scores. In the HOSTAS cohort, mean PCS scores were lower than norm values (−3.5 and −7.9 for hand OA and combined OA, respectively). Mental HRQOL was not clinically relevantly associated in either cohort.

Conclusion.

Hand OA was associated with reduced physical, but not mental, HRQOL in the general population and hospital patients. Physical HRQOL was further reduced in hospital care, and with concurrent knee OA.

TNF inhibitor treatment is associated with a lower risk of hand osteoarthritis progression in rheumatoid arthritis patients after 10 years

Objective

To investigate the effect of TNF inhibitors (TNFis) on incidental and progressive hand OA in recent-onset RA patients after a 10 year follow-up.

Methods

Radiographs of 262 RA patients (mean age 52 years, 66% women) from the BeSt study were scored for osteophytes in DIP/PIP joints using the Osteoarthritis Research Society International atlas (0-3; summed score 0-54) and according to the Kellgren-Lawrence (KL) score (0-4; summed score 0-72) at baseline and 10 year follow-up. TNFi treatment was assessed on visits every 3 months. Associations between TNFi treatment and hand OA were analysed on the patient and joint level using generalized linear models and generalized estimating equations, respectively.

Results

Fifty-eight percent of the patients were treated with TNFi, with a median duration of 42 months. A total of 143 patients (55%) had hand OA in any IP joint at baseline based on the Osteoarthritis Research Society International osteophyte score. On the patient level, TNFi treatment duration did not affect incidental hand OA. However, every month of TNFi treatment resulted in a reduced relative risk (RR) of hand OA progression in DIP joints [relative risk (RR) 0.987 (95% CI 0.978, 0.996)] but not in PIP joints. On the joint level, the effect on hand OA progression was observed in DIP joints [RR 0.996 (95% CI 0.991, 1.000)] but not in PIP joints. The results from the KL score analyses were comparable to the osteophyte score.

Conclusion

TNFi treatment was associated with a reduced risk on radiographic hand OA progression in DIP joints but not in PIP joints after 10 years. Although the effect sizes are small, these results provide evidence for influence of TNF-α in hand OA pathogenesis.

Fatty acids and osteoarthritis: different types, different effects

While the association between obesity and osteoarthritis used to be solely regarded as a result of increased mechanical loading, systemic factors also likely play a role in the pathophysiology of osteoarthritis. Nutrient excess leading to obesity may result in lipotoxicity, which might be involved in the development of osteoarthritis. The different fatty acid types have distinct effects on inflammation. This review focusses on the currently available studies, summarizing the effects of the different fatty acid types on osteoarthritis and involved joint tissues. In animal studies omega-3 polyunsaturated fatty acids reduced the expression of inflammatory markers, cartilage degradation and oxidative stress in chondrocytes. In contrast, these markers were increased upon omega-6 polyunsaturated fatty acid and saturated fatty acid stimulation. Additionally, a decrease in pain and dysfunction was observed upon omega-3 supplementation in cats and dogs. In line, most human in vitro studies show pro-apoptotic and pro-inflammatory actions of saturated fatty acids. While all polyunsaturated fatty acids reduced markers of oxidative stress, omega-3 polyunsaturated fatty acids additionally decreased prostaglandin production. Human intervention studies with omega-3 polyunsaturated fatty acid supplementation may indicate a beneficial effect on pain and function and might be associated with less structural damage. In contrast, an adverse effect of saturated fatty acids on osteoarthritis has been observed. Monounsaturated fatty acids have been infrequently studied and findings are inconclusive. Existing studies indicate a promising effect of especially omega-3 polyunsaturated fatty acids on osteoarthritis signs and symptoms. However, more human intervention studies are warranted to draw robust conclusions.

Comparison of histological and morphometrical changes underlying subchondral bone abnormalities in inflammatory and degenerative musculoskeletal disorders: a systematic review

OBJECTIVE

Subchondral bone abnormalities (SBAs) on magnetic resonance imaging (MRI) are observed frequently and associated with disease course in various musculoskeletal disorders. This review aims to map the existing knowledge of their underlying histological features, and to identify needs for future research.

DESIGN

We conducted a systematic review following PRISMA guidelines until September 2017, including all studies correlating histological features to on MRI defined SBAs in patients with osteoarthritis (OA), rheumatoid arthritis (RA), spondyloarthritis (SpA) and degenerative disc disease (DDD). Two authors independently retrieved articles and assessed study quality.

RESULTS

A total of 21 studies (466 patients) correlated histological features to SBAs in OA (n = 13), RA (n = 3), ankylosing spondylitis (AS) (n = 1) and DDD (n = 4). Reported changes in OA were substitution of normal subchondral bone with fibrosis and necrosis, and increased bone remodeling. In contrast, in RA, AS or DDD fibrosis was not reported and SBAs correlated to an increase in inflammatory cell number. In DDD necrosis was observed. Similar to OA, increased bone remodeling was shown in RA and DDD. The risk of bias assessment showed a lack in described patient criteria, blinding and/or adequate topographic correlation in approximately half of studies. There was heterogeneity regarding the investigated histological features between the different disorders.

CONCLUSIONS

Current studies suggest that SBAs correlate to various histological features, including fibrosis, cell death, inflammation and bone remodeling. In the majority of studies most quality criteria were not met. Future studies should aim for high quality research, and consistency in investigated features between different disorders.

[Relapse of chronic inflammatory demyelinating polyneuropathy following treatment with zoledronic acid]

BACKGROUND

Zoledronic acid is a nitrogen-containing bisphosphonate that is frequently used in the treatment of osteoporosis. Many patients experience a so-called acute-phase reaction during initial treatment; this is characterized by flu-like symptoms and fever.

CASE DESCRIPTION

We describe a 61-year-old woman who suffered from chronic inflammatory demyelinating polyneuropathy (CIDP), and who was started on intravenous zoledronic acid treatment as adjuvant therapy for breast cancer. Within 24 hours of the initial treatment she developed cold shivers, extreme fatigue, muscle pain and headache. These symptoms resolved spontaneously in the course of the following days. At the same time, she also experienced a CIDP relapse, with a tingling sensation in her arms and legs and deterioration in her ability to walk. Considering the course of the symptoms and the absence of any other cause, CIDP relapse was very probably the result of the acute-phase reaction induced by zoledronic acid.

CONCLUSION

Caution is warranted when using nitrogen-containing bisphosphonates such as zoledronic acid, particularly in patients with known neuromuscular disorders.

How applicable are results of systematic reviews and meta-analyses of health behaviour maintenance? A critical evaluation

OBJECTIVE

To evaluate the practical applicability of systematic reviews and meta-analyses to the maintenance of physical activity or weight loss by assessing methodological and reporting aspects.

METHODS

To identify relevant studies a literature search was conducted in MEDLINE, EMBASE, Cochrane Library, PsycINFO, PSYNDEX, Google scholar, and reference lists. Each article was evaluated for methodological quality, operationalization of maintenance, and practicability following the RE-AIM framework and the PRISMA statement.

RESULTS

Twenty-four systematic reviews and meta-analyses were included of which 14 were published in the last four years. There were multiple definitions of maintenance. In addition the instances of redundancy, and neglect of thematic fields are identified. Eighty-seven percent of the reviews showed methodological flaws. The potential practical use of the outcomes was limited.

CONCLUSION

The applicability of systematic reviews and meta-analyses regarding health behaviour maintenance is limited with regard to reporting, methodology and thematic coverage. For practitioners, synthesis of quantitative and qualitative evidence with theoretical models is lacking.

Adiposity and hand osteoarthritis: the Netherlands Epidemiology of Obesity study

Introduction

Obesity, usually characterized by the body mass index (BMI), is a risk factor for hand osteoarthritis (OA). We investigated whether adipose tissue and abdominal fat distribution are associated with hand OA.

Methods

The Netherlands Epidemiology of Obesity (NEO) study is a population-based cohort aged 45 to 65 years, including 5315 participants (53% women, median BMI 29.9 kg/m²). Fat percentage and fat mass (FM) (kg) were estimated using bioelectrical impedance analysis. The waist-to-hip ratio (WHR) was calculated. In 1721 participants, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) (cm²) were assessed using abdominal MR imaging. Hand OA was defined according to the ACR criteria.

Odds ratios (OR) with 95% confidence intervals (CI) were calculated for the association of fat percentage, FM, WHR, VAT and SAT with hand OA using logistic regression analyses per standard deviation, stratified by sex and adjusted for age.

Results

Hand OA was present in 8% of men and 20% of women. Fat percentage was associated with hand OA in men (OR 1.34 (95% CI 1.11 to 1.61)) and women (OR 1.26 (1.05 to 1.51)), as was FM. WHR was associated with hand OA in men (OR 1.45 (1.13 to 1.85)), and to a lesser extent in women (OR 1.17 (1.00 to 1.36)). Subgroup analysis revealed that VAT was associated with hand OA in men (OR1.33 (1.01 to 1.75)). This association increased after additional adjustment for FM (OR 1.51 (1.13 to 2.03)).

Conclusions

Fat percentage, FM and WHR were associated with hand OA. VAT was associated with hand OA in men, suggesting involvement of visceral fat in hand OA.

Fruit, vegetables and prevention of cognitive decline or dementia: a systematic review of cohort studies

BACKGROUND

Regular consumption of fruit and vegetables has been considered to be associated with a reduced risk of dementia and age-associated cognitive decline, although the association is currently unsupported by a systematic review of the literature.

METHODS

We searched Medline, Embase, Biosis, ALOIS, the Cochrane library, different publisher databases as well as bibliographies of retrieved articles. All cohort studies with a follow-up of 6 months or longer were included if they reported an association of Alzheimer's disease or cognitive decline in regard to the frequency of fruit and vegetables consumption.

FINDINGS

Nine studies with a total of 44,004 participants met the inclusion criteria. Six studies analyzed fruit and vegetables separately and five of them found that higher consumption of vegetables, but not fruit is associated with a decreased risk of dementia or cognitive decline. The same association was found by three further studies for fruit and vegetable consumption analytically combined.

CONCLUSION

Increased intake of vegetables is associated with a lower risk of dementia and slower rates of cognitive decline in older age. Yet, evidence that this association is also valid for high fruit consumption is lacking.