Evidence for familial aggregation of hand, hip, and spine but not knee osteoarthritis in siblings with multiple joint involvement: the GARP study

Technical Report: A Comprehensive Comparison between Different Quantification Versions of Nightingale Health's 1H-NMR Metabolomics Platform

1H-NMR metabolomics data is increasingly used to track health and disease. Nightingale Health, a major supplier of 1H-NMR metabolomics, has recently updated the quantification strategy to further align with clinical standards. Such updates, however, might influence backward replicability, particularly affecting studies with repeated measures. Using data from BBMRI-NL consortium (~28,000 samples from 28 cohorts), we compared Nightingale data, originally released in 2014 and 2016, with a re-quantified version released in 2020, of which both versions were based on the same NMR spectra. Apart from two discontinued and twenty-three new analytes, we generally observe a high concordance between quantification versions with 73 out of 222 (33%) analytes showing a mean ρ > 0.9 across all cohorts. Conversely, five analytes consistently showed lower Spearman's correlations (ρ < 0.7) between versions, namely acetoacetate, LDL-L, saturated fatty acids, S-HDL-C, and sphingomyelins. Furthermore, previously trained multi-analyte scores, such as MetaboAge or MetaboHealth, might be particularly sensitive to platform changes. Whereas MetaboHealth replicated well, the MetaboAge score had to be retrained due to use of discontinued analytes. Notably, both scores in the re-quantified data recapitulated mortality associations observed previously. Concluding, we urge caution in utilizing different platform versions to avoid mixing analytes, having different units, or simply being discontinued.

The genetic contribution to hand osteoarthritis

OBJECTIVE

To estimate the genetic contribution to doctor-diagnosed hand osteoarthritis (OA).

METHODS

Using data from the Swedish Twin Registry and National Patient Register, we conducted a 20-year population-based longitudinal cohort study including 59,970 twins aged 35 years or older. We studied inpatient and outpatient doctor-diagnosed hand OA using ICD-10 codes from 1997 until 2016, including both the distal/proximal interphalangeal (DIP/PIP) joints and/or the first carpometacarpal (CMC-1) joints. We calculated intra-pair correlation, estimated the heritability (i.e., the percentage variation in hand OA that can be explained by genetic factors) as well as a genetic risk.

RESULTS

Among 59,970 included persons, 936 had a hand OA diagnosis registered during the study period. The heritabilities of hand OA (any joint), CMC-1 OA and DIP/PIP OA were ∼87%, 86% and 48%, respectively, yet the two latter should be interpreted with care due to low numbers. Hand OA in any joint in both twins in a pair occurred more frequently in identical twins (54/554 = 9.7%, intra-pair correlation = 0.54, 95% CI = 0.44-0.63) than in fraternal twins (18/1,246 = 1.4%, intra-pair correlation = 0.10, 95% CI = -0.01-0.22). Identical twins who were diagnosed with hand OA in any joint had a far higher risk than fraternal twins with hand OA to also have their co-twin diagnosed with hand OA in any joint (Hazard Ratio = 6.98, 95% CI = 3.08-15.45).

CONCLUSION

The genetic contribution to hand OA is high and likely varying between 48% and 87%. Potential differential heritability by hand OA phenotypes should be further explored.

A protocol for recruiting and analyzing the disease-oriented Russian disc degeneration study (RuDDS) biobank for functional omics studies of lumbar disc degeneration

Lumbar intervertebral disc degeneration (DD) disease is one of the main risk factors for low back pain and a leading cause of population absenteeism and disability worldwide. Despite a variety of biological studies, lumbar DD is not yet fully understood, partially because there are only few studies that use systematic and integrative approaches. This urges the need for studies that integrate different omics (including genomics and transcriptomics) measured on samples within a single cohort. This protocol describes a disease-oriented Russian disc degeneration study (RuDDS) biobank recruitment and analyses aimed to facilitate further omics studies of lumbar DD integrating genomic, transcriptomic and glycomic data. A total of 1,100 participants aged over 18 with available lumbar MRI scans, medical histories and biological material (whole blood, plasma and intervertebral disc tissue samples from surgically treated patients) will be enrolled during the three-year period from two Russian clinical centers. Whole blood, plasma and disc tissue specimens will be used for genotyping with genome-wide SNP-arrays, glycome profiling and RNA sequencing, respectively. Omics data will be further used for a genome-wide association study of lumbar DD with in silico functional annotation, analysis of plasma glycome and lumbar DD disease interactions and transcriptomic data analysis including an investigation of differential expression patterns associated with lumbar DD disease. Statistical tests applied in each of the analyses will meet the standard criteria specific to the attributed study field. In a long term, the results of the study will expand fundamental knowledge about lumbar DD development and contribute to the elaboration of novel personalized approaches for disease prediction and therapy. Additionally to the lumbar disc degeneration study, a RuDDS cohort could be used for other genetic studies, as it will have unique omics data.

Trial registration numberNCT04600544.

High-impact FN1 mutation decreases chondrogenic potential and affects cartilage deposition via decreased binding to collagen type II

Osteoarthritis is the most prevalent joint disease worldwide, yet progress in development of effective disease-modifying treatments is slow because of lack of insight into the underlying disease pathways. Therefore, we aimed to identify the causal pathogenic mutation in an early-onset osteoarthritis family, followed by functional studies in human induced pluripotent stem cells (hiPSCs) in an in vitro organoid cartilage model. We demonstrated that the identified causal missense mutation in the gelatin-binding domain of the extracellular matrix protein fibronectin resulted in significant decreased binding capacity to collagen type II. Further analyses of formed hiPSC-derived neo-cartilage tissue highlighted that mutated fibronectin affected chondrogenic capacity and propensity to a procatabolic osteoarthritic state. Together, we demonstrate that binding of fibronectin to collagen type II is crucial for fibronectin downstream gene expression of chondrocytes. We advocate that effective treatment development should focus on restoring or maintaining proper binding between fibronectin and collagen type II.

Higher thyrotropin leads to unfavorable lipid profile and somewhat higher cardiovascular disease risk: evidence from multi-cohort Mendelian randomization and metabolomic profiling

BACKGROUND

Observational studies suggest interconnections between thyroid status, metabolism, and risk of coronary artery disease (CAD), but causality remains to be proven. The present study aimed to investigate the potential causal relationship between thyroid status and cardiovascular disease and to characterize the metabolomic profile associated with thyroid status.

METHODS

Multi-cohort two-sample Mendelian randomization (MR) was performed utilizing genome-wide significant variants as instruments for standardized thyrotropin (TSH) and free thyroxine (fT4) within the reference range. Associations between TSH and fT4 and metabolic profile were investigated in a two-stage manner: associations between TSH and fT4 and the full panel of 161 metabolomic markers were first assessed hypothesis-free, then directional consistency was assessed through Mendelian randomization, another metabolic profile platform, and in individuals with biochemically defined thyroid dysfunction.

RESULTS

Circulating TSH was associated with 52/161 metabolomic markers, and fT4 levels were associated with 21/161 metabolomic markers among 9432 euthyroid individuals (median age varied from 23.0 to 75.4 years, 54.5% women). Positive associations between circulating TSH levels and concentrations of very low-density lipoprotein subclasses and components, triglycerides, and triglyceride content of lipoproteins were directionally consistent across the multivariable regression, MR, metabolomic platforms, and for individuals with hypo- and hyperthyroidism. Associations with fT4 levels inversely reflected those observed with TSH. Among 91,810 CAD cases and 656,091 controls of European ancestry, per 1-SD increase of genetically determined TSH concentration risk of CAD increased slightly, but not significantly, with an OR of 1.03 (95% CI 0.99-1.07; p value 0.16), whereas higher genetically determined fT4 levels were not associated with CAD risk (OR 1.00 per SD increase of fT4; 95% CI 0.96-1.04; p value 0.59).

CONCLUSIONS

Lower thyroid status leads to an unfavorable lipid profile and a somewhat increased cardiovascular disease risk.

Serum fatty acid chain length associates with prevalent symptomatic end-stage osteoarthritis, independent of BMI

Higher body mass index (BMI) is associated with osteoarthritis (OA) in both weight-bearing and non-weight-bearing joints, suggesting a link between OA and poor metabolic health beyond mechanical loading. This risk may be influenced by systemic factors accompanying BMI. Fluctuations in concentrations of metabolites may mark or even contribute to development of OA. This study explores the association of metabolites with radiographic knee/hip OA prevalence and progression. A ¹H-NMR-metabolomics assay was performed on plasma samples of 1564 cases for prevalent OA and 2,125 controls collected from the Rotterdam Study, CHECK, GARP/NORREF and LUMC-arthroplasty cohorts. OA prevalence and 5 to 10 year progression was assessed by means of Kellgren-Lawrence (KL) score and the OARSI-atlas. End-stage knee/hip OA (TJA) was defined as indication for arthroplasty surgery. Controls did not have OA at baseline or follow-up. Principal component analysis of 227 metabolites demonstrated 23 factors, of which 19 remained interpretable after quality-control. Associations of factor scores with OA definitions were investigated with logistic regression. Fatty acids chain length (FALen), which was included in two factors which associated with TJA, was individually associated with both overall OA as well as TJA. Increased Fatty Acid chain Length is associated with OA.

The Maternal and Paternal Effects on Clinically and Surgically Defined Osteoarthritis

OBJECTIVE

It is currently unknown whether osteoarthritis (OA) is inherited mainly from the mother, father, or both. This study was undertaken to explore the effect of maternal and paternal factors on hip, knee, and hand OA in offspring.

METHODS

Participants from the Musculoskeletal Pain in Ullensaker Study (MUST) (69% female; mean ± SD age 64 ± 9 years) and a Norwegian OA twin study (Nor-Twin) (56% female; 49 ± 11 years) reported whether their mother and/or father had OA. Using a recurrence risk estimation approach, we calculated whether maternal and paternal OA increased the risk of 1) surgically defined hip and knee OA (i.e., total joint replacement) and 2) clinically defined hip, knee, and hand OA (i.e., the American College of Rheumatology criteria) using logistic regression. Relative risks (RRs) with 95% confidence intervals (95% CIs) were calculated.

RESULTS

Maternal OA consistently increased the risk of offspring OA across different OA locations and severities. Having a mother with OA increased the risk of any OA in daughters (RR 1.13 [95% CI 1.02-1.25] in the MUST cohort; RR 1.44 [95% CI 1.05-1.97] in the Nor-Twin cohort) but not (or with less certainty) in sons (RR 1.16 [95% CI 0.95-1.43] in the MUST cohort; RR 1.31 [95% CI 0.71-2.41] in the Nor-Twin cohort). Having a father with OA was less likely to increase the risk of any OA in daughters (RR 1.00 [95% CI 0.85-1.16] in the MUST cohort; RR 1.52 [95% CI 0.94-2.46] in the Nor-Twin cohort) and sons (RR 1.08 [95% CI 0.83-1.41] in the MUST cohort; RR 0.93 [95% CI 0.35-2.48] in the Nor-Twin cohort).

CONCLUSION

OA in the mother increased the risk of surgically and clinically defined hip, knee, and hand OA in offspring, particularly in daughters. Our findings imply that heredity of OA may be linked to maternal genes and/or maternal-specific factors such as the fetal environment.

Hand osteoarthritis: clinical phenotypes, molecular mechanisms and disease management

Osteoarthritis (OA) is a highly prevalent condition, and the hand is the most commonly affected site. Patients with hand OA frequently report symptoms of pain, functional limitations and frustration in undertaking everyday activities. The condition presents clinically with changes to the bone, ligaments, cartilage and synovial tissue, which can be observed using radiography, ultrasonography or MRI. Hand OA is a heterogeneous disorder and is considered to be multifactorial in aetiology. This Review provides an overview of the epidemiology, presentation and burden of hand OA, including an update on hand OA imaging (including the development of novel techniques), disease mechanisms and management. In particular, areas for which new evidence has substantially changed the way we understand, consider and treat hand OA are highlighted. For example, genetic studies, clinical trials and careful prospective imaging studies from the past 5 years are beginning to provide insights into the pathogenesis of hand OA that might uncover new therapeutic targets in the disease.

Men Have a Stronger Monocyte-Derived Cytokine Production Response upon Stimulation with the Gram-Negative Stimulus Lipopolysaccharide than Women: A Pooled Analysis Including 15 Study Populations

The incidence of bacterial infections and sepsis, as well as the mortality risk from sepsis, is sex specific. These clinical findings have been attributed to sex differences in immune responsiveness. The aim of the present study was to investigate sex differences in monocyte-derived cytokine production response upon stimulation with the gram-negative stimulus lipopolysaccharide (LPS) using cytokine data from 15 study populations. Individual data on ex vivo cytokine production response upon stimulation with LPS in whole blood were available for 4,020 subjects originating from these 15 study populations, either from the general population or from patient populations with specific diseases. Men had a stronger cytokine production response than women to LPS for tumour necrosis factor-α, interleukin (IL)-6, IL-12, IL-1β, IL-1RA, and IL-10, but not for interferon-γ. The granulocyte-macrophage colony-stimulating factor production response was lower in men than in women. These sex differences were independent of chronological age. As men had higher monocyte concentrations, we normalized the cytokine production responses for monocyte concentration. After normalization, the sex differences in cytokine production response to LPS disappeared, except for IL-10, for which the production response was lower in men than in women. A sex-based approach to interpreting immune responsiveness is crucial.

Validity, reliability, responsiveness and feasibility of four hand mobility measures in hand osteoarthritis

Objectives

To investigate metric properties of four hand mobility tests in hand OA patients, using the OMERACT filter.

Methods

Trained assessors examined the Hand Mobility in Scleroderma test (HAMIS), fingertip-to-palm distance (FPD), modified Kapandji index (MKI) and number of hand joints with limited mobility in participants from two cohorts [Genetics ARthrosis and Progression (n = 207) and Hand OSTeoArthritis in Secondary care (n = 174)]. Validity was appraised by assessment of correlations with other outcome measures, and ability to measure thumb vs finger mobility specifically, using cumulative probability plots. The proportion of participants changing in hand mobility based on the smallest detectable difference was calculated for responsiveness. Intraclass correlation coefficients (ICCs) for intra- and interobserver reliability, and feasibility (time to perform tests) were studied in a random sample (n = 20).

Results

Participants displayed large variation in mobility scores. Strongest correlations were observed with structural damage (rs = 0.43-0.52) and bony swelling (rs = 0.46-0.58); correlation patterns were similar among tests. HAMIS, FPD and MKI could all measure finger mobility specifically, but only HAMIS measured thumb mobility particularly. Interobserver reliability was best for HAMIS, ICC 0.90 (95% CI: 0.76, 0.96); intraobserver reliability was excellent for all (ICCs 0.94-0.97). In 2 years, little change was observed; HAMIS was the most sensitive-to-change (smallest detectable difference 3.7% of maximum score). The mean performance time ranged from 0.7 (s.d. 0.5, for FPD) to 5.7 (s.d. 1.3, for HAMIS) min.

Conclusion

HAMIS, FPD, MKI and number of joints with limited mobility are all valid, reliable and feasible measures for assessing hand mobility in hand OA, although HAMIS had slightly more favourable properties. Studies assessing sensitivity-to-change in a clinical trial setting are warranted.

A hospital-based observational cohort study exploring pain and biomarkers in patients with hand osteoarthritis in Norway: The Nor-Hand protocol

INTRODUCTION

We have limited knowledge about the underlying disease mechanisms and causes of pain in hand osteoarthritis (OA). Consequently, no disease-modifying drug exists, and more knowledge about the pathogenesis of hand OA is needed, as well as a validation of different outcome measures. Our first aim of this study is to explore the validity of various imaging modalities for the assessment of hand OA. Second, we want to gain a better understanding of the disease processes, with a special focus on pain mechanisms.

METHODS AND ANALYSIS

The Nor-Hand study is a hospital-based observational study including 300 patients with evidence of hand OA by ultrasound and/or clinical examination. The baseline examination consists of functional tests and joint assessment of the hands, medical assessment, pain sensitisation tests, ultrasound (hands, acromioclavicular joint, hips, knees and feet), CT and MRI of the dominant hand, conventional radiographs of the hands and feet, fluorescence optical imaging of the hands, collection of blood and urine samples as well as self-reported demographic factors and OA-related questionnaires. Two follow-up examinations are planned. Cross-sectional analyses will be used to investigate agreements and associations between different relevant measures at the baseline examination, whereas the longitudinal data will be used for evaluation of predictors for clinical outcomes.

ETHICS AND DISSEMINATION

The protocol is approved by the Norwegian Regional Committee for Medical and Health Research Ethics (Ref. no: 2014/2057). The participants receive oral and written information about the project and sign a consent form before participation. They can, whenever they want, withdraw from the study, and all de-identified data will be safely stored on the research server at Diakonhjemmet Hospital. Results will be presented at international and national congresses and in peer-reviewed rheumatology journals.

TRIAL REGISTRATION NUMBER

NCT03083548; Pre-results.

Epidemiology of knee osteoarthritis in India and related factors

BACKGROUND

Among the chronic rheumatic diseases, hip and knee osteoarthritis (OA) is the most prevalent and is a leading cause of pain and disability in most countries worldwide. Its prevalence increases with age and generally affects women more frequently than men. OA is strongly associated with aging and heavy physical occupational activity, a required livelihood for many people living in rural communities in developing countries. Determining region-specific OA prevalence and risk factor profiles will provide important information for planning future cost effective preventive strategies and health care services.

MATERIALS AND METHODS

The study was a community based cross sectional study to find out the prevalence of primary knee OA in India which has a population of 1.252 billion. The study was done across five sites in India. Each site was further divided into big city, small city, town, and village. The total sample size was 5000 subjects. Tools consisted of a structured questionnaire and plain skiagrams for confirmation of OA. Diagnosis was done using Kellgren and Lawrence scale for osteoarthritis.

RESULTS

Overall prevalence of knee OA was found to be 28.7%. The associated factors were found to be female gender (prevalence of 31.6%) (P = 0.007), obesity (P = 0.04), age (P = 0.001) and sedentary work (P = 0.001).

CONCLUSIONS

There is scarcity of studies done in India which has varied socio geographical background and communities. We conducted this study for analyzing the current prevalence of OA in different locations. This study has evidenced a large percentage of population as borderline OA; therefore, it depends mainly on the prevention of modifiable risk factors to preserve at ease movement in elderly population through awareness programs.

Severe Hand Osteoarthritis Strongly Correlates With Major Joint Involvement and Surgical Intervention

BACKGROUND

The presence of hand osteoarthritis (OA) increases the risk for developing OA in other major joints. Although genetic predisposition has been implicated in its causation, its exact role has yet to be established. The association of hand OA with symptomatic and asymptomatic major joints has not been previously studied.

METHODS

Hundred consecutive patients had a hand photo taken for visual documentation of the hand joints. Radiographs of hand and all major symptomatic joints were analyzed and classified using the Kellgren-Lawrence scale by 2 independent observers including an orthopedic radiologist.

RESULTS

Severe hand OA was present in 91% of the patients. Radiographic analysis showed that the hip was involved in 88% of the patients, of whom 85.2% (75) were symptomatic and 14.7% (13) were asymptomatic. Hip arthroplasty was required by 62.5% (55) of symptomatic hip patients. Knee involvement was present in 37% of the patients; all were symptomatic and 81.1% (30) of these required knee arthroplasty. Bilateral surgery was performed in 33% (28) and "2 joint (hip and knee)" surgery was performed in 6% (5). Spine involvement was present in 72% of the patients. There was a significant correlation between hand radiographic findings of OA and hip (r = 0.68; P = .03), knee (r = 0.58; P = .042), and spine (r = .39; P = .05) involvement.

CONCLUSION

There was a significant correlation between severe hand OA and hip, knee, and spine involvement. Severity of Hand OA can have a predictive value on multiple joint involvement and risk of surgical intervention. This study emphasizes the need to investigate the genetic predisposition in causation of OA.

Translating Genomic Advances to Physical Therapist Practice: A Closer Look at the Nature and Nurture of Common Diseases

The Human Genome Project and the International HapMap Project have yielded new understanding of the influence of the human genome on health and disease, advancing health care in significant ways. In personalized medicine, genetic factors are used to identify disease risk and tailor preventive and therapeutic regimens. Insight into the genetic bases of cellular processes is revealing the causes of disease and effects of exercise. Many diseases known to have a major lifestyle contribution are highly influenced by common genetic variants. Genetic variants are associated with increased risk for common diseases such as cardiovascular disease and osteoarthritis. Exercise response also is influenced by genetic factors. Knowledge of genetic factors can help clinicians better understand interindividual differences in disease presentation, pain experience, and exercise response. Family health history is an important genetic tool and encourages clinicians to consider the wider client-family unit. Clinicians in this new era need to be prepared to guide patients and their families on a variety of genomics-related concerns, including genetic testing and other ethical, legal, or social issues. Thus, it is essential that clinicians reconsider the role of genetics in the preservation of wellness and risk for disease to identify ways to best optimize fitness, health, or recovery. Clinicians with knowledge of the influence of genetic variants on health and disease will be uniquely positioned to institute individualized lifestyle interventions, thereby fulfilling roles in prevention and wellness. This article describes how discoveries in genomics are rapidly evolving the understanding of health and disease by highlighting 2 conditions: cardiovascular disease and osteoarthritis. Genetic factors related to exercise effects also are considered.

Radiographic progression of knee osteoarthritis is associated with MRI abnormalities in both the patellofemoral and tibiofemoral joint

OBJECTIVE

To investigate patterns of MRI abnormalities in the patellofemoral (PFJ) and tibiofemoral joint (TFJ) and their association with radiographic progression, using hypothesis free analyses.

DESIGN

205 patients from the GARP study with symptomatic OA at multiple sites (mean age 60 years, 80% woman, median BMI 26 kg/m(2)), underwent knee MRI at baseline. Cartilage damage, osteophytes, cysts, bone marrow lesions (BMLs) and effusion/synovitis were scored according to a validated scoring method. Baseline and 6-year TFJ and PFJ radiographs were scored (0-3) for JSN and osteophytes according to OARSI and Burnett atlases, respectively; progression was defined as ≥1 point increase. Baseline patterns of MRI abnormalities derived from principal component analysis (PCA) were associated with progression using adjusted generalized estimating equations (GEE).

RESULTS

PCA resulted in extraction of six components, explaining 69% of variance. In 29% and 29% of 133 patients with follow-up the TFJ progressed, whereas in 15% and 9% the PFJ progressed for osteophytes and JSN, respectively. Component 1 (cartilage damage of the PFJ and osteophytes of both joints) was statistically significant associated with TFJ JSN progression and PFJ osteophyte progression. Component 2 (all lateral PFJ abnormalities except osteophytes) was associated with JSN/osteophyte progression in the PFJ alone, whereas component 3 (all medial TFJ abnormalities except osteophytes) was associated with JSN and osteophyte progression in both PFJ and TFJ.

CONCLUSION

Baseline structural damage and bone turnover activity, as reflected by BMLs, seem to be involved in knee OA progression. Moreover, progression in PFJ and TFJ seems to be related.

Associations between joint effusion in the knee and gene expression levels in the circulation: a meta-analysis

Objective: To identify molecular biomarkers for early knee osteoarthritis (OA), we examined whether joint effusion in the knee associated with different gene expression levels in the circulation.

Materials and Methods: Joint effusion grades measured with magnetic resonance (MR) imaging and gene expression levels in blood were determined in women of the Rotterdam Study (N=135) and GARP (N=98). Associations were examined using linear regression analyses, adjusted for age, fasting status, RNA quality, technical batch effects, blood cell counts, and BMI. To investigate enriched pathways and protein-protein interactions, we used the DAVID and STRING webtools.

Results: In a meta-analysis, we identified 257 probes mapping to 189 unique genes in blood that were nominally significantly associated with joint effusion grades in the knee. Several compelling genes were identified such as C1orf38 and NFATC1. Significantly enriched biological pathways were: response to stress, gene expression, negative regulation of intracellular signal transduction, and antigen processing and presentation of exogenous pathways.

Conclusion: Meta-analyses and subsequent enriched biological pathways resulted in interesting candidate genes associated with joint effusion that require further characterization. Associations were not transcriptome-wide significant most likely due to limited power. Additional studies are required to replicate our findings in more samples, which will greatly help in understanding the pathophysiology of OA and its relation to inflammation, and may result in biomarkers urgently needed to diagnose OA at an early stage.

Mortality in osteoarthritis patients

OBJECTIVES

To investigate whether all-cause mortality and deaths due to cardiovascular disease are increased in patients who have consulted primary or secondary health care with symptoms and signs of osteoarthritis (OA).

METHOD

This study included 383 patients with symptomatic OA at multiple sites from the Genetics ARthrosis and Progression (GARP) study (mean age 60 years, 82% women, 3693 person-years of follow-up) and 459 patients with primary hand, knee, or hip OA from the Osteoarthritis Care Clinic (OCC) study (mean age 61 years, 88% women, 1890 person-years of follow-up). Standardized mortality ratios (SMRs) with 95% confidence intervals (CIs) were calculated for all-cause mortality and causes of deaths in comparison to the general population. Cox proportional hazard ratios (HRs) with 95% CIs were used to associate baseline characteristics with all-cause mortality.

RESULTS

In the GARP study, 26 patients died whereas 48 deaths were expected (SMR 0.54, 95% CI 0.37-0.79). The SMR was 0.47 (95% CI 0.29-0.76) in women and 0.73 (95% CI 0.39-1.35) in men. Similar results were found in the OCC study (SMR 0.45, 95% CI 0.25-0.82). Malignancy and cardiovascular disease were the main causes of deaths in GARP. Male sex (HR 3.04, 95% CI 1.38-6.69), increasing age (HR 1.10, 95% CI 1.05-1.16), and self-reported cancer (HR 8.29, 95% CI 3.12-22.03) were associated with increased mortality in GARP.

CONCLUSIONS

Patients consulting health care for their OA are not at higher risk of death than the general population. These results suggest that the management of OA patients may not need to focus specifically on the treatment of cardiovascular risk factors and comorbidities.

Meta-analysis identifies loci affecting levels of the potential osteoarthritis biomarkers sCOMP and uCTX-II with genome wide significance

BACKGROUND

Research for the use of biomarkers in osteoarthritis (OA) is promising, however, adequate discrimination between patients and controls may be hampered due to innate differences. We set out to identify loci influencing levels of serum cartilage oligomeric protein (sCOMP) and urinary C-telopeptide of type II collagen (uCTX-II).

METHODS

Meta-analysis of genome-wide association studies was applied to standardised residuals of sCOMP (N=3316) and uCTX-II (N=4654) levels available in 6 and 7 studies, respectively, from TreatOA. Effects were estimated using a fixed-effects model. Six promising signals were followed up by de novo genotyping in the Cohort Hip and Cohort Knee study (N = 964). Subsequently, their role in OA susceptibility was investigated in large-scale genome-wide association studies meta-analyses for OA. Differential expression of annotated genes was assessed in cartilage.

RESULTS

Genome-wide significant association with sCOMP levels was found for a SNP within MRC1 (rs691461, p = 1.7 × 10(-12)) and a SNP within CSMD1 associated with variation in uCTX-II levels with borderline genome-wide significance (rs1983474, p = 8.5 × 10(-8)). Indication for association with sCOMP levels was also found for a locus close to the COMP gene itself (rs10038, p = 7.1 × 10(-6)). The latter SNP was subsequently found to be associated with hip OA whereas COMP expression appeared responsive to the OA pathophysiology in cartilage.

CONCLUSIONS

We have identified genetic loci affecting either uCTX-II or sCOMP levels. The genome wide significant association of MRC1 with sCOMP levels was found likely to act independent of OA subtypes. Increased sensitivity of biomarkers with OA may be accomplished by taking genetic variation into account.

Assessment of osteoarthritis candidate genes in a meta-analysis of nine genome-wide association studies

Objective

To assess candidate genes for association with osteoarthritis (OA) and identify promising genetic factors and, secondarily, to assess the candidate gene approach in OA.

Methods

A total of 199 candidate genes for association with OA were identified using Human Genome Epidemiology (HuGE) Navigator. All of their single-nucleotide polymorphisms (SNPs) with an allele frequency of >5% were assessed by fixed-effects meta-analysis of 9 genome-wide association studies (GWAS) that included 5,636 patients with knee OA and 16,972 control subjects and 4,349 patients with hip OA and 17,836 control subjects of European ancestry. An additional 5,921 individuals were genotyped for significantly associated SNPs in the meta-analysis. After correction for the number of independent tests, P values less than 1.58 × 10⁻⁵ were considered significant.

Results

SNPs at only 2 of the 199 candidate genes (COL11A1 and VEGF) were associated with OA in the meta-analysis. Two SNPs in COL11A1 showed association with hip OA in the combined analysis: rs4907986 (P = 1.29 × 10⁻⁵, odds ratio [OR] 1.12, 95% confidence interval [95% CI] 1.06−1.17) and rs1241164 (P = 1.47 × 10⁻⁵, OR 0.82, 95% CI 0.74−0.89). The sex-stratified analysis also showed association of COL11A1 SNP rs4908291 in women (P = 1.29 × 10⁻⁵, OR 0.87, 95% CI 0.82−0.92); this SNP showed linkage disequilibrium with rs4907986. A single SNP of VEGF, rs833058, showed association with hip OA in men (P = 1.35 × 10⁻⁵, OR 0.85, 95% CI 0.79−0.91). After additional samples were genotyped, association at one of the COL11A1 signals was reinforced, whereas association at VEGF was slightly weakened.

Conclusion

Two candidate genes, COL11A1 and VEGF, were significantly associated with OA in this focused meta-analysis. The remaining candidate genes were not associated.

SMAD3 is associated with the total burden of radiographic osteoarthritis: the Chingford study

Background

A newly-described syndrome called Aneurysm-Osteoarthritis Syndrome (AOS) was recently reported. AOS presents with early onset osteoarthritis (OA) in multiple joints, together with aneurysms in major arteries, and is caused by rare mutations in SMAD3. Because of the similarity of AOS to idiopathic generalized OA (GOA), we hypothesized that SMAD3 is also associated with GOA and tested the hypothesis in a population-based cohort.

Methods

Study participants were derived from the Chingford study. Kellgren-Lawrence (KL) grades and the individual features of osteophytes and joint space narrowing (JSN) were scored from radiographs of hands, knees, hips, and lumbar spines. The total KL score, osteophyte score, and JSN score were calculated and used as indicators of the total burden of radiographic OA. Forty-one common SNPs within SMAD3 were genotyped using the Illumina HumanHap610Q array. Linear regression modelling was used to test the association between the total KL score, osteophyte score, and JSN score and each of the 41 SNPs, with adjustment for patient age and BMI. Permutation testing was used to control the false positive rate.

Results

A total of 609 individuals were included in the analysis. All were Caucasian females with a mean age of 60.9±5.8. We found that rs3825977, with a minor allele (T) frequency of 20%, in the last intron of SMAD3, was significantly associated with total KL score (β = 0.14, P_permutation = 0.002). This association was stronger for the total JSN score (β = 0.19, P_permutation = 0.002) than for total osteophyte score (β = 0.11, P_permutation = 0.02). The T allele is associated with a 1.47-fold increased odds for people with 5 or more joints to be affected by radiographic OA (P_permutation = 0.046).

Conclusion

We found that SMAD3 is significantly associated with the total burden of radiographic OA. Further studies are required to reveal the mechanism of the association.

Large scale meta-analysis of urinary C-terminal telopeptide, serum cartilage oligomeric protein and matrix metalloprotease degraded type II collagen and their role in prevalence, incidence and progression of osteoarthritis

OBJECTIVE

To evaluate the role of three cartilage-derived biomarkers on osteoarthritis (OA): urinary C-terminal telopeptide (uCTX-II), serum cartilage oligomeric protein (sCOMP), and serum MMP degraded type II collagen (sC2M).

SUBJECTS AND METHODS

Samples from 3582 individuals from the Rotterdam Study, the Genetics osteoArthritis and Progression (GARP), the Chingford Study and the TwinsUK cohort were assayed using enzyme-linked immune sorbent assays. Log10 of concentration levels were correlated with risk of hip, hand and knee OA, hip and knee OA severity and incidence, and progression of knee OA, adjusting for age, gender and body mass index (BMI). Results were meta-analysed to assess overall significance.

RESULTS

After adjusting for covariates, sCOMP was associated with knee OA and hip and knee OA incidence. Furthermore, sC2M was associated with knee OA incidence and progression. After adjustment for multiple tests (Bonferroni P < 0.002) only the association between sCOMP and knee OA remained significant (odds ratio (OR) = 3.26 (95%CI 1.63-10.1) P = 0.0008 for each standard deviation (SD) increase in biomarker levels). Levels of uCTX-II were significantly associated with risk of hand, hip and knee OA, progression and incidence of knee OA. A receiver operating characteristics (ROC) analysis showed a consistent improvement in prediction of knee OA progression from an average area under the curve (AUC) is 0.646 for age, sex and BMI alone to an AUC = 0.668 including uCTX-II for prediction.

CONCLUSIONS

uCTX-II is the most informative biochemical marker for prediction of OA. Both sCOMP and C2M showed some association with OA, thus indicating that they are descriptive of disease activity.

Are baseline high molecular weight adiponectin levels associated with radiographic progression in rheumatoid arthritis and osteoarthritis?

OBJECTIVE

To investigate whether high molecular weight adiponectin (hmwAPN) mediates the associations of total adiponectin (totAPN) with radiographic progression in rheumatoid arthritis (RA) and hand osteoarthritis (HOA).

METHODS

Associations between baseline hmwAPN or totAPN levels with radiographic progression were determined using multivariate linear regression or generalized estimated equations.

RESULTS

In patients with RA, totAPN associated positively, whereas in patients with HOA it associated negatively with radiographic progression. In contrast, hmwAPN did not associate significantly with radiographic progression in either cohort.

CONCLUSION

Our data indicate that the differential effects associated between totAPN and radiographic progression in either RA or HOA are not mediated by hmwAPN.

Increased clinical symptoms of acromegalic arthropathy in patients with long-term disease control: a prospective follow-up study

Arthropathy is an invalidating complication of acromegaly. This arthropathy deteriorates radiographically despite long-term disease control. However, the clinical course and its relationship to the radiographic course are currently unknown. We aimed to investigate the clinical course of arthropathy during follow-up and its relationship to radiographic progression in long-term controlled acromegaly patients. Prospective follow-up study. We studied 58 patients (mean age 62 years, women 41 %) with controlled acromegaly for a mean of 17.6 years. Clinical progression of joint disease was defined at baseline and after 2.6 years, by the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and Australian/Canadian Osteoarthritis Index (AUSCAN) questionnaires for lower limb and hand OA, respectively, and performance tests. Potential risk factors for progression were assessed. The clinical course of arthropathy was related to the radiographic course. On average, hand and lower limb function deteriorated during follow-up, despite large interindividual variations. Joint pain was stable over time. High levels of pain and functional impairment at baseline were related to clinical progression of hand pain and functional limitations. High baseline BMI was a risk factor for functional deterioration in the lower limb. The changes in symptoms and radiographic progression during follow-up were not related. In treated acromegaly patients, joint function deteriorates during prolonged follow-up, despite biochemical disease control, although there was interindividual variation. Clinical and radiographic course of arthropathy were not related. Therefore, in clinical practice, a combination of clinical and radiographic assessment is necessary to evaluate the course of acromegalic arthropathy.

Genes expressed in blood link osteoarthritis with apoptotic pathways

OBJECTIVE

To identify novel gene expression networks in blood of osteoarthritis patients compared to controls.

METHODS

A comprehensive exploration of gene expression in peripheral blood was performed by microarray analysis for a subset of osteoarthritis patients from the Genetics osteoARthritis and Progression (GARP) study in comparison with sex and age-matched healthy controls. To identify pathways, we performed gene enrichment analyses (database for annotation, visualisation and integrated discovery and search tool for the retrieval of interacting genes). Quantitative PCR analysis in overlapping and in additional osteoarthritis samples was performed for prioritised genes to validate and replicate findings. Classification of cases and controls was explored by applying statistical models.

RESULTS

741 probes representing 694 unique genes were differentially expressed between cases and controls, including 86 genes expressed with at least a 1.5-fold difference. ATF4, GPR18 and H3F3B were among the top genes identified (p<4.5 × 10(-8)). We found that in the blood of osteoarthritis patients the apoptosis pathway, including the well-known gene CASP3, was significantly enriched among the differentially expressed genes. Our findings were validated in independent samples and when using a small subset of the validated genes, we could accurately distinguish patients from controls (area under the curve 98%).

CONCLUSIONS

In the current study, we have identified specific gene expression networks, in the easily accessible tissue blood, which associated consistently with osteoarthritis among GARP study cases. Our data further hint at the relevance of apoptosis as an aetiological factor in osteoarthritis onset, thereby qualifying expression profiling of blood as a useful tool to understand the underlying molecular mechanisms of osteoarthritis.

Association study of candidate genes for the progression of hand osteoarthritis

OBJECTIVE

Although a few consistent osteoarthritis (OA) susceptibility genes have been identified, little is known on OA progression. Since OA progression is clinically the most relevant phenotype, we investigate the association between asporin (ASPN), bone morphogenetic protein 5 (BMP5) and growth differentiation factor 5 (GDF5) polymorphisms and progression of hand OA.

METHODS

Single-nucleotide polymorphisms (SNPs) ASPN rs13301537, BMP5 rs373444 and GDF5 rs143383 were genotyped in 251 hand OA patients from the Genetics osteoARthritis and Progression (GARP) study and 725 controls. In a case-control comparison we assessed the association between these SNPs and radiographic progression of hand OA over 6 years, which was based on change in osteophytes or joint space narrowing (JSN), above the smallest detectable change. SNPs with suggestive evidence for association were further analysed for their effect on progression over 2 years, and for the mean change in osteophytes and JSN.

RESULTS

The minor allele of ASPN SNP rs13301537 was associated with hand OA progression over 6 years (odds ratio (OR) (95% CI) 1.49 (1.06-2.07); P = 0.020). The mean change in osteophytes and JSN was higher in carriers of the minor allele compared to homozygous carriers of the common allele with mean difference of 0.73 (95% CI - 0.07-1.56; P = 0.073) and 0.82 (95% CI 0.12-1.52; P = 0.022), respectively. An association with similar effect size was found between ASPN SNP rs13301537 and 2-year progression, and the mean change in osteophytes and JSN was significantly higher in homozygotes.

CONCLUSION

ASPN is associated with hand OA progression. This gives insight in the pathogenesis of hand OA progression and identified a potential target for therapeutic approaches.

Genome-wide association study meta-analysis of chronic widespread pain: evidence for involvement of the 5p15.2 region

BACKGROUND AND OBJECTIVES

Chronic widespread pain (CWP) is a common disorder affecting ∼10% of the general population and has an estimated heritability of 48-52%. In the first large-scale genome-wide association study (GWAS) meta-analysis, we aimed to identify common genetic variants associated with CWP.

METHODS

We conducted a GWAS meta-analysis in 1308 female CWP cases and 5791 controls of European descent, and replicated the effects of the genetic variants with suggestive evidence for association in 1480 CWP cases and 7989 controls. Subsequently, we studied gene expression levels of the nearest genes in two chronic inflammatory pain mouse models, and examined 92 genetic variants previously described associated with pain.

RESULTS

The minor C-allele of rs13361160 on chromosome 5p15.2, located upstream of chaperonin-containing-TCP1-complex-5 gene (CCT5) and downstream of FAM173B, was found to be associated with a 30% higher risk of CWP (minor allele frequency=43%; OR=1.30, 95% CI 1.19 to 1.42, p=1.2×10(-8)). Combined with the replication, we observed a slightly attenuated OR of 1.17 (95% CI 1.10 to 1.24, p=4.7×10(-7)) with moderate heterogeneity (I2=28.4%). However, in a sensitivity analysis that only allowed studies with joint-specific pain, the combined association was genome-wide significant (OR=1.23, 95% CI 1.14 to 1.32, p=3.4×10(-8), I2=0%). Expression levels of Cct5 and Fam173b in mice with inflammatory pain were higher in the lumbar spinal cord, not in the lumbar dorsal root ganglions, compared to mice without pain. None of the 92 genetic variants previously described were significantly associated with pain (p>7.7×10(-4)).

CONCLUSIONS

We identified a common genetic variant on chromosome 5p15.2 associated with joint-specific CWP in humans. This work suggests that CCT5 and FAM173B are promising targets in the regulation of pain.

Clustering of hand osteoarthritis progression and its relationship to progression of osteoarthritis at the knee

Objective

To investigate patterns of osteoarthritis (OA) progression within hand joints and the relationship between hand OA progression and progression of OA at the knee.

Methods

Radiographic progression over 6 years, defined as change in osteophytes or joint space narrowing above the smallest detectable change, was assessed on hand and knee radiographs of 236 hand OA patients participating in the Genetics, Arthrosis and Progression (GARP) sibling pair cohort study using OARSI atlas. Clustering of radiographic progression between hand joint groups (DIP, PIP, IP-1 and CMC-1) was assessed using χ2 test. Symmetry, clustering by row and ray and familial aggregation in sibling pairs were also evaluated. The association between hand OA progression and progression of OA at the knee was assessed using generalised estimating equation analysis.

Results

There was clustering of OA progression between hand joint groups, the strongest relationship among DIP, PIP and IP-1 joints. Other patterns were symmetry (OR 4.7 (95% CI 3.3 to 6.5)) and clustering by row (OR 2.9 (95% CI 1.9 to 4.6)) but not by ray (OR 1.3 (95% CI 0.7 to 2.4)). There was familial aggregation of hand OA progression. Patients with progression of hand OA had a higher risk for radiographic change at the knee than those without hand OA progression (OR 2.3 (95% CI 1.3 to 4.0)).

Conclusions

Progression of hand OA clusters between hand joint groups, especially between IP joints, and within sibling pairs. It is associated with OA change at the knee. These findings contribute to defining hand OA subsets and suggest a role for systemic factors.

Brief report: differences in multijoint symptomatic osteoarthritis phenotypes by race and sex: the Johnston County Osteoarthritis Project

OBJECTIVE

To determine differences in the phenotypes (patterns) of multiple-joint symptomatic osteoarthritis (OA) involvement by race and sex.

METHODS

A cross-sectional analysis of symptomatic OA phenotypes was performed in a community-based cohort, comprising subjects for whom data were collected from 4 sites of symptomatic OA involvement (the hands, knees, hips, and lumbosacral [LS] spine) at a single visit (2003-2010). Mutually exclusive phenotypes describing all combinations of these 4 sites were compared by race and by sex, using Fisher's exact tests. For those phenotypes occurring in >40 subjects, logistic regression was performed, with adjustments for race, sex, age, and body mass index (BMI), and interactions of race and sex were assessed.

RESULTS

The sample included 1,650 participants, of whom 36% were men and 32% were African American. The mean age of the subjects was 66 years, and the mean BMI was 31 kg/m(2). Overall, in this sample, 13% of subjects had symptomatic hand OA, 25% had symptomatic knee OA, 11% had symptomatic hip OA, and 28% had symptomatic LS spine OA. African Americans, as compared with Caucasians, were less likely to have involvement of symptomatic OA in the hand only, or in some combination of the hand and other sites, but were more likely to have involvement of the knee only. Men, as compared to women, were less likely to have involvement of the hand only, but were more likely to have involvement of the LS spine only.

CONCLUSION

There are differences in the phenotypes of multiple-joint symptomatic OA involvement by race and by sex that may influence the definitions of multiple-joint, or generalized, OA.

Novel genetic variants associated with lumbar disc degeneration in northern Europeans: a meta-analysis of 4600 subjects

OBJECTIVE

Lumbar disc degeneration (LDD) is an important cause of low back pain, which is a common and costly problem. LDD is characterised by disc space narrowing and osteophyte growth at the circumference of the disc. To date, the agnostic search of the genome by genome-wide association (GWA) to identify common variants associated with LDD has not been fruitful. This study is the first GWA meta-analysis of LDD.

METHODS

We have developed a continuous trait based on disc space narrowing and osteophytes growth which is measurable on all forms of imaging (plain radiograph, CT scan and MRI) and performed a meta-analysis of five cohorts of Northern European extraction each having GWA data imputed to HapMap V.2.

RESULTS

This study of 4600 individuals identified four single nucleotide polymorphisms with p<5×10(-8), the threshold set for genome-wide significance. We identified a variant in the PARK2 gene (p=2.8×10(-8)) associated with LDD. Differential methylation at one CpG island of the PARK2 promoter was observed in a small subset of subjects (β=8.74×10(-4), p=0.006).

CONCLUSIONS

LDD accounts for a considerable proportion of low back pain and the pathogenesis of LDD is poorly understood. This work provides evidence of association of the PARK2 gene and suggests that methylation of the PARK2 promoter may influence degeneration of the intervertebral disc. This gene has not previously been considered a candidate in LDD and further functional work is needed on this hitherto unsuspected pathway.

Genetic predisposition to the presence and 5-year clinical progression of hip osteoarthritis

OBJECTIVE

Genetic factors are important in the aetiology of hip osteoarthritis (OA), but studies are limited by cross-sectional design and poor association with clinically important disease. Identifying cohorts with progressive OA will facilitate development of OA biomarkers. Using a middle-aged cohort with genetic predisposition to hip OA and a control group, we compared the prevalence of clinical and radiographic hip OA and incidence of progression over 5 years.

DESIGN

123 individuals (mean age 52 years) with a family history of total hip arthroplasty (THA) ('sibkids') were compared with 80 (mean age 54 years) controls. The prevalence of radiographic OA [scored according to Kellgren & Lawrence (K&L)], clinical features, and incidence of clinical progression over a 5-year period were compared. A multivariate logistic regression model was used to adjust for confounders.

RESULTS

Sibkids had odds ratios (ORs) of 2.7 [95% confidence interval (CI) 1.1-6.3, P = 0.02] for hip OA (K&L grade ≥2), 3.4 (1.4-8.4, P = 0.008) for clinical signs, and 2.1 (0.8-5.8, P = 0.14) for signs and symptoms. Over 5 years, sibkids had ORs of 4.7 (1.7-13.2, P = 0.003) for the development of signs, and 3.2 (1.0-10.3, P = 0.047) for the development of signs and symptoms.

DISCUSSION

Compared to a control group and after adjustment for confounders, individuals with genetic predisposition to end-stage hip OA have higher prevalence of OA, clinical features, and progression. In addition to structural degeneration, the inherited risk may include predisposition to pain. Genetically-loaded cohorts are useful to develop hip OA biomarkers, as they develop progressive disease at a young age.

High Microsatellite and SNP Genotyping Success Rates Established in a Large Number of Genomic DNA Samples Extracted From Mouth Swabs and Genotypes

In this article, we present the genomic DNA yield and the microsatellite and single nucleotide polymorphism (SNP) genotyping success rates of genomic DNA extracted from a large number of mouth swab samples. In total, the median yield and quality was determined in 714 individuals and the success rates in 378,480 genotypings of 915 individuals. The median yield of genomic DNA per mouth swab was 4.1 μg (range 0.1–42.2 μg) and was not reduced when mouth swabs were stored for at least 21 months prior to extraction. A maximum of 20 mouth swabs is collected per participant. Mouth swab samples showed in, respectively, 89% for 390 microsatellites and 99% for 24 SNPs a genotyping success rate higher than 75%. A very low success rate of genotyping (0%–10%) was obtained for 3.2% of the 915 mouth swab samples using microsatellite markers. Only 0.005% of the mouth swab samples showed a geno-typing success rate lower than 75% (range 58%–71%) using SNPs. Our results show that mouth swabs can be easily collected, stored by our conditions for months prior to DNA extraction and result in high yield and high-quality DNA appropriate for genotyping with high success rate including whole genome searches using microsatellites or SNPs.

Differences in multijoint radiographic osteoarthritis phenotypes among African Americans and Caucasians: the Johnston County Osteoarthritis project

OBJECTIVE

To define and contrast multiple joint radiographic osteoarthritis (OA) phenotypes describing hand and whole-body radiographic OA among African Americans and Caucasians.

METHODS

We conducted a cross-sectional analysis in the Johnston County Osteoarthritis Project, using radiographic data for the hands, tibiofemoral (TF) joints, patellofemoral joints, hips, and lumbosacral (LS) spine. Radiographs were read for OA by a single radiologist using standard atlases. Fisher's exact test, with correction for multiple comparisons, was used to compare phenotype frequencies by race and sex. Logistic regression was used to provide odds ratios, which were adjusted for sex, age, and body mass index (BMI).

RESULTS

Sixteen mutually exclusive hand (n = 2,083) and 32 whole-body (n = 1,419) radiographic OA phenotypes were identified. We found that in comparison to Caucasians, African Americans had significantly less frequent radiographic OA of the distal interphalangeal joints, both in isolation and in combination with other hand joint sites, but had comparable frequencies of radiographic OA for other hand joint sites. Moreover, African Americans had less frequent radiographic OA of the hand, both in isolation and in combination with other joint sites, as compared to Caucasians. In contrast, African Americans had more than twice the odds of isolated OA of the TF joint and 77% higher odds of radiographic OA of the TF joint and LS spine together as compared to Caucasians.

CONCLUSION

Even after adjustment for sex, age, and BMI, African Americans were less likely than Caucasians to have hand radiographic OA phenotypes, but more likely to have knee radiographic OA phenotypes involving the TF joint. African Americans may have a higher burden of multiple large-joint OA involvement not captured by most definitions of "generalized OA."

Validity of joint space width measurements in hand osteoarthritis

OBJECTIVE

To investigate the validity of joint space width (JSW) measurements in millimeters (mm) in hand osteoarthritis (OA) patients by comparison to controls, grading of joint space narrowing (JSN), and clinical features.

METHODS

Hand radiographs of 235 hand OA patients (mean age 65 years, 83% women) and 471 controls were used. JSW was measured with semi-automated image analysis software in the distal, proximal interphalangeal and metacarpal joints (DIPJs, PIPJs and MCPJs). JSN (grade 0-3) was assessed using the osteoarthritis research society international (OARSI) atlas. Associations between the two methods and clinical determinants (presence of pain, nodes and/or erosions, decreased mobility) were assessed using Generalized Estimating Equations with adjustments for age, sex, body mass index (BMI) and mean width of proximal phalanx.

RESULTS

JSW was measured in 5631 joints with a mean JSW of 0.98 mm (standard deviation (SD) 0.21), being the smallest for DIPJs (0.70 (SD 0.25)) and largest for MCPJs (1.40 (SD 0.25)). The JSN=0 group had a mean JSW of 1.28 mm (SD 0.34), the JSN=3 group 0.17 mm (SD 0.23). Controls had larger JSW than hand OA patients (P-value<0.001). In hand OA, females had smaller JSW than men (β -0.08, (95% confidence interval (95% CI) -0.15 to -0.01)) and lower JSW was associated with the presence of pain, nodes, erosions and decreased mobility (adjusted β -0.21 (95% CI -0.27, -0.16), -0.37 (-0.40, -0.34), -0.61 (-0.68, -0.54) and -0.46 (-0.68, -0.24) respectively). These associations were similar for JSN in grades.

CONCLUSION

In hand OA the quantitative JSW measurement is a valid method to measure joint space and shows a good relation with clinical features.

Association between several clinical and radiological determinants with long-term clinical progression and good prognosis of lower limb osteoarthritis

Objective

To investigate the factors associated with clinical progression and good prognosis in patients with lower limb osteoarthritis (OA).

Methods

Cohort study of 145 patients with OA in either knee, hip or both. Progression was defined as 1) new joint prosthesis or 2) increase in WOMAC pain or function score during 6-years follow-up above pre-defined thresholds. Patients without progression with decrease in WOMAC pain or function score lower than pre-defined thresholds were categorized as good prognosis. Relative risks (RRs) for progression and good prognosis with 95% confidence interval (95% CI) were calculated by comparing the highest tertile or category to the lowest tertile, for baseline determinants (age, sex, BMI, WOMAC pain and function scores, pain on physical examination, total range of motion (tROM), osteophytes and joint space narrowing (JSN) scores), and for worsening in WOMAC pain and function score in 1-year. Adjustments were performed for age, sex, and BMI.

Results

Follow-up was completed by 117 patients (81%, median age 60 years, 84% female); 62 (53%) and 31 patients (26%) showed progression and good prognosis, respectively. These following determinants were associated with progression: pain on physical examination (RR 1.2 (1.0 to 1.5)); tROM (1.4 (1.1 to 1.6); worsening in WOMAC pain (1.9 (1.2 to 2.3)); worsening in WOMAC function (2.4 (1.7 to 2.6)); osteophytes 1.5 (1.0 to 1.8); and JSN scores (2.3 (1.5 to 2.7)). Worsening in WOMAC pain (0.1 (0.1 to 0.8)) and function score (0.1 (0.1 to 0.7)), were negatively associated with good prognosis.

Conclusion

Worsening of self-reported pain and function in one year, limited tROM and higher osteophytes and JSN scores were associated with clinical progression. Worsening in WOMAC pain and function score in 1- year were associated with lower risk to have good prognosis. These findings help to inform patients with regard to their OA prognosis.

Body mass index and alignment and their interaction as risk factors for progression of knees with radiographic signs of osteoarthritis

OBJECTIVE

To investigate in which way body mass index (BMI) and alignment affect the risk for knee osteoarthritis (OA) progression.

METHODS

Radiographs of 181 knees from 155 patients (85% female, mean age 60 years) with radiographic signs of OA were analyzed at baseline and after 6 years. Progression was defined as 1-point increase in joint space narrowing score in the medial or lateral tibiofemoral (TF) compartment or having knee prosthesis during the follow-up for knees with a Kellgren and Lawrence score ≥ 1 at baseline. BMI at baseline was classified as normal (<25 kg/m(2)), overweight (25-30) and obese (>30). Knee alignment on baseline radiographs was categorized as normal (TF angle between 182° and 184°) and malalignment (<182° or >184°). We estimated the risk ratio (RR) with 95% confidence interval for knee OA progression for overweight and obese patients and for malaligned knees relative to normal using generalized estimating equations (GEE). Additionally, we estimated the added effect when BMI and malalignment were present together on progression of knee OA. Adjustments were made for age and sex.

RESULTS

Seventy-six knees (42%) showed progression: 27 in lateral and 66 in medial compartment. Knees from overweight and obese patients had an increased risk for progression (RR 2.4 (1.-3.6) and 2.9 (1.7-4.1), respectively). RRs of progression for malaligned, varus and valgus knee were 2.0 (1.3-2.8), 2.3 (1.4-3.1), and 1.7 (0.97-2.6), respectively. When BMI and malalignment were included in one model, the effect of overweight, obesity and malalignment did not change. The added effect when overweight and malalignment were present was 17%.

CONCLUSION

Overweight is associated with progression of knee OA and shows a small interaction with alignment. Losing weight might be helpful in preventing the progression of knee OA.

Hip osteoarthritis susceptibility is associated with IL1B -511(G>A) and IL1 RN (VNTR) genotypic polymorphisms in Croatian Caucasian population

Among the predisposing factors to osteoarthritis (OA), a frequent destructive joint disease, is the complex genetic heritage including the interleukin-1 family members like the IL1β (IL1B) and the IL1 receptor antagonist (IL1RN) genes. The aim of this study was to investigate allelic and genotypic frequencies of the IL1B gene single nucleotide polymorphism (SNP) at -511(G>A) and the variable number tandem repeat (VNTR) in the IL1RN gene in a Croatian Caucasian population of hip OA (HOA) cases and healthy controls. A total of 259 HOA patients with total hip replacement (THR) and 518 healthy blood donors as controls were genotyped for IL1B gene SNP -511(G>A) and the VNTR in the IL1RN gene associated with HOA. The genotype G/A (1/2) at IL1B was significantly associated with the protection of the HOA (p < 0.036, OR = 0.72, 95% CI = 0.52-0.99). The genotype G/G (1/1) had only a trend towards the susceptibility (p = 0.053, OR = 1.35, 95% CI = 0.98-1.86) to disease. None of the haplotypes IL1B -511(G>A) and IL1RN (VNTR) were found associated with the HOA. The haplotype 1-2 at these loci had only a trend to susceptibility (p = 0.065). Haplotype 1-3 had a significant male bias in diseased. Furthermore, genotype comprising 2-1/2-2 haplotypes was found significantly associated with predisposition to HOA (p = 0.027, OR = 2.23, 95% CI = 1.03-4.88), whereas genotype 1-1/2-2 with protection to disease (p = 0.028, OR = 0.65, 95% CI = 0.43-0.97). Our findings suggest that HOA in Croatian population might have a different genetic risk regarding the IL1 locus than has been reported for other Caucasian populations previously.

Osteoarthritis susceptibility genes influence the association between hip morphology and osteoarthritis

OBJECTIVE

The identified osteoarthritis (OA) susceptibility genes are mainly active in skeletal development and could thus affect joint geometry. Because nonoptimal joint geometry is a risk factor for the development of OA, we investigated if and how the path that leads from nonoptimal joint geometry to OA of the hip is influenced by these genes.

METHODS

The shape of the hips of subjects in the Genetics, Osteoarthritis and Progression Study, consisting of sibling pairs with symptomatic OA at multiple joint locations, was quantified by applying a statistical shape model to radiographs. Shape aspects (modes) were correlated to OA characteristics. We then tested for the association of shape modes with OA susceptibility single-nucleotide polymorphisms (SNPs) of GDF5, FRZB, and DIO2.

RESULTS

Four of 23 shape modes (mode 1, mode 17, mode 18, and mode 21) were strongly associated with OA characteristics. We observed a significant interaction between carrier status of DIO2 rs12885300 and hip OA characteristics for mode 1 (P = 0.005). This indicates that this specific aspect of hip shape correlates with OA characteristics only in carriers of the susceptibility allele.

CONCLUSION

Our results suggest that it is more likely that the rs12885300 SNP of DIO2 increases the vulnerability of cartilage to nonoptimal bone shapes rather than directly influencing the formation of these shapes.

Recommendations for standardization and phenotype definitions in genetic studies of osteoarthritis: the TREAT-OA consortium

OBJECTIVE

To address the need for standardization of osteoarthritis (OA) phenotypes by examining the effect of heterogeneity among symptomatic (SOA) and radiographic osteoarthritis (ROA) phenotypes.

METHODS

Descriptions of OA phenotypes of the 28 studies involved in the TREAT-OA consortium were collected. We investigated whether different OA definitions result in different association results by creating various hip OA definitions in one large population based cohort (the Rotterdam Study I (RSI)) and testing those for association with gender, age and body mass index using one-way ANOVA. For ROA, we standardized the hip-, knee- and hand ROA definitions and calculated prevalence's of ROA before and after standardization in nine cohort studies. This procedure could only be performed in cohort studies and standardization of SOA definitions was not feasible at this moment.

RESULTS

In this consortium, all studies with SOA phenotypes (knee, hip and hand) used a different definition and/or assessment of OA status. For knee-, hip- and hand ROA five, four and seven different definitions were used, respectively. Different hip ROA definitions do lead to different association results. For example, we showed in the RSI that hip OA defined as "at least definite joint space narrowing (JSN) and one definite osteophyte" was not associated with gender (P =0.22), but defined as "at least one definite osteophyte" was significantly associated with gender (P=3×10(-9)). Therefore, a standardization process was undertaken for ROA definitions. Before standardization a wide range of ROA prevalence's was observed in the nine cohorts studied. After standardization the range in prevalence of knee- and hip ROA was small.

CONCLUSION

Phenotype definitions influence the prevalence of OA and association with clinical variables. ROA phenotypes within the TREAT-OA consortium were standardized to reduce heterogeneity and improve power in future genetics studies.

How pleiotropic genetics of the musculoskeletal system can inform genomics and phenomics of aging

Genetic study can provide insight into the biologic mechanisms underlying inter-individual differences in susceptibility to (or resistance to) organisms' aging. Recent advances in molecular genetics and genetic epidemiology provide the necessary tools to perform a study of the genetic sources of biological aging. However, to be successful, the genetic study of a complex condition requires a heritable phenotype to be developed and validated. Genome-wide association studies offer an unbiased approach to identify new candidate genes for human diseases. It is hypothesized that convergent results from multiple aging-related traits will point out the genes responsible for the general aging of the organism. This perspective focuses on the musculoskeletal aging as an example of an approach to identify a downstream common pathway that summarizes aging processes. Since the musculoskeletal traits are linked to the state of many vital functions, disability, and ultimately survival rates, we postulate that there is significance in studying musculoskeletal aging. Construction of an integrated phenotype of aging can be achieved based on shared genetics among multiple musculoskeletal biomarkers. Valid biomarkers from other systems of the organism should be similarly explored. The new composite aging score needs to be validated by determining whether it predicts all-cause mortality, incidences of major chronic diseases, and disability late in life. Comprehensive databases on biomarkers of musculoskeletal aging in multiple large cohort studies, along with information on various health outcomes, are needed to validate the proposed measure of biological aging.

Large-scale meta-analysis of interleukin-1 beta and interleukin-1 receptor antagonist polymorphisms on risk of radiographic hip and knee osteoarthritis and severity of knee osteoarthritis

OBJECTIVE

To clarify the role of common genetic variation in the Interleukin-1β (IL1B) and Interleukin-1R antagonist (IL1RN) genes on risk of knee and hip osteoarthritis (OA) and severity of knee OA by means of large-scale meta-analyses.

METHODS

We searched PubMed for articles assessing the role of IL1B and IL1RN polymorphisms/haplotypes on the risk of hip and/or knee OA. Novel data were included from eight unpublished studies. Meta-analyses were performed using fixed- and random-effects models with a total of 3595 hip OA and 5013 knee OA cases, and 6559 and 9132 controls respectively. The role of ILRN haplotypes on radiographic severity of knee OA was tested in 1918 cases with Kellgren-Lawrence (K/L) 1 or 2 compared to 199 cases with K/L 3 or 4.

RESULTS

The meta-analysis of six published studies retrieved from the literature search and eight unpublished studies showed no evidence of association between common genetic variation in the IL1B or IL1RN genes and risk of hip OA or knee OA (P>0.05 for rs16944, rs1143634, rs419598 and haplotype C-G-C (rs1143634, rs16944 and rs419598) previously implicated in risk of hip OA). The C-T-A haplotype formed by rs419598, rs315952 and rs9005, previously implicated in radiographic severity of knee OA, was associated with reduced severity of knee OA (odds ratio (OR)=0.71 95%CI 0.56-0.91; P=0.006, I(2)=74%), and achieved borderline statistical significance in a random-effects model (OR=0.61 95%CI 0.35-1.06 P=0.08).

CONCLUSION

Common genetic variation in the Interleukin-1 region is not associated with prevalence of hip or knee OA but our data suggest that IL1RN might have a role in severity of knee OA.