A Large-Scale Genome-Wide Study of Gene-Sleep Duration Interactions for Blood Pressure in 811,405 Individuals from Diverse Populations

Although both short and long sleep duration are associated with elevated hypertension risk, our understanding of their interplay with biological pathways governing blood pressure remains limited. To address this, we carried out genome-wide cross-population gene-by-short-sleep and long-sleep duration interaction analyses for three blood pressure traits (systolic, diastolic, and pulse pressure) in 811,405 individuals from diverse population groups. We discover 22 novel gene-sleep duration interaction loci for blood pressure, mapped to 23 genes. Investigating these genes' functional implications shed light on neurological, thyroidal, bone metabolism, and hematopoietic pathways that necessitate future investigation for blood pressure management that caters to sleep health lifestyle. Non-overlap between short sleep (12) and long sleep (10) interactions underscores the plausible nature of distinct influences of both sleep duration extremes in cardiovascular health. Several of our loci are specific towards a particular population background or sex, emphasizing the importance of addressing heterogeneity entangled in gene-environment interactions, when considering precision medicine design approaches for blood pressure management.

Defining the relationship between lipids and immune traits in TwinsUK

Introduction

Lipid metabolism plays a crucial role in both innate and adaptive immune responses. Blood lipids are well known biomarkers of heart disease and atherosclerosis. Given that immune responses are involved in atherosclerosis development and progression, it is of utmost importance to explore the mutual relationship between circulating lipid measures and immunology markers, to better manage cardiovascular disease (CVD).

Purpose

The aim of this work was to evaluate relationships of distinct immune cell subtypes and circulating lipids in a general population setting.

Methods

We investigated the associations between 3,734 immune traits and circulating lipids [LDL-C, HDL-C, total cholesterol (TC), triglycerides (TG), non-HDL-C) in 2,056 individuals from the TwinsUK cohort. Immune traits were defined by high-dimensional flow-cytometry which enabled in-depth assessment of all major lymphocyte and myeloid subsets in peripheral blood. Information on immune cell subset frequency (FREQ) and mean fluorescence intensity (MFI) was available. A linear mixed model regression analysis adjusted for family structure, gender, age and BMI was used to examine the associations between immune traits and lipids. We then undertook a sub-analysis in 608 individuals and 131 lipid metabolites quantified using nuclear magnetic resonance spectroscopy to investigate the associations of specific immune traits and lipoprotein particles.

Results

We observed 18 significant associations (Bonferroni P-value <7.3x10–6) between 9 MFI immune traits and lipids. These involved associations between circulating lipids and 7 different myeloid or lymphoid subsets of immune cells including monocytes and natural killer cells. The top associations were found between CD14+ classical monocytes and non-HDL-C, LDL-C, HDL-C and TG. Increased levels of non-HDL-C (P=4.7x10–14), HDL-C (P=1.9x10–13) and TG (P=8.5x10–10) were associated with lower expression of CD14+ monocytes whereas increased LDL-C was associated with elevated expression of both CD14+ monocytes (P=1.0x10–13) and CD16+CD14+ monocytes (P=2.7x10–8). No significant association was detected between FREQ traits and lipids. We also observed 39 associations (Bonferroni P-value <3.1x10–4) between 19 lipid metabolites and CD14+ classical monocytes. The top associations were linked to different HDL particles (Free cholesterol in L-HDL: P=3.5x10–6; Total cholesterol in L-HDL: P=3.5x10–6; Cholesterol esters in L-HDL: P=4.1x10–6). Different subclasses of VLDL particles were also associated with CD14+ monocytes.

Conclusion

The present study provides the first comprehensive picture of lipid-immune cell associations in the circulatory system. We observed a link between expression levels of CD14+ classical monocytes and circulating lipid metabolites. The same lipid metabolites were previously associated with risk of developing myocardial infarction and stroke speculating a link between CD14+ classical monocytes and CVD risk.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): SYSCID - A Systems medicine approach to chronic inflammatory diseases

The gut microbiome: what the oncologist ought to know

The gut microbiome (GM) has been implicated in a vast number of human pathologies and has become a focus of oncology research over the past 5 years. The normal gut microbiota imparts specific function in host nutrient metabolism, xenobiotic and drug metabolism, maintenance of structural integrity of the gut mucosal barrier, immunomodulation and protection against pathogens. Strong evidence is emerging to support the effects of the GM on the development of some malignancies but also on responses to cancer therapies, most notably, immune checkpoint inhibition. Tools for manipulating the GM including dietary modification, probiotics and faecal microbiota transfer (FMT) are in development. Current understandings of the many complex interrelationships between the GM, cancer, the immune system, nutrition and medication are ultimately based on a combination of short-term clinical trials and observational studies, paired with an ever-evolving understanding of cancer biology. The next generation of personalised cancer therapies focusses on molecular and phenotypic heterogeneity, tumour evolution and immune status; it is distinctly possible that the GM will become an increasingly central focus amongst them. The aim of this review is to provide clinicians with an overview of microbiome science and our current understanding of the role the GM plays in cancer.

Diagnostic value of cutaneous manifestation of SARS-CoV-2 infection

Background

One of the challenging aspects of SARS‐CoV‐2 infection is its diverse multisystemic disease presentation.

Objectives

To evaluate the diagnostic value of cutaneous manifestations of SARS‐CoV‐2 infection and investigate their duration and timing in relation to other COVID‐19 symptoms.

Methods

We used data from 336 847 UK users of the COVID Symptom Study app to assess the diagnostic value of body rash or an acral rash in SARS‐CoV‐2 infection, and data from an independent online survey of 11 544 respondents to investigate skin‐specific symptoms and collect their photographs.

Results

Using data from the app, we show significant association between skin rashes and a positive swab test result (odds ratio 1·67, 95% confidence interval 1·42–1·97). Strikingly, among the respondents of the independent online survey, we found that 17% of SARS‐CoV‐2‐positive cases reported skin rashes as the first presentation, and 21% as the only clinical sign of COVID‐19. Together with the British Association of Dermatologists, we have compiled a catalogue of images of the most common skin manifestations of COVID‐19 from 400 individuals (https://covidskinsigns.com), which we have made publicly available to assist clinicians in recognition of this early clinical feature of COVID‐19.

Conclusions

Skin rashes cluster with other COVID‐19 symptoms, are predictive of a positive swab test, and occur in a significant number of cases, either alone or before other classical symptoms. Recognizing rashes is important in identifying new and earlier cases of COVID‐19.

What is already known about this topic?

Several studies conducted in hospital settings reported that patients with COVID‐19 presented with unusual skin rashes, including urticarial rashes, vesicular lesions and, less frequently, chilblains in fingers or toes.

What does this study add?

We confirmed, in a community‐based setting that also includes milder forms of the disease, that the presence of a skin rash is predictive of SARS‐CoV‐2 infection.

We provide a website with photos of skin manifestations to help healthcare professionals in diagnosing COVID‐19.

Skin rashes should be taken into account to provide a quick COVID‐19 diagnosis to curb the spread of the disease.

Linked Comment: Naldi. Br J Dermatol 2021; 184:793–794.

Optimal symptom combinations to aid COVID-19 case identification: Analysis from a community-based, prospective, observational cohort

Objectives

Diagnostic work-up following any COVID-19 associated symptom will lead to extensive testing, potentially overwhelming laboratory capacity whilst primarily yielding negative results. We aimed to identify optimal symptom combinations to capture most cases using fewer tests with implications for COVID-19 vaccine developers across different resource settings and public health.

Methods

UK and US users of the COVID-19 Symptom Study app who reported new-onset symptoms and an RT-PCR test within seven days of symptom onset were included. Sensitivity, specificity, and number of RT-PCR tests needed to identify one case (test per case [TPC]) were calculated for different symptom combinations. A multi-objective evolutionary algorithm was applied to generate combinations with optimal trade-offs between sensitivity and specificity.

Findings

UK and US cohorts included 122,305 (1,202 positives) and 3,162 (79 positive) individuals. Within three days of symptom onset, the COVID-19 specific symptom combination (cough, dyspnoea, fever, anosmia/ageusia) identified 69% of cases requiring 47 TPC. The combination with highest sensitivity (fatigue, anosmia/ageusia, cough, diarrhoea, headache, sore throat) identified 96% cases requiring 96 TPC.

Interpretation

We confirmed the significance of COVID-19 specific symptoms for triggering RT-PCR and identified additional symptom combinations with optimal trade-offs between sensitivity and specificity that maximize case capture given different resource settings.

Optimal symptom combinations to aid COVID-19 case identification: analysis from a community-based, prospective, observational cohort

OBJECTIVES

Diagnostic work-up following any COVID-19 associated symptom will lead to extensive testing, potentially overwhelming laboratory capacity whilst primarily yielding negative results. We aimed to identify optimal symptom combinations to capture most cases using fewer tests with implications for COVID-19 vaccine developers across different resource settings and public health.

METHODS

UK and US users of the COVID-19 Symptom Study app who reported new-onset symptoms and an RT-PCR test within seven days of symptom onset were included. Sensitivity, specificity, and number of RT-PCR tests needed to identify one case (test per case [TPC]) were calculated for different symptom combinations. A multi-objective evolutionary algorithm was applied to generate combinations with optimal trade-offs between sensitivity and specificity.

FINDINGS

UK and US cohorts included 122,305 (1,202 positives) and 3,162 (79 positive) individuals. Within three days of symptom onset, the COVID-19 specific symptom combination (cough, dyspnoea, fever, anosmia/ageusia) identified 69% of cases requiring 47 TPC. The combination with highest sensitivity (fatigue, anosmia/ageusia, cough, diarrhoea, headache, sore throat) identified 96% cases requiring 96 TPC.

INTERPRETATION

We confirmed the significance of COVID-19 specific symptoms for triggering RT-PCR and identified additional symptom combinations with optimal trade-offs between sensitivity and specificity that maximize case capture given different resource settings.

Untangling the relationship between diet and visceral fat mass through blood metabolomics and gut microbiome profiling

BACKGROUND/OBJECTIVES

Higher visceral fat mass (VFM) is associated with an increased risk for developing cardio-metabolic diseases. The mechanisms by which an unhealthy diet pattern may influence visceral fat (VF) development has yet to be examined through cutting-edge multi-omic methods. Therefore, our objective was to examine the dietary influences on VFM and identify gut microbiome and metabolite profiles that link food intakes to VFM.

SUBJECTS/METHODS

In 2218 twins with VFM, food intake and metabolomics data available we identified food intakes most strongly associated with VFM in 50% of the sample, then constructed and tested the 'VFM diet score' in the remainder of the sample. Using linear regression (adjusted for covariates, including body mass index and total fat mass), we investigated associations between the VFM diet score, the blood metabolomics profile and the fecal microbiome (n=889), and confirmed these associations with VFM. We replicated top findings in monozygotic (MZ) twins discordant (⩾1 s.d. apart) for VFM, matched for age, sex and the baseline genetic sequence.

RESULTS

Four metabolites were associated with the VFM diet score and VFM: hippurate, alpha-hydroxyisovalerate, bilirubin (Z,Z) and butyrylcarnitine. We replicated associations between VFM and the diet score (beta (s.e.): 0.281 (0.091); P=0.002), butyrylcarnitine (0.199 (0.087); P=0.023) and hippurate (-0.297 (0.095); P=0.002) in VFM-discordant MZ twins. We identified a single species, Eubacterium dolichum to be associated with the VFM diet score (0.042 (0.011), P=8.47 × 10-5), VFM (0.057 (0.019), P=2.73 × 10-3) and hippurate (-0.075 (0.032), P=0.021). Moreover, higher blood hippurate was associated with elevated adipose tissue expression neuroglobin, with roles in cellular oxygen homeostasis (0.016 (0.004), P=9.82x10-6).

CONCLUSIONS

We linked a dietary VFM score and VFM to E. dolichum and four metabolites in the blood. In particular, the relationship between hippurate, a metabolite derived from microbial metabolism of dietary polyphenols, and reduced VFM, the microbiome and increased adipose tissue expression of neuroglobin provides potential mechanistic insight into the influence of diet on VFM.

Pain in knee osteoarthritis is associated with variation in the neurokinin 1/substance P receptor (TACR1) gene

BACKGROUND

Substance P (SP) is a pain- and inflammation-related neuropeptide which preferentially binds to the neurokinin receptor 1 (NK₁ ). SP and NK₁ receptors have been implicated in joint pain, inflammation and damage in animal models and human studies of osteoarthritis (OA). The aim of this study was to test if genetic variation at the neurokinin 1 receptor gene (TACR1) is associated with pain in individuals with radiographic knee OA.

METHODS

Participants from the Genetics of OA and Lifestyle study were used for the discovery group (n = 1615). Genotype data for six SNPs selected to cover most variation in the TACR1 gene were used to test for an association with symptomatic OA. Replication analysis was performed using data from the Chingford 1000 Women Study, Hertfordshire Cohort Study, Tasmanian Older Adult Cohort Study and the Clearwater OA Study. In total, n = 1715 symptomatic OA and n = 735 asymptomatic OA individuals were analysed.

RESULTS

Out of six SNPs tested in the TACR1 gene, one (rs11688000) showed a nominally significant association with a decreased risk of symptomatic OA in the discovery cohort. This was then replicated in four additional cohorts. After adjusting for age, gender, body mass index and radiographic severity, the G (minor) allele at rs11688000 was associated with a decreased risk of symptomatic OA compared to asymptomatic OA cases (p = 9.90 × 10^-4 , OR = 0.79 95% 0.68-0.90 after meta-analysis).

CONCLUSIONS

This study supports a contribution from the TACR1 gene in human OA pain, supporting further investigation of this gene's function in OA.

SIGNIFICANCE

This study contributes to the knowledge of the genetics of painful osteoarthritis, a condition which affects millions of individuals worldwide. Specifically, a contribution from the TACR1 gene to modulating pain sensitivity in osteoarthritis is suggested.

Gut microbiome diversity and high-fibre intake are related to lower long-term weight gain

Background:

Cross-sectional studies suggest that the microbes in the human gut have a role in obesity by influencing the human body’s ability to extract and store calories. The aim of this study was to assess if there is a correlation between change in body weight over time and gut microbiome composition.

Methods:

We analysed 16S ribosomal RNA gene sequence data derived from the faecal samples of 1632 healthy females from TwinsUK to investigate the association between gut microbiome measured cross-sectionally and longitudinal weight gain (adjusted for caloric intake and baseline body mass index). Dietary fibre intake was investigated as a possible modifier.

Results:

Less than half of the variation in long-term weight change was found to be heritable (h²=0.41 (0.31, 0.47)). Gut microbiota diversity was negatively associated with long-term weight gain, whereas it was positively correlated with fibre intake. Nine bacterial operational taxonomic units (OTUs) were significantly associated with weight gain after adjusting for covariates, family relatedness and multiple testing (false discovery rate <0.05). OTUs associated with lower long-term weight gain included those assigned to Ruminococcaceae (associated in mice with improved energy metabolism) and Lachnospiraceae. A Bacterioides species OTU was associated with increased risk of weight gain but this appears to be driven by its correlation with lower levels of diversity.

Conclusions:

High gut microbiome diversity, high-fibre intake and OTUs implicated in animal models of improved energy metabolism are all correlated with lower term weight gain in humans independently of calorie intake and other confounders.

Purine Arabinosides as Inhibitors of Human Haemopoietic Progenitor Cells

Four purine arabinosides that inhibit varicella-zoster virus (VZV) replication in vitro were tested as inhibitors of colony formation by progenitor cells from normal human bone marrow. In general, erythroid burst forming cells (BFU-E) were more sensitive to inhibition by these compounds than were either erythroid colony forming cells (CFU-E) or granulocyte/macrophage colony forming cells (CFU-GM). A 50% reduction in colony formation (IC50) was observed for BFU-E in the presence of 8 μM 6-methoxypurine arabinoside. Adenine arabinoside and hypoxanthine arabinoside had IC50 values of 1 μM and 4 μM respectively, whereas 6-ethoxypurine arabinoside was not inhibitory (IC50 > 50 μM). Enzyme studies showed that both 6-methoxypurine arabinoside and adenine arabinoside were converted to hypoxanthine arabinoside by adenosine deaminase. 6-Ethoxypurine arabinoside was a much less efficient substrate. When the BFU-E assays were performed in the presence of an inhibitor of adenosine deaminase, 6-methoxypurine arabinoside became non-inhibitory. In contrast, adenine arabinoside became much more inhibitory (IC50 = 0.03 μM). The potency of hypoxanthine arabinoside was unaffected. Thus, incubation of 6-methoxypurine arabinoside and adenine arabinoside under conditions appropriate for the BFU-E assay resulted in the in situ conversion of these compounds to hypoxanthine arabinoside. Biotransformation of compounds must be considered in the assessment of toxicity in vitro.

Quantitative genetics of circulating Dickkopf-related protein 1 (DKK1) in community-based sample of UK twins

Dickkopf-related protein 1 (DKK1) is a major inhibitor of Wnt signalling pathway but also plays an important role in bone formation. Its circulating levels appear to correlate significantly with plasma levels of inflammatory factors, fractalkine and IL-6. This study, using a large sample of UK twins, showed that the variation of each of these factors and correlation between them was explained by the genetic factors, and indicated possible association with DKK1 gene variants.

INTRODUCTION

DKK1 is involved in the development of several inflammatory conditions related to bone and joint degradation. Our objectives were to explore the genetic contribution (heritability) to circulating DKK1 variation and its correlation with other inflammatory cytokines, interleukin 6 (IL-6) and fractalkine, and to test whether the DKK1 heritability could be attributable to single nucleotide polymorphisms (SNPs) mapped to DKK1, IL-6 and FRCT genes.

METHODS

The study included a large community-based sample of 4939 women drawn from the general UK population. Plasma samples were analysed for circulating levels of DKK1, IL-6 and fractalkine (FRCT); 65 SNPs of DKK1, IL-6 and FRCT candidate genes, with MAF >0.1, were examined. We applied variance component analysis to evaluate contribution of putative genetic (including above SNPs) and environmental factors to variation of DKK1, and its correlation with IL-6 and FRCT.

RESULTS

Putative genetic factors explained 42.2 ± 2 % of the total variation of circulating DKK1 levels, and were also significant for fractalkine and IL-6 variations. Most importantly, we report significant phenotypic (0.208 ± 0.006-0.459 ± 0.007) and genetic (0.338 ± 0.069-0.617 ± 0.033) correlations between these molecules. We found evidence suggestive of association between the DKK1 and its structural genes variants.

CONCLUSIONS

Circulating DKK1 levels correlated significantly with levels of IL-6 and FRCT, known risk factors for several inflammatory processes suggesting a potential role of DKK1 in inflammation and tissue injury. Our results suggest the contribution of genetic factors in inter-individual variation of DKK1 levels in human population. However, further studies are required to determine genetic polymorphisms affecting DKK1 variation and its correlation with IL-6 and FRCT.

Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium

Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40-48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13-20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10(-8)) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use.

Plasma protein biomarkers of Alzheimer's disease endophenotypes in asymptomatic older twins: early cognitive decline and regional brain volumes

There is great interest in blood-based markers of Alzheimer's disease (AD), especially in its pre-symptomatic stages. Therefore, we aimed to identify plasma proteins whose levels associate with potential markers of pre-symptomatic AD. We also aimed to characterise confounding by genetics and the effect of genetics on blood proteins in general. Panel-based proteomics was performed using SOMAscan on plasma samples from TwinsUK subjects who are asymptomatic for AD, measuring the level of 1129 proteins. Protein levels were compared with 10-year change in CANTAB-paired associates learning (PAL; n = 195), and regional brain volumes (n = 34). Replication of proteins associated with regional brain volumes was performed in 254 individuals from the AddNeuroMed cohort. Across all the proteins measured, genetic factors were found to explain ~26% of the variability in blood protein levels on average. The plasma level of the mitogen-activated protein kinase (MAPK) MAPKAPK5 protein was found to positively associate with the 10-year change in CANTAB-PAL in both the individual and twin difference context. The plasma level of protein MAP2K4 was found to suggestively associate negatively (Q < 0.1) with the volume of the left entorhinal cortex. Future studies will be needed to assess the specificity of MAPKAPK5 and MAP2K4 to eventual conversion to AD.

Individuals with high bone mass have an increased prevalence of radiographic knee osteoarthritis

We previously reported an association between high bone mass (HBM) and a bone-forming phenotype of radiographic hip osteoarthritis (OA). As knee and hip OA have distinct risk factors, in this study we aimed to determine (i) whether HBM is also associated with knee OA, and (ii) whether the HBM knee OA phenotype demonstrates a similar pattern of radiographic features to that observed at the hip. HBM cases (defined by DXA BMD Z-scores) from the UK-based HBM study were compared with unaffected family controls and general population controls from the Chingford and Hertfordshire cohort studies. A single blinded observer graded AP weight-bearing knee radiographs for features of OA (Kellgren-Lawrence score, osteophytes, joint space narrowing (JSN), sclerosis) using an atlas. Analyses used logistic regression, adjusting a priori for age and gender, and additionally for BMI as a potential mediator of the HBM-OA association, using Stata v12. 609 HBM knees in 311 cases (mean age 60.8years, 74% female) and 1937 control knees in 991 controls (63.4years, 81% female) were analysed. The prevalence of radiographic knee OA, defined as Kellgren-Lawrence grade≥2, was increased in cases (31.5% vs. 20.9%), with age and gender adjusted OR [95% CI] 2.38 [1.81, 3.14], p<0.001. The association between HBM and osteophytosis was stronger than that for JSN, both before and after adjustment for BMI which attenuated the ORs for knee OA and osteophytes in cases vs. controls by approximately 50%. Our findings support a positive association between HBM and knee OA. This association was strongest for osteophytes, suggesting HBM confers a general predisposition to a subtype of OA characterised by increased bone formation.

Subclinical deformities of the hip are significant predictors of radiographic osteoarthritis and joint replacement in women. A 20 year longitudinal cohort study

OBJECTIVE

Femoroacetabular Impingement (FAI) and Acetabular Dysplasia are common deformities, which have been implicated as a major cause of hip osteoarthritis (OA). We examined whether these subtle deformities of the hip are associated with the development of radiographic OA and total hip replacement (THR) in women.

DESIGN

A population-based, longitudinal cohort of 1003 women underwent pelvis radiographs at years 2 and 20. Alpha Angle, Triangular Index Height, Lateral Centre Edge (LCE) angle and Extrusion Index were measured. An alpha angle of greater than 65° was defined as Cam-type FAI. Radiographic OA and the presence of a THR were then determined at 20 years.

RESULTS

Cam-type FAI was significantly associated with the development of radiographic OA. Each degree increase in alpha angle above 65° was associated with an increase in risk of 5% (Odds Ratio (OR) 1.05 [95% confidence interval (CI) 1.01-1.09]) for radiographic OA and 4% (OR 1.04 [95% CI 1.00-1.08]) for THR. For Acetabular Dysplasia, each degree reduction in LCE angle below 28° was associated with an increase in risk of 13.0% (OR 0.87 [95% CI 0.78-0.96]) for radiographic OA and 18% (OR 0.82 [95% CI 0.75-0.89]) for THR.

CONCLUSIONS

This study demonstrates that Cam-type FAI and mild Acetabular Dysplasia are predictive of subsequent OA and THR in a large female population cohort. These are independent of age, BMI and joint space and significantly improve current predictive models of hip OA development.

Prevalence of radiographic hip osteoarthritis is increased in high bone mass

OBJECTIVE

Epidemiological studies have shown an association between increased bone mineral density (BMD) and osteoarthritis (OA), but whether this represents cause or effect remains unclear. In this study, we used a novel approach to investigate this question, determining whether individuals with High Bone Mass (HBM) have a higher prevalence of radiographic hip OA compared with controls.

DESIGN

HBM cases came from the UK-based HBM study: HBM was defined by BMD Z-score. Unaffected relatives of index cases were recruited as family controls. Age-stratified random sampling was used to select further population controls from the Chingford and Hertfordshire cohort studies. Pelvic radiographs were pooled and assessed by a single observer blinded to case-control status. Analyses used logistic regression, adjusted for age, gender and body mass index (BMI).

RESULTS

530 HBM hips in 272 cases (mean age 62.9 years, 74% female) and 1702 control hips in 863 controls (mean age 64.8 years, 84% female) were analysed. The prevalence of radiographic OA, defined as Croft score ≥3, was higher in cases compared with controls (20.0% vs 13.6%), with adjusted odds ratio (OR) [95% CI] 1.52 [1.09, 2.11], P = 0.013. Osteophytes (OR 2.12 [1.61, 2.79], P < 0.001) and subchondral sclerosis (OR 2.78 [1.49, 5.18], P = 0.001) were more prevalent in cases. However, no difference in the prevalence of joint space narrowing (JSN) was seen (OR 0.97 [0.72, 1.33], P = 0.869).

CONCLUSIONS

An increased prevalence of radiographic hip OA and osteophytosis was observed in HBM cases compared with controls, in keeping with a positive association between HBM and OA and suggesting that OA in HBM has a hypertrophic phenotype.

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.