Subluxation of the first carpometacarpal joint and age are important factors in reduced hand strength in patients with hand osteoarthritis

OBJECTIVE

To investigate the determinants of hand strength in patients with hand osteoarthritis (OA).

METHOD

Pinch and cylinder grip strength were measured in 527 patients with hand OA diagnosed by their treating rheumatologist from the Hand OSTeoArthritis in Secondary care (HOSTAS) study. Radiographs of hands (22 joints) were scored 0-3 (scaphotrapeziotrapezoid and first interphalangeal joints 0-1) on osteophytes and joint space narrowing following the Osteoarthritis Research Society International atlas. The first carpometacarpal joint (CMC1) was scored 0-1 for subluxation. Pain was assessed with the Australian/Canadian Hand Osteoarthritis Index pain subscale, and health-related quality of life with the Short Form-36. Regression analysis served to investigate associations of hand strength with patient, disease, and radiographic features.

RESULTS

Hand strength was negatively associated with female sex, age, and pain. Reduced hand strength was associated with reduced quality of life, although less after adjusting for pain. Radiographic features of hand OA were associated with reduced grip strength when solely adjusted for sex and body mass index, but only CMC1 subluxation in the dominant hand remained significantly associated with pinch grip adjusted additionally for age (-0.511 kg, 95% confidence interval -0.975; -0.046). Mediation analysis showed low and not significant percentages of mediation of hand OA in the association between age and grip strength.

CONCLUSIONS

Subluxation of CMC1 is associated with reduced grip strength, whereas associations with other radiographic features seem to be confounded by age. In the relationship between age and hand strength, radiographic hand OA severity is not an important mediator.

The argument for adopting a jurisprudence platform for scientific misconduct

In this paper we will describe the arguments to adopt a jurisprudence platform for scientific misconduct, we argue that this will increase the principle of legal certainty, improve procedures, and will promote scientific integrity in other, indirect ways. With the platform that we are currently setting up in the Netherlands as a motivating example, we finally also describe the prerequisites for such a platform, its contents as well as its value in the international context.

Neuropathic‐like pain symptoms in inflammatory hand osteoarthritis lower quality of life and may not decrease under prednisolone treatment

Background

Pain is common in hand osteoarthritis (OA) and multiple types may occur. We investigated the prevalence, associated patient characteristics, influence on health‐related quality of life (HR‐QoL) and response to anti‐inflammatory treatment of neuropathic‐like pain in inflammatory hand OA.

Methods

Data were analysed from a 6‐week, randomized, double‐blind, placebo‐controlled trial investigating prednisolone treatment in 92 patients with painful inflammatory hand OA. Neuropathic‐like pain was measured with the painDETECT questionnaire. Associations between baseline characteristics and baseline neuropathic‐like pain were analysed with ordinal logistic regression, association of baseline neuropathic‐like pain symptoms with baseline HR‐QoL with linear regression, painDETECT and visual analogue scale (VAS) change from baseline to week 6 and interaction of painDETECT with prednisolone efficacy on VAS pain change from baseline to week 6 with generalized estimating equations (GEE).

Results

Of 91 patients (79% female, mean age 64) with complete painDETECT data at baseline, 53% were unlikely to have neuropathic‐like pain, 31% were indeterminate and 16% were likely to have neuropathic‐like pain. Neuropathic‐like pain was associated with female sex, less radiographic damage and more comorbidities. Patients with neuropathic‐like pain had lower HR‐QoL (PCS‐6.5 [95% CI −10.4 to −2.6]) than those without. Neuropathic‐like pain symptoms remained under prednisolone treatment and no interaction was seen between painDETECT and prednisolone efficacy on VAS pain.

Conclusions

In this study, 16% of inflammatory hand OA patients had neuropathic‐like pain. They were more often female, had more comorbidities and had lower QoL than those without. Neuropathic‐like pain symptoms remained despite prednisolone treatment and did not seem to affect the outcome of prednisolone treatment.

Significance

Pain is the dominant symptom in hand OA, with an unclear aetiology. In this study, we found that neuropathic‐like pain may play a role in hand OA, that it showed associations with female sex, younger age and more comorbidities and that it lowered health‐related quality of life in hand OA. Neuropathic‐like pain in hand OA seems resistant to prednisolone therapy but did not seem to interfere with the treatment of inflammatory pain with prednisolone.

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

Coded diagnoses from general practice electronic health records are a feasible and valid alternative to self-report to define diabetes cases in research

AIMS

To examine the feasibility and validity of obtaining International Classification of Primary Care (ICPC)-coded diagnoses of diabetes mellitus (DM) from general practice electronic health records for case definition in epidemiological studies, as alternatives to self-reported DM.

METHODS

The Netherlands Epidemiology of Obesity study is a population-based cohort study of 6671 persons aged 45-65 years at baseline, included between 2008-2012. Data from electronic health records were collected between 2012-2014. We defined a reference standard using diagnoses, prescriptions and consultation notes and investigated its agreement with ICPC-coded diagnoses of DM and self-reported DM.

RESULTS

After a median follow-up of 1.8 years, data from 6442 (97%) participants were collected. With the reference standard, 506 participants (79/1000 person-years) were classified with prevalent DM at baseline and 131 participants (11/1000 person-years) were classified with incident DM during follow-up. The agreement of prevalent DM between self-report and the reference standard was 98% (kappa 0.86), the agreement between ICPC-coded diagnoses and the reference standard was 99% (kappa 0.95). The agreement of incident DM between ICPC-coded diagnoses and the reference standard was >99% (kappa 0.92).

CONCLUSIONS

ICPC-coded diagnoses of DM from general practice electronic health records are a feasible and valid alternative to self-reported diagnoses of DM.

Effusion attenuates the effect of synovitis on radiographic progression in patients with hand osteoarthritis: a longitudinal magnetic resonance imaging study

An exploratory study to determine the role of effusion, i.e., fluid in the joint, in pain, and radiographic progression in patients with hand osteoarthritis. Distal and proximal interphalangeal joints (87 patients, 82% women, mean age 59 years) were assessed for pain. T2-weighted and Gd-chelate contrast-enhanced T1-weighted magnetic resonance images were scored for enhanced synovial thickening (EST, i.e., synovitis), effusion (EST and T2-high signal intensity [hsi]) and bone marrow lesions (BMLs). Effusion was defined as follows: (1) T2-hsi > 0 and EST = 0; or 2) T2-hsi = EST but in different joint locations. Baseline and 2-year follow-up radiographs were scored following Kellgren-Lawrence, increase ≥ 1 defined progression. Associations between the presence of effusion and pain and radiographic progression, taking into account EST and BML presence, were explored on the joint level. Effusion was present in 17% (120/691) of joints, with (63/120) and without (57/120) EST. Effusion on itself was not associated with pain or progression. The association with pain and progression, taking in account other known risk factors, was stronger in the absence of effusion (OR [95% CI] 1.7 [1.0–2.9] and 3.2 [1.7–5.8]) than in its presence (1.6 [0.8–3.0] and 1.3 [0.5–3.1]). Effusion can be assessed on MR images and seems not to be associated with pain or radiographic progression but attenuates the association between synovitis and progression.

Key Points • Effusion is present apart from synovitis in interphalangeal joints in patients with hand OA. • Effusion in finger joints can be assessed as a separate feature on MR images. • Effusion seems to be of importance for its attenuating effect on the association between synovitis and radiographic progression.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prevalence and Incidence of Non-neutralizing Antibodies in Congenital Hemophilia A- A Systematic Review and Meta-Analysis

Objectives: In hemophilia A the presence of non-neutralizing antibodies (NNAs) against Factor VIII (FVIII) may predict the development of neutralizing antibodies (inhibitors) and accelerate the clearance of administrated FVIII concentrates. This systematic review aimed to assess: (1) the prevalence and incidence of NNAs in patients with congenital hemophilia without inhibitors and (2) the association between NNAs and patient and treatment characteristics.

Methods: We conducted a search in MEDLINE, Embase, Web of Science and the Cochrane database. We included cross-sectional and longitudinal studies reporting on NNAs in patients with hemophilia A and B, who were inhibitor-negative at the start of the observation period. Data were extracted on: hemophilia type and severity, patient and treatment characteristics, NNA prevalence and incidence, NNA assays and inhibitor development. Two independent reviewers performed study selection, data extraction and risk of bias assessment, using adapted criteria of the Joanna Briggs Institute. Studies were classified as high-quality when ≥5/9 criteria were met. NNA assays were classified as high-quality when both quality criteria were met: (1) use of positive controls and (2) competition with FVIII to establish FVIII-specificity. We reported NNA prevalence and incidence for each study. The pooled NNA prevalence was assessed for well-designed studies in previously treated patients, employing high-quality NNA assays.

Results: We included data from 2,723 inhibitor-negative patients with hemophilia A, derived from 28 studies. Most studies were cross-sectional (19/28) and none reported on NNAs in hemophilia B. Study design was of high quality in 16/28 studies and the NNA assay quality was high in 9/28 studies. Various NNA assays were used, predominantly ELISA (18/28) with different cut-off values. We found a large variety in NNA prevalence (Range, 0–100%). The pooled NNA prevalence in high-quality studies was 25% (95% CI, 16–38%). The incidence of new NNA development was reported in one study (0.01 NNA per person-exposure day).

Conclusion: This systematic review identified studies that were heterogeneous in study design, patient population and NNA assay type, with NNA prevalence ranging from 0 to 100% in inhibitor-negative patients with hemophilia A. The pooled NNA prevalence was 25% in high-quality studies including only previously treated patients and performing high-quality NNA assays.

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSION

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

The association between leptin concentration and blood coagulation: Results from the NEO study

BACKGROUND

The adipocyte-derived hormone leptin has been associated with altered blood coagulation in in vitro studies. However, it is unclear whether this association is relevant in vivo and to what extent this association is influenced by total body fat. Therefore, we aimed to examine the association between serum leptin and blood coagulation while taking total body fat into account in a population-based cohort study.

METHODS

We performed a cross-sectional analysis with baseline measurements of 5797 participants of the Netherlands Epidemiology of Obesity (NEO) study, a population-based cohort of middle-aged men and women. We examined associations between serum leptin concentration and coagulation factor concentrations and parameters of platelet activation in linear regression analyses. All analyses were adjusted for multiple covariates, including total body fat.

RESULTS

In multivariable adjusted analyses a 1 μg/L higher serum leptin concentration was associated with a 0.22 IU/dL (95% CI: 0.11, 0.32) higher FVIII concentration and a 0.20 IU/dL (95% CI: 0.14, 0.27) higher FIX concentration (3.5 IU/dL FVIII and 3.2 IU/dL FIX per SD leptin). Serum leptin concentration was not associated with FXI, fibrinogen, platelet count, mean platelet volume and platelet distribution width in multivariable adjusted analyses.

DISCUSSION

This study showed that serum leptin concentration was associated with higher concentrations of FVIII and FIX in an observational study, which could be clinically relevant.

The role of leptin and adiponectin as mediators in the relationship between adiposity and hand and knee osteoarthritis

OBJECTIVES

To investigate associations of leptin and adiponectin levels with knee and hand osteoarthritis, and explore whether these mediate the association between adiposity and osteoarthritis.

METHODS

This is a cross-sectional analysis of baseline data from the population-based Netherlands Epidemiology of Obesity study. Adiposity was assessed with body mass index (BMI) and percentage total body fat (%TBF). Osteoarthritis, defined as hand or knee osteoarthritis, was determined using American College of Rheumatology criteria. Fasting serum adipokine levels were measured using immunoassays. Associations between adiposity and osteoarthritis were examined with logistic regression, adjusted for age, sex, ethnicity and education, and additionally for leptin and adiponectin as potential mediators.

RESULTS

In 6408 participants (56% women, median age 56 years), prevalence of osteoarthritis was 22% (10% isolated knee and 8% isolated hand osteoarthritis). Leptin levels were positively associated with osteoarthritis, while adiponectin levels were not. Leptin partially mediated the association of adiposity with osteoarthritis (OR 1.40 (95%CI 1.30; 1.52) attenuated to 1.38 (1.24; 1.54) per 5 units BMI and OR 1.25 (1.17; 1.35) to 1.20 (1.10; 1.32) per 5 units %TBF, representing 4% and 17% mediation, respectively). Larger proportion mediation by leptin was found in knee (13%/27%) than in hand osteoarthritis (9%/18%). Sex-stratified analyses generally showed stronger associations between adiposity, leptin and osteoarthritis in women than in men.

CONCLUSIONS

Serum leptin levels were associated with osteoarthritis, and partially mediated the association between adiposity and osteoarthritis, while adiponectin levels were not associated with osteoarthritis. These findings provide evidence for systemic effects of adipose tissue in osteoarthritis.

The role of inflammation in the association between overall and visceral adiposity and subclinical atherosclerosis

BACKGROUND AND AIMS

Inflammation may underlie the association between obesity, atherosclerosis and cardiovascular disease. We investigated to what extent markers of inflammation mediate associations between overall and visceral body fat and subclinical atherosclerosis.

METHODS AND RESULTS

In this cross-sectional analysis of the Netherlands Epidemiology of Obesity study we estimated total body fat (TBF) by bio-impedance analysis, carotid artery intima media thickness (cIMT) by ultrasound, C-reactive protein (hs-CRP) and glycoprotein acetyls (GlycA) concentrations in fasting blood samples (n = 5627), and visceral adipose tissue (VAT) by magnetic resonance imaging (n = 2247). We examined associations between TBF and VAT, and cIMT using linear regression, adjusted for potential confounding factors, and for mediators: cardiometabolic risk factors (blood pressure, glucose and low-density lipoprotein cholesterol), and inflammation using CRP and GlycA as proxies. Mean (SD) cIMT was 615 (90) μm. Per SD of TBF (8%), cIMT was 19 μm larger (95% confidence interval, CI: 10, 28). This association was 17 μm (95% CI: 8, 27) after adjustment for cardiometabolic risk factors, and did not change after adjustment for markers of inflammation. Per SD (56 cm²) VAT, cIMT was 9 μm larger (95% CI: 2, 16) which changed to 5 μm (95% CI: -3, 12) after adjustment for cardiometabolic risk factors, and did not change after adjustment for inflammatory markers.

CONCLUSION

Our results suggest that associations between measures of overall and visceral body fat and subclinical atherosclerosis are not mediated by inflammation as measured by CRP and GlycA. Obesity may exert cardiovascular risk via other markers of systemic inflammation.

In finger osteoarthritis, change in synovitis is associated with change in pain on a joint-level; a longitudinal magnetic resonance imaging study

OBJECTIVE

To investigate determinants of decrease and increase in joint pain in symptomatic finger osteoarthritis (OA) on magnetic resonance (MR) imaging over 2 years.

DESIGN

Eighty-five patients (81.2% women, mean age 59.2 years) with primary hand OA (89.4% fulfilling American College of Rheumatology (ACR) classification criteria) from a rheumatology outpatient clinic received contrast-enhanced MR imaging (1.5T) and physical examination of the right interphalangeal finger joints 2-5 at baseline and at follow-up 2 years later. MR images were scored paired in unknown time order, following the Hand OA MRI scoring system (HOAMRIS). Joint pain upon palpation was assessed by research nurses. Odds ratios (ORs; 95% confidence intervals) were estimated on joint level (n = 680), using generalized estimating equations (GEE) to account for the within patient effects. Additional adjustments were made for change in MR-defined osteophytes, synovitis, and bone marrow lesions (BMLs).

RESULTS

Of 116 painful joints at baseline, at follow-up: 76 had less pain, 21 less synovitis, and 13 less BMLs. A decrease in synovitis (OR = 5.9; 1.12─31.0), but not in BMLs (OR = 0.39; 0.10─1.50), was associated with less pain. Of 678 joints without maximum baseline pain, at follow-up: 115 had increased pain, 132 increased synovitis, 96 increased BMLs, and 44 increased osteophytes. Increased synovitis (OR = 1.81; 1.11─2.94), osteophytes (OR = 2.75; 1.59─4.8), but not BMLs (OR = 1.14; 0.81─1.60), was associated with increased pain. Through stratification it became apparent that BMLs were mainly acting as effect modifier of the synovitis-pain association.

CONCLUSION

Decrease in MR-defined synovitis is associated with reduced joint pain, identifying synovitis as a possible target for treatment of finger OA.

Genetic determinants of activity and antigen levels of contact system factors

Essentials Genetic variation may provide valuable insight into the role of the contact system in thrombosis. Explored associations of genetic variants with activity, antigen, and disease in RATIO study. Two novel loci were identified: KLKB1 rs4253243 for prekallikrein; KNG1 rs5029980 for HMWK levels. Contact system variants and haplotypes were not associated with myocardial infarction or stroke. SUMMARY: Background The complex, interdependent contact activation system has been implicated in thrombotic disease, although few genetic determinants of levels of proteins from this system are known. Objectives Our primary aim was to study the influence of common F11, F12, KLKB1, and KNG1 variants on factor (F) XI activity and FXI, FXII, prekallikrein (PK) and high-molecular-weight kininogen (HMWK) antigen levels, as well as the risk of myocardial infarction and ischemic stroke. Patients/methods We analyzed samples from all 630 healthy participants, 182 ischemic stroke patients and 216 myocardial infarction patients in the RATIO case-control study of women aged < 50 years. Forty-three tagging single nucleotide variants (SNVs) were genotyped to represent common genetic variation in the contact system genes. Antigen and activity levels were measured with sandwich-ELISA-based and one-stage clotting assays. We performed single variant, age-adjusted, linear regression analyses per trait and disease phenotype, assuming additive inheritance and determined conditionally independent associations. Haplotypes based on the lead SNV and all conditionally independent SNVs were tested for association with traits and disease. Results We identified two novel associations of KLKB1 SNV rs4253243 with PK antigen (βconditional = -12.38; 95% CI, -20.07 to -4.69) and KNG1 SNV rs5029980 with HMWK antigen (βconditional = 5.86; 95% CI, 2.40-9.32) and replicated previously reported associations in a single study. Further analyses probed whether the observed associations were indicative of linkage, pleiotropic effects or mediation. No individual SNVs or haplotypes were associated with the disease outcomes. Conclusion This study adds to current knowledge of how genetic variation influences contact system protein levels and clarifies interdependencies.

High levels of coagulation factors and venous thrombosis risk: strongest association for factor VIII and von Willebrand factor

Essentials Elevated procoagulant levels are associated with an increased risk of venous thrombosis (VT). The dependency on concurrent increased factor levels and VT was analyzed in a large study. Factor VIII (FVIII) and von Willebrand factor (VWF) were associated with the highest VT risk. The risks for other procoagulant factor levels were largely explained by FVIII and VWF. SUMMARY: Background Coagulation factors are essential for robust clot formation. However, elevated levels of procoagulant factors are associated with an increased risk of venous thrombosis (VT). The precise contribution of these factors to the development of VT is not yet understood. Objectives We determined the thrombosis risk for the highest levels of eight selected coagulation factors. Furthermore, we analyzed which of these coagulation factors had the strongest impact on the supposed association. Methods We used data of 2377 patients with a first VT and 2940 control subjects in whom fibrinogen, von Willebrand factor (VWF), factor II, FVII, FVIII, FIX, FX and FXI levels were measured. Results The odds ratios (ORs) for the various coagulation factor levels (> 99th percentile versus ≤ 25th percentile) varied between 1.8 and 4, except for FVIII (OR 23.0; 95% confidence interval [CI] 14.7-36.0) and VWF (OR 24.0; 95% CI 15.3-37.3). Adjustment for FVIII and VWF in a mediation analysis reduced the risks of the other factors to unity, with the exception of FIX and FXI (remaining ORs between 1.7 and 1.9). Conversely, the ORs for FVIII and VWF levels remained high after adjustment for all other procoagulant factors (FVIII: 16.0; 95% CI 9.7-26.3; VWF: 17.6; 95% CI 10.7-28.8). Conclusions Our results imply that the observed relationship between VT and coagulation factor levels can be largely explained by FVIII and VWF. FVIII and VWF levels were also associated with the highest VT risk.

Targeted sequencing to identify novel genetic risk factors for deep vein thrombosis: a study of 734 genes

Essentials Deep vein thrombosis (DVT) has a large unknown genetic component. We sequenced coding areas of 734 hemostasis-related genes in 899 DVT patients and 599 controls. Variants in F5, FGA-FGG, CYP4V2-KLKB1-F11, and ABO were associated with DVT risk. Associations in KLKB1 and F5 suggest a more complex genetic architecture than previously thought. SUMMARY: Background Although several genetic risk factors for deep vein thrombosis (DVT) are known, almost all related to hemostasis, a large genetic component remains unexplained. Objectives To identify novel genetic determinants by using targeted DNA sequencing. Patients/Methods We included 899 DVT patients and 599 controls from three case-control studies (DVT-Milan, Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis [MEGA], and the Thrombophilia, Hypercoagulability and Environmental Risks in Venous Thromboembolism [THE-VTE] study) for sequencing of the coding regions of 734 genes involved in hemostasis or related pathways. We performed single-variant association tests for common variants (minor allele frequency [MAF] ≥ 1%) and gene-based tests for rare variants (MAF ≤ 1%), accounting for multiple testing by use of the false discovery rate (FDR). Results Sixty-two of 3617 common variants were associated with DVT risk (FDR < 0.10). Most of these mapped to F5,ABO,FGA-FGG, and CYP4V2-KLKB1-F11. The lead variant at F5 was rs6672595 (odds ratio [OR] 1.58, 95% confidence interval [CI] 1.29-1.92), in moderate linkage with the known variant rs4524. Reciprocal conditional analyses suggested that intronic variation might drive this association. We also observed a secondary association at the F11 region: missense KLKB1 variant rs3733402 remained associated conditional on known variants rs2039614 and rs2289252 (OR 1.36, 95% CI 1.10-1.69). Two novel variant associations were observed, in CBS and MASP1, but these were not replicated in the meta-analysis data from the International Network against Thrombosis (INVENT) consortium. There was no support for a burden of rare variants contributing to DVT risk (FDR > 0.2). Conclusions We confirmed associations between DVT and common variants in F5,ABO,FGA-FGG, and CYP4V2-KLKB1-F11, and observed secondary signals in F5 and CYP4V2-KLKB1-F11 that warrant replication and fine-mapping in larger studies.

Performance of the Michigan Hand Outcomes Questionnaire in hand osteoarthritis

OBJECTIVE

To investigate the performance of the Michigan Hand Outcomes Questionnaire (MHQ) in hand osteoarthritis (OA) by evaluating truth, discrimination and feasibility.

DESIGN

Symptomatic hand OA patients from the Hand Osteoarthritis in Secondary Care (HOSTAS) cohort completed questionnaires (demographics, MHQ, Australian/Canadian Hand Osteoarthritis Index [AUSCAN], Functional Index for Hand Osteoarthritis [FIHOA] and visual analogue scale [VAS] pain) at baseline (n = 383), 1- and 2-year follow-up (n = 312, n = 293). Anchor questions at follow-up assessed whether pain/function levels were (un)acceptable and had changed compared to baseline. Correlations between MHQ and other pain/function questionnaires were calculated. Validity of unique MHQ domains (work performance, aesthetics, satisfaction), discrimination across disease stages, and responsiveness were assessed by categorizing patients by external anchors (employment, joint deformities, erosions, and anchor questions). Between-group differences were assessed with linear regression, probability plots and comparison of medians.

RESULTS

MHQ pain and function subscales correlated moderately-to-good with other instruments (r_s 0.63-0.81). Work performance scores were worse in patients with reduced working capacity than in employed patients. Aesthetics scores were worse in patients with more deformities. Patients with unacceptable complaints had worse satisfaction scores. All pain/function instruments discriminated between patients with acceptable vs unacceptable pain/function, while only MHQ activities of daily living (ADL), FIHOA, and MHQ aesthetics could discriminate between erosive and non-erosive disease. MHQ and AUSCAN were most responsive.

CONCLUSIONS

MHQ has several unique aspects and advantages justifying its use in hand OA, including the unique assessment of work performance, aesthetics, and satisfaction. However, MHQ, AUSCAN and FIHOA appear to measure different aspects of pain and function.

High risk of recurrent venous thrombosis in patients with lower-leg cast immobilization

Essentials The risk of recurrent venous thrombosis (VT) after leg-cast in patients with prior VT is unknown. In a nested case-control study within the MEGA follow-up study we aimed to estimate this risk. Patients with a history of VT who require lower-leg cast have a 4.5-fold risk for recurrence. This relative risk translates to an absolute risk for recurrent VT of about 3.2% within 3 months. SUMMARY: Background Patients with lower-leg cast immobilization have a substantially increased risk of developing a first venous thrombosis (VT), whereas the risk in patients with a history of VT is as yet unknown. Aims To estimate the risk of recurrent VT after lower-leg cast immobilization in patients with a history of VT. Methods A case-control study nested within a cohort of 4597 patients with a first VT who were followed over time for recurrence from 1999 to 2010 (MEGA follow-up study). Participants completed a questionnaire on risk factors for recurrent thrombosis, including having a cast in the first 3 months before a recurrence (cases) or a random 3-month period during follow-up for participants without recurrence (controls). In total, 2723/4597 (59%) participants returned the questionnaire. Odds ratios (ORs), adjusted for age and sex, were calculated to compare risks of recurrence between subjects with and without a cast. Results A total of 2525/2723 participants (93%) filled out information on cast immobilization and were included in the analysis (451 cases; 2074 controls). Twenty (1.0%) controls and 10 (2.2%) cases reported having had a lower-leg cast in the 3 months before the control or recurrence date (adjusted OR, 2.4; 95% confidence Interval [CI], 1.1-5.3). We cross-checked the data with these patients' medical records. Cast application within 3 months was verified in seven (0.3%) controls vs. six (1.3%) cases, leading to an adjusted OR of 4.5 (95% CI, 1.5-14.0) and corresponding cumulative incidence of 3.2%. Conclusions Lower-leg cast immobilization increases the risk of recurrent VT in the 3 months after its application in patients with a history of VT.

In thumb base osteoarthritis structural damage is more strongly associated with pain than synovitis

OBJECTIVE

Osteoarthritis in thumb base joints (first carpometacarpal (CMC-1), scaphotrapeziotrapezoid (STT)) is prevalent and disabling, yet focussed studies are scarce. Our aim was to investigate associations between ultrasonographic and magnetic resonance imaging (MRI) inflammatory features, radiographic osteophytes, and thumb base pain in hand osteoarthritis patients.

DESIGN

Cross-sectional analyses were performed in cohorts with MRI (n = 202) and ultrasound measurements (n = 87). Pain upon thumb base palpation was assessed. Radiographs were scored for CMC-1/STT osteophytes. Synovial thickening, effusion and power Doppler signal in CMC-1 joints were assessed with ultrasound. MRIs were scored for synovitis and bone marrow lesions (BMLs) in CMC-1 and STT joints using OMERACT-TOMS. Associations between ultrasound/MRI features, osteophytes, and thumb base pain were assessed. Interaction between MRI features and osteophytes was explored.

RESULTS

In 289 patients (mean age 60.2, 83% women) 139/376 thumb bases were painful. Osteophyte presence was associated with pain (MRI cohort: odds ratio (OR) 5.1 (2.7-9.8)). Ultrasound features were present in 25-33% of CMC-1 joints, though no associations were seen with pain. MRI-synovitis and BMLs grade ≥2 were scored in 25% and 43% of thumb bases, and positively associated with pain (OR 3.6 (95% CI 1.7-7.6) and 3.0 (1.6-5.5)). Associations attenuated after adjustment for osteophyte presence. Combined presence of osteophytes and MRI-synovitis had an additive effect.

CONCLUSIONS

Ultrasonographic and MRI inflammatory features were often present in the thumb base. Osteophytes were more strongly associated with thumb base pain than inflammatory features, in contrast to findings in finger OA studies, supporting thumb base osteoarthritis as a distinct phenotype.

Factor V Leiden (FV R506Q) in Families with Inherited Antithrombin Deficiency

We investigated the presence of the gene mutation of factor V, FV R506Q or factor V Leiden, responsible for activated protein C resistance, in DNA samples of 127 probands and 188 relatives from 128 families with antithrombin deficiency. The factor V mutation was identified in 18 families. Nine families were available to assess the mode of inheritance and the clinical relevance of combined defects.

The factor V and antithrombin genes both map to chromosome 1. Segregation of the defects on opposite chromosomes was observed in three families. Co-segregation with both defects on the same chromosome was demonstrated in four families. In one family a de novo mutation of the antithrombin gene and in another a crossing-over event were the most likely explanations for the observed inheritance patterns.

In six families with type I or II antithrombin deficiency (reactive site or pleiotropic effect), 11 of the 12 individuals with both antithrombin deficiency and the factor V mutation developed thrombosis. The median age of their first thrombotic episode was 16 years (range 0-19); this is low compared with a median age of onset of 26 years (range 20-49) in 15 of 30 carriers with only a defect in the antithrombin gene. One of five subjects with only factor V mutation experienced thrombosis at 40 years of age. In three families with type II heparin binding site deficiencies, two of six subjects with combined defects experienced thrombosis; one was homozygous for the heparin binding defect.

Our results show that, when thrombosis occurs at a young age in antithrombin deficiency, the factor V mutation is a likely additional risk factor. Co-segregation of mutations in the antithrombin and factor V genes provides a molecular explanation for severe thrombosis in several generations. The findings support that combinations of genetic risk factors underly differences in thrombotic risk in families with thrombophilia.

Hereditary Protein S Deficiency in Young Adults with Arterial Occlusive Disease

Protein S is the vitamin K dependent cofactor of activated protein C. It has an important role in the regulation of blood coagulation and fibrinolysis. Hereditary protein S deficiency is associated with familial venous thrombophilia. Since a few patients with arterial occlusions have been reported to be protein S deficient, it is speculated that hereditary protein S deficiency may be also a risk factor for the development of arterial thrombosis. In a group of 37 consecutive patients with arterial occlusive disease presenting before the age of 45, three patients were found heterozygous for hereditary protein S deficiency. None of the patients had a protein C deficiency or an antithrombin III deficiency. Family investigations showed a clear association between the hereditary deficiency and venous thrombosis, but a relation between the deficiency and arterial thrombosis was less obvious. A review of previous literature on patients with arterial thrombosis and protein S deficiency revealed that more extensive studies are needed to demonstrate whether or not hereditary protein S deficiency is a risk factor for the development of arterial thrombosis.

Relation of Plasma Coagulation Factor VII and Fibrinogen to Carotid Artery Intima-Media Thickness

Plasma clotting factor VII and plasma fibrinogen have been claimed as independent risk factors for occlusive cardiovascular disease. The aim of this study was to investigate whether these coagulation parameters affect early atherosclerosis, additional to their possible effect on arterial thrombosis.

We used high-resolution quantitative ultrasonography to measure carotid intima-media thickness in 121 healthy volunteers, aged 18 to 56 years. It has previously been demonstrated that an increased artery wall thickness is seen in advanced atherosclerosis. To validate our methodology for relatively young individuals, we assessed the association of intima-media thickness with the risk-factor status of our subjects, by including classical cardiovascular risk factors, e. g. age, sex, serum cholesterol, smoking habits and blood pressure. Thereafter, we studied the effect of factor VII and fibrinogen plasma levels on carotid intimamedia thickness, as well as that of polymorphisms of the factor VII and fibrinogen genes.

All classical risk factors except smoking and family history were associated with intima-media thickness. When adjusted for by multivariate linear regression analysis, age, blood pressure and cholesterol appeared to be independent determinants of intima-media thickness. Factor VII and fibrinogen levels showed no association in multivariate analysis with intima-media thickness. We conclude that artery wall thickness measurement by ultrasound is a useful tool to investigate the role of clotting factors in early atherosclerosis. Factor VII and fibrinogen levels in young and middle-aged volunteers have no association with early artherosclerotic vessel wall changes.

Mortality and Causes of Death in Inherited Antithrombin Deficiency

To assess the contribution of inherited antithrombin deficiency to mortality, we investigated the causes of death in 14 families with inherited antithrombin deficiency. Between 1830 and 1994, 86 of 266 family members who had a probability of 0.5 or more for heterozygosity died. The causes of death were obtained for 58 of 66 deaths occurring between 1940 and 1994. Standardized mortality ratios (SMR) were calculated using mortality rates from the general population adjusted for age, sex and calendar period.

The overall SMR was 0.90 from 1830 to 1994 (95% C.1.0.72-1.11). From 1940 until 1994 44 men and 22 women died (SMR = 1.09, 95% C.I. 0.84-1.39; SMR men = 1.20, 95% C.I. 0.87-1.61; SMR women = 0.92,95% C.I. 0.58-1.39). No excess mortality compared to the general population was found for cancer (14 deaths) or circulatory diseases (28 deaths). A slightly increased mortality caused by respiratory diseases (7 deaths, SMR = 1.68,95% C.I. 0.68-3.47) seemed due to pneumonia (4 deaths, SMR = 2.86, 95% C.I. 0.78-7.32). Venous thromboembolic complications were listed once in association with a risk situation, and one other death could be attributed to fatal pulmonary embolism. Cerebral hemorrhages were listed three times. It could not be verified whether these hemorrhages were related to anticoagulant therapy; the frequency was slightly higher than the expected population figure (SMR = 1.49,95% C.I. 0.31-4.36). The mean age of death for all causes was 64 years; the two fatal thromboembolic episodes occurred at age 20 and 30 years.

The data show that antithrombin deficiency is associated with a normal survival and a low risk of fatal thromboembolic events. The use of long-term anticoagulant treatment in asymptomatic individuals should be considered carefully in view of the greater risk of fatal bleeding associated with long-term anticoagulant prophylaxis.

Assessment of a Bleeding Risk Index in Two Cohorts of Patients Treated with Oral Anticoagulants

In two cohorts of patients on oral anticoagulant therapy, routinely treated by the Leiden Thrombosis Service, the frequency of major bleeding complications was assessed during two years (1988 and 1991). With Poisson regression analysis the influence of the risk factors age, sex, target zone, achieved INR and type of coumarin derivative used were determined. Subsequently, a bleeding risk index was calculated, combining the results of the two cohorts. For various types of patients the relative risk of major bleeding complications was assessed.

Age and achieved INR were the most important and consistent risk factors: rate ratio (RR) for age in 1988 1.46 per 10 years increase (95% confidence interval [Cl] 1.20-1.78) and in 1991 1.57 per 10 years increase (95% Cl 1.23-2.00); RR per unit increase in achieved INR in 1988 1.42 (95% Cl 1.21-1.68) and in 1991 1.44 per unit increase in achieved INR (95% Cl 1.18-1.74). Two methods were used to combine the results of 1988 and 1991. In the first method the mean bleeding risk index was calculated: In (incidence) [natural logarithm of the incidence rate of major bleeding] = -5.64 +0.42 * age +0.26 % sex -0.29 * target range +0.36 % achieved INR -0.36 * coumarin type. In the second method only the consistent risk factors age and achieved INR were used: In (incidence) = -5.64 +0.42 % age +0.36 % achieved INR. These bleeding risk indexes can be used to assess the risk of major bleeding complications of individual patients and allow more individualized care by individual tailoring the desired anticoagulation.

Factor VII and Fibrinogen Levels as Risk Factors for Venous Thrombosis

The plasma levels of coagulation factor VII and fibrinogen are well known risk factors for arterial thrombosis. We tested the hypothesis that this association also exists for venous thrombosis. Additionally, MspI and Haelll polymorphisms in the factor VII and fibrinogen genes have recently been reported to be associated with the concentration of both proteins in the plasma. However, no conclusion could be drawn with respect to an increase or decrease in thrombosis risk. We undertook a population-based case-control study, in which 199 patients with a first, objectively confirmed episode of deep vein thrombosis, aged less than 70, and without a known malignant disorder were compared to 199 age-and sex-matched healthy controls, to evaluate the clinical importance of these reported findings.

For fibrinogen we found a positive level-related association between the plasma fibrinogen level and thrombotic risk. Subjects with a plasma fibrinogen greater than 5 g/1 had an almost 4-fold increase of thrombosis risk. The frequencies of the different Haelll genotypes were out of balance only for the thrombosis patients, with a deficit of the H1H2 genotype. Possession of an H1H2 genotype was associated with a 40% reduction in thrombosis risk.

For factor VII, neither the plasma level nor the MspI genotypes were related to deep vein thrombosis, although possession of a M2 allele was clearly associated with significantly lower factor VII levels. The frequencies of the Mspl-genotypes were the same for patients and control subjects and, exhibited Hardy-Weinberg equilibrium.

Our results support that plasma fibrinogen, a determinant of arterial thrombosis is also a risk factor for venous thrombosis, while factor VII plasma concentration is unrelated to deep vein thrombosis, which is supported by the data from the DNA analysis of polymorphisms.

Clinical Course of Factor VIII Inhibitors Developed after Exposure to a Pasteurised Dutch Concentrate Compared to Classic Inhibitors in Hemophilia A

After the introduction of a new pasteurised factor VIII concentrate (Factor VIII CPS-P) in The Netherlands in June 1990, an increase in the occurrence of inhibitors in hemophilia A patients was reported. The clinical course of this group of inhibitors (n = 12) was compared with hemophilia patients in whom an inhibitor developed before June 1990 (classic inhibitors) (n = 32). Striking differences were found between both groups not only in patient age (median 22 years versus 8 years) and number of exposure days (<50 − >1000 versus <50), as described in previous reports, but also in clinical course and response to treatment. In the recent group of inhibitors antibody titers showed a rapid decline when product was changed which was not the case in the group with classic inhibitors. In the group of classic inhibitors immune tolerance therapy with low dose factor VIII succeeded in 83%. Success was to a high degree dependent on the inhibitor level. In the group of recent inhibitors immune tolerance with the same concentrate was only successful in a single patient. However, once the patients were switched to another concentrate, antibody levels dropped to less than 2 BU/ml within 8 months in all patients.

It seems likely that in this group of product associated inhibitors, treatment success was due to elimination of antigen stimulation rather than induction of immune tolerance.

A Method to Determine the Optimal Intensity of Oral Anticoagulant Therapy

Oral anticoagulant therapy has been shown to be effective for several indications. The optimal intensity of anticoagulation for each indication, however, is largely unknown. To determine this optimal intensity, randomised clinical trials are conducted in which two target levels of anticoagulation are compared. This approach is inefficient, since the choice of the target levels will be arbitrary. Moreover, the achieved intensity is not taken into account.

We propose a method to determine the optimal achieved intensity of anticoagulation. This method can be applied within a clinical trial as an “efficacy-analysis”, but also on data gathered in day-to-day patient care.

In this method, INR-specific incidence rates of events, either thromboembolic or hemorrhagic, are calculated. The numerator of the incidence rate is based on data on the INR at the time of the event. The denominator consists of the person-time at each INR value, summed over all patients, and is calculated from all INR measurements of all patients during the follow-up interval. This INR-specific person-time is calculated with the assumption of a linear increase or decrease between two consecutive INR determinations. Since the incidence rates may be substratified on covariates, efficient assessment of the effects of other factors (e.g. age, sex, comedication) by multivariate regression analysis becomes possible.

This method allows the determination of the optimal pharmacological effects of anticoagulation, which can form a rational starting point for choosing the target levels in subsequent clinical trials.

Impact of time since diagnosis and mortality rate on cancer-associated venous thromboembolism: the Scandinavian Thrombosis and Cancer (STAC) cohort

Essentials Competing risk by death may lead to overestimation of venous thromboembolism (VTE) risk in cancers. We assessed the risk of VTE in cancer with and without accounting for competing risk by death. The risk of VTE was influenced by the mortality rate and the time since cancer diagnosis. Competing risk by death should be taken into account when exploring VTE risk in cancer.

SUMMARY

Background Venous thromboembolism (VTE) is a common complication in cancer, and studies have suggested that aggressive cancers create the highest risk of VTE. However, competing risk by death may result in overestimation of VTE risk in patients with cancers associated with high mortality. Therefore, we estimated the risk of VTE by cancer site, accounting for the differential mortality between cancers. Methods The Scandinavian Thrombosis and Cancer cohort included 144 952 participants followed from 1993-1997 to 2008-2012. Incidence rates, cause-specific hazard ratios (HRs) and subdistribution HRs (SHRs) were assessed for overall cancer and by cancer site according to time intervals since cancer diagnosis. Results During follow-up, 14 272 subjects developed cancer, and 567 had cancer-related VTE. In cause-specific analyses, the VTE risk was highest in the first 6 months after cancer diagnosis (HR 17.5, 95% confidence interval [CI] 15.1-20.3), and declined rapidly thereafter. However, when mortality was taken into account, the risk was similar in the periods 6 months before (SHR 4.8, 95% CI 3.6-6.4) and 6 months after (SHR 4.6, 95% CI 3.9-5.4) cancer diagnosis. The range of the 2-year cumulative VTE incidence rates was substantially narrowed for all cancer sites after competing risk by death was taken into account (from 1-10% to 1-4%). Conclusion VTE risk by cancer site was influenced by the mortality rate and the time since cancer diagnosis. Our findings suggest that the cancer itself is a major contributor to VTE risk, and that competing risk by death should be taken into account when VTE risk in cancer is explored.

Factor VIII products and inhibitor development in previously treated patients with severe or moderately severe hemophilia A: a systematic review

Essentials Data on product-related immunogenicity in previously treated haemophilia A patients is scarce. A systematic review and meta-analysis of all currently available evidence was conducted. The overall incidence rate was 2.06 per 1000 person-years (95% confidence interval: 1.06-4.01). Some recombinant factor VIII products were associated with increased immunogenicity.

SUMMARY

Background Patients with severe hemophilia A who have been treated extensively with factor VIII products have a low but potentially serious risk of inhibitor development. It is unknown why these patients develop inhibitors, and data on product-related immunogenicity are scarce. Aims To summarize the currently available evidence on the relationship between inhibitor development and recombinant FVIII product type in previously treated patients (PTPs) with severe hemophilia A. Methods Longitudinal studies were included that reported on de novo inhibitor formation in patients with baseline FVIII activity levels of < 0.02 IU mL-1 who had been treated with FVIII for at least 50 days. Pooled incidence rates of inhibitor development according to product types were calculated with a random intercept Poisson regression model. Results Forty-one independent cohorts were included; 39 patients developed de novo inhibitors during 19 157 person-years of observation. The overall incidence rate was 2.06 per 1000 person-years, with a 95% confidence interval (CI) of 1.06-4.01. According to product type, the pooled incidence rates were 0.99 (95% CI 0.37-2.70) per 1000 person-years for patients treated with Advate, 5.86 (95% CI 0.25-134.92) per 1000 person-years for those treated with Kogenate/Helixate, 1.35 (95% CI 0.66-2.77) per 1000 person-years for those treated with Kogenate FS/Helixate NexGen, 12.05 (95% CI 1.53-94.78) per 1000 person-years for those treated with Refacto, and 4.64 (95% CI 0.82-26.43) per 1000 person-years for those treated with Refacto AF. Conclusion These results suggest that some products may be associated with increased immunogenicity. However, the low incidence of inhibitors in PTPs and the differences in study design may cause significant variation in estimates of risk.

Mild antithrombin deficiency and risk of recurrent venous thromboembolism: results from the MEGA follow-up study

Essentials Mild antithrombin deficiency may increase the risk of recurrent venous thromboembolism (VTE). In a cohort study, we stratified patients with VTE to various cut-off antithrombin levels. A 1.6-3.7-fold increased risk of recurrent VTE was observed in the lowest antithrombin categories. Mild antithrombin deficiency (activity < 5th percentile of normal) increases recurrent VTE risk.

SUMMARY

Background Mild antithrombin deficiency (previously defined as antithrombin activity below 70% or 80%) has been associated with a 2.4-3.5-fold increased risk of recurrent venous thromboembolism (VTE). This finding may have implications for duration of antithrombotic therapy in VTE patients with mild antithrombin deficiency. Objectives To externally validate whether mild antithrombin deficiency is a risk factor for recurrent VTE. Methods In a population-based cohort study, patients with a first VTE (n = 2357) were stratified according to percentile cut-off antithrombin levels (< 5th [< 87%], 5-10th [87-92%], > 10th percentile [> 92%]) and functional antithrombin levels (< 70%, 70-80%, > 80%). Results During a median follow-up of 7.4 years, 361 recurrent events occurred (incidence rate, 2.5/100 patient-years). We observed an increased risk of recurrent VTE in the lowest antithrombin activity category (< 5th percentile; < 87%) as compared with antithrombin activity that was > 10th percentile (> 92%), with an adjusted hazard ratio (HR) of 1.5 (95%CI, 1.0-2.3). When analyses were stratified to antithrombin cut-off criteria of< 70% vs. patients with antithrombin activity > 80%, the adjusted HR for venous recurrence was 3.7 (95% CI, 1.4-9.9). Mild antithrombin deficiency was able to predict recurrent VTE over at least 8 years of follow-up and the association remained present when the population was stratified to the presence or absence of thrombosis risk factors. Restriction analyses, where patients who used anticoagulation at time of blood draw and those who reported drinking ≥ 5 glasses alcohol daily were excluded, did not materially affect these outcomes. Conclusion This study confirms that mild antithrombin deficiency is a risk factor for recurrent VTE.

Prediction of factor VIII inhibitor development in the SIPPET cohort by mutational analysis and factor VIII antigen measurement

Essentials A residual factor VIII synthesis is likely to be protective towards inhibitor (INH) development. Mutation type-inhibitor risk association was explored in 231 patients with severe hemophilia A. A 2-fold increase in INH development for in silico null vs. non-null mutations was found. A 3.5-fold increase in INH risk for antigen negative vs. antigen positive mutations was found.

SUMMARY

Background The type of F8 mutation is the main predictor of inhibitor development in patients with severe hemophilia A. Mutations expected to allow residual synthesis of factor VIII are likely to play a protective role against alloantibody development by inducing immune tolerance. According to the expected full or partial impairment of FVIII synthesis, F8 variants are commonly classified as null and non-null. Objectives To explore the mutation type-inhibitor risk association in a cohort of 231 patients with severe hemophilia A enrolled in the Survey of Inhibitors in Plasma-Product Exposed Toddlers (SIPPET) randomized trial. Methods The genetic defects in these patients, consisting of inversions of intron 22 (n = 110) and intron 1 (n = 6), large deletions (n = 16), and nonsense (n = 38), frameshift (n = 28), missense (n = 19) and splicing (n = 14) variants, of which 34 have been previously unreported, were reclassified according to two additional criteria: the functional effects of missense and splicing alterations as predicted by multiple in silico analyses, and the levels of FVIII antigen in patient plasma. Results A two-fold increase in inhibitor development for in silico null mutations as compared with in silico non-null mutations (hazard ratio [HR] 2.08, 95% confidence interval [CI] 0.84-5.17) and a 3.5-fold increase in inhibitor development for antigen-negative mutations as compared with antigen-positive mutations (HR 3.61, 95% CI 0.89-14.74] were found. Conclusions Our findings confirm an association between the synthesis of minute amounts of FVIII and inhibitor protection, and underline the importance of investigating the residual FVIII antigen levels associated with causative variants in order to understand their clinical relevance.

Pharmacogenomics study of thiazide diuretics and QT interval in multi-ethnic populations: the cohorts for heart and aging research in genomic epidemiology

Thiazide diuretics, commonly used antihypertensives, may cause QT interval (QT) prolongation, a risk factor for highly fatal and difficult to predict ventricular arrhythmias. We examined whether common single-nucleotide polymorphisms (SNPs) modified the association between thiazide use and QT or its component parts (QRS interval, JT interval) by performing ancestry-specific, trans-ethnic and cross-phenotype genome-wide analyses of European (66%), African American (15%) and Hispanic (19%) populations (N=78 199), leveraging longitudinal data, incorporating corrected standard errors to account for underestimation of interaction estimate variances and evaluating evidence for pathway enrichment. Although no loci achieved genome-wide significance (P<5 × 10-8), we found suggestive evidence (P<5 × 10-6) for SNPs modifying the thiazide-QT association at 22 loci, including ion transport loci (for example, NELL1, KCNQ3). The biologic plausibility of our suggestive results and simulations demonstrating modest power to detect interaction effects at genome-wide significant levels indicate that larger studies and innovative statistical methods are warranted in future efforts evaluating thiazide-SNP interactions.

Determinants of impaired renal and vascular function are associated with elevated levels of procoagulant factors in the general population

Essentials Why venous thrombosis is more prevalent in chronic kidney disease is unclear. We investigated whether renal and vascular function are associated with hypercoagulability. Coagulation factors showed a procoagulant shift with impaired renal and vascular function. This suggests that renal and vascular function play a role in the etiology of thrombosis.

SUMMARY

Background Impaired renal and vascular function have been associated with venous thrombosis, but the mechanism is unclear. Objectives We investigated whether estimated glomerular filtration rate (eGFR), urinary albumin-creatinine ratio (UACR), and pulse wave velocity (PWV) are associated with a procoagulant state. Methods In this cross-sectional analysis of the NEO Study, eGFR, UACR, fibrinogen, and coagulation factors (F)VIII, FIX and FXI were determined in all participants (n = 6536), and PWV was assessed in a random subset (n = 2433). eGFR, UACR and PWV were analyzed continuously and per percentile: per six categories for eGFR (> 50th [reference] to < 1st) and UACR (< 50th [reference] to > 99th), and per four categories (< 50th [reference] to > 95th percentile) for PWV. Linear regression was used and adjusted for age, sex, total body fat, smoking, education, ethnicity, total cholesterol, C-reactive protein (CRP) and vitamin K antagonists use (FIX). Results Mean age was 55.6 years, mean eGFR 86.0 (12SD) mL 1.73 m- ² and median UACR 0.4 mg mmol-1 (25th, 75th percentile; 0.3, 0.7). All coagulation factors showed a procoagulant shift with lower renal function and albuminuria. For example, FVIII was 22 IU dL-1 (95% CI, 13-32) higher in the eGFR < 1st percentile compared with the > 50th percentile, and FVIII was 12 IU dL-1 (95% CI, 3-22) higher in the UACR > 99th percentile compared with the < 50th percentile. PWV was positively associated with coagulation factors FIX and FXI in continuous analysis; per m/s difference in PWV, FIX was 2.0 IU dL-1 (95% CI, 0.70-3.2) higher. Conclusions Impaired renal and vascular function was associated with higher levels of coagulation factors, underlining the role of renal function and vascular function in the development of venous thrombosis.