Coma in adult cerebral venous thrombosis: The BEAST study

BACKGROUND AND PURPOSE

Coma is an independent predictor of poor clinical outcomes in cerebral venous thrombosis (CVT). We aimed to describe the association of age, sex, and radiological characteristics of adult coma patients with CVT.

METHODS

We used data from the international, multicentre prospective observational BEAST (Biorepository to Establish the Aetiology of Sinovenous Thrombosis) study. Only positively associated variables with coma with <10% missing data in univariate analysis were considered for the multivariate logistic regression model.

RESULTS

Of the 596 adult patients with CVT (75.7% women), 53 (8.9%) patients suffered coma. Despite being a female-predominant disease, the prevalence of coma was higher among men than women (13.1% vs. 7.5%, p = 0.04). Transverse sinus thrombosis was least likely to be associated with coma (23.9% vs. 73.3%, p < 0.001). The prevalence of superior sagittal sinus thrombosis was higher among men than women in the coma sample (73.6% vs. 37.5%, p = 0.01). Men were significantly older than women, with a median (interquartile range) age of 51 (38.5-60) versus 40 (33-47) years in the coma (p = 0.04) and 44.5 (34-58) versus 37 (29-48) years in the non-coma sample (p < 0.001), respectively. Furthermore, an age- and superior sagittal sinus-adjusted multivariate logistic regression model found male sex (odds ratio = 1.8, 95% confidence interval [CI] = 1.0-3.4, p = 0.04) to be an independent predictor of coma in CVT, with an area under the receiver operating characteristic curve of 0.61 (95% CI = 0.52-0.68, p = 0.01).

CONCLUSIONS

Although CVT is a female-predominant disease, men were older and nearly twice as likely to suffer from coma than women.

Meta-analysis and construction of simple-to-use nomograms for approximating testosterone levels gained from weight loss in obese men

BACKGROUND

Obesity-induced hypogonadism, which manifests as erectile dysfunction and a lack of libido, is a less visible and under-recognized obesity-related disorder in men.

OBJECTIVE

We examined the impact of weight loss on total (TT) and free testosterone (FT) levels, and constructed nomograms to provide an easy-to-use visual aid for clinicians.

MATERIALS AND METHODS

Meta-analysis was conducted using RevMan (v5.3) and expressed in standardized mean differences (SMD) for testosterone. Parallel-scale nomograms were constructed from baseline and target body mass index values to estimate the gain in testosterone.

RESULTS

In total, 44 studies were included, comprising 1,774 participants and 2,159 datasets, as some studies included several datasets at different time points. Weight loss was controlled by low calorie diet (LCD) in 19 studies (735 participants, 988 datasets), by bariatric surgery (BS) in 26 studies (1,039 participants, 1,171 datasets), and by both in one study. The median follow-up was 26 weeks (interquartile range = 12-52). The range of baseline mean age was 21-68 yr, BMI: 26.2-71.2 kg/m2 , TT: 7-20.2 nmol/L and FT: 140-583 pmol/L. TT levels increased after weight loss by LCD: SMD (95%CI) = 2.5 nmol/L (1.9-3.1) and by BS: SMD = 7.2 nmol/L (6.0-8.4); the combined TT gain was 4.8 nmol/L (3.9-5.6). FT levels increased after weight reduction by LCD: SMD = 19.9 pmol/L (7.3-32.5) and by BS: SMD = 58.0 pmol/L (44.3-71.7); the combined gain was 42.2 pmol/L (31.4-52.9). Greater amounts of total and free testosterone could be gained by weight loss in men with higher baseline BMI, or lower levels of SHBG, TT and FT, while gain in TT was relatively greater in older and FT in younger age. Age-stratified nomograms revealed that compared to older men (> 40 yr), younger men (≤ 40 yr) gained less TT but more FT for a given weight loss.

DISCUSSION AND CONCLUSION

Both TT and FT levels increased after weight loss, relatively greater with higher baseline BMI, or lower levels of SHBG, TT and FT. Nomograms constructed from a large number of participants with a wide range of BMI and testosterone values provide an evidence-based and simple-to-use tool in clinical practice.

Diabetes mellitus and obesity among South Asians with ischemic stroke across three countries

BACKGROUND

Diabetes mellitus and central obesity are more common among South Asian populations than among White British people. This study explores the differences in diabetes and obesity in South Asians with stroke living in the United Kingdom, India, and Qatar compared with White British stroke patients.

METHODS

The study included the UK, Indian, and Qatari arms of the ongoing large Bio-Repository of DNA in Stroke (BRAINS) international prospective hospital-based study for South Asian stroke. BRAINS includes 4580 South Asian and White British recruits from UK, Indian, and Qatar sites with first-ever ischemic stroke.

RESULTS

The study population comprises 1751 White British (WB) UK residents, 1165 British South Asians (BSA), 1096 South Asians in India (ISA), and 568 South Asians in Qatar (QSA). ISA, BSA, and QSA South Asians suffered from higher prevalence of diabetes compared with WB by 14.5% (ISA: 95% confidence interval (CI) = 18.6-33.0, p < 0.001), 31.7% (BSA: 95% CI = 35.1-50.2, p < 0.001), and 32.7% (QSA: 95% CI = 28.1-37.3, p < 0.001), respectively. Although WB had the highest prevalence of body mass index (BMI) above 27 kg/m2 compared with South Asian patients (37% vs 21%, p < 0.001), South Asian patients had a higher waist circumference than WB (94.8 cm vs 90.8 cm, p < 0.001). Adjusting for traditional stroke risk factors, ISA, BSA, and QSA continued to display an increased risk of diabetes compared with WB by 3.28 (95% CI: 2.53-4.25, p < 0.001), 3.61 (95% CI: 2.90-4.51, p < 0.001), and 5.24 (95% CI: 3.93-7.00, p < 0.001), respectively.

CONCLUSION

South Asian ischemic stroke patients living in Britain and Qatar have a near 3.5-fold risk of diabetes compared with White British stroke patients. Their body composition may partly help explain that increased risk. These findings have important implications for public health policymakers in nations with large South Asian populations.

ABO blood group associated with cerebral venous thrombosis after Oxford-AstraZeneca COVID-19 vaccination: a case-control study

OBJECTIVES

To determine whether blood group influences development of cerebral venous thrombosis (CVT) after administration of the coronavirus disease 2019 (COVID-19) AstraZeneca ChAdOx1-S vaccine.

DESIGN

A case-control study. Univariate and multivariate logistic regression was used to determine the association between blood type and COVID-19 vaccination status.

SETTING

Vaccinated and unvaccinated patients recruited from the international Bio-Repository to Establish the Aetiology of Sinovenous Thrombosis study and the Cerebral Venous Sinus Thrombosis With Thrombocytopenia Syndrome Study Group.

PARTICIPANTS

All patients were of European descent and age and sex matched. Cases (n = 82) were patients ≥18 years old who suffered a CVT within 28 days of a first dose of ChAdOx1-S vaccine. Controls (n = 441) were unvaccinated CVT patients ≥18 years old. All patients were of European descent.

MAIN OUTCOME MEASURES

Frequency of blood type and ABO allele distribution by vaccination status.

RESULTS

Blood group O was found to be more prevalent among CVT patients with vaccine-induced thrombotic thrombocytopenia (VITT-CVT) after ChAdOx1-S vaccination compared with unvaccinated CVT cases (43% vs. 17%, respectively, p < 0.001). Blood group A was less prevalent, though still high, in the vaccinated group compared with the unvaccinated group (47% vs. 71%, respectively, p < 0.001). No significant differences were observed in the VITT-CVT non-ChAdOx1-S vaccine group and unvaccinated pre-COVID-19 CVT group for blood group.

CONCLUSIONS

Blood group O is more prevalent among patients with VITT-CVT after ChAdOx1-S vaccination compared with unvaccinated cases, independent of well-established CVT risk factors. A larger dataset may be able to determine whether those of blood groups B and/or AB may be safely vaccinated with the low cost, readily available and easily transported ChAdOx1-S rather than adopting a complete ban.

Cigarette smoking as a risk factor for ischaemic stroke in young South Asian male migrants to Qatar: The BRAINS study

BACKGROUND

The incidence of stroke in the Middle East is high, given its relatively young population. Smoking is a well-recognized risk factor for ischaemic stroke, and its high regional prevalence may partly account for this increased stroke risk. This research aims to determine whether young male South Asian migrants in Qatar were adversely affected by stroke depending on their smoking status.

METHODS

Data from the ongoing international prospective BRAINS study was analysed. Male South Asian migrants to Qatar with a history of ischaemic stroke were recruited. Multivariate regression analysis was used to estimate the effects of comorbidities, such as BMI, hypertension, diabetes, hypercholesterolemia, alcohol consumption, and ischemic heart disease, on the association of age of stroke onset and smoking status.

RESULTS

We identified 778 (mean age 49.5±10.2) migrant male workers of South Asian descent with ischaemic stroke in Qatar, of which 41.3% of the sample were current smokers. Compared to non-smokers, current smokers suffered a stroke 2.03 years earlier (95%CI: 0.60-3.46, P=0.005). Multivariate regression analysis demonstrated that only current smoking status was associated with an earlier age of stroke onset (β=2.03, SE=0.74, P=0.006).

CONCLUSION

Smoking is associated with at least a two-year earlier onset of ischaemic stroke in male South Asian migrants to the Middle East. Our study has important implications for the public health management of migrants in host countries.

Pathophysiology, diagnosis and management of cerebral venous thrombosis: A comprehensive review

Cerebral venous thrombosis is a rare cause of stroke in young mostly female adults which is frequently overlooked due to its variable clinical and radiological presentation. This review summarizes current knowledge on it risk factors, management and outcome in adults and highlights areas for future research. Females are 3 times more commonly affected and are significantly younger than males. The presenting symptoms can range from headache to loss of consciousness. However, the often-nebulous nature of symptoms can make the diagnosis challenging. Magnetic resonance imaging with venography is often the diagnostic imaging of choice. While unfractionated or low molecular-weight heparin is the mainstay of treatment, endovascular intervention with thrombolysis or thrombectomy and decompressive craniectomy may be required depending on clinical status. Nevertheless, approximately 80% of patients have a good recovery but mortality rates of -5% to 10% are not uncommon. Diagnosing cerebral venous thrombosis can be challenging but with vigilance and expert care patients have the best chance of a good clinical outcome.

Cerebral Venous Thrombosis Among Bangladeshi Population: A Systematic Review

Cerebral venous thrombosis (CVT) is a rare cause of stroke which remains unsung among Bangladeshi physicians and the general population. Our objective was to provide a comprehensive review of published data on Bangladeshi CVT patients. We searched all-electronic databases for Bangladeshi studies on CVT until November 2023, including literature in all languages. This study reviews the age of onset, gender distribution, radiological characteristics, and outcomes of Bangladeshi CVT patients. We included 13 studies (two observational and 11 case reports) that evaluated 102 CVT patients and found that women suffered CVT significantly higher than men (59.8% vs 40.2%; P =0.04), respectively. The overall age of the study population was 36.6±6.8, and men were significantly older than women (45.4±12.3 vs. 32.4±8.3; P<0.001). The most commonly affected sites were the superior sagittal sinus and transverse sinus thrombosis. Rivaroxaban was primarily used for long-term anticoagulation after initial low molecular weight heparin therapy. Furthermore, most studies observed an excellent clinical outcome with completed recanalisation on early follow-up angiography in three studies. In Bangladesh, women 1.5 times more commonly suffer from CVT and 13 years earlier than men. Although this review found that prompt diagnosis and anticoagulation therapy provides good clinical outcome, we recommended further studies to evaluate the long-term outcome, especially the safety and efficacy of oral anticoagulants, with recanalisation and recurrence rate.

Blood group and ischemic stroke, myocardial infarction, and peripheral vascular disease: A meta-analysis of over 145,000 cases and 2,000,000 controls

OBJECTIVE

Cardiovascular illnesses have been associated to ABO blood types, specifically through an effect on von Willebrand factor and factor FVIII levels. We conducted a meta-analysis to comprehensively explore the relationship between blood groups and ischemic stroke, myocardial infarction, and peripheral vascular disease.

MATERIALS AND METHODS

A comprehensive meta-analysis was undertaken to investigate blood groups and ischemic stroke (IS), myocardial infarction (MI) and peripheral vascular disease (PVD). Odds ratios (OR) were used to assess the relationship between blood groups and disease. RevMan v5,4 was used to statistically analyse the results. Risk of bias was assessed using the Newcastle-Ottawa scale.

RESULTS

A total of 72 studies (18 ischemic stroke, 37 myocardial infarction, 17 peripheral vascular disease) met our search criteria, totalling 145,499 cases and 2,113,736 controls. Mean age ranged between 18 and 90 years. Compared to blood group-O, non-O blood group had an increased association with IS (OR=1.13, 95%Cl: 1.07-1.21, P < 0.001), MI (OR=1.17, 95%Cl: 1.11-1.24, P < 0.001) and PVD (OR=1.15, 95%Cl: 1.04-1.28, P=0.005). Compared to blood group-O, blood group A had a stronger statistically significant association to IS (OR=1.19, P=0.001), MI (OR=1.22, P < 0.001) and PVD (OR=1.15, P=0.03). Blood group-B has the lowest risk associated with MI (OR=1.09, P=0.01). In addition, blood groups AB had a stronger statistically significant association to IS (OR=1.24, P=0.01), and MI (OR=1.20, P < 0.001) compared with the other blood groups.

CONCLUSIONS

Compared to blood group-O, groups A and AB are strongly associated to ischemic stroke, myocardial infarction, and peripheral vascular disease.

Non-Parametric MCMC Gibbs Sampler Approach and Misclassification Assessment of Estimating Haplotype Frequencies among Related Statistical Approaches

Introduction: Haplotype analysis allows higher resolution analysis in genetic association studies and is used as a reference panel for genotype imputation in genome-wide association studies. Haplotypes estimates from genotypes among unrelated individuals but misclassification of the haplotype reconstruction will directly affect the accuracy of the results. Methods: This study proposes a novel statistical method Gibbs sampler algorithm to estimate haplotype frequency and quantify the influence of misclassification bias of the estimate haplotype. The performance of the algorithm is evaluated on simulated datasets assuming that linkage phase unknown. The simulation used different minor allele frequencies at each single nucleotide polymorphism (SNP) and different linkagedisequilibrium between the SNPs. Results: The Gibbs sampler algorithm presents higher accuracy among over seven SNPs or less, validated, and deals with missing genotype compared to previous related statistical approaches. Misclassification of estimated haplotypes leads to non-differential bias in exposure and affects haplotype estimates in haplotype analysis. The observed odds ratio underestimates the association between haplotype and phenotype by 36% to 99%. Conclusion: The Gibbs sampler algorithm provides higher accuracy and robust effectiveness performance, handles missing genotypes and provides uncertain probabilities of haplotype frequencies. The misclassification bias of the estimate haplotype underestimates the genetic association by more than forty percent.

Age of onset of cerebral venous thrombosis: the BEAST study

Background

Cerebral venous thrombosis (CVT) is an uncommon cause of stroke in young adults. We aimed to determine the impact of age, gender and risk factors (including sex-specific) on CVT onset.

Methods

We used data from the BEAST (Biorepository to Establish the Aetiology of Sinovenous Thrombosis), a multicentre multinational prospective observational study on CVT. Composite factors analysis (CFA) was performed to determine the impact on the age of CVT onset in males and females.

Results

A total of 1309 CVT patients (75.3% females) aged ⩾18 years were recruited. The overall median (IQR-interquartile range) age for males and females was 46 (35-58) years and 37 (28-47) years (p < 0.001), respectively. However, the presence of antibiotic-requiring sepsis (p = 0.03, 95% CI 27-47 years) among males and gender-specific risk factors like pregnancy (p < 0.001, 95% CI 29-34 years), puerperium (p < 0.001, 95% CI 26-34 years) and oral contraceptive use (p < 0.001, 95% CI 33-36 years) were significantly associated with earlier onset of CVT among females. CFA demonstrated a significantly earlier onset of CVT in females, ~12 years younger, in those with multiple (⩾1) compared to '0' risk factors (p < 0.001, 95% CI 32-35 years).

Conclusions

Women suffer CVT 9 years earlier in comparison to men. Female patients with multiple (⩾1) risk factors suffer CVT ~12 years earlier compared to those with no identifiable risk factors.

Atrial fibrillation in UK South Asian hospitalized ischemic stroke patients: The BRAINS study

INTRODUCTION

South Asian diaspora comprise one of the largest ethnic minority groups in the world yet data about atrial fibrillation (AF) in this demographic is understudied. Our aim is to identify differences in AF prevalence and treatment between South Asians and white British stroke patients.

METHOD

The UK arm of a prospective ongoing large international repository on stroke was analysed. Ethnic differences in AF prevalence and management in those with ischemic stroke were analysed.

RESULTS

Of the 3515 individuals recruited with ischemic stroke, 1482 (men: 972, women: 510) were South Asian and 2033 (men:1141, women:892) of white British ethnicity. AF was present in 462 white British and 193 South Asians stroke patients, with South Asians displaying a lower prevalence of AF (South Asians: 13.0% vs white British 22.7%, P<0.001). Despite adjustment for traditional AF risk factors, South Asians had a significantly lower OR of AF compared to white British stroke patients (OR: 0.40, 95%CI: 0.33:0.49, P<0.001). Among confirmed AF cases, 31.8% of South Asians and 41.4% of white British were untreated at admission (P = 0.02). Antiplatelet treatment was significantly higher among South Asians at both admission (South Asian: 47.4% vs. white British: 29.9%, P<0.001) and discharge (South Asian: 49.5% vs. white British: 34.7%, P = 0.001), although anticoagulation treatment was similar across both ethnic groups at admission (South Asian: 28.5% vs white British: 28.1%, P = 0.93), and discharge (South Asian: 45.1% vs white British: 43.1%, P = 0.64).

CONCLUSION

Stroke patients of South Asian descent are at significantly lower risk of AF but more likely to be on antiplatelet treatment compared to their white British counterparts.

Ischaemic stroke in South Asians: The BRAINS study

BACKGROUND AND PURPOSE

Studies on stroke in South Asian populations are sparse. The aim of this study was to compare differences in age of onset of ischaemic stroke in South Asian patients living in the United Kingdom and South Asian patients living in India versus White British stroke patients.

METHODS

We studied the UK and Indian arms of the ongoing BRAINS study, an international prospective hospital-based study of South Asian stroke patients. The BRAINS study includes 4038 South Asian and White British patients with first-ever ischaemic stroke, recruited from sites in the United Kingdom and India.

RESULTS

Of the included patients, 1126 were South Asians living in India (ISA), while 1176 were British South Asian (BSA) and 1736 were White British (WB) UK residents. Patients in the ISA and BSA groups experienced stroke 19.5 years and 7.2 years earlier than their WB counterparts, respectively (mean [interquartile range] age: BSA 64.3 [22] years vs. ISA 52.0 [18] years vs. WB 71.5 [19] years; p < 0.001). Patients in the BSA group had higher rates of hypertension, diabetes mellitus and hypercholesterolaemia than those in the ISA and WB groups. After adjustment for traditional stroke risk factors, an earlier age of stroke onset of 18.9 years (p < 0.001) and 8.9 years (p < 0.001) was still observed in the ISA and BSA groups, respectively. In multivariable stepwise linear regression analysis, ethnicity accounted for 24.7% of the variance in early age onset.

CONCLUSION

Patients in the BSA and ISA groups experienced ischaemic stroke approximately 9 and 19 years earlier, respectively, than their WB counterparts. Ethnicity is an independent predictor of early age of stroke onset. Our study has considerable implications for public health policymakers in countries with sizable South Asian populations.

Efficacy of mirror therapy and virtual reality therapy in alleviating phantom limb pain: a meta-analysis and systematic review

INTRODUCTION

Amputations result from trauma, war, conflict, vascular diseases and cancer. Phantom limb pain (PLP) is a potentially debilitating form of chronic pain affecting around 100 million amputees across the world. Mirror therapy and virtual reality (VR) are two commonly used treatments, and we evaluated their respective success rates.

METHODS

A meta-analysis and systematic review was undertaken to investigate mirror therapy and VR in their ability to reduce pain levels. A mean difference (MD) model to compare group pain levels pretreatment and post-treatment via aggregating these results from numerous similar studies was employed. Meta-analysis was conducted using RevMan (V.5.4) and expressed in MD for visual analogue scale (VAS) score.

RESULTS

A total of 15 studies met our search criteria; they consisted of eight mirror therapy with 214 participants and seven VR including 86 participants, totalling 300 participants. Mean age ranged from 36 to 63 years, 77% male, of which 61% were lower body amputees. Both led to a VAS reduction (mirror therapy mean reduction VAS score was 2.54, 95% CI 1.42 to 3.66; p<0.001; VR 2.24, 95% CI 1.28 to 3.20; p<0.001). There was no statistically significant difference in pain alleviation between mirror therapy and VR (p=0.69).

CONCLUSIONS

Mirror therapy and VR are both equally efficacious in alleviating PLP, but neither is more effective than the other. However, due to small sample size and limited number of studies, factors such as gender, cause of amputation, site of limb loss or length of time from amputation, which may influence treatment success, could not be explored.

Changes in cortisol levels by continuous positive airway pressure in patients with obstructive sleep apnoea: Meta-analysis of 637 individuals

BACKGROUND

Obesity, obstructive sleep apnoea (OSA) and hypertension frequently coexist and are associated with elevated cortisol levels. Identification and treatment of such patients is important when investigating for suspected Cushing's syndrome and hypertension. Studies of the impact of continuous positive airway pressure (CPAP) on cortisol and blood pressure are limited by the small sample size and show conflicting findings. We conducted a meta-analysis to document changes in the levels of cortisol and blood pressure in response to CPAP treatment of OSA.

METHODS

Meta-analysis was conducted using RevMan (v5.3) and expressed in standardized mean difference (SMD) for catecholamines and mean difference for systolic (SBP) and diastolic blood pressure (DBP). The quality of the studies was evaluated using standard tools for assessing the risk of bias.

RESULTS

A total of 22 studies met our search criteria; they consisted of 16 prospective cohort studies (PCS) that recruited 385 participants and six randomized control trials (RCT) totalling 252 participants. The range of mean age was 41-62 years and BMI 27.2-35.1 kg/m² . CPAP treatment reduced plasma cortisol levels in PCS: SMD = -0.28 [95% confidence interval (95% CI) = -0.45 to -0.12], I²  = 0%, p = .79 and in RCT: SMD = -0.39 (95% CI = -0.75 to -0.03), I²  = 28.3%, p = .25. CPAP treatment reduced SBP by 5.4 mmHg (95% CI = 1.7-9.1) and DBP by 3.3 mmHg (95% CI = 1.0-5.7). Interstudy heterogeneity was low for all studies. Bias in most RCT arose from the lack of blinding of participants and personnel.

CONCLUSION

CPAP treatment in individuals with OSA reduces cortisol levels and blood pressure.

Genome-Wide Association Study Identifies First Locus Associated with Susceptibility to Cerebral Venous Thrombosis

OBJECTIVE

Cerebral venous thrombosis (CVT) is an uncommon form of stroke affecting mostly young individuals. Although genetic factors are thought to play a role in this cerebrovascular condition, its genetic etiology is not well understood.

METHODS

A genome-wide association study was performed to identify genetic variants influencing susceptibility to CVT. A 2-stage genome-wide study was undertaken in 882 Europeans diagnosed with CVT and 1,205 ethnicity-matched control subjects divided into discovery and independent replication datasets.

RESULTS

In the overall case-control cohort, we identified highly significant associations with 37 single nucleotide polymorphisms (SNPs) within the 9q34.2 region. The strongest association was with rs8176645 (combined p = 9.15 × 10-24 ; odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.76-2.31). The discovery set findings were validated across an independent European cohort. Genetic risk score for this 9q34.2 region increases CVT risk by a pooled estimate OR = 2.65 (95% CI = 2.21-3.20, p = 2.00 × 10-16 ). SNPs within this region were in strong linkage disequilibrium (LD) with coding regions of the ABO gene. The ABO blood group was determined using allele combination of SNPs rs8176746 and rs8176645. Blood groups A, B, or AB, were at 2.85 times (95% CI = 2.32-3.52, p = 2.00 × 10-16 ) increased risk of CVT compared with individuals with blood group O.

INTERPRETATION

We present the first chromosomal region to robustly associate with a genetic susceptibility to CVT. This region more than doubles the likelihood of CVT, a risk greater than any previously identified thrombophilia genetic risk marker. That the identified variant is in strong LD with the coding region of the ABO gene with differences in blood group prevalence provides important new insights into the pathophysiology of CVT. ANN NEUROL 2021;90:777-788.

Markov chain Monte Carlo Gibbs sampler approach for estimating haplotype frequencies among multiple malaria infected human blood samples

Background

Malaria patients can have two or more haplotypes in their blood sample making it challenging to identify which haplotypes they carry. In addition, there are challenges in measuring the type and frequency of resistant haplotypes in populations. This study presents a novel statistical method Gibbs sampler algorithm to investigate this issue.

Results

The performance of the algorithm is evaluated on simulated datasets consisting of patient blood samples characterized by their multiplicity of infection (MOI) and malaria genotype. The simulation used different resistance allele frequencies (RAF) at each Single Nucleotide Polymorphisms (SNPs) and different limit of detection (LoD) of the SNPs and the MOI. The Gibbs sampler algorithm presents higher accuracy among high LoD of the SNPs or the MOI, validated, and deals with missing MOI compared to previous related statistical approaches.

Conclusions

The Gibbs sampler algorithm provided robust results when faced with genotyping errors caused by LoDs and functioned well even in the absence of MOI data on individual patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03841-9.

SARS-CoV-2 antibody seroprevalence in NHS healthcare workers in a large double-sited UK hospital

We determined the seroprevalence of SARS-CoV-2 antibodies in NHS healthcare workers (HCWs) in a cross-sectional study from a large general hospital located in a double-sited rural and semi-rural area. The sample size of 3,119 HCWs (mean age 43±13) consisted of 75.2% women, 61.1% White individuals and predominantly (62.4%) asymptomatic individuals. Seroprevalence of SARS-CoV-2 antibodies was 19.7%. Determinants of seropositivity were preceding symptomatic infection and non-White ethnicity. Regardless of staff role or sex, multivariate regression analysis revealed that non-White HCWs were three times (odds ratio [OR] 3.12, 95% confidence interval [CI] 2.53-3.86, P<0.001) more likely to have antibodies than White staff, and seven times (OR 7.10, 95% CI 5.72-8.87, P<0.001) more likely if there was a history of preceding symptoms. We report relatively high rates of seropositivity in all NHS healthcare workers. Non-White symptomatic HCWs were significantly more likely to be seropositive than their colleagues, independent of age, sex or staff role.

Continuous positive airway pressure therapy reduces the levels of catecholamines and blood pressure in pseudophaeochromocytoma with coexisting obstructive sleep apnoea

Background

Stress from obstructive sleep apnoea (OSA) stimulates catecholamine release and consequently can exacerbate hypertension, even in the absence of a catecholamine-producing tumour (phaeochromocytoma). As such, a positive screening test for suspected phaeochromocytoma may be misleading. There exists only a handful case reports, and no controlled trials, how continuous positive airway pressure (CPAP) to treat OSA influences catecholamine levels. We examined changes to levels of urinary catecholamine and blood pressure in response to CPAP treatment.

Methods

We conducted a meta-analysis of data aggregated from published case reports of individual patient data up to April 2020. The quality of the reports was evaluated using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool.

Results

A total of 13 cases (seven men and six women) from seven reports met our search criteria. Patients had mean age of 49.1 years (range = 36-62) and body mass index of 37.4 kg/m² (range = 27-56). Most had moderate to severe OSA with CPAP treatment. Nine cases had 24-hour urinary noradrenaline assessment before and after CPAP treatment. CPAP treatment led to a 21% reduction (104 nmol/24-hours, 95% credible interval =59 to 148) in 24-hour urinary noradrenaline to within reference ranges, and 25% reduction (from 131 to 100 mmHg) in mean arterial pressure. The risk of overall bias evaluated by the ROBINS-I tool was found to be low in the majority of reports.

Conclusions

Investigations of patients suspected of phaeochromocytoma, particularly obese individuals, should exclude OSA and treat this condition if present before performing screening tests to assess for catecholamine levels.

COVID-19 outcomes in UK centre within highest health and wealth band: a prospective cohort study

OBJECTIVES

To describe the characteristics and outcomes of hospitalised patients with COVID-19 from UK in the highest decile of health and gross regional products per capita.

DESIGN

Prospective cohort study.

SETTING

Recruited all adult inpatients with laboratory-confirmed COVID-19 symptoms admitted to a single Surrey centre between March and April 2020. Extensive demographic details were documented.

OUTCOME MEASURE

COVID-19 status of alive/dead and intensive care unit (ICU) status of yes/no.

PARTICIPANTS

Patients with COVID-19 from Surrey centre UK (n=429).

RESULTS

429 adult inpatients (mean age 70±18 years; men 56.4%) were included in this study, of whom, 19.1% required admission to ICU and 31.9% died. Adverse outcomes were associated with age (OR with each decade of years: 1.78, 95% CI 1.53 to 2.11, p<0.001 for mortality); male gender (OR=1.08, 95% CI 0.72 to 1.63, p=0.72, present in 70.7%, of admissions to ICU versus 53% of other cases, p=0.004); cardiac disease (OR=3.43, 95% CI 2.10 to 5.63, p<0.001), diabetes mellitus (OR=2.37, 95% CI 1.09 to 5.17, p=0.028) and dementia (OR=5.06, 95% CI 2.79 to 9.44, p<0.001). There was no significant impact of ethnicity or body mass index on disease outcome.

CONCLUSIONS

Despite reports of worse outcomes in deprived regions, we show similar complication and mortality rates due to COVID-19 in an affluent and high life expectancy region.

Meta-analysis of changes in the levels of catecholamines and blood pressure with continuous positive airway pressure therapy in obstructive sleep apnea

Stress from obstructive sleep apnea (OSA) stimulates catecholamine release consequently exacerbating hypertension. However, different studies have shown a conflicting impact of continuous positive airway pressure (CPAP) treatment in patients with OSA on catecholamine levels and blood pressure. We aimed to examine changes to catecholamine levels and blood pressure in response to CPAP treatment. We conducted a meta‐analysis of data published up to May 2020. The quality of the studies was evaluated using standard tools for assessing the risk of bias. Meta‐analysis was conducted using RevMan (v5.3) and expressed in standardized mean difference (SMD) for catecholamines and mean difference (MD) for systolic (SBP) and diastolic blood pressure (DBP). A total of 38 studies met our search criteria; they consisted of 14 randomized control trials (RCT) totaling 576 participants and 24 prospective cohort studies (PCS) of 547 participants. Mean age ranged between 41 and 62 year and body mass index between 27.2 and 35.1 kg/m². CPAP treatment reduced 24‐hour urinary noradrenaline levels both in RCT (SMD = −1.1; 95% confidence interval (CI): −1.63 to − 0.56) and in PCS (SMD = 0.38 (CI: 0.24 to 0.53). SBP was also reduced by CPAP treatment in RCT (4.8 mmHg; CI: 2.0‐7.7) and in PCS (7.5 mmHg; CI: 3.3‐11.7). DBP was similarly reduced (3.0 mmHg; CI: 1.4‐4.6) and in PCS (5.1 mmHg; CI: 2.3‐8.0). In conclusion, CPAP treatment in patients with OSA reduces catecholamine levels and blood pressure. This suggests that sympathetic activity plays an intermediary role in hypertension associated with OSA‐related stress.

Comparing the Efficacy of Drug Regimens for Pulmonary Tuberculosis: Meta-analysis of Endpoints in Early-Phase Clinical Trials

Background

A systematic review of early clinical outcomes in tuberculosis was undertaken to determine ranking of efficacy of drugs and combinations, define variability of these measures on different endpoints, and to establish the relationships between them.

Methods

Studies were identified by searching PubMed, Medline, Embase, LILACS (Latin American and Caribbean Health Sciences Literature), and reference lists of included studies. Outcomes were early bactericidal activity results over 2, 7, and 14 days, and the proportion of patients with negative culture at 8 weeks.

Results

One hundred thirty-three trials reporting phase 2A (early bactericidal activity) and phase 2B (culture conversion at 2 months) outcomes were identified. Only 9 drug combinations were assessed on >1 phase 2A endpoint and only 3 were assessed in both phase 2A and 2B trials.

Conclusions

The existing evidence base supporting phase 2 methodology in tuberculosis is highly incomplete. In future, a broader range of drugs and combinations should be more consistently studied across a greater range of phase 2 endpoints.

Quality of reporting of outcomes in phase III studies of pulmonary tuberculosis: a systematic review

Background

Despite more than 60 years of clinical trials, tuberculosis (TB) still causes a high global burden of mortality and morbidity. Treatment currently requires multiple drugs in combination, taken over a prolonged period. New drugs are needed to shorten treatment duration, prevent resistance and reduce adverse events. However, to improve on current methodology in drug development, a more complete understanding of the existing clinical evidence base is required.

Methods

A systematic review was undertaken to summarise outcomes reported in phase III trials of patients with newly diagnosed pulmonary TB. A systematic search of databases (PubMed, MEDLINE, EMBASE, CENTRAL and LILACs) was conducted on 30 November 2017 to retrieve relevant peer-reviewed articles. Reference lists of included studies were also searched. This systematic review considered all reported outcomes.

Results

Of 248 included studies, 229 considered “on-treatment” outcomes whilst 148 reported “off-treatment” outcomes. There was wide variation and ambiguity in the definition of reported outcomes, including their relationship to treatment and in the time points evaluated. Additional challenges were observed regarding the analysis approach taken (per protocol versus intention to treat) and the varying durations of “intensive” and “continuation” phases of treatment. Bacteriological outcomes were most frequently reported but radiological and clinical data were often included as an implicit or explicit component of the overall definition of outcome.

Conclusions

Terminology used to define long-term outcomes in phase III trials is inconsistent, reflecting evolving differences in protocols and practices. For successful future cumulative meta-analysis, the findings of this review suggest that greater availability of individual patient data and the development of a core outcome set would be desirable. In the meantime, we propose a simple and logical approach which should facilitate combination of key evidence and inform improvements in the methodology of TB drug development and clinical trials.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2522-x) contains supplementary material, which is available to authorized users.

Markov chain Monte Carlo and expectation maximization approaches for estimation of haplotype frequencies for multiply infected human blood samples

Background

Haplotypes are important in anti-malarial drug resistance because genes encoding drug resistance may accumulate mutations at several codons in the same gene, each mutation increasing the level of drug resistance and, possibly, reducing the metabolic costs of previous mutation. Patients often have two or more haplotypes in their blood sample which may make it impossible to identify exactly which haplotypes they carry, and hence to measure the type and frequency of resistant haplotypes in the malaria population.

Results

This study presents two novel statistical methods expectation–maximization (EM) and Markov chain Monte Carlo (MCMC) algorithms to investigate this issue. The performance of the algorithms is evaluated on simulated datasets consisting of patient blood characterized by their multiplicity of infection (MOI) and malaria genotype. The datasets are generated using different resistance allele frequencies (RAF) at each single nucleotide polymorphisms (SNPs) and different limit of detection (LoD) of the SNPs and the MOI. The EM and the MCMC algorithm are validated and appear more accurate, faster and slightly less affected by LoD of the SNPs and the MOI compared to previous related statistical approaches.

Conclusions

The EM and the MCMC algorithms perform well when analysing malaria genetic data obtained from infected human blood samples. The results are robust to genotyping errors caused by LoDs and function well even in the absence of MOI data on individual patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1473-5) contains supplementary material, which is available to authorized users.

The effect of pro-inflammatory conditioning and/or high glucose on telomere shortening of aging fibroblasts

Cardiovascular disease and diabetes have been linked to shorter telomeres, but it is not yet clear which risk factors contribute to shorter telomeres in patients. Our aim was to examine whether pro-inflammatory conditioning, in combination or not with high glucose, result in a higher rate of telomere shortening during in vitro cellular ageing. Human fibroblasts from four donors were cultured for 90 days in: 1) medium lacking ascorbic acid only, 2) 10 mM buthionine sulphoximine (BSO) (pro-oxidant), 3) 25 mM D-glucose, 4) 1 ng/ml IL1B and 5) 25 mM D-glucose+1 ng/ml IL1B. Telomere length was measured with qPCR and intracellular reactive oxygen species (ROS) content and cell death with flow cytometry. Cultures treated with high glucose and BSO displayed a significantly lower growth rate, and cultures treated with IL1B showed a trend towards a higher growth rate, compared to the control [Glucose:0.14 PD/day, p<0.001, BSO: 0.11 PD/day, p = 0.006 and IL1B: 0.19 PD/day, p = 0.093 vs.

CONTROL

0.16 PD/day]. Telomere shortening with time was significantly accelerated in cultures treated with IL1B compared to the control [IL1B:-0.8%/day (95%CI:-1.1, -0.5) vs.

CONTROL

-0.6%/day (95%CI:-0.8, -0.3), p = 0.012]. The hastening of telomere shortening by IL1B was only in part attenuated after adjustment for the number of cell divisions [IL1B:-4.1%/PD (95%CI:-5.7, -2.4) vs.

CONTROL

-2.5%/PD (95%CI:-4.4, -0.7), p = 0.067]. The intracellular ROS content displayed 69% increase (p = 0.033) in BSO compared to the control. In aging fibroblasts, pro-inflammatory conditioning aggravates the shortening of telomeres, an effect which was only in part driven by increased cell turnover. High glucose alone did not result in greater production of ROS or telomere shortening.

The use of haplotypes in the identification of interaction between SNPs

Although haplotypes can provide great insight into the complex relationships between functional polymorphisms at a locus, their use in modern association studies has been limited. This is due to our inability to directly observe haplotypes in studies of unrelated individuals, but also to the extra complexity involved in their analysis and the difficulty in identifying which is the truly informative haplotype. Using a series of simulations, we tested a number of different models of a haplotype carrying two functional single nucleotide polymorphisms (SNPs) to assess the ability of haplotypic analysis to identify functional interactions between SNPs at the same locus. We found that, when phase is known, analysis of the haplotype is more powerful than analysis of the individual SNPs. The difference between the two approaches becomes less either as an increasing number of non-informative SNPs are included, or when the haplotypic phase is unknown, while in both cases the SNP association becomes progressively better at identifying the association. Our results suggest that when novel genotyping and bioinformatics methods are available to reconstruct haplotypic phase, this will permit the emergence of a new wave of haplotypic analysis able to consider interactions between SNPs with increased statistical power.

Free protein S level as a risk factor for coronary heart disease and stroke in a prospective cohort study of healthy United Kingdom men

Plasma protein S (PS) levels are reportedly low in patients with venous thrombosis but high in coronary heart disease (CHD) patients. The authors examined the association between free PS concentration and CHD or stroke risk and assessed risk in combination with C-reactive protein (CRP) levels. Free PS concentration was determined in 6 annual visits among 3,052 middle-aged (49-64 years) United Kingdom men from the Second Northwick Park Heart Study, with 297 CHD events from 1989 to 2005. The highest (vs. first) quintile was associated with a significantly increased CHD risk after adjustment for all other risk factors and correction for regression dilution bias (hazard ratio = 1.85, 95% confidence interval: 1.08, 3.16; P = 0.024). Models that included all well-known risk factors plus PS quintiles improved prediction of CHD (net reclassification improvement (NRI) = 7.0% (P = 0.007), category-less NRI (>0) = 22.1% (P < 0.001)), and the likelihood ratio statistic increased significantly (P = 0.018). The increase in CHD risk was particularly strong when subjects also had high CRP levels. There was no association between free PS level and stroke risk. This study confirms the independent association of elevated free PS levels with future risk of CHD, although elevated PS levels added only modestly to prediction metrics. The novel finding of increased CHD risk, particularly when CRP and PS levels are high, requires further study.

Genetic variation within IL18 is associated with insulin levels, insulin resistance and postprandial measures

BACKGROUND AND AIMS

IL-18 expression is up-regulated in atherosclerotic plaques, and higher levels are seen in obese and Type 2 Diabetic individuals. More recently, a possible role for IL-18 in glucose and energy homeostasis has been suggested.

METHODS AND RESULTS

We investigated variation within the IL18 gene and its association with measures of obesity and the metabolic syndrome. Five IL18 tagging single nucleotide polymorphisms (rs1946519, rs2043055, rs549908, rs360729, rs3882891) were selected and genotyped in the Gene-Diet Attica Investigation on childhood obesity (GENDAI) (age range 10-14 yrs); in young European men in the second European Atherosclerosis Research offspring Study (EARSII), an offspring study (age range 18-28 yrs) and in a group of healthy women from the Greek Obese Women study (GrOW) (age range 18-74 yrs). Six common haplotypes were observed. In GrOW, Hap6 (Frequency-2.6%) was associated with higher insulin levels (p<0.0001), estimates of HOMA(-Insulin Resistance) (p<0.0001) and HOMA(-β-cell) (p<0.0001) compared to the common haplotype Hap1 (Frequency-33.2%). In EARSII, rs2043055 was associated with peak and area under the curve triglycerides (p=0.001 and p=0.002, respectively) after an oral fat tolerance test in 'cases' but not 'controls'. None of the haplotypes were associated with measures of body fatness in any of the studies.

CONCLUSION

Association of IL18 variation with insulin levels and estimates of insulin resistance were only observed in our adult study, suggesting that the effects of IL-18 are only associated with increasing age. Taken together with the association of IL18 variants with post-prandial measures, this provides support for IL-18 as a metabolic factor.

Haplotype and genotype effects of the F7 gene on circulating factor VII, coagulation activation markers and incident coronary heart disease in UK men

BACKGROUND

Evidence for the associations of single nucleotide polymorphisms (SNPs) in the F7 gene and factor (F)VII levels and with risk of coronary heart disease (CHD) is inconsistent. We examined whether F7 tagging SNPs (tSNPs) and haplotypes were associated with FVII levels, coagulation activation markers (CAMs) and CHD risk in two cohorts of UK men.

METHODS

Genotypes for eight SNPs and baseline levels of FVIIc, FVIIag and CAMs (including FVIIa) were determined in 2773 healthy men from the Second Northwick Park Heart Study (NPHS-II). A second cohort, Whitehall II study (WH-II, n = 4055), was used for replication analysis of FVIIc levels and CHD risk.

RESULTS

In NPHS-II the minor alleles of three SNPs (rs555212, rs762635 and rs510317; haplotype H2) were associated with higher levels of FVIIag, FVIIc and FVIIa, whereas the minor allele for two SNPs (I/D323 and rs6046; haplotype H5) was associated with lower levels. Adjusted for classic risk factors, H2 carriers had a CHD hazard ratio of 1.34 [95% confidence interval (CI): 1.12-1.59; independent of FVIIc], whereas H5 carriers had a CHD risk of 1.29 (95% CI: 1.01-1.56; not independent of FVIIc) and significantly lower CAMs. Effects of haplotypes on FVIIc levels were replicated in WH-II, as was the association of H5 with higher CHD risk [pooled-estimate odds ratio (OR) 1.16 (1.00-1.36), P = 0.05], but surprisingly, H2 exhibited a reduced risk for CHD.

CONCLUSION

 tSNPs in the F7 gene strongly influence FVII levels. The haplotype associated with low FVIIc level, with particularly reduced functional activity, was consistently associated with increased risk for CHD, whereas the haplotype associated with high FVIIc level was not.

APOE/C1/C4/C2 gene cluster genotypes, haplotypes and lipid levels in prospective coronary heart disease risk among UK healthy men

The role of common APOE variants on plasma lipids, particularly low density lipoprotein (LDL) levels, and coronary heart disease (CHD) risk is well known; the influence of variation in the other nearby apolipoprotein genes APOC1, APOC4 and APOC2 is unclear. This study examines the association between APOE/C1/C4/C2 gene cluster variation using tagging SNPs and plasma lipid concentration along with risk of CHD in a prospective cohort. Genotypes for 11 common APOE/C1/C4/C2 SNPs were determined in 2,767 middle-aged (49 to 64 years) men from the Second Northwick Park Heart Study, with 275 CHD events over a 15-year follow-up period. Seven SNPs showed significant associations with one or more lipid trait in univariate analysis. Multivariate and haplotype analysis showed that the APOE genotypes are most strongly associated with effects on LDL-C and apoB concentration (explaining 3.4% of the LDL-C variance) while the other SNPs in this gene cluster explained an additional 1.2%. Haplotypes in APOC2 and APOC4 were associated with modest effects on HDL-C and apoAI (explaining respectively 1.4% and 1.2%). Carriers of the APOE ɛ2 SNP had a significantly lower risk of CHD hazard ratio (HR) of 0.63 (95% confidence interval [CI]: 0.42-0.95), as did carriers of the APOC2 SNP rs5127 (HR = 0.72, 95% CI: 0.56-0.93), while carriers of APOC1 SNP rs4803770 had higher risk of CHD (HR = 1.36, 95% CI: 1.04-1.78) compared with noncarriers. While the common APOE polymorphism explains the majority of the locus genetic determinants of plasma lipid levels, additional SNPs in the APOC1/C2 region may contribute to CHD risk, but these effects require confirmation.

APOE/C1/C4/C2 gene cluster genotypes, haplotypes and lipid levels in prospective coronary heart disease risk among UK healthy men

The role of common APOE variants on plasma lipids, particularly low density lipoprotein (LDL) levels, and coronary heart disease (CHD) risk is well known; the influence of variation in the other nearby apolipoprotein genes APOC1, APOC4 and APOC2 is unclear. This study examines the association between APOE/C1/C4/C2 gene cluster variation using tagging SNPs and plasma lipid concentration along with risk of CHD in a prospective cohort. Genotypes for 11 common APOE/C1/C4/C2 SNPs were determined in 2,767 middle-aged (49 to 64 years) men from the Second Northwick Park Heart Study, with 275 CHD events over a 15-year follow-up period. Seven SNPs showed significant associations with one or more lipid trait in univariate analysis. Multivariate and haplotype analysis showed that the APOE genotypes are most strongly associated with effects on LDL-C and apoB concentration (explaining 3.4% of the LDL-C variance) while the other SNPs in this gene cluster explained an additional 1.2%. Haplotypes in APOC2 and APOC4 were associated with modest effects on HDL-C and apoAI (explaining respectively 1.4% and 1.2%). Carriers of the APOE ɛ2 SNP had a significantly lower risk of CHD hazard ratio (HR) of 0.63 (95% confidence interval [CI]: 0.42-0.95), as did carriers of the APOC2 SNP rs5127 (HR = 0.72, 95% CI: 0.56-0.93), while carriers of APOC1 SNP rs4803770 had higher risk of CHD (HR = 1.36, 95% CI: 1.04-1.78) compared with noncarriers. While the common APOE polymorphism explains the majority of the locus genetic determinants of plasma lipid levels, additional SNPs in the APOC1/C2 region may contribute to CHD risk, but these effects require confirmation.

Different effects of apolipoprotein A5 SNPs and haplotypes on triglyceride concentration in three ethnic origins

Several polymorphisms in the ApoA5 gene emerged as important candidate genes in triglyceride metabolism. The aim of this study was to determine the associations between ApoA5 polymorphisms, plasma triglyceride concentrations and the presence of cardiovascular disease (CVD) in three ethnic origins. Genotypes for 15 single nucleotide polymorphisms (SNPs) were determined in 659 older adults (mean age 71+/-7 years) who immigrated to Israel or whose ancestors originated from East Europe (Ashkenazi), North Africa, Asia (Sephardic) or Yemen (Yemenite). The minor alleles of the four common SNPs (rs662799, rs651821, rs2072560 and rs2266788) are associated with an increase of 27-38% in triglyceride concentration among Ashkenazi and Yemenite Jews compared with the major alleles, but not among those of Sephardic origin. Conversely, among the Sephardic group, the presence of the minor allele in SNP rs3135506 compared with the major allele was associated with an increase of 34% in triglyceride concentration. The four SNPs were in significant linkage disequilibrium (D'=0.96-0.99), resulting in three haplotypes H1, H2 and H3, representing 98-99% of the population. Haplotype H2 was significantly associated with triglyceride concentration among Ashkenazi and Yemenite but not among Sephardic Jews. Conversely, haplotype H3 was associated with triglyceride concentration in Sephardic but not in Ashkenazi and Yemenite Jews. Ashkenazi carriers of H2 haplotype had a CVD odds ratio of 2.19 (95% CI: 1.05-4.58) compared with H1 (the most frequent), after adjustment for all other risk factors. These results suggest that different SNPs in ApoA5 polymorphisms may be associated with triglyceride concentration and CVD in each of these ethnic origins.

A coding VKORC1 Asp36Tyr polymorphism predisposes to warfarin resistance

CYP2C9 and VKORC1 genetic variants are associated with low and intermediate warfarin dose requirements, but markers of high doses are less well characterized. We analyzed the VKORC1 coding sequence and known CYP2C9 and VKORC1 polymorphisms in 15 selected warfarin-resistant (dose, 80 to 185 mg/wk) and 8 warfarin-sensitive patients (7 to 13 mg/wk) and 99 unselected controls (8 to 105 mg/wk). We identified a coding VKORC1 Asp36Tyr polymorphism in 7 of 15 resistant compared with 0 of 8 sensitive patients (P = .026) Carriers of Asp36Tyr in the control group (8 of 99) required significantly higher warfarin doses of 80.9 ± 10.1 mg/wk compared with 42.7 ± 7.5 mg/wk in noncarriers (F = 9.79, P = .002). Asp36Tyr was significantly associated with doses of more than 70 mg/wk (odds ratio, 13.0; 95% confidence limit, 1.3 to 124.2), while doses of 20 to 70 mg/wk were associated with Asp36Tyr (partial r2 = .11; P = .004), CYP2C9*2 and *3 (r2 = .08; P = .01), and VKORC1*2 and *3 markers (r2 = .05; P = .05). All Asp36Tyr carriers also had VKORC1*1 tag–single nucleotide polymorphisms (tag-SNPs) indicating a new haplotype. Asp36Tyr was common in Jewish ethnic groups of Ethiopian (15%) and Ashkenazi (4%) origin. We suggest that Asp36Tyr is a new marker of the high end of the warfarin dosing range.

Central corneal thickness measurement with the Pentacam Scheimpflug system, optical low-coherence reflectometry pachymeter, and ultrasound pachymetry

PURPOSE

To assess the intraoperator repeatability and interoperator reproducibility of central corneal thickness measurements by the Pentacam Scheimpflug imaging system (Oculus) and the optical low-coherence reflectometer (OLCR) pachymeter (Haag-Streit) and to compare them with those of ultrasound (US) pachymetry.

SETTING

Assaf Harofe Medical Center Ophthalmology Outpatient Clinic, Zerifin, Israel.

METHODS

Repeatability was determined from 10 successive measurements in each of 4 healthy patients. Reproducibility for the Pentacam Scheimpflug system was determined from measurements by 2 operators in each of 24 patients; in these 24 patients, central corneal thickness measurements were compared between the Pentacam and US pachymetry. For the OLCR pachymeter, reproducibility was determined from measurements by 2 operators in each of 16 patients, in whom central corneal thickness was also measured with the Pentacam.

RESULTS

Mean coefficient of repeatability was 0.84% for the Pentacam Scheimpflug system and 0.33% for the OLCR pachymeter. For the Pentacam, the coefficient of interoperator reproducibility was 1.10% and the 95% limits of agreement were -10.2 microm to +11.9 microm. Mean difference between Pentacam and US was 6.09 microm. For the OLCR pachymeter, the coefficient of interoperator reproducibility was 0.59% and the 95% limits of agreement were -5.4 microm to +7.0 microm. Mean difference between central corneal thickness values obtained with the OLCR pachymeter and Pentacam Scheimpflug system was 1.7 microm.

CONCLUSIONS

Objective, noncontact measurement of central corneal thickness with the Pentacam Scheimpflug system and OLCR pachymeter was convenient and yielded excellent intraoperator repeatability and interoperator reproducibility. Central corneal thickness values obtained with the Pentacam were similar to those obtained with both the OLCR pachymeter and an US pachymeter. Further research is needed to corroborate whether central corneal thickness measurements by the Pentacam and OLCR devices can be used interchangeably and are more clinically useful than US pachymetry.

[DNA adducts as biological markers for human exposure to polycyclic aromatic compounds]

Polycyclic Aromatic Hydrocarbons (PAH) in human carcinogenesis is undisputed. Measurements of PAH-DNA adduct levels in easily accessible white blood cells therefore represent useful early endpoints in exposure intervention or preventive study. The successful applicability of DNA adducts as early endpoints depends on several criteria: (1) Adduct levels in easily accessible surrogate tissues should reflect adduct levels in target tissues (2) Toxic-kinetics and the temporal relevance should be properly defined (3) Sources of inter and intra individual variability must be know and controllable (4) Adduct analysis must have advantages as compared to other markers of PAH exposure. Higher proportions of subjects with detectable DNA adduct levels were found in exposed individuals as compared with non-exposed subjects, but saturation may occur at high exposure. Furthermore, DNA adducts levels varied according to changes in exposure. Intra-individual variation during continuous exposure was low over a short period of time (weeks), but varied significantly when longer time periods (months) were investigated. Intra-individual variation is currently only partly explained by genetic polymorphisms in genes involved in PAH metabolism. DNA adducts measurements have three advantages over traditional exposure assessment: (1) they can smooth the extreme variability in exposure which is typical for environmental toxicants and may integrate exposure over longer periods of time (2) Biological monitoring of DNA adducts accounts for all exposure routes (3) DNA adduct may account for inter-individual differences in uptake, elimination, distribution, metabolism and repair amongst exposed individuals. There is a sufficiently large scientific basis to justify the application of DNA adduct measurements as biomarkers in exposure assessment. However, their use in risk assessment requires further investigation.

[Measurement and assessment of habitual physical activity in epidemiological studies]

Epidemiological study and laboratory evidence show that physical activity protects against the development and progression of chronic diseases. The physiological and biomechanical principles of the assessment of physical activity are ambiguous, energy expenditure calculations are complex, and numerous difficulties can be encountered in developing simple field techniques for assessing habitual activity. The greatest obstacle to validating field methods of assessing habitual physical activity or energy expenditure in humans has been the lack of adequate comparison criteria for the technique. Physical activity can be described as having four dimensions: duration (minutes/hours), frequency (time per week/per month), intensity (rate of energy expenditure) and circumstances or purpose of the activity. Methodology incorporating questionnaires/interviews are relatively inexpensive, and at present are the only methods feasible for large population studies. Specific activities can be identified in conjunction with frequency and duration. The procedure does not influence subjects' activities to the extent that can occur with observation or diary keeping. The limitations of questionnaires/interviews are the actual definitions and interpretations of the term "physical activity", despite the attempts of interviewers to provide a clear definition. Subjects do not necessarily recall their activities accurately; they may tend to overestimate time or intensity. A self-administered questionnaire must be suited to respondents' ages and education levels. Detailed questionnaires/interviews place a considerable burden on subjects.

[Development of a Hebrew questionnaire to be used in epidemiological studies to assess physical fitness--validation against sub maximal stress test and predicted VO2max]

BACKGROUND

The physical activity questionnaire is typically chosen for population studies because it is practical and does not interfere with the behavior of the surveyed individual. This instrument can be adapted for the particular studied population, and in terms of accuracy it is both reliable and valid.

AIM

To develop a valid and appropriate measure to assess physical fitness according to the level of physical activity throughout the day, and to estimate the relation between a subjective questionnaire measurement evaluating physical activity, to predicted VO2max, as an objective measure of physical fitness.

METHODS

Three hundred healthy subjects, 150 men and 150 women, aged 25-65 years old participated in this study. All subjects were routinely examined in the Sheba Medical Center Executive Screening Survey. They were asked to complete a self-administered questionnaire and report on the level of physical activity at work, the level of sports activity and the level of leisure time non-sport activity. The index calculated from the questionnaire was compared to the result from a sub-maximal exercise test, which they performed in The Executive Screening Survey, to composite a valid questionnaire to estimate physical fitness.

RESULTS

A high and statistically significant correlation (r = 0.64, P < 0.01) was found between the indexes of physical activity calculated from the questionnaire to the predicted VO2max, measured from the sub-maximal exercise test. The reliability of the questionnaire was examined by test-retest and a high and statistically significant correlation (r = 0.89, P < 0.01) was found between the first and the proceeding one month administration of the questionnaire. The final modal to predict VO2max included a total index of physical activity, gender, BMI, age and resting heart rate. Overall this model predicted 58% of the VO2max.

CONCLUSIONS

The self-administered questionnaire developed in this study has high construct validity and a significant correlation to predicted VO2max, with high sensitivity in both sexes and among active and non-active subjects. It is therefore an appropriate tool to be used in epidemiological studies.