Novel loci affecting iron homeostasis and their effects in individuals at risk for hemochromatosis

Variation in body iron is associated with or causes diseases, including anaemia and iron overload. Here, we analyse genetic association data on biochemical markers of iron status from 11 European-population studies, with replication in eight additional cohorts (total up to 48,972 subjects). We find 11 genome-wide-significant (P<5 × 10−8) loci, some including known iron-related genes (​HFE, ​SLC40A1, ​TF, ​TFR2, ​TFRC, ​TMPRSS6) and others novel (​ABO, ​ARNTL, ​FADS2, ​NAT2, ​TEX14). SNPs at ​ARNTL, ​TF, and ​TFR2 affect iron markers in ​HFE C282Y homozygotes at risk for hemochromatosis. There is substantial overlap between our iron loci and loci affecting erythrocyte and lipid phenotypes. These results will facilitate investigation of the roles of iron in disease.

Five years of GWAS discovery

The past five years have seen many scientific and biological discoveries made through the experimental design of genome-wide association studies (GWASs). These studies were aimed at detecting variants at genomic loci that are associated with complex traits in the population and, in particular, at detecting associations between common single-nucleotide polymorphisms (SNPs) and common diseases such as heart disease, diabetes, auto-immune diseases, and psychiatric disorders. We start by giving a number of quotes from scientists and journalists about perceived problems with GWASs. We will then briefly give the history of GWASs and focus on the discoveries made through this experimental design, what those discoveries tell us and do not tell us about the genetics and biology of complex traits, and what immediate utility has come out of these studies. Rather than giving an exhaustive review of all reported findings for all diseases and other complex traits, we focus on the results for auto-immune diseases and metabolic diseases. We return to the perceived failure or disappointment about GWASs in the concluding section. © 2012 The American Society of Human Genetics.

Novel risk loci for rheumatoid arthritis in Han Chinese and congruence with risk variants in Europeans

Objective To investigate differences in genetic risk factors for rheumatoid arthritis (RA) in Han Chinese as compared with Europeans. Methods A genome-wide association study was conducted in China with 952 patients and 943 controls, and 32 variants were followed up in 2,132 patients and 2,553 controls. A transpopulation meta-analysis with results from a large European RA study was also performed to compare the genetic architecture across the 2 ethnic remote populations. Results Three non-major histocompatibility complex (non-MHC) loci were identified at the genome-wide significance level, the effect sizes of which were larger in anti-citrullinated protein antibody (ACPA)-positive patients than in ACPA-negative patients. These included 2 novel variants, rs12617656, located in an intron of DPP4 (odds ratio [OR] 1.56, P = 1.6 × 10 -21), and rs12379034, located in the coding region of CDK5RAP2 (OR 1.49, P = 1.1 × 10-16), as well as a variant at the known CCR6 locus, rs1854853 (OR 0.71, P = 6.5 × 10-15). The analysis of ACPA-positive patients versus ACPA-negative patients revealed that rs12617656 at the DPP4 locus showed a strong interaction effect with ACPAs (P = 5.3 × 10-18), and such an interaction was also observed for rs7748270 at the MHC locus (P = 5.9 × 10-8). The transpopulation meta-analysis showed genome-wide overlap and enrichment in association signals across the 2 populations, as confirmed by prediction analysis. Conclusion This study has expanded the list of alleles that confer risk of RA, provided new insight into the pathogenesis of RA, and added empirical evidence to the emerging polygenic nature of complex trait variation driven by common genetic variants. Copyright © 2014 by the American College of Rheumatology.

Risedronate in adults with osteogenesis imperfecta type I: Increased bone mineral density and decreased bone turnover, but high fracture rate persists

Summary Bisphosphonates can increase bone mineral density (BMD) in children with osteogenesis imperfecta (OI). In this study of adults with OI type I, risedronate increased BMD at lumbar spine (but not total hip) and decreased bone turnover. However, the fracture rate in these patients remained high. Introduction Intravenous bisphosphonates given to children with OI can increase BMD and reduce fracture incidence. Oral and/or intravenous bisphosphonates may have similar effects in adults with OI. We completed an observational study of the effect of risedronate in adults with OI type I. Methods Thirty-two adults (mean age, 39 years) with OI type I were treated with risedronate (total dose, 35 mg weekly) for 24 months. Primary outcome measures were BMD changes at lumbar spine (LS) and total hip (TH). Secondary outcome measures were fracture incidence, bone pain, and change in bone turnover markers (serum procollagen type I aminopropeptide (P1NP) and bone ALP). A meta-analysis of published studies of oral bisphosphonates in adults and children with OI was performed. Results Twenty-seven participants (ten males and seventeen females) completed the study. BMD increased at LS by 3.9% (0.815 vs. 0.846 g/cm 2, p=0.007; mean Z-score, -1.93 vs. -1.58, p=0.002), with no significant change at TH. P1NP fell by 37% (p=0.00041), with no significant change in bone ALP (p=0.15). Bone pain did not change significantly (p=0.6). Fracture incidence remained high, with 25 clinical fractures and 10 major fractures in fourteen participants (0.18 major fractures per person per year), with historical data of 0.12 fractures per person per year. The meta-analysis did not demonstrate a significant difference in fracture incidence in patients with OI treated with oral bisphosphonates. Conclusions Risedronate in adults with OI type I results in modest but significant increases in BMD at LS, and decreased bone turnover. However, this may be insufficient to make a clinically significant difference to fracture incidence.

Assessing the discipline : an analysis of Australian journalism review articles 2000-2010

In recent years, there has been much discussion about the quality of research published by Australian journalism academics, without much empirical evidence about what kind of work the field actually engages in. This paper attempts to map the relatively young field of Australian journalism research by presenting the results of a comprehensive meta-analysis of articles published in the Australian Journalism Review between 2000 and 2010. Our findings show that, contrary to evidence elsewhere, a gender balance exists in terms of absolute numbers of authors, although a "glass-ceiling effect" is still discernible. Queensland universities dominate the publications, and most studies employ qualitative rather than quantitative methods. Journalism education is the most popular topic, yet a large variety of topics are evident overall. Despite a heavy focus on Australia, and to a smaller extent New Zealand, the journal also displays a sizeable international touch.

The genetic association between personality and major depression or bipolar disorder. A polygenic score analysis using genome-wide association data

The relationship between major depressive disorder (MDD) and bipolar disorder (BD) remains controversial. Previous research has reported differences and similarities in risk factors for MDD and BD, such as predisposing personality traits. For example, high neuroticism is related to both disorders, whereas openness to experience is specific for BD. This study examined the genetic association between personality and MDD and BD by applying polygenic scores for neuroticism, extraversion, openness to experience, agreeableness and conscientiousness to both disorders. Polygenic scores reflect the weighted sum of multiple single-nucleotide polymorphism alleles associated with the trait for an individual and were based on a meta-analysis of genome-wide association studies for personality traits including 13,835 subjects. Polygenic scores were tested for MDD in the combined Genetic Association Information Network (GAIN-MDD) and MDD2000+ samples (N=8921) and for BD in the combined Systematic Treatment Enhancement Program for Bipolar Disorder and Wellcome Trust Case-Control Consortium samples (N=6329) using logistic regression analyses. At the phenotypic level, personality dimensions were associated with MDD and BD. Polygenic neuroticism scores were significantly positively associated with MDD, whereas polygenic extraversion scores were significantly positively associated with BD. The explained variance of MDD and BD, approximately 0.1%, was highly comparable to the variance explained by the polygenic personality scores in the corresponding personality traits themselves (between 0.1 and 0.4%). This indicates that the proportions of variance explained in mood disorders are at the upper limit of what could have been expected. This study suggests shared genetic risk factors for neuroticism and MDD on the one hand and for extraversion and BD on the other.

The role of adiposity in cardiometabolic traits:a Mendelian randomization analysis

The association between adiposity and cardiometabolic traits is well known from epidemiological studies. Whilst the causal relationship is clear for some of these traits, for others it is not. We aimed to determine whether adiposity is causally related to various cardiometabolic traits using the Mendelian randomization approach.

How individual participant data meta-analyses have influenced trial design, conduct, and analysis

OBJECTIVES: To demonstrate how individual participant data (IPD) meta-analyses have impacted directly on the design and conduct of trials and highlight other advantages IPD might offer.

STUDY DESIGN AND SETTING: Potential examples of the impact of IPD meta-analyses on trials were identified at an international workshop, attended by individuals with experience in the conduct of IPD meta-analyses and knowledge of trials in their respective clinical areas. Experts in the field who did not attend were asked to provide any further examples. We then examined relevant trial protocols, publications, and Web sites to verify the impacts of the IPD meta-analyses. A subgroup of workshop attendees sought further examples and identified other aspects of trial design and conduct that may inform IPD meta-analyses.

RESULTS: We identified 52 examples of IPD meta-analyses thought to have had a direct impact on the design or conduct of trials. After screening relevant trial protocols and publications, we identified 28 instances where IPD meta-analyses had clearly impacted on trials. They have influenced the selection of comparators and participants, sample size calculations, analysis and interpretation of subsequent trials, and the conduct and analysis of ongoing trials, sometimes in ways that would not possible with systematic reviews of aggregate data. We identified additional potential ways that IPD meta-analyses could be used to influence trials.

CONCLUSIONS: IPD meta-analysis could be better used to inform the design, conduct, analysis, and interpretation of trials.

La influencia del tabaquismo en la actividad de la artritis reumatoide y progresión de erosiones articulares: Una revision sistemática y meta-análisis.

Objetivos: Sintetizar a través de una revisión sistemática y un meta-análisis los datos disponibles en la literatura sobre el tabaquismo y la artritis reumatoide (AR), teniendo en cuenta su efecto sobre la actividad de la enfermedad y la progresión radiográfica de erosiones. Métodos: Se realizo una revisión sistemática usando las guías PRISMA en las bases de datos de MEDLINE hasta Julio 2013. Los términos de búsqueda incluían tabaquismo, tabaco, humo, cigarrillo y artritis reumatoide. Se consideró incluir cualquier tipo de de estudio realizado con casos de AR, definida por criterios aceptados de clasificación y que incluyeran información que indicara la relación entre tabaquismo y DAS28 o por lo menos un puntaje de erosión. Un tamaño común del efecto se calculó usando un modelo de efectos aleatorios. Resultados: De un total de 2215 artículos obtenidos, 45 cumplían los criterios de inclusión. De estos 27 fueron incluidos en el meta-análisis. Doce contenían información sobre la relación con DAS28 y 17 acerca del efecto en progresión radiográfica. Se encontró una asociación negativa entre tabaquismo y respuesta EULAR (OR: 0.72; 95% CI:0.57-0.91; p=0.005) y Remisión definida por DAS28 (OR:0.78; 95%CI:0.63-0.96; p=0.023). EL puntaje de DAS28 era significativamente mas alto en fumadores actuales (MD:0.29; 95% CI:0.12-0.44;p<0.001) de igual forma el puntaje de erosión era mas alto en fumadores actuales (SMD:0.38;95% CI:0.04-0.72; p=0.028). Los datos para progresión de erosiones eran ambiguos (OR: 0.93; 95% CI: 0.72-1,2; p=0.59). Un análisis de sensibilidad confirmo que los resultados no eran sensibles a la restricción de los datos incluidos. El sesgo de publicación fue mínimo. Conclusiones: El tabaquismo se encuentra asociado a una respuesta disminuida a tratamiento (definido por criterios EULAR) y un puntaje de erosión, pero no se logro demostrar una mayor progresión radiográfica en los pacientes fumadores.

The effects of excluding patients from the analysis in randomised controlled trials: meta-epidemiological study

OBJECTIVE: To examine whether excluding patients from the analysis of randomised trials are associated with biased estimates of treatment effects and higher heterogeneity between trials. DESIGN: Meta-epidemiological study based on a collection of meta-analyses of randomised trials. DATA SOURCES: 14 meta-analyses including 167 trials that compared therapeutic interventions with placebo or non-intervention control in patients with osteoarthritis of the hip or knee and used patient reported pain as an outcome. METHODS: Effect sizes were calculated from differences in means of pain intensity between groups at the end of follow-up, divided by the pooled standard deviation. Trials were combined by using random effects meta-analysis. Estimates of treatment effects were compared between trials with and trials without exclusions from the analysis, and the impact of restricting meta-analyses to trials without exclusions was assessed. RESULTS: 39 trials (23%) had included all patients in the analysis. In 128 trials (77%) some patients were excluded from the analysis. Effect sizes from trials with exclusions tended to be more beneficial than those from trials without exclusions (difference -0.13, 95% confidence interval -0.29 to 0.04). However, estimates of bias between individual meta-analyses varied considerably (tau(2)=0.07). Tests of interaction between exclusions from the analysis and estimates of treatment effects were positive in five meta-analyses. Stratified analyses indicated that differences in effect sizes between trials with and trials without exclusions were more pronounced in meta-analyses with high between trial heterogeneity, in meta-analyses with large estimated treatment benefits, and in meta-analyses of complementary medicine. Restriction of meta-analyses to trials without exclusions resulted in smaller estimated treatment benefits, larger P values, and considerable decreases in between trial heterogeneity. CONCLUSION: Excluding patients from the analysis in randomised trials often results in biased estimates of treatment effects, but the extent and direction of bias is unpredictable. Results from intention to treat analyses should always be described in reports of randomised trials. In systematic reviews, the influence of exclusions from the analysis on estimated treatment effects should routinely be assessed.

The evidence from systematic reviews and meta-analyses published in orthodontic literature. Where do we stand?

AIM To analyse meta-analyses included in systematic reviews (SRs) published in leading orthodontic journals and the Cochrane Database of Systematic Reviews (CDSR) focusing on orthodontic literature and to assess the quality of the existing evidence. MATERIALS AND METHODS Electronic searching was undertaken to identify SRs published in five major orthodontic journals and the CDSR between January 2000 and June 2014. Quality assessment of the overall body of evidence from meta-analyses was conducted using the Grading of Recommendations Assessment, Development and Evaluation working group (GRADE) tool. RESULTS One hundred and fifty-seven SRs were identified; meta-analysis was present in 43 of these (27.4 per cent). The highest proportion of SRs that included a meta-analysis was found in Orthodontics and Craniofacial Research (6/13; 46.1 per cent), followed by the CDSR (12/33; 36.4 per cent) and the American Journal of Orthodontics and Dentofacial Orthopaedics (15/44; 34.1 per cent). Class II treatment was the most commonly addressed topic within SRs in orthodontics (n = 18/157; 11.5 per cent). The number of trials combined to produce a summary estimate was small for most meta-analyses with a median of 4 (range: 2-52). Only 21 per cent (n = 9) of included meta-analyses were considered to have a high/moderate quality of evidence according to GRADE, while the majority were of low or very low quality (n = 34; 79.0 per cent). CONCLUSIONS Overall, approximately one quarter of orthodontic SRs included quantitative synthesis, with a median of four trials per meta-analysis. The overall quality of evidence from the selected orthodontic SRs was predominantly low to very low indicating the relative lack of high quality of evidence from SRs to inform clinical practice guidelines.

Immune response to hepatitis B vaccination in drug using populations: A systematic review and meta-regression analysis

Hepatitis B virus (HBV) is a significant cause of liver diseases and related complications worldwide. Both injecting and non-injecting drug users are at increased risk of contracting HBV infection. Scientific evidence suggests that drug users have subnormal response to HBV vaccination and the seroprotection rates are lower than that in the general population; potentially due to vaccine factors, host factors, or both. The purpose of this systematic review is to examine the rates of seroprotection following HBV vaccination in drug using populations and to conduct a meta-analysis to identify the factors associated with varying seroprotection rates. Seroprotection is defined as developing an anti-HBs antibody level of ≥ 10 mIU/ml after receiving the HBV vaccine. Original research articles were searched using online databases and reference lists of shortlisted articles. HBV vaccine intervention studies reporting seroprotection rates in drug users and published in English language during or after 1989 were eligible. Out of 235 citations reviewed, 11 studies were included in this review. The reported seroprotection rates ranged from 54.5 – 97.1%. Combination vaccine (HAV and HBV) (Risk ratio 12.91, 95% CI 2.98-55.86, p = 0.003), measurement of anti-HBs with microparticle immunoassay (Risk ratio 3.46, 95% CI 1.11-10.81, p = 0.035) and anti-HBs antibody measurement at 2 months after the last HBV vaccine dose (RR 4.11, 95% CI 1.55-10.89, p = 0.009) were significantly associated with higher seroprotection rates. Although statistically nonsignificant, the variables mean age>30 years, higher prevalence of anti-HBc antibody and anti-HIV antibody in the sample population, and current drug use (not in drug rehabilitation treatment) were strongly associated with decreased seroprotection rates. Proportion of injecting drug users, vaccine dose and accelerated vaccine schedule were not predictors of heterogeneity across studies. Studies examined in this review were significantly heterogeneous (Q = 180.850, p = 0.000) and factors identified should be considered when comparing immune response across studies. The combination vaccine showed promising results; however, its effectiveness compared to standard HBV vaccine needs to be examined systematically. Immune response in DUs can possibly be improved by the use of bivalent vaccines, booster doses, and improving vaccine completion rates through integrated public programs and incentives.^

Safety and Efficacy of Oral Fexofenadine in Children with Seasonal Allergic Rhinitis - a Pooled Analysis of Three Studies

Allergic rhinitis is one of the most common clinical conditions in children; however, data regarding the safety of antihistamines in children with seasonal allergic rhinitis are limiting. To evaluate the safety and efficacy of fexofenadine in children with seasonal allergic rhinitis, data were pooled from three, double-blind, randomized, placebo-controlled, parallel-group, 2-week trials in children (6-11 year) with seasonal allergic rhinitis. All studies assessed fexofenadine HCl 30 mg b.i.d.; two studies included fexofenadine HCl at 15 and 60 mg b.i.d. Patients (and investigators) reported any adverse events during the trial. Physical examinations, including measurements of vital signs and laboratory tests, were performed. Efficacy assessments (total symptom score and individual symptom scores) were evaluated. Exposure to fexofenadine HCl 30 mg b.i.d. and to any fexofenadine dose exceeded 10,000 and 17,000 patient days, respectively. Incidences of adverse events, and discontinuations because of adverse events, were low and similar across treatment groups. In the placebo group, 24.4% of subjects reported adverse events compared with 24.1% for fexofenadine HCl 30 mg b.i.d., and 28.4% for all fexofenadine-treated groups. The most common adverse event overall was headache (4.3% placebo; 5.8% fexofenadine HCl 30 mg b.i.d.; and 7.2% any fexofenadine doses). Treatment-related adverse events were similar across treatment groups with no sedative effects. Fexofenadine HCl 30 mg b.i.d. was significantly superior to placebo in reducing the total symptom score and all individual seasonal allergic rhinitis symptoms, including nasal congestion (p < 0.05). Fexofenadine, at doses of up to 60 mg b.i.d., is safe and non-sedating, and fexofenadine HCl 30 mg b.i.d. effectively reduces all seasonal allergic rhinitis symptoms in children aged 6-11 years.

Difference-based meta-analytic procedures for between-participant and/or within-participant designs : a tutorial review for sports and exercise scientists

The aim of this paper is to provide a contemporary summary of statistical and non-statistical meta-analytic procedures that have relevance to the type of experimental designs often used by sport scientists when examining differences/change in dependent measure(s) as a result of one or more independent manipulation(s). Using worked examples from studies on observational learning in the motor behaviour literature, we adopt a random effects model and give a detailed explanation of the statistical procedures for the three types of raw score difference-based analyses applicable to between-participant, within-participant, and mixed-participant designs. Major merits and concerns associated with these quantitative procedures are identified and agreed methods are reported for minimizing biased outcomes, such as those for dealing with multiple dependent measures from single studies, design variation across studies, different metrics (i.e. raw scores and difference scores), and variations in sample size. To complement the worked examples, we summarize the general considerations required when conducting and reporting a meta-analysis, including how to deal with publication bias, what information to present regarding the primary studies, and approaches for dealing with outliers. By bringing together these statistical and non-statistical meta-analytic procedures, we provide the tools required to clarify understanding of key concepts and principles.