A first step towards best practice recommendations for the design and statistical analyses of pragmatic clinical trials: A modified Delphi approach.

AIM: Pragmatic clinical trials (PCTs) are randomized trials implemented through routine clinical practice, where design parameters of traditional randomized controlled trials are modified to increase generalizability. However, this may introduce statistical challenges. We aimed to identify these challenges and discuss possible solutions leading to best practice recommendations for the design and analysis of PCTs. METHODS: A modified Delphi method was used to reach consensus among a panel of 11 experts in clinical trials and statistics. Statistical issues were identified in a focused literature review and aggregated with insights and possible solutions from experts collected through a series of survey iterations. Issues were ranked according to their importance. RESULTS: Twenty-seven articles were included and combined with experts' insight to generate a list of issues categorized into participants, recruiting sites, randomization, blinding and intervention, outcome (selection and measurement) and data analysis. Consensus was reached about the most important issues: risk of participants' attrition, heterogeneity of "usual care" across sites, absence of blinding, use of a subjective endpoint and data analysis aligned with the trial estimand. Potential issues should be anticipated and preferably be addressed in the trial protocol. The experts provided solutions regarding data collection and data analysis, which were considered of equal importance. DISCUSSION: A set of important statistical issues in PCTs was identified and approaches were suggested to anticipate and/or minimize these through data analysis. Any impact of choosing a pragmatic design feature should be gauged in the light of the trial estimand.

Cyclin-dependent Kinase 9 as a Potential Target for Anti-TNF-resistant Inflammatory Bowel Disease.

BACKGROUND & AIMS: Resistance to single cytokine blockade, namely anti-tumor necrosis factor (TNF) therapy, is a growing concern for patients with inflammatory bowel disease (IBD). The transcription factor T-bet is a critical regulator of intestinal homeostasis, is genetically linked to mucosal inflammation and controls the expression of multiples genes such as the pro-inflammatory cytokines interferon (IFN)-γ and TNF. Inhibiting T-bet may therefore offer a more attractive prospect for treating IBD but remains challenging to target therapeutically. In this study, we evaluate the effect of targeting the transactivation function of T-bet using inhibitors of P-TEFb (CDK9-cyclin T), a transcriptional elongation factor downstream of T-bet. METHODS: Using an adaptive immune-mediated colitis model, human colonic lymphocytes from patients with IBD and multiple large clinical datasets, we investigate the effect of cyclin-dependent kinase 9 (CDK9) inhibitors on cytokine production and gene expression in colonic CD4+ T cells and link these genetic modules to clinical response in patients with IBD. RESULTS: Systemic CDK9 inhibition led to histological improvement of immune-mediated colitis and was associated with targeted suppression of colonic CD4+ T cell-derived IFN-γ and IL-17A. In colonic lymphocytes from patients with IBD, CDK9 inhibition potently repressed genes responsible for pro-inflammatory signalling, and in particular genes regulated by T-bet. Remarkably, CDK9 inhibition targeted genes that were highly expressed in anti-TNF resistant IBD and that predicted non-response to anti-TNF therapy. CONCLUSION: Collectively, our findings reveal CDK9 as a potential target for anti-TNF-resistant IBD, which has the potential for rapid translation to the clinic.

The unintended consequences of clinical trials regulations.

Alex McMahon and colleagues critique the International Conference on Harmonisation (ICH) guidance on good clinical practice (GCP), arguing that it is having a disastrous effect on noncommerical randomized clinical trials in Europe.

Human Intestinal Barrier Function in Health and Disease.

The gastrointestinal tract consists of an enormous surface area that is optimized to efficiently absorb nutrients, water, and electrolytes from food. At the same time, it needs to provide a tight barrier against the ingress of harmful substances, and protect against a reaction to omnipresent harmless compounds. A dysfunctional intestinal barrier is associated with various diseases and disorders. In this review, the role of intestinal permeability in common disorders such as infections with intestinal pathogens, inflammatory bowel disease, irritable bowel syndrome, obesity, celiac disease, non-celiac gluten sensitivity, and food allergies will be discussed. In addition, the effect of the frequently prescribed drugs proton pump inhibitors and non-steroidal anti-inflammatory drugs on intestinal permeability, as well as commonly used methods to assess barrier function will be reviewed.

Organisational factors in relation to control of blood pressure: an observational study.

BACKGROUND: Studies show that 60-75% of treated patients with hypertension in general practice, still do not reach the recommended blood pressure targets of <150/90 mmHg. AIM: To investigate aspects of hypertension management in relation to sociodemographic variables, antihypertensive drug treatment, and organisational factors in primary care. DESIGN OF STUDY: Observational study over 3 years. SETTING: Eight general practices in Tayside, UK. METHOD: Participants were 560 randomly selected patients aged 40-79 years receiving treatment for hypertension. The outcome measurement was blood pressure control, expressed in binary form based on the British Hypertension Society audit standard of <150/90 mmHg. RESULTS: Of 536 eligible patients, 261 (49%) were defined as having inadequate blood pressure control at the end of the study period. No significant associations were discovered with sex, age, deprivation score and comorbidity. In those patients with inadequate control, 30% had no modifications to their drug treatment during the study period. Blood pressure control at the end of the study period was not associated with number of antihypertensive drugs taken or number of antihypertensive drug modifications. The mean number of clinician contacts was 11 (standard deviation = 8), and mean continuity in primary care was high, although this was not associated with improved blood pressure control. A higher proportion of hypertension-related consultations were associated with increased odds of having inadequate blood pressure control. CONCLUSION: Achieving adequate blood pressure control continues to represent a substantial health problem in a significant proportion of the hypertensive population. Patient, physician and organisational elements play a role in ensuring effective delivery of hypertension care in the community.

An increased B-type natriuretic peptide in the absence of a cardiac abnormality identifies those whose left ventricular mass will increase over time.

OBJECTIVES: The purpose of this study was to identify the relationship of B-type natriuretic peptide (BNP) with evolution of left ventricular mass (LVM) in optimally treated primary prevention patients. BACKGROUND: Patients who have an elevated BNP no cardiac abnormality on echocardiography are common and at increased risk of adverse events. One hypothesis is that an elevated BNP is an early sensitive indicator of who will develop future structural abnormalities such as left ventricular (LV) hypertrophy. METHODS: We identified optimally treated primary prevention patients with no cardiac abnormality at baseline. In particular, they had no myocardial ischemia, LV hypertrophy, LV dysfunction, or left atrial enlargement. They had a diverse range of plasma BNP levels and underwent cardiac magnetic resonance at baseline and 3 years later on a 3-T scanner. RESULTS: Fifty patients with a diverse range of BNP were studied (with BNP ≤ 10 pg/ml in 25 patients and >10 pg/ml in 25 patients). LVM increased (+4.7 ± 3.5 g) in 24 patients and decreased (-4.9 ± 2.8 g) in 26 patients (p < 0.01). Blood pressure by 24-h monitoring was virtually identical between those whose LVM increased (systolic blood pressure 122 ± 14 mm Hg) and those whose LVM decreased (systolic blood pressure 121 ± 11 mm Hg, p = 0.77). Plasma BNP was nearly 3 times higher in those whose LVM increased versus those in whom LVM decreased (21 ± 9.6 pg/ml vs. 7.9 ± 3.9 pg/ml, p < 0.01). The c-statistic for BNP was 0.88. CONCLUSIONS: In optimally treated primary prevention patients, plasma BNP levels are able to distinguish between those whose LVM will increase during the next 3 years versus those whose LVM will decrease during the next 3 years. This may explain why individuals with high BNP are at increased risk even if no cardiac abnormality can be detected initially.

How to ascertain drug safety in the context of benefit. Controversies and concerns.

There is great concern about clearly defining benefit and risk in the context of both drug development and clinical practice. In view of this pressure, the OMERACT Executive identified the need to bring together clinical trialists, pharmacoepidemiologists, clinicians, clinical epidemiologists, statistical experts, and regulatory representatives to discuss different approaches to define risk and perhaps improved ways to express it. Each attendee spoke on a given topic and the group was charged to consider the issue of risk in the context of formally posed questions. This article provides a summary of the presentations and outlines the discussions that followed.

Functional effects of genetic variants in the 11beta-hydroxylase (CYP11B1) gene.

OBJECTIVE: We previously described an association between the -344C/T 5'-untranslated region (UTR) polymorphism in the CYP11B2 (aldosterone synthase) gene and hypertension with a raised aldosterone to renin ratio (ARR); the same genetic variant is also associated with impaired adrenal 11beta-hydroxylase efficiency. The -344 polymorphism does not seem to be functional, so is likely to be in linkage with variants in CYP11B1 that determine the associated variation in 11beta-hydroxylase efficiency. We therefore aimed to determine whether there is an association between CYP11B1 variants and hypertension and/or an altered ARR. DESIGN AND MEASUREMENTS: We screened 160 subjects divided into four groups, normotensive controls, unselected hypertensive subjects, and hypertensive subjects with either a high (> or = 750) or low ARR (< or = 200), for variants in the coding region of CYP11B1 by single-stranded conformation polymorphism (SSCP) and direct sequencing. The effects of these variants on enzyme function were assessed by conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone (DOC) to corticosterone. RESULTS: Eight novel missense mutations were identified in the CYP11B1 gene that alter the encoded amino acids: R43Q, L83S, H125R, P135S, F139L, L158P, L186V and T196A. In each case they were heterozygous changes. However, no mutations were identified that could account for hypertension and/or a raised ARR. The variants L158P and L83S severely impaired enzyme function while R43Q, F139L, P135S and T196A enzymes resulted in product levels that were approximately 30-50% that of wild-type levels. The variant enzymes H125R and L186V resulted in substrate-specific alterations in enzyme function. H125R decreased conversion of 11-deoxycortisol to cortisol and L186V increased 11-deoxycortisol conversion. Neither had an effect on the conversion of DOC to corticosterone. CONCLUSION: No variants were identified in the coding region of CYP11B1 that could account for hypertension and/or a raised ARR. However, this in vitro study identifies the importance of these affected residues to enzyme function and will inform subsequent studies of structure-function relationships.