Level of evidence for promising subgroup findings: The case of trends and multiple subgroups

Subgroup analyses are an essential part of fully understanding the complete results from confirmatory clinical trials. However, they come with substantial methodological challenges. In case no statistically significant overall treatment effect is found in a clinical trial, this does not necessarily indicate that no patients will benefit from treatment. Subgroup analyses could be conducted to investigate whether a treatment might still be beneficial for particular subgroups of patients. Assessment of the level of evidence associated with such subgroup findings is primordial as it may form the basis for performing a new clinical trial or even drawing the conclusion that a specific patient group could benefit from a new therapy. Previous research addressed the overall type I error and the power associated with a single subgroup finding for continuous outcomes and suitable replication strategies. The current study aims at investigating two scenarios as part of a nonconfirmatory strategy in a trial with dichotomous outcomes: (a) when a covariate of interest is represented by ordered subgroups, eg, in case of biomarkers, and thus, a trend can be studied that may reflect an underlying mechanism, and (b) when multiple covariates, and thus multiple subgroups, are investigated at the same time. Based on simulation studies, this paper assesses the credibility of subgroup findings in overall nonsignificant trials and provides practical recommendations for evaluating the strength of evidence of subgroup findings in these settings.

Pharyngeal electrical stimulation for early decannulation in tracheotomised patients with neurogenic dysphagia after stroke (PHAST-TRAC): a prospective, single-blinded, randomised trial

BACKGROUND

Dysphagia after stroke is common, especially in severely affected patients who have had a tracheotomy. In a pilot trial, pharyngeal electrical stimulation (PES) improved swallowing function in this group of patients. We aimed to replicate and extend this single-centre experience.

METHODS

We did a prospective, single-blind, randomised controlled trial across nine sites (seven acute care hospitals, two rehabilitation facilities) in Germany, Austria, and Italy. Patients with recent stroke who required tracheotomy were randomly assigned to receive 3 days of either PES or sham treatment (1:1). All patients had the stimulation catheter inserted; sham treatment was applied by connecting the PES base station to a simulator box instead of the catheter. Randomisation was done via a computerised interactive system (stratified by site) in blocks of four patients per site. Patients and investigators applying PES were not masked. The primary endpoint was assessed by a separate investigator at each site who was masked to treatment assignment. The primary outcome was readiness for decannulation 24-72 h after treatment, assessed using fibreoptic endoscopic evaluation of swallowing and based on a standardised protocol, including absence of massive pooling of saliva, presence of one or more spontaneous swallows, and presence of at least minimum laryngeal sensation. We planned a sequential statistical analysis of superiority for the primary endpoint. Interim analyses were to be done after primary outcome data were available for 50 patients (futility), 70 patients, and every additional ten patients thereafter, up to 140 patients. Analysis was by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN18137204.

FINDINGS

From May 29, 2015, to July 5, 2017, of 81 patients assessed, 69 patients from nine sites were randomly assigned to receive PES (n=35) or sham (n=34) treatment. Median onset to randomisation time was 28 days (IQR 19-41; PES 28 [20-49]; sham 28 [18-40]). The Independent Data and Safety Monitoring Board recommended that the trial was stopped early for efficacy after 70 patients had been recruited and primary endpoint data for 69 patients were available. This decision was approved by the steering committee. More patients were ready for decannulation in the PES group (17 [49%] of 35 patients) than in the sham group (three [9%] of 34 patients; odds ratio [OR] 7·00 [95% CI 2·41-19·88]; p=0·0008). Adverse events were reported in 24 (69%) patients in the PES group and 24 (71%) patients in the sham group. The number of patients with at least one serious adverse event did not differ between the groups (ten [29%] patients in the PES group vs eight [23%] patients in the sham group; OR 1·30 [0·44-3·83]; p=0·7851). Seven (20%) patients in the PES group and three (9%) patients in the sham group died during the study period (OR 2·58 [0·61-10·97]; p=0·3059). None of the deaths or serious adverse events were judged to be related to PES.

INTERPRETATION

In patients with stroke and subsequent tracheotomy, PES increased the proportion of patients who were ready for decannulation in this study population, many of whom received PES within a month of their stroke. Future trials should confirm whether PES is beneficial in tracheotomised patients who receive stimulation similarly early after stroke and explore its effects in other cohorts.

FUNDING

Phagenesis Ltd.

Comparison of nuisance parameters in pediatric versus adult randomized trials: a meta-epidemiologic empirical evaluation

Background

We wished to compare the nuisance parameters of pediatric vs. adult randomized-trials (RCTs) and determine if the latter can be used in sample size computations of the former.

Methods

In this meta-epidemiologic empirical evaluation we examined meta-analyses from the Cochrane Database of Systematic-Reviews, with at least one pediatric-RCT and at least one adult-RCT. Within each meta-analysis of binary efficacy-outcomes, we calculated the pooled-control-group event-rate (CER) across separately all pediatric and adult-trials, using random-effect models and subsequently calculated the control-group event-rate risk-ratio (CER-RR) of the pooled-pediatric-CERs vs. adult-CERs. Within each meta-analysis with continuous outcomes we calculated the pooled-control-group effect standard deviation (CE-SD) across separately all pediatric and adult-trials and subsequently calculated the CE-SD-ratio of the pooled-pediatric-CE-SDs vs. adult-CE-SDs. We then calculated across all meta-analyses the pooled-CER-RRs and pooled-CE-SD-ratios (primary endpoints) and the pooled-magnitude of effect-sizes of CER-RRs and CE-SD-ratios using REMs. A ratio < 1 indicates that pediatric trials have smaller nuisance parameters than adult trials.

Results

We analyzed 208 meta-analyses (135 for binary-outcomes, 73 for continuous-outcomes). For binary outcomes, pediatric-RCTs had on average 10% smaller CERs than adult-RCTs (summary-CE-RR: 0.90; 95% CI: 0.83, 0.98). For mortality outcomes the summary-CE-RR was 0.48 (95% CIs: 0.31, 0.74). For continuous outcomes, pediatric-RCTs had on average 26% smaller CE-SDs than adult-RCTs (summary-CE-SD-ratio: 0.74).

Conclusions

Clinically relevant differences in nuisance parameters between pediatric and adult trials were detected. These differences have implications for design of future studies. Extrapolation of nuisance parameters for sample-sizes calculations from adult-trials to pediatric-trials should be cautiously done.

Electromagnetic-guided placement of nasoduodenal feeding tubes versus endoscopic placement: a randomized, multicenter trial

BACKGROUND AND AIMS

Electromagnetic-guided placement (EMP) of a nasoduodenal feeding tube by trained nurses is an attractive alternative to EGD-guided placement (EGDP). We aimed to compare EMP and EGDP in outpatients, ward patients, and critically ill patients with normal upper GI anatomy.

METHODS

In 3 centers with no prior experience in EMP, patients were randomized to placement of a single-lumen nasoduodenal feeding tube either with EGDP or EMP. The primary endpoint was post-pyloric position of the tube on abdominal radiography. Patients were followed for 10 days to assess patency and adverse events. The analyses were performed according to the intention-to-treat principle.

RESULTS

In total, 160 patients were randomized to EGDP (N = 76) or EMP (N = 84). Three patients withdrew informed consent, and no abdominal radiography was performed in 2 patients. Thus, 155 patients (59 intensive care unit, 38%) were included in the analyses. Rates of post-pyloric tube position between EGDP and EMP were comparable (79% vs 82%, odds ratio 1.16; 90% confidence interval, 0.58-2.38; P = .72). Adverse events were observed in 4 patients after EMP (hypoxia, GI blood loss, atrial fibrillation, abdominal pain) and in 4 after EGDP (epistaxis N = 2, GI blood loss, hypoxia). Costs of tube placements were lower for EMP compared with EGDP: $519.09 versus $622.49, respectively (P = .04).

CONCLUSIONS

Success rates and safety of EMP and EGDP in patients with normal upper GI anatomy were comparable. Lower costs and potential logistic advantages may drive centers to adopt EMP as their new standard of care. (Clinical trial registration number: NTR4286.).

Dynamic borrowing through empirical power priors that control type I error

In order for historical data to be considered for inclusion in the design and analysis of clinical trials, prospective rules are essential. Incorporation of historical data may be of particular interest in the case of small populations where available data is scarce and heterogeneity is not as well understood, and thus conventional methods for evidence synthesis might fall short. The concept of power priors can be particularly useful for borrowing evidence from a single historical study. Power priors employ a parameter <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi> <mml:mo>∈</mml:mo> <mml:mo>[</mml:mo> <mml:mn>0</mml:mn> <mml:mo>,</mml:mo> <mml:mn>1</mml:mn> <mml:mo>]</mml:mo></mml:math> that quantifies the heterogeneity between the historical study and the new study. However, the possibility of borrowing data from a historical trial will usually be associated with an inflation of the type I error. We suggest a new, simple method of estimating the power parameter suitable for the case when only one historical dataset is available. The method is based on predictive distributions and parameterized in such a way that the type I error can be controlled by calibrating to the degree of similarity between the new and historical data. The method is demonstrated for normal responses in a one or two group setting. Generalization to other models is straightforward.

Positive predictive value of ELISpot in BAL and pleural fluid from patients with suspected pulmonary tuberculosis

BACKGROUND

The aim of this study was to evaluate the positive predictive value (PPV) of ELISpot in bronchoalveolar lavage (BAL) and pleural fluid for the diagnosis of active tuberculosis (TB) in real-life clinical practice, together with the added value of a cut-off >1.0 for the ratio between the extra-sanguineous and systemic interferon-gamma responses in positive samples.

METHODS

A retrospective, single-centre study was performed. Patients with positive ELISpot in BAL and pleural fluid were included.

RESULTS

The PPV for TB in patients with positive ELISpot in BAL (n = 40) was 64.9%, which increased to 82.6% for the ESAT-6 panel and 71.4% for the CFP-10 panel after the introduction of a cut-off >1.0 for the ratio between the BAL and blood interferon-gamma responses. In patients with positive ELISpot in pleural fluid (n = 16), the PPV for TB was 85.7%, which increased to 91.7% for the ESAT-6 panel and 92.3% for the CFP-10 panel after the introduction of a cut-off >1.0 for the ratio between the pleural fluid and blood interferon-gamma responses.

CONCLUSIONS

This report describes the PPV of ELISpot in BAL and pleural fluid for the diagnosis of active TB in real-life clinical practice. The results indicate the possibility of an increase of the PPV using a cut-off >1.0 for the ratio between the extra-sanguineous and systemic interferon-gamma responses. Further studies are needed to underline this ratio-approach and to evaluate the full diagnostic accuracy of ELISpot in extra-sanguineous fluids like BAL and pleural fluid.

Sequential designs with small samples: Evaluation and recommendations for normal responses

Sequential monitoring is a well-known methodology for the design and analysis of clinical trials. Driven by the lower expected sample size, recent guidelines and published research suggest the use of sequential methods for the conduct of clinical trials in rare diseases. However, the vast majority of the developed and most commonly used sequential methods relies on asymptotic assumptions concerning the distribution of the test statistics. It is not uncommon for trials in (very) rare diseases to be conducted with only a few decades of patients and the use of sequential methods that rely on large-sample approximations could inflate the type I error probability. Additionally, the setting of a rare disease could make the traditional paradigm of designing a clinical trial (deciding on the sample size given type I and II errors and anticipated effect size) irrelevant. One could think of the situation where the number of patients available has a maximum and this should be utilized in the most efficient way. In this work, we evaluate the operational characteristics of sequential designs in the setting of very small to moderate sample sizes with normally distributed outcomes and demonstrate the necessity of simple corrections of the critical boundaries. We also suggest a method for deciding on an optimal sequential design given a maximum sample size and some (data driven or based on expert opinion) prior belief on the treatment effect.

Subgroup analyses in confirmatory clinical trials: time to be specific about their purposes

Background

It is well recognized that treatment effects may not be homogeneous across the study population. Subgroup analyses constitute a fundamental step in the assessment of evidence from confirmatory (Phase III) clinical trials, where conclusions for the overall study population might not hold. Subgroup analyses can have different and distinct purposes, requiring specific design and analysis solutions. It is relevant to evaluate methodological developments in subgroup analyses against these purposes to guide health care professionals and regulators as well as to identify gaps in current methodology.

Methods

We defined four purposes for subgroup analyses: (1) Investigate the consistency of treatment effects across subgroups of clinical importance, (2) Explore the treatment effect across different subgroups within an overall non-significant trial, (3) Evaluate safety profiles limited to one or a few subgroup(s), (4) Establish efficacy in the targeted subgroup when included in a confirmatory testing strategy of a single trial. We reviewed the methodology in line with this “purpose-based” framework. The review covered papers published between January 2005 and April 2015 and aimed to classify them in none, one or more of the aforementioned purposes.

Results

In total 1857 potentially eligible papers were identified. Forty-eight papers were selected and 20 additional relevant papers were identified from their references, leading to 68 papers in total. Nineteen were dedicated to purpose 1, 16 to purpose 4, one to purpose 2 and none to purpose 3. Seven papers were dedicated to more than one purpose, the 25 remaining could not be classified unambiguously. Purposes of the methods were often not specifically indicated, methods for subgroup analysis for safety purposes were almost absent and a multitude of diverse methods were developed for purpose (1).

Conclusions

It is important that researchers developing methodology for subgroup analysis explicitly clarify the objectives of their methods in terms that can be understood from a patient’s, health care provider’s and/or regulator’s perspective. A clear operational definition for consistency of treatment effects across subgroups is lacking, but is needed to improve the usability of subgroup analyses in this setting. Finally, methods to particularly explore benefit-risk systematically across subgroups need more research.

Electronic supplementary material

The online version of this article (doi:10.1186/s12874-016-0122-6) contains supplementary material, which is available to authorized users.

Results of ENHANCED Implantable Cardioverter Defibrillator Programming to Reduce Therapies and Improve Quality of Life (from the ENHANCED-ICD Study)

Novel implantable cardioverter defibrillator (ICD) discrimination algorithms and programming strategies have significantly reduced the incidence of inappropriate shocks, but there are still gains to be made with respect to reducing appropriate but unnecessary antitachycardia pacing (ATP) and shocks. We examined whether programming a number of intervals to detect (NID) of 60/80 for ventricular tachyarrhythmia (VT)/ventricular fibrillation (VF) detection was safe and the impact of this strategy on (1) adverse events related to ICD shocks and syncopal events; (2) ATPs/shocks; and (3) patient-reported outcomes. The "ENHANCED Implantable Cardioverter Defibrillator programming to reduce therapies and improve quality of life" study (ENHANCED-ICD study) was a prospective, safety-monitoring study enrolling 60 primary and secondary prevention patients at the University Medical Center Utrecht. Patients implanted with any type of ICD with SmartShock technology and aged 18 to 80 years were eligible to participate. In all patients, a prolonged NID 60/80 was programmed. The cycle length for VT/fast VT/VF was 360/330/240 ms, respectively. Programming a NID 60/80 proved safe for ICD patients. Because of the new programming strategy, unnecessary ICD therapy was prevented in 10% of ENHANCED-ICD patients during a median follow-up period of 1.3 years. With respect to patient-reported outcomes, levels of distress were highest and perceived health status lowest at the time of implantation, which both gradually improved during follow-up. In conclusion, the ENHANCED-ICD study demonstrates that programming a NID 60/80 for VT/VF detection is safe for ICD patients and does not negatively impact their quality of life.

The need to balance merits and limitations from different disciplines when considering the stepped wedge cluster randomized trial design

Background

Various papers have addressed pros and cons of the stepped wedge cluster randomized trial design (SWD). However, some issues have not or only limitedly been addressed. Our aim was to provide a comprehensive overview of all merits and limitations of the SWD to assist researchers, reviewers and medical ethics committees when deciding on the appropriateness of the SWD for a particular study.

Methods

We performed an initial search to identify articles with a methodological focus on the SWD, and categorized and discussed all reported advantages and disadvantages of the SWD. Additional aspects were identified during multidisciplinary meetings in which ethicists, biostatisticians, clinical epidemiologists and health economists participated. All aspects of the SWD were compared to the parallel group cluster randomized design. We categorized the merits and limitations of the SWD to distinct phases in the design and conduct of such studies, highlighting that their impact may vary depending on the context of the study or that benefits may be offset by drawbacks across study phases. Furthermore, a real-life illustration is provided.

Results

New aspects are identified within all disciplines. Examples of newly identified aspects of an SWD are: the possibility to measure a treatment effect in each cluster to examine the (in)consistency in effects across clusters, the detrimental effect of lower than expected inclusion rates, deviation from the ordinary informed consent process and the question whether studies using the SWD are likely to have sufficient social value. Discussions are provided on e.g. clinical equipoise, social value, health economical decision making, number of study arms, and interim analyses.

Conclusions

Deciding on the use of the SWD involves aspects and considerations from different disciplines not all of which have been discussed before. Pros and cons of this design should be balanced in comparison to other feasible design options as to choose the optimal design for a particular intervention study.

An Application of Sequential Meta-Analysis to Gene Expression Studies

Most of the discoveries from gene expression data are driven by a study claiming an optimal subset of genes that play a key role in a specific disease. Meta-analysis of the available datasets can help in getting concordant results so that a real-life application may be more successful. Sequential meta-analysis (SMA) is an approach for combining studies in chronological order while preserving the type I error and pre-specifying the statistical power to detect a given effect size. We focus on the application of SMA to find gene expression signatures across experiments in acute myeloid leukemia. SMA of seven raw datasets is used to evaluate whether the accumulated samples show enough evidence or more experiments should be initiated. We found 313 differentially expressed genes, based on the cumulative information of the experiments. SMA offers an alternative to existing methods in generating a gene list by evaluating the adequacy of the cumulative information.

The Effect of Online Hemodiafiltration on Infections: Results from the CONvective TRAnsport STudy

BACKGROUND

Hemodialysis (HD) patients have a high risk of infections. The uremic milieu has a negative impact on several immune responses. Online hemodiafiltration (HDF) may reduce the risk of infections by ameliorating the uremic milieu through enhanced clearance of middle molecules. Since there are few data on infectious outcomes in HDF, we compared the effects of HDF with low-flux HD on the incidence and type of infections.

PATIENTS AND METHODS

We used data of the 714 HD patients (age 64 ±14, 62% men, 25% Diabetes Mellitus, 7% catheters) participating in the CONvective TRAnsport STudy (CONTRAST), a randomized controlled trial evaluating the effect of HDF as compared to low-flux HD. The events were adjudicated by an independent event committee. The risk of infectious events was compared with Cox regression for repeated events and Cox proportional hazard models. The distributions of types of infection were compared between the groups.

RESULTS

Thirty one percent of the patients suffered from one or more infections leading to hospitalization during the study (median follow-up 1.96 years). The risk for infections during the entire follow-up did not differ significantly between treatment arms (HDF 198 and HD 169 infections in 800 and 798 person-years respectively, hazard ratio HDF vs. HD 1.09 (0.88-1.34), P = 0.42. No difference was found in the occurrence of the first infectious event (either fatal, non-fatal or type specific). Of all infections, respiratory infections (25% in HDF, 28% in HD) were most common, followed by skin/musculoskeletal infections (21% in HDF, 13% in HD).

CONCLUSIONS

HDF as compared to HD did not result in a reduced risk of infections, larger studies are needed to confirm our findings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00205556.

Abstract 510: Effect of Repetitive Intra-Arterial Infusion of Bone Marrow Mononuclear Cells in Patients With No-Option Limb Ischemia: The Randomized, Double-Blind, Placebo-Controlled JUVENTAS Trial

Background: Patients with severe limb ischemia may not be eligible for conventional therapeutic interventions. Pioneering clinical trials suggest that bone marrow-derived cell therapy enhances neovascularization, improves tissue perfusion, and prevents amputation. The objective of this trial was to determine whether repetitive intra-arterial infusion of bone marrow mononuclear cells (BMMNCs) in patients with severe, nonrevascularizable limb ischemia can prevent major amputation.

Methods and Results: The Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial is a randomized, double-blind, placebo-controlled clinical trial in 160 patients with severe, nonrevascularizable limb ischemia. Patients were randomly assigned to repetitive (3 times; 3-week interval) intraarterial infusion of BMMNC or placebo. No significant differences were observed for the primary outcome, ie, major amputation at 6 months, with major amputation rates of 19% in the BMMNC versus 13% in the placebo group (relative risk, 1.46; 95% confidence interval, 0.62-3.42). The safety outcome (all-cause mortality, occurrence of malignancy, or hospitalization due to infection) was not significantly different between the groups (relative risk, 1.46; 95% confidence interval, 0.63-3.38), neither was all-cause mortality at 6 months with 5% versus 6% (relative risk, 0.78; 95% confidence interval, 0.22-2.80). Secondary outcomes quality of life, rest pain, ankle-brachial index, and transcutaneous oxygen pressure improved during follow-up, but there were no significant differences between the groups.

Conclusions: Repetitive intra-arterial infusion of autologous BMMNCs into the common femoral artery did not reduce major amputation rates in patients with severe, nonrevascularizable limb ischemia in comparison with placebo. The general improvement in secondary outcomes during follow-up in both the BMMNC and the placebo group, as well, underlines the essential role for placebo-controlled design of future trials.

Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00371371.

Effect of repetitive intra-arterial infusion of bone marrow mononuclear cells in patients with no-option limb ischemia: the randomized, double-blind, placebo-controlled Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial

BACKGROUND

Patients with severe limb ischemia may not be eligible for conventional therapeutic interventions. Pioneering clinical trials suggest that bone marrow-derived cell therapy enhances neovascularization, improves tissue perfusion, and prevents amputation. The objective of this trial was to determine whether repetitive intra-arterial infusion of bone marrow mononuclear cells (BMMNCs) in patients with severe, nonrevascularizable limb ischemia can prevent major amputation.

METHODS AND RESULTS

The Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial is a randomized, double-blind, placebo-controlled clinical trial in 160 patients with severe, nonrevascularizable limb ischemia. Patients were randomly assigned to repetitive (3 times; 3-week interval) intra-arterial infusion of BMMNC or placebo. No significant differences were observed for the primary outcome, ie, major amputation at 6 months, with major amputation rates of 19% in the BMMNC versus 13% in the placebo group (relative risk, 1.46; 95% confidence interval, 0.62-3.42). The safety outcome (all-cause mortality, occurrence of malignancy, or hospitalization due to infection) was not significantly different between the groups (relative risk, 1.46; 95% confidence interval, 0.63-3.38), neither was all-cause mortality at 6 months with 5% versus 6% (relative risk, 0.78; 95% confidence interval, 0.22-2.80). Secondary outcomes quality of life, rest pain, ankle-brachial index, and transcutaneous oxygen pressure improved during follow-up, but there were no significant differences between the groups.

CONCLUSIONS

Repetitive intra-arterial infusion of autologous BMMNCs into the common femoral artery did not reduce major amputation rates in patients with severe, nonrevascularizable limb ischemia in comparison with placebo. The general improvement in secondary outcomes during follow-up in both the BMMNC and the placebo group, as well, underlines the essential role for placebo-controlled design of future trials.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00371371.

Primary Care Triple P for parents of NICU graduates with behavioral problems: a randomized, clinical trial using observations of parent-child interaction

Background

Preterm-born or asphyxiated term-born children show more emotional and behavioral problems at preschool age than term-born children without a medical condition. It is uncertain whether parenting intervention programs aimed at the general population, are effective in this specific group. In earlier findings from the present trial, Primary Care Triple P was not effective in reducing parent-reported child behavioral problems. However, parenting programs claim to positively change child behavior through enhancement of the parent–child interaction. Therefore, we investigated whether Primary Care Triple P is effective in improving the quality of parent–child interaction and increasing the application of trained parenting skills in parents of preterm-born or asphyxiated term-born preschoolers with behavioral problems.

Methods

For this pragmatic, open randomized clinical trial, participants were recruited from a cohort of infants admitted to the neonatal intensive care units of two Dutch hospitals. Children aged 2–5 years, with a gestational age <32 weeks and/or birth weight <1500 g and children with a gestational age 37–42 weeks and perinatal asphyxia were included. After screening for a t-score ≥60 on the Child Behavior Checklist, children were randomly assigned to Primary Care Triple P (n = 34) or a wait-list control group (n = 33). Trial outcomes were the quality of parent–child interaction and the application of trained parenting skills, both scored from structured observation tasks.

Results

There was no effect of the intervention on either of the observational outcome measures at the 6-month trial endpoint.

Conclusions

Primary Care Triple P, is not effective in improving the quality of parent–child interaction nor does it increase the application of trained parenting skills in parents of preterm-born or asphyxiated term-born children with behavioral problems. Further research should focus on personalized care for these parents, with an emphasis on psychological support to reduce stress and promote self-regulation.

Trial registration

Netherlands National Trial Register NTR2179. Registered 26 January 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-014-0305-4) contains supplementary material, which is available to authorized users.

Sample size calculations in pediatric clinical trials conducted in an ICU: a systematic review

At the design stage of a clinical trial, several assumptions have to be made. These usually include guesses about parameters that are not of direct interest but must be accounted for in the analysis of the treatment effect and also in the sample size calculation (nuisance parameters, e.g. the standard deviation or the control group event rate). We conducted a systematic review to investigate the impact of misspecification of nuisance parameters in pediatric randomized controlled trials conducted in intensive care units. We searched MEDLINE through PubMed. We included all publications concerning two-arm RCTs where efficacy assessment was the main objective. We included trials with pharmacological interventions. Only trials with a dichotomous or a continuous outcome were included. This led to the inclusion of 70 articles describing 71 trials. In 49 trial reports a sample size calculation was reported. Relative misspecification could be calculated for 28 trials, 22 with a dichotomous and 6 with a continuous primary outcome. The median [inter-quartile range (IQR)] overestimation was 6.9 [-12.1, 57.8]% for the control group event rate in trials with dichotomous outcomes and -1.5 [-15.3, 5.1]% for the standard deviation in trials with continuous outcomes. Our results show that there is room for improvement in the clear reporting of sample size calculations in pediatric clinical trials conducted in ICUs. Researchers should be aware of the importance of nuisance parameters in study design and in the interpretation of the results.

Level of evidence for promising subgroup findings in an overall non-significant trial

In drug development and drug licensing, it sometimes occurs that a new drug does not demonstrate effectiveness for the full study population, but there appears to be benefit in a relevant, pre-defined subgroup. This raises the question, how strong the evidence from such a subgroup is, and which confirmatory testing strategies are the most appropriate ones. Hence, we considered the type I error and the power of a subgroup result in a trial with non-significant overall results and of suitable replication strategies. In the case of a single trial, the inflation of the overall type I error is substantial and can be up to twice as large, especially in relatively small subgroups. This also increases to the risk of starting a replication trial that should not be done, if such a second trial is not already available. The overall type I error is almost controlled by using an appropriate replication strategy. This confirms the required cautious interpretation of promising subgroups, even in the case that overall trial results were perceived to be close to significance.

Periprocedural hemodynamic depression is associated with a higher number of new ischemic brain lesions after stenting in the International Carotid Stenting Study-MRI Substudy

BACKGROUND AND PURPOSE

Carotid artery stenting (CAS) is associated with a higher risk of both hemodynamic depression and new ischemic brain lesions on diffusion-weighted imaging than carotid endarterectomy (CEA). We assessed whether the occurrence of hemodynamic depression is associated with these lesions in patients with symptomatic carotid stenosis treated by CAS or CEA in the randomized International Carotid Stenting Study (ICSS)-MRI substudy.

METHODS

The number and total volume of new ischemic lesions on diffusion-weighted imaging 1 to 3 days after CAS or CEA was measured in the ICSS-MRI substudy. Hemodynamic depression was defined as periprocedural bradycardia, asystole, or hypotension requiring treatment. The number of new ischemic lesions was the primary outcome measure. We calculated risk ratios and 95% confidence intervals per treatment with Poisson regression comparing the number of lesions in patients with or without hemodynamic depression.

RESULTS

A total of 229 patients were included (122 allocated CAS; 107 CEA). After CAS, patients with hemodynamic depression had a mean of 13 new diffusion-weighted imaging lesions, compared with a mean of 4 in those without hemodynamic depression (risk ratio, 3.36; 95% confidence interval, 1.73-6.50). The number of lesions after CEA was too small for reliable analysis. Lesion volumes did not differ between patients with or without hemodynamic depression.

CONCLUSIONS

In patients treated by CAS, periprocedural hemodynamic depression is associated with an excess of new ischemic lesions on diffusion-weighted imaging. The findings support the hypothesis that hypoperfusion increases the susceptibility of the brain to embolism.

CLINICAL TRIAL REGISTRATION

URL: http://www.controlled-trials.com. Unique identifier: ISRCTN25337470.

Brief parenting intervention for parents of NICU graduates: a randomized, clinical trial of Primary Care Triple P

BACKGROUND

Preterm-born or asphyxiated term-born children who received neonatal intensive care show more emotional and behavioral problems than term-born children without a medical condition. It is uncertain whether regular parenting intervention programs to which the parents of these children are usually referred, are effective in reducing child problem behavior in this specific population. Our objective was to investigate whether a regular, brief parenting intervention, Primary Care Triple P, is effective in decreasing emotional and behavioral problems in preterm-born or asphyxiated term-born preschoolers.

METHODS

For this pragmatic, open randomized clinical trial, participants were recruited from a cohort of infants admitted to the neonatal intensive care units (NICU) of two Dutch hospitals. Children born with a gestational age <32 weeks or birth weight <1500 g and children born at a gestational age 37-42 weeks with perinatal asphyxia were included. After screening for a t-score ≥60 on the Child Behavior Checklist (CBCL), children were randomly assigned to Primary Care Triple P (n = 34) or a wait-list control group (n = 33). The primary outcome was child emotional and behavioral problems reported by parents on the CBCL, 6 months after the start of the trial.

RESULTS

There was no effect of the intervention on the CBCL at the trial endpoint (t64 = 0.54, P = .30). On secondary measurements of child problem behavior, parenting style, parenting stress, and parent perceived child vulnerability, groups either did not differ significantly or the intervention group showed more problems. In both the intervention and control group there was a significant decrease in emotional and behavioral problems during the trial.

CONCLUSIONS

Primary Care Triple P, a brief parenting intervention, is not effective in reducing child emotional and behavioral problems in preterm-born children or term-born children with perinatal asphyxia.

TRIAL REGISTRATION

Netherlands National Trial Register (NTR): NTR2179.

Laparoscopic total gastrectomy versus open total gastrectomy for cancer: a systematic review and meta-analysis

BACKGROUND

The possible advantages of laparoscopic (assisted) total gastrectomy (LTG) versus open total gastrectomy (OTG) have not been reviewed systematically. The aim of this study was to systematically review the short-term outcomes of LTG versus OTG in the treatment of gastric cancer.

METHODS

A systematic search of PubMed, Cochrane, CINAHL, and Embase was conducted. All original studies comparing LTG with OTG were included for critical appraisal. Data describing short-term outcomes were pooled and analyzed.

RESULTS

A total of eight original studies that compared LTG (n = 314) with OTG (n = 384) in patients with gastric cancer fulfilled quality criteria and were selected for review and meta-analysis. LTG compared with OTG was associated with a significant reduction of intraoperative blood loss (weighted mean difference = 227.6 ml; 95 % CI 144.3-310.9; p < 0.001), a reduced risk of postoperative complications (risk ratio = 0.51; 95 % CI 0.33-0.77), and shorter hospital stay (weighted mean difference 4.0 = days; 95 % CI 1.4-6.5; p < 0.001). These benefits were at the cost of longer operative time (weighted mean difference = 55.5 min; 95 % CI 24.8-86.2; p < 0.001). In-hospital mortality rates were comparable for LTG (0.9 %) and OTG (1.8 %) (risk ratio = 0.68; 95 % CI 0.20-2.36).

CONCLUSION

LTG shows better short term outcomes compared with OTG in eligible patients with gastric cancer. Future studies should evaluate 30- and 60-day mortality, radicality of resection, and long-term follow-up in LTG versus OTG, preferably in randomized trials.

Poor compliance with guidelines on anemia treatment in a cohort of chronic hemodialysis patients

BACKGROUND/AIMS

Guidelines for the management of anemia and iron deficiency in chronic hemodialysis (HD) patients have been developed to standardize therapy and improve clinical outcome. The present study evaluated compliance with anemia guidelines and investigated whether differences between centers were present.

METHODS

Data on anemia management from patients in the baseline cohort of the CONTRAST study (NCT00205556) were analyzed. 598 chronic HD patients (62% male, age 63.6 ± 14.0 years) from 26 Dutch dialysis centers were included.

RESULTS

Mean hemoglobin (Hb) level was 11.9 ± 1.3 g/dl and Hb was ≥11.0 g/dl in 81% of the patients. Compliance with all anemia targets (Hb 11.0-12.0 g/dl, transferrin saturation ratio ≥20%, ferritin 100-500 ng/ml) was reached in 11.6% (95% CI 7.8-17.0) of the patients, with a wide range among centers (4-26%, adjusted for case mix, treatment-related factors and center-specific characteristics).

CONCLUSION

Compliance with anemia targets in stable HD patients was poor and showed a wide variation between treatment facilities.

Combination of biodegradable stent placement and single-dose brachytherapy is associated with an unacceptably high complication rate in the treatment of dysphagia from esophageal cancer

BACKGROUND

For the palliative treatment of dysphagia, esophageal stent placement provides immediate improvement, whereas brachytherapy offers better long-term relief.

OBJECTIVE

To evaluate safety and efficacy of concurrent brachytherapy and biodegradable stent placement.

DESIGN

Prospective, single-arm study.

SETTING

Two tertiary-care referral centers.

PATIENTS

Nineteen consecutive patients with significant dysphagia resulting from unresectable esophageal cancer, with a life expectancy of more than 3 months.

INTERVENTION

Single-dose brachytherapy (12 Gy) on day 1 followed by biodegradable stent placement on day 2.

MAIN OUTCOME MEASUREMENTS

Intervention-related major complications (determined by an expert panel) and dysphagia.

RESULTS

Nineteen patients (13 men, median age 66 years [interquartile range (IQR) 59-71] years) were included; 7 patients (37%) also received palliative chemotherapy. After inclusion of 19 patients, the study was ended prematurely because the safety threshold was exceeded. In total, 28 major complications occurred in 17 patients (89%). In 9 patients (47%), major complications were determined intervention-related (severe retrosternal pain with or without vomiting [n = 6], hematemesis [n = 1], recurrent dysphagia [n = 2]. Dysphagia scores decreased significantly from a median of 3 (IQR 3-4) to a median of 1 (IQR 0-3) after 1 month (P < .001). Despite adequate luminal patency in 17 patients (89%), normal diet could not be tolerated in 7 patients (37%) because of retrosternal pain and vomiting.

LIMITATIONS

Lack of routine endoscopy or contrast esophagram to evaluate recurrent dysphagia during follow-up.

CONCLUSION

Despite restoration of luminal patency, a combined treatment of brachytherapy and biodegradable stent placement cannot be recommended for the palliative treatment of esophageal cancer because of an unacceptably high intervention-related major complication rate.

Multifactorial intervention with nurse practitioners does not change cardiovascular outcomes in patients with chronic kidney disease

Strict implementation of guidelines directed at multiple targets reduces vascular risk in diabetic patients. Whether this also applies to patients with chronic kidney disease (CKD) is uncertain. To evaluate this, the MASTERPLAN Study randomized 788 patients with CKD (estimated GFR 20-70 ml/min) to receive additional intensive nurse practitioner support (the intervention group) or nephrologist care (the control group). The primary end point was a composite of myocardial infarction, stroke, or cardiovascular death. During a mean follow-up of 4.62 years, modest but significant decreases were found for blood pressure, LDL cholesterol, anemia, proteinuria along with the increased use of active vitamin D or analogs, aspirin and statins in the intervention group compared to the controls. No differences were found in the rate of smoking cessation, weight reduction, sodium excretion, physical activity, or glycemic control. Intensive control did not reduce the rate of the composite end point (21.3/1000 person-years in the intervention group compared to 23.8/1000 person-years in the controls (hazard ratio 0.90)). No differences were found in the secondary outcomes of vascular interventions, all-cause mortality or end-stage renal disease. Thus, the addition of intensive support by nurse practitioner care in patients with CKD improved some risk factor levels, but did not significantly reduce the rate of the primary or secondary end points.

Lithium lacks effect on survival in amyotrophic lateral sclerosis: a phase IIb randomised sequential trial

OBJECTIVES

To determine the safety and efficacy of lithium for the treatment of amyotrophic lateral sclerosis (ALS) in a randomised, placebo controlled, double blind, sequential trial.

METHODS

Between November 2008 and June 2011, 133 patients were randomised to receive lithium carbonate (target blood level 0.4-0.8 mEq/l) or placebo as add-on treatment with riluzole. The primary endpoint was survival, defined as death, tracheostomal ventilation or non-invasive ventilation for more than 16 h/day. Secondary outcome measures consisted of the revised ALS Functional Rating Scale and forced vital capacity. Analysis was by intention to treat and according to a sequential trial design.

RESULTS

61 patients reached a primary endpoint, 33 of 66 in the lithium group and 28 of 67 patients in the placebo group. Lithium did not significantly affect survival (cumulative survival probability of 0.73 in the lithium group (95% CI 0.63 to 0.86) vs 0.75 in the placebo group (95% CI 0.65 to 0.87) at 12 months and 0.62 in the lithium group (95% CI 0.50 to 0.76) vs 0.67 in the placebo group (95% CI 0.56 to 0.81) at 16 months). Secondary outcome measures did not differ between treatment groups. No major safety concerns were encountered.

CONCLUSIONS

This trial, designed to detect a modest effect of lithium, did not demonstrate any beneficial effect on either survival or functional decline in patients with ALS.

TRIAL REGISTRATION NUMBER

NTR1448. Name of trial registry: Lithium trial in ALS.

Effect of online hemodiafiltration on all-cause mortality and cardiovascular outcomes

In patients with ESRD, the effects of online hemodiafiltration on all-cause mortality and cardiovascular events are unclear. In this prospective study, we randomly assigned 714 chronic hemodialysis patients to online postdilution hemodiafiltration (n=358) or to continue low-flux hemodialysis (n=356). The primary outcome measure was all-cause mortality. The main secondary endpoint was a composite of major cardiovascular events, including death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, therapeutic coronary intervention, therapeutic carotid intervention, vascular intervention, or amputation. After a mean 3.0 years of follow-up (range, 0.4-6.6 years), we did not detect a significant difference between treatment groups with regard to all-cause mortality (121 versus 127 deaths per 1000 person-years in the online hemodiafiltration and low-flux hemodialysis groups, respectively; hazard ratio, 0.95; 95% confidence interval, 0.75-1.20). The incidences of cardiovascular events were 127 and 116 per 1000 person-years, respectively (hazard ratio, 1.07; 95% confidence interval, 0.83-1.39). Receiving high-volume hemodiafiltration during the trial associated with lower all-cause mortality, a finding that persisted after adjusting for potential confounders and dialysis facility. In conclusion, this trial did not detect a beneficial effect of hemodiafiltration on all-cause mortality and cardiovascular events compared with low-flux hemodialysis. On-treatment analysis suggests the possibility of a survival benefit among patients who receive high-volume hemodiafiltration, although this subgroup finding requires confirmation.

Optimization of the excimer laser assisted non-occlusive anastomosis (ELANA) flap retrieval rate

BACKGROUND AND OBJECTIVES

A key element in the Excimer Laser Assisted Non-occlusive Anastomosis (ELANA) technique is the retrieval of a disc ("flap") of artery wall from the anastomosis by the laser catheter tip. We assessed if the flap retrieval rate could be optimized.

METHODS

We used a specially designed in vitro model using rabbit aortas. We tested three essential elements of the technique: (1) laser energy (10, 13, 15, or 18 mJ), (2) pressure on the catheter (0, 0.1, 0.2, or 0.4 N), and (3) number of lasing episodes (1 or 2). We made 2,280 anastomoses using different combinations of settings. With a logistic regression model we assessed the influence of each parameter. Current clinical settings (10 mJ, 0.2 N, 1 episode) were reference categories.

RESULTS

Flap retrieval rate using conventional settings was 86.7%, equivalent to earlier reported clinical data. A significantly higher flap retrieval appeared when laser energy was increased to 13 mJ (OR 3.0, 95% CI 1.8-4.8), 15 mJ (OR 3.2, 95% CI 1.9-5.3), and 18 mJ (OR 3.7, 95% CI 2.2-6.2). A second lasing episode also significantly increased flap retrieval (OR 2.1, 95% CI 1.4-3.0). However, if we increased energy to 15 or 18 mJ, the effect of a second laser episode was insignificant. When the catheter was pushed down with 0.4 N, flap retrieval decreased significantly in all subgroups (OR 0.07, 95% CI 0.04-0.14).

CONCLUSION

The flap retrieval of the ELANA anastomosis technique can be optimized to 100% by setting the laser energy at 15 mJ. However, safety studies are necessary before clinical application. A second lasing episode of 10 mJ is a good alternative to increase the flap retrieval. Moreover, the surgeon should be trained to apply not more than 0.2 N on the catheter.

Sequential meta-analysis: an efficient decision-making tool

BACKGROUND

A cumulative meta-analysis of successive randomized controlled trials (RCTs) can be used to decide whether enough evidence has been obtained comparing a control and an intervention treatment or whether a new RCT should be initiated. In general, no adjustment is made for repeatedly testing the null hypothesis of treatment equivalence on cumulative data. Neither can the power of the statistical test be quantified. Recently, trial sequential analysis (TSA) was suggested to '. . . establish when firm evidence is reached in cumulative meta-analysis'. TSA is based on alpha-spending functions and necessitates a prior estimate of the total information size. Various information sizes were suggested.

PURPOSE

The aim of this study is to compare TSA with sequential meta-analysis (SMA) following Whitehead's boundaries approach.

METHODS

We compare TSA and SMA by re-analysis of a number of published examples.

RESULTS

Re-analysis of the examples shows that for an SMA: (1) no prior estimate for total information size is necessary and thus one set of boundaries suffices; (2) stopping a cumulative meta-analysis for futility is an option; (3) the power can be quantified; (4) point and interval estimates are adjusted for the multiple testing; and (5) gains in efficiency can be achieved, both for efficacy and for futility and thus ethical and economical benefits can be obtained.

LIMITATIONS

Estimates for between-trial variability are unstable for a small number of trials. The behavior of a newly proposed estimate should be subject of further investigation.

CONCLUSION

SMA is a useful tool to investigate the cumulative evidence from successive RCTs.

Preventing surgical-site infections in nasal carriers of Staphylococcus aureus

BACKGROUND

Nasal carriers of Staphylococcus aureus are at increased risk for health care-associated infections with this organism. Decolonization of nasal and extranasal sites on hospital admission may reduce this risk.

METHODS

In a randomized, double-blind, placebo-controlled, multicenter trial, we assessed whether rapid identification of S. aureus nasal carriers by means of a real-time polymerase-chain-reaction (PCR) assay, followed by treatment with mupirocin nasal ointment and chlorhexidine soap, reduces the risk of hospital-associated S. aureus infection.

RESULTS

From October 2005 through June 2007, a total of 6771 patients were screened on admission. A total of 1270 nasal swabs from 1251 patients were positive for S. aureus. We enrolled 917 of these patients in the intention-to-treat analysis, of whom 808 (88.1%) underwent a surgical procedure. All the S. aureus strains identified on PCR assay were susceptible to methicillin and mupirocin. The rate of S. aureus infection was 3.4% (17 of 504 patients) in the mupirocin-chlorhexidine group, as compared with 7.7% (32 of 413 patients) in the placebo group (relative risk of infection, 0.42; 95% confidence interval [CI], 0.23 to 0.75). The effect of mupirocin-chlorhexidine treatment was most pronounced for deep surgical-site infections (relative risk, 0.21; 95% CI, 0.07 to 0.62). There was no significant difference in all-cause in-hospital mortality between the two groups. The time to the onset of nosocomial infection was shorter in the placebo group than in the mupirocin-chlorhexidine group (P=0.005).

CONCLUSIONS

The number of surgical-site S. aureus infections acquired in the hospital can be reduced by rapid screening and decolonizing of nasal carriers of S. aureus on admission. (Current Controlled Trials number, ISRCTN56186788.)

Incidence, case fatality, and functional outcome of intracerebral haemorrhage over time, according to age, sex, and ethnic origin: a systematic review and meta-analysis

BACKGROUND

Since the early 1980s, imaging techniques have enabled population-based studies of intracerebral haemorrhage. We aimed to assess the incidence, case fatality, and functional outcome of intracerebral haemorrhage in relation to age, sex, ethnic origin, and time period in studies published since 1980.

METHODS

From PubMed and Embase searches with predefined inclusion criteria, we identified population-based studies published between January, 1980, and November, 2008. We calculated incidence and case fatality. Incidences for multiple studies were pooled in a random-effects binomial meta-analysis. Time trends of case fatality were assessed with weighted linear-regression analysis.

FINDINGS

36 eligible studies described 44 time periods (mid-year range 1983-2006). These studies included 8145 patients with intracerebral haemorrhage. Incidence did not decrease between 1980 and 2008. Overall incidence was 24.6 per 100 000 person-years (95% CI 19.7-30.7). Incidence was not significantly lower in women than in men (overall incidence ratio 0.85, 95% CI 0.61-1.18). Using the age group 45-54 years as reference, incidence ratios increased from 0.10 (95% CI 0.06-0.14) for people aged less than 45 years to 9.6 (6.6-13.9) for people older than 85 years. Median case fatality at 1 month was 40.4% (range 13.1-61.0) and did not decrease over time, and was lower in Japan (16.7%, 95% CI 15.0-18.5) than elsewhere (42.3%, 40.9-43.6). Six studies reported functional outcome, with independency rates of between 12% and 39%. Incidence of intracerebral haemorrhage per 100 000 person-years was 24.2 (95% CI 20.9-28.0) in white people, 22.9 (14.8-35.6) in black people, 19.6 (15.7-24.5) in Hispanic people, and 51.8 (38.8-69.3) in Asian people.

INTERPRETATION

Incidence of intracerebral haemorrhage increases with age and has not decreased between 1980 and 2006. Case fatality is lower in Japan than elsewhere, increases with age, and has not decreased over time. More data on functional outcome are needed.

FUNDING

Netherlands Heart Foundation.

Randomized sequential trial of valproic acid in amyotrophic lateral sclerosis

OBJECTIVE

To determine whether valproic acid (VPA), a histone deacetylase inhibitor that showed antioxidative and antiapoptotic properties and reduced glutamate toxicity in preclinical studies, is safe and effective in amyotrophic lateral sclerosis (ALS) using a sequential trial design.

METHODS

Between April 2005 and January 2007, 163 ALS patients received VPA 1,500mg or placebo daily. Primary end point was survival. Secondary outcome measure was decline of functional status measured by the revised ALS Functional Rating Scale. Analysis was by intention to treat and according to a sequential trial design. This trial was registered with ClinicalTrials.gov (number NCT00136110).

RESULTS

VPA did not affect survival (cumulative survival probability of 0.72 in the VPA group [standard error (SE), 0.06] vs 0.88 in the placebo group [SE, 0.04] at 12 months, and 0.59 in the VPA group [SE, 0.07] vs 0.68 in the placebo group [SE, 0.08] at 16 months) or the rate of decline of functional status. VPA intake did not cause serious adverse reactions.

INTERPRETATION

Our finding that VPA, at a dose used in epilepsy, does not show a beneficial effect on survival or disease progression in patients with ALS has implications for future trials with histone deacetylase inhibitors in ALS and other neurodegenerative diseases. The use of a sequential trial design allowed inclusion of only half the number of patients required for a classic trial design and prevented patients from unnecessarily continuing potentially harmful study medication.

Alternative trial design in amyotrophic lateral sclerosis saves time and patients

A sequential trial design is an alternative for the classical trial design with a fixed sample size, that permits stopping a trial as soon as enough evidence for a treatment effect, or a lack thereof, is obtained. This study aimed to determine the difference in efficiency of time and patient number between a classical trial design and a sequential trial design. In this study we re-analysed a previously published classically designed clinical trial according to a sequential trial design. We subsequently determined the difference in total running time and patient number. We found that the sequential analysis offered a gain in time of 38%. We conclude that the sequential trial design may in certain situations be superior to the classical design.

Psychosis risk for parents and siblings of Dutch and Moroccan-Dutch patients with non-affective psychotic disorder

BACKGROUND

Studies in the UK compared psychosis risks for first-degree relatives of White and African-Caribbean patients and found "normal" risks for the parents of Caribbean patients, but very high risks for siblings of second-generation Caribbean patients.

AIM

To compare the risk of non-affective psychotic disorder (NAPD) for the parents and siblings of Moroccan-Dutch patients to that for the parents and siblings of Dutch patients. The "Moroccan-Dutch" are Dutch residents of Moroccan origin (first or second generation).

METHOD

Informants related to 29 Moroccan-Dutch and 63 Dutch patients were interviewed about the presence of psychiatric disorders in first-degree relatives (N=508), by means of the Family Interview for Genetic Studies.

RESULTS

The risks for NAPD in both parent groups were similar (age and sex-adjusted odds ratio 1.0; 95% CI: 0.3-3.8). However, among the siblings, the risk for NAPD was significantly higher for the Moroccan-Dutch than for the Dutch (sex-adjusted hazard ratio 4.5; 95% Confidence Interval: 1.5-14.0). This was due to a large number of cases among the brothers of the Moroccan-Dutch patients (N=14), not among their sisters (N=1). Owing to small numbers separate hazard ratios for the first and the second generation were not calculated.

CONCLUSION

These preliminary results suggest that environmental factors in the Netherlands have a great impact on the psychosis risk for male immigrants from Morocco.

Assessment of cognitive brain function in ecstasy users and contributions of other drugs of abuse: results from an FMRI study

Heavy ecstasy use has been associated with neurocognitive deficits in various behavioral and brain imaging studies. However, this association is not conclusive owing to the unavoidable confounding factor of polysubstance use. The present study, as part of the Netherlands XTC Toxicity study, investigated specific effects of ecstasy on working memory, attention, and associative memory, using functional magnetic resonance imaging (fMRI). A large sample (n=71) was carefully composed based on variation in the amount and type of drugs that were used. The sample included 33 heavy ecstasy users (mean 322 pills lifetime). Neurocognitive brain function in three domains: working memory, attention, and associative memory, was assessed with performance measures and fMRI. Independent effects of the use of ecstasy, amphetamine, cocaine, cannabis, alcohol, tobacco, and of gender and IQ were assessed and separated by means of multiple regression analyses. Use of ecstasy had no effect on working memory and attention, but drug use was associated with reduced associative memory performance. Multiple regression analysis showed that associative memory performance was affected by amphetamine much more than by ecstasy. Both drugs affected associative memory-related brain activity, but the effects were consistently in opposite directions, suggesting that different mechanisms are at play. This could be related to the different neurotransmitter systems these drugs predominantly act upon, that is, serotonin (ecstasy) vs dopamine (amphetamine) systems.

Early course of schizophrenia in a representative Dutch incidence cohort

PURPOSE

To describe the early course of psychotic disorders in general and to examine whether certain variables can predict the early course of schizophrenic disorders (DSM-IV: schizophrenia, schizophreniform or schizoaffective disorder).

SUBJECTS AND METHOD

Follow-up and re-diagnosis of a highly representative Dutch incidence cohort (N=181), thirty months after first contact with a physician for a psychotic disorder. Poor course was defined as a continuous psychotic illness or a score of less than 39 on the Global Assessment of Functioning scale.

RESULTS

The follow-up rate was 92%. 125 Subjects were diagnosed with a schizophrenic disorder. Poor course was present in 70 of these subjects (56%). Univariable analysis showed that male sex, heavy cannabis use during the follow-up period (sometimes or often more than one joint a day) and long duration of dysfunctioning before psychosis onset (>1 month) were predictors of poor course, while age at onset, ethnicity, socioeconomic status and duration of untreated psychosis (trend, p=0.08) were not. The effect of cannabis was confounded by sex. Multivariable analysis showed that male sex was the sole significant and independent predictor of poor course and explained 13% of the variation. The odds ratio for males, adjusted for duration of pre-psychotic dysfunctioning and cannabis use during the follow-up period, was 3.0 (95% CI, 1.0-8.9). STRENGTHS AND LIMITATIONS: This is the first study to examine the influence of cannabis in an epidemiological, highly representative sample. A limitation was the sample size.

CONCLUSION

Male sex is an independent risk factor for an unfavorable early course in schizophrenia.

Estimating interaction on an additive scale between continuous determinants in a logistic regression model

BACKGROUND

To determine the presence of interaction in epidemiologic research, typically a product term is added to the regression model. In linear regression, the regression coefficient of the product term reflects interaction as departure from additivity. However, in logistic regression it refers to interaction as departure from multiplicativity. Rothman has argued that interaction estimated as departure from additivity better reflects biologic interaction. So far, literature on estimating interaction on an additive scale using logistic regression only focused on dichotomous determinants. The objective of the present study was to provide the methods to estimate interaction between continuous determinants and to illustrate these methods with a clinical example.

METHODS

and results From the existing literature we derived the formulas to quantify interaction as departure from additivity between one continuous and one dichotomous determinant and between two continuous determinants using logistic regression. Bootstrapping was used to calculate the corresponding confidence intervals. To illustrate the theory with an empirical example, data from the Utrecht Health Project were used, with age and body mass index as risk factors for elevated diastolic blood pressure.

CONCLUSIONS

The methods and formulas presented in this article are intended to assist epidemiologists to calculate interaction on an additive scale between two variables on a certain outcome. The proposed methods are included in a spreadsheet which is freely available at: http://www.juliuscenter.nl/additive-interaction.xls.

A randomised clinical trial on cardiotocography plus fetal blood sampling versus cardiotocography plus ST-analysis of the fetal electrocardiogram (STAN) for intrapartum monitoring

BACKGROUND

Cardiotocography (CTG) is worldwide the method for fetal surveillance during labour. However, CTG alone shows many false positive test results and without fetal blood sampling (FBS), it results in an increase in operative deliveries without improvement of fetal outcome. FBS requires additional expertise, is invasive and has often to be repeated during labour. Two clinical trials have shown that a combination of CTG and ST-analysis of the fetal electrocardiogram (ECG) reduces the rates of metabolic acidosis and instrumental delivery. However, in both trials FBS was still performed in the ST-analysis arm, and it is therefore still unknown if the observed results were indeed due to the ST-analysis or to the use of FBS in combination with ST-analysis.

METHODS/DESIGN

We aim to evaluate the effectiveness of non-invasive monitoring (CTG + ST-analysis) as compared to normal care (CTG + FBS), in a multicentre randomised clinical trial setting. Secondary aims are: 1) to judge whether ST-analysis of fetal electrocardiogram can significantly decrease frequency of performance of FBS or even replace it; 2) perform a cost analysis to establish the economic impact of the two treatment options. Women in labour with a gestational age > or = 36 weeks and an indication for CTG-monitoring can be included in the trial. Eligible women will be randomised for fetal surveillance with CTG and, if necessary, FBS or CTG combined with ST-analysis of the fetal ECG. The primary outcome of the study is the incidence of serious metabolic acidosis (defined as pH < 7.05 and Bdecf > 12 mmol/L in the umbilical cord artery). Secondary outcome measures are: instrumental delivery, neonatal outcome (Apgar score, admission to a neonatal ward), incidence of performance of FBS in both arms and cost-effectiveness of both monitoring strategies across hospitals. The analysis will follow the intention to treat principle. The incidence of metabolic acidosis will be compared across both groups. Assuming a reduction of metabolic acidosis from 3.5% to 2.1 %, using a two-sided test with an alpha of 0.05 and a power of 0.80, in favour of CTG plus ST-analysis, about 5100 women have to be randomised. Furthermore, the cost-effectiveness of CTG and ST-analysis as compared to CTG and FBS will be studied.

DISCUSSION

This study will provide data about the use of intrapartum ST-analysis with a strict protocol for performance of FBS to limit its incidence. We aim to clarify to what extent intrapartum ST-analysis can be used without the performance of FBS and in which cases FBS is still needed.

TRIAL REGISTRATION NUMBER

ISRCTN95732366.

Physical Activity and Breast Cancer

BACKGROUND

Many epidemiologic studies have found an association between physical activity and breast cancer risk, although this has not been a consistent finding.

METHODS

Studies were identified through a systematic review of literature available on PubMed through February 2006. We included all cohort and case-control studies that assessed total or leisure time activities in relation to occurrence or mortality of breast cancer. The fully adjusted risk estimates and 95% confidence intervals for the highest versus lowest level of activity were documented for each study as well as evidence for a dose-response relationship. Methodologic quality was also assessed. Due to statistical and methodologic heterogeneity among studies, we did not carry out statistical pooling. To draw conclusions, we performed a best-evidence synthesis taking study quality into account.

RESULTS

Nineteen cohort studies and 29 case-control studies were evaluated. There was strong evidence for an inverse association between physical activity and postmenopausal breast cancer with risk reductions ranging from 20% to 80%. For premenopausal breast cancer, however, the evidence was much weaker. For pre- and postmenopausal breast cancer combined, physical activity was associated with a modest (15-20%) decreased risk. Evidence for a dose-response relationship was observed in approximately half of the higher-quality studies that reported a decreased risk. A trend analysis indicated a 6% (95% confidence interval = 3% to 8%) decrease in breast cancer risk for each additional hour of physical activity per week assuming that the level of activity would be sustained.

CONCLUSIONS

There is evidence for an inverse association between physical activity and breast cancer risk. The evidence is stronger for postmenopausal breast cancer than for premenopausal breast cancer.

Sequential Meta-analysis of Past Clinical Trials to Determine the Use of a New Trial

BACKGROUND

Clinical trials can be stopped early based on interim analyses or sequential analyses. In principle, sequential analyses can also be used to decide whether enough evidence has been gathered in completed trials to make further trials unnecessary. We demonstrate such an application through a retrospective analysis of clinical trials comparing ventilation methods for the treatment of preterm newborns.

METHODS

We identified 5 recent trials that compared high-frequency ventilation with conventional mechanical ventilation in the treatment of preterm newborns. Death or chronic lung disease and chronic lung disease in survivors were the primary clinical outcomes of interest. We applied sequential meta-analyses to these 5 studies.

RESULTS

After including the first study of the last 5 trials in a sequential meta-analysis, the boundary of "no clinically relevant effect" was crossed for both outcomes (death or chronic lung disease). A sensitivity analysis using a reduction in the size of assumed clinically relevant effect showed the same findings after 2 trials.

CONCLUSIONS

Sequential meta-analyses showed that a lack of clinically relevant effect had been established after the first of the 5 trials. If such an analysis had been conducted after the first or second of these clinical trials, it might have led to changes in the study design of subsequent trials or even to a reassessment of the need for further trials.

Oral Decontamination with Chlorhexidine Reduces the Incidence of Ventilator-associated Pneumonia

RATIONALE

Ventilator-associated pneumonia (VAP) is the most frequently occurring nosocomial infection associated with increased morbidity and mortality. Although oral decontamination with antibiotics reduces incidences of VAP, it is not recommended because of potential selection of antibiotic-resistant pathogens. We hypothesized that oral decontamination with either chlorhexidine (CHX, 2%) or CHX/colistin (CHX/COL, 2%/2%) would reduce and postpone development of VAP, and oral and endotracheal colonization.

OBJECTIVES

To determine the effect of oral decontamination with CHX or CHX/COL on VAP incidence and time to development of VAP.

METHODS

Consecutive patients needing mechanical ventilation for 48 h or more were enrolled in a randomized, double-blind, placebo-controlled trial with three arms: CHX, CHX/COL, and placebo (PLAC). Trial medication was applied every 6 h into the buccal cavity. Oropharyngeal swabs were obtained daily and quantitatively analyzed for gram-positive and gram-negative microorganisms. Endotracheal colonization was monitored twice weekly.

RESULTS

Of 385 patients included, 130 received PLAC, 127 CHX and 128 CHX/COL. Baseline characteristics were comparable. The daily risk of VAP was reduced in both treatment groups compared with PLAC: 65% (hazard ratio [HR]=0.352; 95% confidence interval [CI], 0.160, 0. 791; p=0.012) for CHX and 55% (HR=0.454; 95% CI, 0.224, 0. 925; p=0.030) for CHX/COL. CHX/COL provided significant reduction in oropharyngeal colonization with both gram-negative and gram-positive microorganisms, whereas CHX mostly affected gram-positive microorganisms. Endotracheal colonization was reduced for CHX/COL patients and to a lesser extent for CHX patients. No differences in duration of mechanical ventilation, intensive care unit stay, or intensive care unit survival could be demonstrated.

CONCLUSIONS

Topical oral decontamination with CHX or CHX/COL reduces the incidence of VAP.