Joanna IntHout

The Hartung-Knapp-Sidik-Jonkman method for random effects meta-analysis is straightforward and considerably outperforms the standard DerSimonian-Laird method

BackgroundThe DerSimonian and Laird approach (DL) is widely used for random effects meta-analysis, but this often results in inappropriate type I error rates. The method described by Hartung, Knapp, Sidik and Jonkman (HKSJ) is known to perform better when trials of similar size are combined. However evidence in realistic situations, where one trial might be much larger than the other trials, is lacking. We aimed to evaluate the relative performance of the DL and HKSJ methods when studies of different sizes are combined and to develop a simple method to convert DL results to HKSJ results.MethodsWe evaluated the performance of the HKSJ versus DL approach in simulated meta-analyses of 2–20 trials with varying sample sizes and between-study heterogeneity, and allowing trials to have various sizes, e.g. 25% of the trials being 10-times larger than the smaller trials. We also compared the number of “positive” (statistically significant at p < 0.05) findings using empirical data of recent meta-analyses with > = 3 studies of interventions from the Cochrane Database of Systematic Reviews.ResultsThe simulations showed that the HKSJ method consistently resulted in more adequate error rates than the DL method. When the significance level was 5%, the HKSJ error rates at most doubled, whereas for DL they could be over 30%. DL, and, far less so, HKSJ had more inflated error rates when the combined studies had unequal sizes and between-study heterogeneity. The empirical data from 689 meta-analyses showed that 25.1% of the significant findings for the DL method were non-significant with the HKSJ method. DL results can be easily converted into HKSJ results.ConclusionsOur simulations showed that the HKSJ method consistently results in more adequate error rates than the DL method, especially when the number of studies is small, and can easily be applied routinely in meta-analyses. Even with the HKSJ method, extra caution is needed when there are = <5 studies of very unequal sizes.

Cytotoxic Markers Associate With Protection Against Malaria in Human Volunteers Immunized With Plasmodium falciparum Sporozoites

Background. Immunization of healthy volunteers by bites from Plasmodium falciparum–infected mosquitoes during chloroquine chemoprophylaxis (hereafter, chemoprophylaxis and sporozoites [CPS] immunization) induces sterile protection against malaria. CPS-induced protection is mediated by immunity against pre-erythrocytic stages, presumably at least partially by cytotoxic cellular responses. We therefore aimed to investigate the association of CPS-induced cytotoxic T-cell markers with protection. Methods. In a double-blind randomized controlled trial, we performed dose titration of CPS immunization followed by homologous challenge infection in 29 subjects. Immune responses were assessed by in vitro restimulation of peripheral blood mononuclear cells and flow cytometry. Results. Dose-dependent complete protection was obtained in 4 of 5 volunteers after immunization with bites from 45 P. falciparum–infected mosquitoes, in 8 of 9 volunteers with bites from 30, and in 5 of 10 volunteers with bites from 15 (odds ratio [OR], 5.0; 95% confidence interval [CI], 1.5–17). Completely protected subjects had significantly higher proportions of CD4 T cells expressing the degranulation marker CD107a (OR, 8.4; 95% CI, 1.5–123; P = .011) and CD8 cells producing granzyme B (OR, 11; 95% CI, 1.9–212; P = .004) after P. falciparum restimulation. Conclusions. These data underline the efficiency of CPS immunization to induce sterile protection and support a possible role for cytotoxic CD4 and CD8 T-cell responses in pre-erythrocytic immunity. Clinical Trials Registration. NCT01218893.

Plea for routinely presenting prediction intervals in meta-analysis

Objectives Evaluating the variation in the strength of the effect across studies is a key feature of meta-analyses. This variability is reflected by measures like τ2 or I2, but their clinical interpretation is not straightforward. A prediction interval is less complicated: it presents the expected range of true effects in similar studies. We aimed to show the advantages of having the prediction interval routinely reported in meta-analyses. Design We show how the prediction interval can help understand the uncertainty about whether an intervention works or not. To evaluate the implications of using this interval to interpret the results, we selected the first meta-analysis per intervention review of the Cochrane Database of Systematic Reviews Issues 2009–2013 with a dichotomous (n=2009) or continuous (n=1254) outcome, and generated 95% prediction intervals for them. Results In 72.4% of 479 statistically significant (random-effects p<0.05) meta-analyses in the Cochrane Database 2009–2013 with heterogeneity (I2>0), the 95% prediction interval suggested that the intervention effect could be null or even be in the opposite direction. In 20.3% of those 479 meta-analyses, the prediction interval showed that the effect could be completely opposite to the point estimate of the meta-analysis. We demonstrate also how the prediction interval can be used to calculate the probability that a new trial will show a negative effect and to improve the calculations of the power of a new trial. Conclusions The prediction interval reflects the variation in treatment effects over different settings, including what effect is to be expected in future patients, such as the patients that a clinician is interested to treat. Prediction intervals should be routinely reported to allow more informative inferences in meta-analyses.

Comparative performance of novel self-sampling methods in detecting high-risk human papillomavirus in 30,130 women not attending cervical screening.

We determined whether the participation rate for a brush‐based cervicovaginal self‐sampling device is noninferior to the participation rate for a lavage‐based one for testing for hrHPV (high‐risk human papillomavirus). Additionally, positivity rates for hrHPV, the detection rates for cervical intraepithelial neoplasia grades 2 and 3 or worse (CIN2+/3+), and user comfort were compared. A total of 35,477 non‐responders of the regular cervical screening program aged 33–63 years were invited to participate. Eligible women (n = 30,130) were randomly assigned to receive either a brush‐based or a lavage‐based device, and a questionnaire for reporting user convenience. Self‐sampling responders testing hrHPV‐positive were invited for a physician‐taken sample for cytology; triage‐positive women were referred for colposcopy. A total of 5,218 women participated in the brush‐based sampling group (34.6%) and 4809 women in the lavage‐based group (31.9%), i.e. an absolute difference of 2.7% (95%CI 1.8–4.2). The hrHPV‐positivity rates in the two groups were identical (8.3%, relative risk (RR) 0.99, 95%CI 0.87–1.13). The detection of CIN2+ and CIN3+ in the brush group (2.0% for CIN2+; 1.3% for CIN3+) was similar to that in the lavage group (1.9% for CIN2+; 1.0% for CIN3+) with a cumulative RR of 1.01, 95%CI 0.83–1.24 for CIN2+ and 1.25, 95%CI 0.92–1.70 for CIN3+. The two self‐sampling devices performed similarly in user comfort. In conclusion, offering a brush‐based device to non‐responders is noninferior to offering a lavage‐based device in terms of participation. The two self‐sampling methods are equally effective in detecting hrHPV, CIN2+/CIN3+ and are both well accepted.

Obtaining evidence by a single well-powered trial or several modestly powered trials:

There is debate whether clinical trials with suboptimal power are justified and whether results from large studies are more reliable than the (combined) results of smaller trials. We quantified the error rates for evaluations based on single conventionally powered trials (80% or 90% power) versus evaluations based on the random-effects meta-analysis of a series of smaller trials. When a treatment was assumed to have no effect but heterogeneity was present, the error rates for a single trial were increased more than 10-fold above the nominal rate, even for low heterogeneity. Conversely, for meta-analyses on a series of trials, the error rates were correct. When selective publication was present, the error rates were always increased, but they still tended to be lower for a series of trials than single trials. We conclude that evidence of efficacy based on a series of (smaller) trials, may lower the error rates compared with using a single well-powered trial. Only when both heterogeneity and selective publication can be excluded, a single trial is able to provide conclusive evidence.

Meta-analyses of animal studies: an introduction of a valuable instrument to further improve healthcare

In research aimed at improving human health care, animal studies still play a crucial role, despite political and scientific efforts to reduce preclinical experimentation in laboratory animals. In animal studies, the results and their interpretation are not always straightforward, as no single study is executed perfectly in all steps. There are several possible sources of bias, and many animal studies are replicates of studies conducted previously. Use of meta-analysis to combine the results of studies may lead to more reliable conclusions and a reduction of unnecessary duplication of animal studies. In addition, due to the more exploratory nature of animal studies as compared to clinical trials, meta-analyses of animal studies have greater potential in exploring possible sources of heterogeneity. There is an abundance of literature on how to perform meta-analyses on clinical data. Animal studies, however, differ from clinical studies in some aspects, such as the diversity of animal species studied, experimental design, and study characteristics. In this paper, we will discuss the main principles and practices for meta-analyses of experimental animal studies.

Cytoreductive surgery followed by chemotherapy versus chemotherapy alone for recurrent platinum-sensitive epithelial ovarian cancer (SOCceR trial): a multicenter randomised controlled study

BackgroundImprovement in treatment for patients with recurrent ovarian cancer is needed. Standard therapy in patients with platinum-sensitive recurrent ovarian cancer consists of platinum-based chemotherapy. Median overall survival is reported between 18 and 35 months. Currently, the role of surgery in recurrent ovarian cancer is not clear. In selective patients a survival benefit up to 62 months is reported for patients undergoing complete secondary cytoreductive surgery. Whether cytoreductive surgery in recurrent platinum-sensitive ovarian cancer is beneficial remains questionable due to the lack of level I-II evidence.Methods/DesignMulticentre randomized controlled trial, including all nine gynecologic oncologic centres in the Netherlands and their affiliated hospitals. Eligible patients are women, with first recurrence of FIGO stage Ic-IV platinum-sensitive epithelial ovarian cancer, primary peritoneal cancer or fallopian tube cancer, who meet the inclusion criteria. Participants are randomized between the standard treatment consisting of at least six cycles of intravenous platinum based chemotherapy and the experimental treatment which consists of secondary cytoreductive surgery followed by at least six cycles of intravenous platinum based chemotherapy. Primary outcome measure is progression free survival. In total 230 patients will be randomized. Data will be analysed according to intention to treat.DiscussionWhere the role of cytoreductive surgery is widely accepted in the initial treatment of ovarian cancer, its value in recurrent platinum-sensitive epithelial ovarian cancer has not been established so far. A better understanding of the benefits and patients selection criteria for secondary cytoreductive surgery has to be obtained. Therefore the 4th ovarian cancer consensus conference in 2010 stated that randomized controlled phase 3 trials evaluating the role of surgery in platinum-sensitive recurrent epithelial ovarian cancer are urgently needed. We present a recently started multicentre randomized controlled trial that will investigate the role of secondary cytoreductive surgery followed by chemotherapy will improve progression free survival in selected patients with first recurrence of platinum-sensitive epithelial ovarian cancer.Trial registrationNetherlands Trial Register number: NTR3337.

Differences between information in registries and articles did not influence publication acceptance

OBJECTIVES To assess whether journals are more likely to reject manuscripts with differences between information in registries and articles. We compared differences by sponsorship and assessed whether selective reporting favored publication of significant outcomes. STUDY DESIGN AND SETTING Drug trials submitted to eight journals (January 2010-April 2012) were included. Publication status, primary outcomes, enrollment, and sponsorship were extracted. Primary outcomes and enrollment in registries and registration timing were reviewed. Prospective registration included registration before study start. Consistency between registered and reported information was evaluated. RESULTS For 226 submitted manuscripts, primary outcomes were specified in both article and registry. Sixty six of 226 (29.2%) had primary outcome differences; 14 of 66 manuscripts with differences (21.2%) and 46 of 160 without differences (28.8%) were accepted. Fifty manuscripts (22.4%) had sample size differences; 10 of 50 with differences (20.0%) and 49 of 173 without differences (28.3%) were accepted. Industry-sponsored trials had less differences and were more often prospectively registered. After adjustment for sponsorship, differences and/or retrospective registration were not associated with decreased chance of acceptance (odds ratio 0.56; 95% confidence interval: 0.27, 1.13). Primary outcome differences favored significant outcomes in 49% of manuscripts. CONCLUSION Differences between registered and reported information are not decisive for rejection. Editors should assess consistency between registries and articles to address selective reporting.

Tissue Engineering in Animal Models for Urinary Diversion: A Systematic Review

Tissue engineering and regenerative medicine (TERM) approaches may provide alternatives for gastrointestinal tissue in urinary diversion. To continue to clinically translatable studies, TERM alternatives need to be evaluated in (large) controlled and standardized animal studies. Here, we investigated all evidence for the efficacy of tissue engineered constructs in animal models for urinary diversion. Studies investigating this subject were identified through a systematic search of three different databases (PubMed, Embase and Web of Science). From each study, animal characteristics, study characteristics and experimental outcomes for meta-analyses were tabulated. Furthermore, the reporting of items vital for study replication was assessed. The retrieved studies (8 in total) showed extreme heterogeneity in study design, including animal models, biomaterials and type of urinary diversion. All studies were feasibility studies, indicating the novelty of this field. None of the studies included appropriate control groups, i.e. a comparison with the classical treatment using GI tissue. The meta-analysis showed a trend towards successful experimentation in larger animals although no specific animal species could be identified as the most suitable model. Larger animals appear to allow a better translation to the human situation, with respect to anatomy and surgical approaches. It was unclear whether the use of cells benefits the formation of a neo urinary conduit. The reporting of the methodology and data according to standardized guidelines was insufficient and should be improved to increase the value of such publications. In conclusion, animal models in the field of TERM for urinary diversion have probably been chosen for reasons other than their predictive value. Controlled and comparative long term animal studies, with adequate methodological reporting are needed to proceed to clinical translatable studies. This will aid in good quality research with the reduction in the use of animals and an increase in empirical evidence of biomedical research.

BDNF polymorphism associates with decline in set shifting in Parkinson's disease

Parkinsons disease (PD) is a neurodegenerative disorder caused by nigrostriatal dopaminergic degeneration. Brain-derived neurotrophic factor (BDNF) is a key protein in brain plasticity and is particularly important for survival of dopaminergic neurons. The Val66Met polymorphism of BDNF (rs6265) has been associated with functional differences (mainly cognitive) between healthy adults and also with differences in the clinical expression of several other neuropsychiatric illnesses including PD. However, these studies used different outcome measures, have not been replicated, and were cross sectional, making it difficult to establish the role of BDNF in the clinical variability of PD. Here, a large cohort of 384 PD patients were followed up for 2 years, and associations between BDNF genotype and various clinical characteristics were examined. The BDNF Met-allele carriers showed a significantly smaller decline in set shifting during follow-up compared with the homozygous BDNF Val-allele carriers. Contrary to previous assumptions, these results indicate that mental flexibility is one of the cognitive processes that may benefit from the BDNF Met allele in PD patients.