Abstracts of randomized controlled trials presented at the society for pediatric research meeting: an example of publication bias. Treatment success in cancer: new cancer treatment successes identified in phase 3 randomized controlled trials conducted by the National Cancer Institute-sponsored cooperative oncology groups, 1955 to 2006. A double-blind clinical trial of mianserin versus amitriptyline: differentiation by adverse symptomatology. Association between pharmaceutical involvement and outcomes in breast cancer clinical trials. New use of rosiglitazone decreased following publication of a meta-analysis suggesting harm. Publication bias and meta-analyses: a practical example. Full publication of trials initially reported as abstracts in the Australian and New Zealand Journal of Medicine 1980-2000. Does the inclusion of grey literature influence estimates of intervention effectiveness reported in meta-analyses? Glycemic durability of rosiglitazone, metformin, or glyburide monotherapy. Whatever happened to abstracts from different sections of the association for research in vision and ophthalmology? Progesterone for the prevention of preterm birth in twin pregnancy (STOPPIT): a randomised, double-blind, placebo-controlled study and meta-analysis. Factors associated with failure to publish large randomized trials presented at an oncology meeting. Adverse event reporting in publications compared with sponsor database for cancer clinical trials. Harnessing the heightened public awareness of celebrity HIV disclosures: "Magic" and "Cookie" Johnson and HIV testing. Association of trial registration with the results and conclusions of published trials of new oncology drugs. Undisclosed changes in outcomes in randomized controlled trials: an observational study.
Publication bias toward studies that favor new therapies has been known to occur for the past 40 years, yet its implications are not well studied in child health. The increased interest in meta-analyses has highlighted the need to identify the totality of evidence when addressing treatment questions.
                To measure the percentage of randomized controlled trials (RCTs) presented at a major pediatric scientific meeting that were subsequently published as full-length articles, to investigate factors associated with publication, and to describe the variables that change from abstract to manuscript form.
                The scientific proceedings from the Society for Pediatric Research were hand searched for RCTs (1992-1995). Subsequent publication was ascertained through a search of various electronic databases. Quality of abstracts and manuscripts was measured, and data were extracted using a structured form.
                A total of 264 (59.1%) of 447 abstracts were subsequently published. Almost 64% of RCTs that were subsequently published favored new therapy compared with 43.5% of studies that were never published (P<.001). Mean effect size for published vs unpublished RCTs was 0.74 vs 0.05 (P<.001). Median sample size was larger in published (n = 45) vs unpublished (n = 34) RCTs (P =.02). Quality was significantly lower for abstracts vs published RCTs (P<.001). For 5% of abstracts that were subsequently published, the conclusion regarding treatment efficacy changed.
                Publication bias is a serious threat to assessing the effectiveness of interventions in child health, as little more than half of RCTs presented at a major scientific meeting are subsequently published. There is a need to institute an international registry of RCTs in children so that the totality of evidence can be accessed when assessing treatment effectiveness. The evaluation of research output, such as estimation of the proportion of treatment successes, is of ethical, scientific, and public importance but has rarely been evaluated systematically. We assessed how often experimental cancer treatments that undergo testing in randomized clinical trials (RCTs) result in discovery of successful new interventions.
                We extracted data from all completed (published and unpublished) phase 3 RCTs conducted by the National Cancer Institute cooperative groups since their inception in 1955. Therapeutic successes were determined by (1) assessing the proportion of statistically significant trials favoring new or standard treatments, (2) determining the proportion of the trials in which new treatments were considered superior to standard treatments according to the original researchers, and (3) quantitatively synthesizing data for main clinical outcomes (overall and event-free survival).
                Data from 624 trials (781 randomized comparisons) involving 216 451 patients were analyzed. In all, 30% of trials had statistically significant results, of which new interventions were superior to established treatments in 80% of trials. The original researchers judged that the risk-benefit profile favored new treatments in 41% of comparisons (316 of 766). Hazard ratios for overall and event-free survival, available for 614 comparisons, were 0.95 (99% confidence interval [CI], 0.93-0.98) and 0.90 (99% CI, 0.87- 0.93), respectively, slightly favoring new treatments. Breakthrough interventions were discovered in 15% of trials.
                Approximately 25% to 50% of new cancer treatments that reach the stage of assessment in RCTs will prove successful. The pattern of successes has become more stable over time. The results are consistent with the hypothesis that the ethical principle of equipoise defines limits of discoverability in clinical research and ultimately drives therapeutic advances in clinical medicine. A 6-week double-blind comparison of mianserin, a new antidepressant, and amitriptyline allowed us to explore the problem of demonstrating main effect differences in drug/drug trials when the focus is primarily only upon efficacy or upon common adverse symptomatology. Statistical analyses of standard psychiatric rating scales revealed no significant treatment differences, while both treatment groups exhibited significant parallel improvement across time. Examination of treatment emergent symptoms indicated that, while it evoked fewer anticholinergic symptoms than amitriptyline, mianserin exhibited a different profile of adverse symptomatology. The usefulness of a measure of the benefit/risk ratio was described as a means of clarifying drug/drug comparisons. Since 1992, pharmaceutical industry support has surpassed National Institutes of Health funding for clinical research in the United States. In this study, the authors sought to evaluate the impact of this shift in funding from public to private sponsors on the nature of published breast cancer clinical research.
                All published breast cancer clinical trials from 2003, 1998, and 1993 were reviewed from 10 select English-language medical journals to evaluate pharmaceutical involvement over time and the association between sponsorship, trial design, and results. Clinical studies that reported disease-specific outcomes from medical therapy for breast cancer were eligible for analysis. Pharmaceutical involvement was defined as reported pharmaceutical industry funding, provision of drug, and/or authorship for each publication.
                In total, 140 eligible studies were identified, including 45 studies that were published in 1993, 39 studies that were published in 1998, and 56 studies that were published in 2003. Among those, 67 publications (48%) reported pharmaceutical industry involvement, 36 publications (26%) had at least >/=1 pharmaceutical industry author, And 100 publications (71%) were considered positive. Pharmaceutical involvement was identified in 44% of the studies published in 1993, in 38% of the studies published in 1998, and in 58% of the studies published in 2003. Pharmaceutical authorship was reported in 22% of the 1993 studies, in 21% of the 1998 studies, and in 34% of the 2003 studies. For studies that were published in 2003, those that reported pharmaceutical involvement were more likely to be positive (84% vs 54%; P = .02; Fisher exact test), to be single-arm studies (66% vs 33%; P = .03), and to evaluate metastatic disease (72% vs 46%; P = .06).
                Pharmaceutical involvement in published clinical breast cancer research may affect study design, focus, and results. Further research is warranted, including analysis of unpublished studies, to evaluate the impact of increasing pharmaceutical industry involvement on clinical research.
                (c) 2007 American Cancer Society. It is uncertain whether meta-analyses lead to changes in prescribing practices. We studied trends in the prescribing of glucose-lowering therapy before and after the publication of a meta-analysis suggesting harm from rosiglitazone.
                We examined the prescription records of all residents of Ontario, Canada, aged > or = 66 years. For each week between January and December 2007, we identified new users of five categories of glucose-lowering medications: rosiglitazone, pioglitazone, metformin, glibenclamide (glyburide) and insulin. The effect of the meta-analysis was assessed using interventional autoregressive integrated moving-average models.
                Following the release of the meta-analysis, there was a sudden decline in new users of rosiglitazone (P = 0.01), mirrored by a nearly identical but transient increase in new users of pioglitazone (P < 0.001). There was also a net decline in new users of thiazolidinediones as a class (P < 0.001). The number of new users of other glucose-lowering medications did not change.
                A highly-publicized meta-analysis regarding rosiglitazone's potential harms led to an abrupt decline in new users of the drug, as well as a transient surge in new use of pioglitazone. Publication bias is widely appreciated, but considerable time and effort are needed to locate and obtain data from unpublished randomized controlled trials (RCTs), those published in non-English language journals or those reported in the gray literature; for this publication, we will call this collection of trials the "gray+literature." However, excluding such trials from systematic reviews could introduce bias and give rise to misleading conclusions.
                We aimed to explore and quantify the impact of inclusion of gray+ literature on the results of all completed individual patient data (IPD) reviews coordinated by our group (13 meta-analyses). For each IPD review, results were calculated for RCTs fully published in English language journals and RCTs fully published in English language journals and the gray+literature.
                The IPD meta-analyses based only on RCTs that were fully published in English language journals tended to give more favorable results than those that included RCTs from the gray+literature. Although in most cases the addition of gray+data gave less encouraging results, moving the estimated treatment effect toward a null result, the direction of effect was not always predictable.
                We recommend that all systematic reviews should at least attempt to identify trials reported in the gray+literature and, where possible, obtain data from them. Abstract Failure to identify all relevant reports of controlled trials is a potential source of bias in systematic reviews of health-care interventions. The present study aims to identify how many reports of trials -initially published as conference abstracts in the Australian and New Zealand Journal of Medicine were subsequently published in full. We identified trial reports by handsearching conference abstracts published in the Journal from 1980 to 2000. We then searched the Cochrane Controlled Trials Register and PubMed to determine how many of these had been subsequently published in full. A total of 962 reports of controlled trials was identified from the conference proceedings of 17 medical societies. Of these, 589 (61%) reports of trials were subsequently published in full, and on average within 1-2 years. Handsearching conference abstracts identified a large number of reports of controlled trials, over one-third of which were unpublished and therefore not easily accessible. The inclusion of only a subset of all available evidence in a meta-analysis may introduce biases and threaten its validity; this is particularly likely if the subset of included studies differ from those not included, which may be the case for published and grey literature (unpublished studies, with limited distribution). We set out to examine whether exclusion of grey literature, compared with its inclusion in meta-analysis, provides different estimates of the effectiveness of interventions assessed in randomised trials.
                From a random sample of 135 meta-analyses, we identified and retrieved 33 publications that included both grey and published primary studies. The 33 publications contributed 41 separate meta-analyses from several disease areas. General characteristics of the meta-analyses and associated studies and outcome data at the trial level were collected. We explored the effects of the inclusion of grey literature on the quantitative results using logistic-regression analyses.
                33% of the meta-analyses were found to include some form of grey literature. The grey literature, when included, accounts for between 4.5% and 75% of the studies in a meta-analysis. On average, published work, compared with grey literature, yielded significantly larger estimates of the intervention effect by 15% (ratio of odds ratios=1.15 [95% CI 1.04-1.28]). Excluding abstracts from the analysis further compounded the exaggeration (1.33 [1.10-1.60]).
                The exclusion of grey literature from meta-analyses can lead to exaggerated estimates of intervention effectiveness. In general, meta-analysts should attempt to identify, retrieve, and include all reports, grey and published, that meet predefined inclusion criteria. The efficacy of thiazolidinediones, as compared with other oral glucose-lowering medications, in maintaining long-term glycemic control in type 2 diabetes is not known.
                We evaluated rosiglitazone, metformin, and glyburide as initial treatment for recently diagnosed type 2 diabetes in a double-blind, randomized, controlled clinical trial involving 4360 patients. The patients were treated for a median of 4.0 years. The primary outcome was the time to monotherapy failure, which was defined as a confirmed level of fasting plasma glucose of more than 180 mg per deciliter (10.0 mmol per liter), for rosiglitazone, as compared with metformin or glyburide. Prespecified secondary outcomes were levels of fasting plasma glucose and glycated hemoglobin, insulin sensitivity, and beta-cell function.
                Kaplan-Meier analysis showed a cumulative incidence of monotherapy failure at 5 years of 15% with rosiglitazone, 21% with metformin, and 34% with glyburide. This represents a risk reduction of 32% for rosiglitazone, as compared with metformin, and 63%, as compared with glyburide (P<0.001 for both comparisons). The difference in the durability of the treatment effect was greater between rosiglitazone and glyburide than between rosiglitazone and metformin. Glyburide was associated with a lower risk of cardiovascular events (including congestive heart failure) than was rosiglitazone (P<0.05), and the risk associated with metformin was similar to that with rosiglitazone. Rosiglitazone was associated with more weight gain and edema than either metformin or glyburide but with fewer gastrointestinal events than metformin and with less hypoglycemia than glyburide (P<0.001 for all comparisons).
                The potential risks and benefits, the profile of adverse events, and the costs of these three drugs should all be considered to help inform the choice of pharmacotherapy for patients with type 2 diabetes. (ClinicalTrials.gov number, NCT00279045 [ClinicalTrials.gov].).
                Copyright 2006 Massachusetts Medical Society. The authors investigated the fate of abstracts from each ARVO section (May 1985 meeting), the overall publication percentage, and the journals in which the abstract-derived articles were published.
                They performed a MEDLINE search by first author for 25 or 26 randomly selected abstracts from each section to identify those that led to full-length articles in peer-reviewed journals.
                Overall, 63% of abstracts led to full-length articles in peer-reviewed journals within our search period of 87 months. The publication rate of oral presentation abstracts (68%) was significantly higher than that of poster presentation abstracts (56%). A greater proportion of basic science-oriented abstracts (67%) led to publication than the clinically oriented abstracts (56%). The rate of publication was lowest for the Cornea section (40%) and highest for Physiology and Pharmacology (80%) and Biochemistry (76%). The abstract-derived articles were published in 67 different peer-reviewed journals, with 43% of the articles appearing in only five journals.
                The fact that the majority of abstracts led to full-length articles supports ARVO's goal of a large interdisciplinary appeal with the exchange of ideas among different investigators. Women with twin pregnancy are at high risk for spontaneous preterm delivery. Progesterone seems to be effective in reducing preterm birth in selected high-risk singleton pregnancies, albeit with no significant reduction in perinatal mortality and little evidence of neonatal benefit. We investigated the use of progesterone for prevention of preterm birth in twin pregnancy.
                In this double-blind, placebo-controlled trial, 500 women with twin pregnancy were recruited from nine UK National Health Service clinics specialising in the management of twin pregnancy. Women were randomised, by permuted blocks of randomly mixed sizes, either to daily vaginal progesterone gel 90 mg (n=250) or to placebo gel (n=250) for 10 weeks from 24 weeks' gestation. All study personnel and participants were masked to treatment assignment for the duration of the study. The primary outcome was delivery or intrauterine death before 34 weeks' gestation. Analysis was by intention to treat. Additionally we undertook a meta-analysis of published and unpublished data to establish the efficacy of progesterone in prevention of early (<34 weeks' gestation) preterm birth or intrauterine death in women with twin pregnancy. This study is registered, number ISRCTN35782581.
                Three participants in each group were lost to follow-up, leaving 247 analysed per group. The combined proportion of intrauterine death or delivery before 34 weeks of pregnancy was 24.7% (61/247) in the progesterone group and 19.4% (48/247) in the placebo group (odds ratio [OR] 1.36, 95% CI 0.89-2.09; p=0.16). The rate of adverse events did not differ between the two groups. The meta-analysis confirmed that progesterone does not prevent early preterm birth in women with twin pregnancy (pooled OR 1.16, 95% CI 0.89-1.51).
                Progesterone, administered vaginally, does not prevent preterm birth in women with twin pregnancy.
                Chief Scientist Office of the Scottish Government Health Directorate. Large clinical trials are the criterion standard for making treatment decisions, and nonpublication of the results of such trials can lead to bias in the literature and contribute to inappropriate medical decisions.
                To determine the rate of full publication of large randomized trials presented at annual meetings of the American Society of Clinical Oncology (ASCO), quantify bias against publishing nonsignificant results, and identify factors associated with time to publication.
                Survey of 510 abstracts from large (sample size, > or =200), phase 3, randomized controlled trials presented at ASCO meetings between 1989 and 1998. Trial results were classified as significant (P< or =.05 for the primary outcome measure) or nonsignificant (P>.05 or not reported), and the type of presentation and sponsorship were identified. Subsequent full publication was identified using a search of MEDLINE and EMBASE, completed November 1, 2001; the search was updated in November 2002, using the Cochrane Register of Controlled Trials. Authors were contacted if the searches did not find evidence of publication.
                Publication rate at 5 years; time from presentation to full publication.
                Of 510 randomized trials, 26% were not published in full within 5 years after presentation at the meeting. Eighty-one percent of the studies with significant results had been published by this time compared with 68% of the studies with nonsignificant results (P<.001). Studies with oral or plenary presentation were published sooner than those not presented (P =.002), and studies with pharmaceutical sponsorship were published sooner than studies with cooperative group sponsorship or studies for which sponsorship was not specified (P =.02). These factors remained significant in a multivariable model. The most frequent reason cited by authors for not publishing was lack of time, funds, or other resources.
                A substantial number of large phase 3 trials presented at an international oncology meeting remain unpublished 5 years after presentation. Bias against publishing nonsignificant results is a problem even for large randomized trials. Nonpublication breaks the contract that investigators make with trial participants, funding agencies, and ethics boards. Prospectively planned collection and analysis of adverse event (AE) data are essential parts of well-conducted clinical trials. The AE data in a trial sponsor's database should be comparable with what is stipulated in the protocol and with the AE data published. We examined whether the published AE data differ from those in the sponsor's database and from the data collection requirements stated in study protocols.
                We searched the National Cancer Institute (NCI) Clinical Data Update System (CDUS) for studies that used the Common Toxicity Criteria version 2.0 and for which a final study publication was available. We extracted from the protocols information pertaining to AE collection and reporting methods and compared it with the methods cited in the article. We also compared the AE data in the trial publication with the AE data submitted by the investigators to CDUS.
                We identified 22 studies meeting the criteria for this review. There was considerable inconsistency between AE collection and reporting methods cited in the protocols versus final publications. AE data in the article and CDUS were not identical. Twenty-seven percent of article high-grade AEs could not be matched to agent-attributable AEs in the CDUS. Twenty-eight percent of CDUS high-grade AEs could not be matched to AEs in the corresponding article. In 14 of 22 articles, the number of high-grade AEs in CDUS differed from the number in the articles by 20% or more.
                Lack of consistency in and reporting of AEs are associated with NCI database and trial publication AE data discrepancy. This article investigates the impact NBA basketball star Earvin ("Magic") Johnson's HIV disclosure had on changes in demand for HIV counseling and testing services in New York State's 61 Anonymous HIV Counseling and Testing sites. Interrupted time-series analyses were conducted on weekly data from over 34,000 clients seeking anonymous HIV counseling and testing services from January 1991 to June 1992, to determine whether demand for these services changed as a result of the disclosure. Results indicated that immediately following the HIV disclosure, there was a substantial increase in service demand, which transcended all sex, race, age, and most HIV risk-related boundaries. Seven months later, demand had not returned to pre-disclosure levels. The strong impact on females, coupled with additional data analyses in obstetrical settings, suggests that previous research has been too narrow in focus, and that the effect of Johnson's HIV disclosure has been enhanced, in part, by the publicity surrounding his wife and baby. The importance of harnessing the heightened public awareness of celebrity HIV disclosures is discussed. Registration of clinical trials has been introduced largely to reduce bias toward statistically significant results in the trial literature. Doubts remain about whether advance registration alone is an adequate measure to reduce selective publication, selective outcome reporting, and biased design. One of the first areas of medicine in which registration was widely adopted was oncology, although the bulk of registered oncology trials remain unpublished. The net influence of registration on the literature remains untested. This study compares the prevalence of favorable results and conclusions among published reports of registered and unregistered randomized controlled trials of new oncology drugs.
                We conducted a cross-sectional study of published original research articles reporting clinical trials evaluating the efficacy of drugs newly approved for antimalignancy indications by the United States Food and Drug Administration (FDA) from 2000 through 2005. Drugs receiving first-time approval for indications in oncology were identified using the FDA web site and Thomson Centerwatch. Relevant trial reports were identified using PubMed and the Cochrane Library. Evidence of advance trial registration was obtained by a search of clinicaltrials.gov, WHO, ISRCTN, NCI-PDQ trial databases and corporate trial registries, as well as articles themselves. Data on blinding, results for primary outcomes, and author conclusions were extracted independently by two coders. Univariate and multivariate logistic regression identified associations between favorable results and conclusions and independent variables including advance registration, study design characteristics, and industry sponsorship.
                Of 137 original research reports from 115 distinct randomized trials assessing 25 newly approved drugs for treating cancer, the 54 publications describing data from trials registered prior to publication were as likely to report statistically significant efficacy results and reach conclusions favoring the test drug (for results, OR = 1.77; 95% CI = 0.87 to 3.61) as reports of trials not registered in advance. In multivariate analysis, reports of prior registered trials were again as likely to favor the test drug (OR = 1.29; 95% CI = 0.54 to 3.08); large sample sizes and surrogate outcome measures were statistically significant predictors of favorable efficacy results at p < 0.05. Subgroup analysis of the main reports from each trial (n = 115) similarly indicated that registered trials were as likely to report results favoring the test drug as trials not registered in advance (OR = 1.11; 95% CI = 0.44 to 2.80), and also that large trials and trials with nonstringent blinding were significantly more likely to report results favoring the test drug.
                Trial registration alone, without a requirement for full reporting of research results, does not appear to reduce a bias toward results and conclusions favoring new drugs in the clinical trials literature. Our findings support the inclusion of full results reporting in trial registers, as well as protocols to allow assessment of whether results have been completely reported. We wanted to investigate the frequency of undisclosed changes in the outcomes of randomized controlled trials (RCTs) between trial registration and publication.
                Using a retrospective, nonrandom, cross-sectional study design, we investigated RCTs published in consecutive issues of 5 major medical journals during a 6-month period and their associated trials registry entries. Articles were excluded if they did not have an available trial registry entry, did not have analyzable outcomes, or were secondary publications. The primary outcome was the proportion of publications in which the primary outcome of the trial was, without disclosure, changed between that recorded in the trial registry and that reported in the final publication. The secondary outcome was the proportion of publications in which the secondary outcome was changed without disclosure.
                We reviewed 158 reports of RCTs and included 110 in the analysis. In 34 (31%), a primary outcome had been changed, and in 77 (70%), a secondary outcome had been changed.
                There are substantial and important undisclosed changes made to the outcomes of published RCTs between trial registration and publication. This finding has important implications for the interpretation of trial results. Disclosure and discussion of changes would improve transparency in the performance and reporting of trials.
New studies should focus on patient-oriented outcomes to clarify the benefit-risk ratio of rosiglitazone therapy. Safety data and adverse events of all investigations (published and unpublished) should be made available to the public.