The belief remains widespread that medical research studies must have statistical power of at least 80% in order to be scientifically sound, and peer reviewers often question whether power is high ...enough.
This requirement and the methods for meeting it have severe flaws. Notably, the true nature of how sample size influences a study's projected scientific or practical value precludes any meaningful blanket designation of <80% power as "inadequate". In addition, standard calculations are inherently unreliable, and focusing only on power neglects a completed study's most important results: estimates and confidence intervals. Current conventions harm the research process in many ways: promoting misinterpretation of completed studies, eroding scientific integrity, giving reviewers arbitrary power, inhibiting innovation, perverting ethical standards, wasting effort, and wasting money. Medical research would benefit from alternative approaches, including established value of information methods, simple choices based on cost or feasibility that have recently been justified, sensitivity analyses that examine a meaningful array of possible findings, and following previous analogous studies. To promote more rational approaches, research training should cover the issues presented here, peer reviewers should be extremely careful before raising issues of "inadequate" sample size, and reports of completed studies should not discuss power.
Common conventions and expectations concerning sample size are deeply flawed, cause serious harm to the research process, and should be replaced by more rational alternatives.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Previous studies of drug trials submitted to regulatory authorities have documented selective reporting of both entire trials and favorable results. The objective of this study is to determine the ...publication rate of efficacy trials submitted to the Food and Drug Administration (FDA) in approved New Drug Applications (NDAs) and to compare the trial characteristics as reported by the FDA with those reported in publications.
This is an observational study of all efficacy trials found in approved NDAs for New Molecular Entities (NMEs) from 2001 to 2002 inclusive and all published clinical trials corresponding to the trials within the NDAs. For each trial included in the NDA, we assessed its publication status, primary outcome(s) reported and their statistical significance, and conclusions. Seventy-eight percent (128/164) of efficacy trials contained in FDA reviews of NDAs were published. In a multivariate model, trials with favorable primary outcomes (OR = 4.7, 95% confidence interval CI 1.33-17.1, p = 0.018) and active controls (OR = 3.4, 95% CI 1.02-11.2, p = 0.047) were more likely to be published. Forty-one primary outcomes from the NDAs were omitted from the papers. Papers included 155 outcomes that were in the NDAs, 15 additional outcomes that favored the test drug, and two other neutral or unknown additional outcomes. Excluding outcomes with unknown significance, there were 43 outcomes in the NDAs that did not favor the NDA drug. Of these, 20 (47%) were not included in the papers. The statistical significance of five of the remaining 23 outcomes (22%) changed between the NDA and the paper, with four changing to favor the test drug in the paper (p = 0.38). Excluding unknowns, 99 conclusions were provided in both NDAs and papers, nine conclusions (9%) changed from the FDA review of the NDA to the paper, and all nine did so to favor the test drug (100%, 95% CI 72%-100%, p = 0.0039).
Many trials were still not published 5 y after FDA approval. Discrepancies between the trial information reviewed by the FDA and information found in published trials tended to lead to more favorable presentations of the NDA drugs in the publications. Thus, the information that is readily available in the scientific literature to health care professionals is incomplete and potentially biased.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
HIV persists in a small pool of latently infected cells despite antiretroviral therapy (ART). Identifying cellular markers expressed at the surface of these cells may lead to novel therapeutic ...strategies to reduce the size of the HIV reservoir. We hypothesized that CD4+ T cells expressing immune checkpoint molecules would be enriched in HIV-infected cells in individuals receiving suppressive ART. Expression levels of 7 immune checkpoint molecules (PD-1, CTLA-4, LAG-3, TIGIT, TIM-3, CD160 and 2B4) as well as 4 markers of HIV persistence (integrated and total HIV DNA, 2-LTR circles and cell-associated unspliced HIV RNA) were measured in PBMCs from 48 virally suppressed individuals. Using negative binomial regression models, we identified PD-1, TIGIT and LAG-3 as immune checkpoint molecules positively associated with the frequency of CD4+ T cells harboring integrated HIV DNA. The frequency of CD4+ T cells co-expressing PD-1, TIGIT and LAG-3 independently predicted the frequency of cells harboring integrated HIV DNA. Quantification of HIV genomes in highly purified cell subsets from blood further revealed that expressions of PD-1, TIGIT and LAG-3 were associated with HIV-infected cells in distinct memory CD4+ T cell subsets. CD4+ T cells co-expressing the three markers were highly enriched for integrated viral genomes (median of 8.2 fold compared to total CD4+ T cells). Importantly, most cells carrying inducible HIV genomes expressed at least one of these markers (median contribution of cells expressing LAG-3, PD-1 or TIGIT to the inducible reservoir = 76%). Our data provide evidence that CD4+ T cells expressing PD-1, TIGIT and LAG-3 alone or in combination are enriched for persistent HIV during ART and suggest that immune checkpoint blockers directed against these receptors may represent valuable tools to target latently infected cells in virally suppressed individuals.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The United States (US) Food and Drug Administration (FDA) approves new drugs based on sponsor-submitted clinical trials. The publication status of these trials in the medical literature and factors ...associated with publication have not been evaluated. We sought to determine the proportion of trials submitted to the FDA in support of newly approved drugs that are published in biomedical journals that a typical clinician, consumer, or policy maker living in the US would reasonably search.
We conducted a cohort study of trials supporting new drugs approved between 1998 and 2000, as described in FDA medical and statistical review documents and the FDA approved drug label. We determined publication status and time from approval to full publication in the medical literature at 2 and 5 y by searching PubMed and other databases through 01 August 2006. We then evaluated trial characteristics associated with publication. We identified 909 trials supporting 90 approved drugs in the FDA reviews, of which 43% (394/909) were published. Among the subset of trials described in the FDA-approved drug label and classified as "pivotal trials" for our analysis, 76% (257/340) were published. In multivariable logistic regression for all trials 5 y postapproval, likelihood of publication correlated with statistically significant results (odds ratio OR 3.03, 95% confidence interval CI 1.78-5.17); larger sample sizes (OR 1.33 per 2-fold increase in sample size, 95% CI 1.17-1.52); and pivotal status (OR 5.31, 95% CI 3.30-8.55). In multivariable logistic regression for only the pivotal trials 5 y postapproval, likelihood of publication correlated with statistically significant results (OR 2.96, 95% CI 1.24-7.06) and larger sample sizes (OR 1.47 per 2-fold increase in sample size, 95% CI 1.15-1.88). Statistically significant results and larger sample sizes were also predictive of publication at 2 y postapproval and in multivariable Cox proportional models for all trials and the subset of pivotal trials.
Over half of all supporting trials for FDA-approved drugs remained unpublished >/= 5 y after approval. Pivotal trials and trials with statistically significant results and larger sample sizes are more likely to be published. Selective reporting of trial results exists for commonly marketed drugs. Our data provide a baseline for evaluating publication bias as the new FDA Amendments Act comes into force mandating basic results reporting of clinical trials.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Published pharmaceutical industry-sponsored trials are more likely than non-industry-sponsored trials to report results and conclusions that favor drug over placebo. Little is known about potential ...biases in drug-drug comparisons. This study examined associations between research funding source, study design characteristics aimed at reducing bias, and other factors that potentially influence results and conclusions in randomized controlled trials (RCTs) of statin-drug comparisons.
This is a cross-sectional study of 192 published RCTs comparing a statin drug to another statin drug or non-statin drug. Data on concealment of allocation, selection bias, blinding, sample size, disclosed funding source, financial ties of authors, results for primary outcomes, and author conclusions were extracted by two coders (weighted kappa 0.80 to 0.97). Univariate and multivariate logistic regression identified associations between independent variables and favorable results and conclusions. Of the RCTs, 50% (95/192) were funded by industry, and 37% (70/192) did not disclose any funding source. Looking at the totality of available evidence, we found that almost all studies (98%, 189/192) used only surrogate outcome measures. Moreover, study design weaknesses common to published statin-drug comparisons included inadequate blinding, lack of concealment of allocation, poor follow-up, and lack of intention-to-treat analyses. In multivariate analysis of the full sample, trials with adequate blinding were less likely to report results favoring the test drug, and sample size was associated with favorable conclusions when controlling for other factors. In multivariate analysis of industry-funded RCTs, funding from the test drug company was associated with results (odds ratio = 20.16 95% confidence interval 4.37-92.98, p < 0.001) and conclusions (odds ratio = 34.55 95% confidence interval 7.09-168.4, p < 0.001) that favor the test drug when controlling for other factors. Studies with adequate blinding were less likely to report statistically significant results favoring the test drug.
RCTs of head-to-head comparisons of statins with other drugs are more likely to report results and conclusions favoring the sponsor's product compared to the comparator drug. This bias in drug-drug comparison trials should be considered when making decisions regarding drug choice.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Rituximab is an anti-CD20 monoclonal antibody approved for non Hodgkin lymphoma and rheumatoid arthritis. It is being considered for the treatment of MS.
To evaluate the efficacy and safety of ...rituximab for MS treatment.
Studies were selected if they were clinical trials, irrespective of the dosage or combination therapies.
Four studies with a total of 599 patients were included. One assessed the efficacy of rituximab for primary progressive (PP) MS while the other three focused on relapsing-remitting (RR) MS. In the PPMS study, rituximab delayed time to confirmed disease progression (CDP) in pre-planned sub-group analyses. The increase in T2 lesion volume was lower in the rituximab group at week 96 compared with placebo. For the RRMS studies, an open-label phase I study found that rituximab reduced the annualized relapse rate to 0.25 from pre-therapy baseline to week 24, while in the randomized placebo-controlled phase II trial, annualized relapse rates were 0.37 in the rituximab group and 0.84 in the placebo group (p = 0.04) at week 24. Rituximab dramatically reduced the number of gadolinium-enhancing lesions on brain MRI scans for both RRMS studies. Off-label rituximab as an add-on therapy in patients with breakthrough disease on first-line agents was associated with an 88% reduction when comparing the mean number of gadolinium-enhancing lesions prior to and after the treatment. Although frequent adverse events classified as mild or moderate occurred in up to 77% of the patients, there were no grade 4 infusion-related adverse events. AUTHOR’S CONCLUSION: Despite the frequent mild/moderate adverse events related to the drug, rituximab appears overall safe for up to 2 years of therapy and has a substantial impact on the inflammatory disease activity (clinical and/or radiological) of RRMS. The effect of rituximab on disease progression in PPMS appears to be marginal.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The source and dynamics of persistent HIV-1 during long-term combinational antiretroviral therapy (cART) are critical to understanding the barriers to curing HIV-1 infection. To address this issue, ...we isolated and genetically characterized HIV-1 DNA from naïve and memory T cells from peripheral blood and gut-associated lymphoid tissue (GALT) from eight patients after 4–12 y of suppressive cART. Our detailed analysis of these eight patients indicates that persistent HIV-1 in peripheral blood and GALT is found primarily in memory CD4 ⁺ T cells CD45RO ⁺/CD27(⁺/⁻). The HIV-1 infection frequency of CD4 ⁺ T cells from peripheral blood and GALT was higher in patients who initiated treatment during chronic compared with acute/early infection, indicating that early initiation of therapy results in lower HIV-1 reservoir size in blood and gut. Phylogenetic analysis revealed an HIV-1 genetic change between RNA sequences isolated before initiation of cART and intracellular HIV-1 sequences from the T-cell subsets after 4–12 y of suppressive cART in four of the eight patients. However, evolutionary rate analyses estimated no greater than three nucleotide substitutions per gene region analyzed during all of the 4–12 y of suppressive therapy. We also identified a clearly replication-incompetent viral sequence in multiple memory T cells in one patient, strongly supporting asynchronous cell replication of a cell containing integrated HIV-1 DNA as the source. This study indicates that persistence of a remarkably stable population of infected memory cells will be the primary barrier to a cure, and, with little evidence of viral replication, this population could be maintained by homeostatic cell proliferation or other processes.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
In vitro, disulfiram activated HIV transcription in a primary T-cell model of HIV latency and in a pilot clinical study increased plasma HIV RNA in individuals with adequate drug exposure. We ...assessed the effect of disulfiram on HIV transcription in a dose-escalation study.
In this prospective dose-escalation study, to optimise disulfiram exposure we included adults with HIV on suppressive antiretroviral therapy, with plasma HIV RNA of less than 50 copies per mL and a CD4 cell count greater than 350 cells per μL. Participants were allocated sequentially to one of three dosing groups (500 mg, 1000 mg, and 2000 mg) and received disulfiram daily for 3 days. Only the staff who did laboratory assays were masked to group assignment. The primary endpoint was change in cell-associated unspliced HIV RNA in CD4 cells. The primary analysis method was a negative binomial regression, with the number of copies as the outcome variable and the input total RNA or plasma volume as an exposure variable, which is equivalent to modelling copies or input. We used these models to estimate changes from before disulfiram to timepoints during and after disulfiram administration. This study is registered with ClinicalTrials.gov, number NCT01944371.
Of 34 participants screened for eligibility at The Alfred Hospital (Melbourne, VIC, Australia), and San Francisco General Hospital (San Francisco, CA, USA), 30 people were enrolled between Sept 24, 2013, and March 31, 2014. The estimated fold increases in cell-associated unspliced HIV RNA from baseline were 1·7 (95% CI 1·3-2·2; p<0·0001) to the timepoint during disulfiram treatment and 2·1 (1·5-2·9; p<0·0001) to the timepoint after disulfiram in the 500 mg group; 1·9 (1·6-2·4; p<0·0001) and 2·5 (1·9-3·3; p<0·0001) in the 1000 mg group; and 1·6 (1·2-2·1; p=0·0026) and 2·1 (1·5-3·1; p=0·0001) in the 2000 mg group. No deaths occurred, and no serious adverse events were noted. Disulfiram was well tolerated at all doses.
Short-term administration of disulfiram resulted in increases in cell-associated unspliced HIV RNA at all doses, consistent with activating HIV latency. Disulfiram may be suited for future studies of combination and prolonged therapy to activate latent HIV.
The Foundation for AIDS Research (amfAR); National Institute of Allergy and Infectious Diseases, National Institutes of Health; Australian National Health and Medical Research Council.
Intrahepatic cholestasis of pregnancy (ICP) has important fetal implications. There is increased risk for poor fetal outcomes, including preterm delivery, meconium staining of amniotic fluid, ...respiratory distress, fetal distress and demise.
One hundred and one women diagnosed with ICP between January 2005 and March 2009 at San Francisco General Hospital were included in this study. Single predictor logistic regression models were used to assess the associations of maternal clinical and biochemical predictors with fetal complications. Clinical predictors analyzed included age, race/ethnicity, gravidity, parity, history of liver or biliary disease, history of ICP in previous pregnancies, and induction. Biochemical predictors analyzed included serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin, direct bilirubin, albumin, total protein, and total bile acids (TBA).
The prevalence of ICP was 1.9%. Most were Latina (90%). Labor was induced in the majority (87%) and most were delivered by normal spontaneous vaginal delivery (84%). Fetal complications occurred in 33% of the deliveries, with respiratory distress accounting for the majority of complications. There were no statistically significant clinical or biochemical predictors associated with an increased risk of fetal complications. Elevated TBA had little association with fetal complications until reaching greater than 100 µmoL/L, with 3 out of 5 having reported complications. ICP in previous pregnancies was associated with decreased risk of fetal complications (OR 0.21, p = 0.046). There were no cases of late term fetal demise.
Maternal clinical and laboratory features, including elevated TBA, did not appear to be substantial predictors of fetal complications in ICP.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related mortality. To determine TRALI incidence by prospective, active surveillance and to identify risk factors by a ...case-control study, 2 academic medical centers enrolled 89 cases and 164 transfused controls. Recipient risk factors identified by multivariate analysis were higher IL-8 levels, liver surgery, chronic alcohol abuse, shock, higher peak airway pressure while being mechanically ventilated, current smoking, and positive fluid balance. Transfusion risk factors were receipt of plasma or whole blood from female donors (odds ratio = 4.5, 95% confidence interval CI, 1.85-11.2, P = .001), volume of HLA class II antibody with normalized background ratio more than 27.5 (OR = 1.92/100 mL, 95% CI, 1.08-3.4, P = .03), and volume of anti–human neutrophil antigen positive by granulocyte immunofluoresence test (OR = 1.71/100 mL, 95% CI, 1.18-2.5, P = .004). Little or no risk was associated with older red blood cell units, noncognate or weak cognate class II antibody, or class I antibody. Reduced transfusion of plasma from female donors was concurrent with reduced TRALI incidence: 2.57 (95% CI, 1.72-3.86) in 2006 versus 0.81 (95% CI, 0.44-1.49) in 2009 per 10 000 transfused units (P = .002). The identified risk factors provide potential targets for reducing residual TRALI.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
