Large-scale randomized evidence: Trials and meta-analyses of trials

Author(s):  
Colin Baigent ◽  
Richard Peto ◽  
Richard Gray ◽  
Natalie Staplin ◽  
Sarah Parish ◽  
...  

Clinical trials generally need to be able to detect or to refute realistically moderate (but still worthwhile) differences between treatments in long-term disease outcome. Large-scale randomized evidence should be able to detect such effects, but medium-sized trials or medium-sized meta-analyses can, and often do, yield false-negative or exaggeratedly positive results. Hundreds of thousands of premature deaths each year could be avoided by seeking appropriately large-scale randomized evidence about various widely practicable treatments for the common causes of death, and by disseminating this evidence appropriately. This chapter takes a look at the use of large-scale randomized evidence—produced from trials and meta-analysis of trials—and how this data should be handled in order to produce accurate result.

2021 ◽  
Author(s):  

ABSTRACTObjectivesEvidence from randomised trials on long-term blood pressure (BP) reduction from pharmacologic treatment is limited. To investigate the effects of antihypertensive drugs on long-term BP change and examine its variation over time and among people with different clinical characteristicsDesignIndividual participant-level data meta-analysisSetting and data sourceThe Blood Pressure Lowering Treatment Trialists’ Collaboration involving 51 large-scale long-term randomised clinical trialsParticipants352,744 people (42% women) with mean age of 65 years and mean baseline systolic/diastolic BP of 152/87 mmHg, of whom 18% were current smokers, 50% had cardiovascular disease, 29% had diabetes, and 72% were taking antihypertensive treatment at baselineInterventionPharmacological BP-lowering treatmentOutcomeDifference in longitudinal changes in systolic and diastolic BP between randomised treatment arms over an average follow-up of four yearsResultDrugs were effective in lowering BP, with the maximum effect becoming apparent after 12-month follow-up and with gradual attenuation towards later years. Based on measures taken ≥12 months post-randomisation, more intense BP-lowering treatment reduced systolic/diastolic BP (95% confidence interval) by −11.2 (−11.4 to −11.0)/−5.6 (−5.8 to −5.5) mmHg than less intense treatment; active treatment by −5.1 (−5.3 to −5.0)/−2.3 (−2.4 to −2.2) mmHg lower than placebo, and active arm by −1.4 (−1.5 to −1.3)/−0.6 (−0.7 to −0.6) mmHg lower than the control arm for drug class comparison trials. BP reductions were consistently observed across a wide range of baseline BP values and ages, and by sex, history of cardiovascular disease and diabetes, and prior antihypertensive treatment use.ConclusionPharmacological agents were effective in lowering long-term BP among individuals with a wide range of characteristics, but the net between-group reductions were modest, which is partly attributable to the intended trial goals.


Heart ◽  
2018 ◽  
pp. heartjnl-2018-313955 ◽  
Author(s):  
Jennifer Susan Lees ◽  
Fiona A Chapman ◽  
Miles D Witham ◽  
Alan G Jardine ◽  
Patrick B Mark

ObjectivesVascular stiffness (VS) and vascular calcification (VC) are surrogate markers of vascular health associated with cardiovascular events. Vitamin K-dependent proteins (VKDP) are associated with VS and VC and require vitamin K for activity. We conducted a systematic review and meta-analysis of: (1) the effect of vitamin K supplementation on VS and VC and (2) association of inactive VKDP levels with incident cardiovascular disease and mortality.MethodsTwo authors searched MEDLINE and Embase databases and Cochrane and ISRCTN registries for studies of vitamin K clinical trials that measured effects on VC, VS or VKDP and longitudinal studies assessing effect of VKDP on incident CVD or mortality. Random effects meta-analyses were performed.ResultsThirteen controlled clinical trials (n=2162) and 14 longitudinal studies (n=10 726) met prespecified inclusion criteria. Vitamin K supplementation was associated with significant reduction in VC (−9.1% (95% CI −17.7 to −0.5); p=0.04) and VKDP (desphospho-uncarboxylated matrix Gla protein; −44.7% (95% CI −65.1 to −24.3), p<0.0001) and uncarboxylated osteocalcin; −12.0% (95% CI −16.7 to −7.2), p<0.0001) compared with control, with a non-significant improvement in VS. In longitudinal studies with median follow-up of 7.8 (IQR 4.9–11.3) years, VKDP levels were associated with a combined endpoint of CVD or mortality (HR 0.45 (95% CI 0.07 to 0.83), p=0.02).ConclusionsSupplementation with vitamin K significantly reduced VC, but not VS, compared with control. The conclusions drawn are limited by small numbers of studies with substantial heterogeneity. VKDP was associated with combined endpoint of CVD or mortality. Larger clinical trials of effect of vitamin K supplementation to improve VC, VS and long-term cardiovascular health are warranted.Trial registration numberCRD42017060344.


2019 ◽  
Author(s):  
Amanda Kvarven ◽  
Eirik Strømland ◽  
Magnus Johannesson

Andrews &amp; Kasy (2019) propose an approach for adjusting effect sizes in meta-analysis for publication bias. We use the Andrews-Kasy estimator to adjust the result of 15 meta-analyses and compare the adjusted results to 15 large-scale multiple labs replication studies estimating the same effects. The pre-registered replications provide precisely estimated effect sizes, which do not suffer from publication bias. The Andrews-Kasy approach leads to a moderate reduction of the inflated effect sizes in the meta-analyses. However, the approach still overestimates effect sizes by a factor of about two or more and has an estimated false positive rate of between 57% and 100%.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sandra Lopez-Leon ◽  
Talia Wegman-Ostrosky ◽  
Carol Perelman ◽  
Rosalinda Sepulveda ◽  
Paulina A. Rebolledo ◽  
...  

AbstractCOVID-19 can involve persistence, sequelae, and other medical complications that last weeks to months after initial recovery. This systematic review and meta-analysis aims to identify studies assessing the long-term effects of COVID-19. LitCOVID and Embase were searched to identify articles with original data published before the 1st of January 2021, with a minimum of 100 patients. For effects reported in two or more studies, meta-analyses using a random-effects model were performed using the MetaXL software to estimate the pooled prevalence with 95% CI. PRISMA guidelines were followed. A total of 18,251 publications were identified, of which 15 met the inclusion criteria. The prevalence of 55 long-term effects was estimated, 21 meta-analyses were performed, and 47,910 patients were included (age 17–87 years). The included studies defined long-COVID as ranging from 14 to 110 days post-viral infection. It was estimated that 80% of the infected patients with SARS-CoV-2 developed one or more long-term symptoms. The five most common symptoms were fatigue (58%), headache (44%), attention disorder (27%), hair loss (25%), and dyspnea (24%). Multi-disciplinary teams are crucial to developing preventive measures, rehabilitation techniques, and clinical management strategies with whole-patient perspectives designed to address long COVID-19 care.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chengxin Luo ◽  
Li Wang ◽  
Guixian Wu ◽  
Xiangtao Huang ◽  
Yali Zhang ◽  
...  

Abstract Background Mobilization failure may occur when the conventional hematopoietic stem cells (HSCs) mobilization agent granulocyte colony-stimulating factor (G-CSF) is used alone, new regimens were developed to improve mobilization efficacy. Multiple studies have been performed to investigate the efficacy of these regimens via animal models, but the results are inconsistent. We aim to compare the efficacy of different HSC mobilization regimens and identify new promising regimens with a network meta-analysis of preclinical studies. Methods We searched Medline and Embase databases for the eligible animal studies that compared the efficacy of different HSC mobilization regimens. Primary outcome is the number of total colony-forming cells (CFCs) in per milliliter of peripheral blood (/ml PB), and the secondary outcome is the number of Lin− Sca1+ Kit+ (LSK) cells/ml PB. Bayesian network meta-analyses were performed following the guidelines of the National Institute for Health and Care Excellence Decision Support Unit (NICE DSU) with WinBUGS version 1.4.3. G-CSF-based regimens were classified into the SD (standard dose, 200–250 μg/kg/day) group and the LD (low dose, 100–150 μg/kg/day) group based on doses, and were classified into the short-term (2–3 days) group and the long-term (4–5 days) group based on administration duration. Long-term SD G-CSF was chosen as the reference treatment. Results are presented as the mean differences (MD) with the associated 95% credibility interval (95% CrI) for each regimen. Results We included 95 eligible studies and reviewed the efficacy of 94 mobilization agents. Then 21 studies using the poor mobilizer mice model (C57BL/6 mice) to investigate the efficacy of different mobilization regimens were included for network meta-analysis. Network meta-analyses indicated that compared with long-term SD G-CSF alone, 14 regimens including long-term SD G-CSF + Me6, long-term SD G-CSF + AMD3100 + EP80031, long-term SD G-CSF + AMD3100 + FG-4497, long-term SD G-CSF + ML141, long-term SD G-CSF + desipramine, AMD3100 + meloxicam, long-term SD G-CSF + reboxetine, AMD3100 + VPC01091, long-term SD G-CSF + FG-4497, Me6, long-term SD G-CSF + EP80031, POL5551, long-term SD G-CSF + AMD3100, AMD1300 + EP80031 and long-term LD G-CSF + meloxicam significantly increased the collections of total CFCs. G-CSF + Me6 ranked first among these regimens in consideration of the number of harvested CFCs/ml PB (MD 2168.0, 95% CrI 2062.0−2272.0). In addition, 7 regimens including long-term SD G-CSF + AMD3100, AMD3100 + EP80031, long-term SD G-CSF + EP80031, short-term SD G-CSF + AMD3100 + IL-33, long-term SD G-CSF + ML141, short-term LD G-CSF + ARL67156, and long-term LD G-CSF + meloxicam significantly increased the collections of LSK cells compared with G-CSF alone. Long-term SD G-CSF + AMD3100 ranked first among these regimens in consideration of the number of harvested LSK cells/ml PB (MD 2577.0, 95% CrI 2422.0–2733.0). Conclusions Considering the number of CFC and LSK cells in PB as outcomes, G-CSF plus AMD3100, Me6, EP80031, ML141, FG-4497, IL-33, ARL67156, meloxicam, desipramine, and reboxetine are all promising mobilizing regimens for future investigation.


Healthcare ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 396
Author(s):  
Purificación Cerrato-Carretero ◽  
Raúl Roncero-Martín ◽  
Juan D. Pedrera-Zamorano ◽  
Fidel López-Espuela ◽  
Luis M. Puerto-Parejo ◽  
...  

Preventive actions and potential obesity interventions for children are mainly researched throughout the school period, either as part of the school curricula or after regular school hours, via interventions mostly lasting less than 12 months. We aimed to perform a meta-analysis on randomized controlled clinical trials to evaluate the evidence of the efficacy of long-term school-based interventions in the management of childhood obesity in terms of BMI from a dietary and physical activity-based approach. Eleven randomized controlled clinical trials were examined using the random effects model, and the results showed that there were no significant effects associated with physical activity + nutrition intervention in school children aged 6–12 years, with a pooled standardized mean difference (SMD) (95% CI) of −0.00 (−0.05, 0.04). No effects were observed after subgroup analysis based on the intervention length. The findings from our study indicate that long-term school-based interventions on physical activity and dietary habits received by children aged 6–12 years seem to have no effect on BMI. However, the promotion of such interventions should not be discouraged, as they promote additional positive health outcomes for other domains of children’s health.


2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yu Chen ◽  
Shaobin Wei ◽  
Li Huang ◽  
Mei Luo ◽  
Yang Wu ◽  
...  

Background. Pelvic inflammatory disease (PID) without timely and proper treatment can cause long-term sequelae; meanwhile, patients will be confronted with the antimicrobial resistance and side effects. Chinese patent medicine as a supplement is used to treat PID with satisfactory clinical efficacy. This study evaluated the efficacy and safety of Fuke Qianjin (FKQJ) combined with antibiotics in the treatment of PID. Methods. Eight electronic databases and other resources were searched to make a collection of the randomized controlled trials (RCTs) from 1990 to 2019. The RCTs contrasting the effect of FKQJ combined with antibiotics regimens and antibiotics alone in reproductive women with PID were included. The antibiotics regimens are all recommended by the guidelines. Two reviewers independently screened the studies, extracted the data, and assessed the methodological quality of the included studies. Then, the meta-analyses were performed by RevMan 5. 3 software if appropriate. Results. Twenty-three RCTs (2527 women) were included in this review. The evidence showed that FKQJ combined with antibiotics improved the markedly effective rate compared to antibiotics alone group (RR = 1.38, 95% CI 1.27 to 1.49, I2 = 42%), shortened the improvement time of low abdominal pain (MD = −1.11, 95% CI −1.39 to −0.84, I2 = 38%), and increased the rate of lower abdominal pain improvement (RR = 1.35, 95% CI 1.19 to 1.55, I2 = 0). The implementation of adjuvant reduced the recurrent rate compared with antibiotics alone (RR = 0.27, 95% CI 0.13 to 0.56, I2 = 0%). Conclusions. Based on available evidence, FKQJ combined with antibiotics therapy have certain outcomes on increasing the markedly effective rate, decreasing the recurrent rate compared with antibiotics alone group. This therapy appears to improve lower abdominal pain and curtail the relief time. Due to the low quality and the risk of bias, any high-quality evidence or longer follow-up period should be advisable and necessary in the future.


2021 ◽  
Vol 28 ◽  
Author(s):  
Douglas Henrique Pereira Damasceno ◽  
Arthur Aguiar Amaral ◽  
Cecília Andrade Silva ◽  
Ana Cristina Simões e Silva

Background: The COVID-19 pandemic demanded a global effort towards quickly developing safe and effective vaccines against SARS-CoV-2. Objective: This review aimed to discuss the main vaccines available, their mechanisms of action, results of clinical trials and epidemiological behavior. The implications of viral variants were also debated. Methods: A non-systematic literature review was performed between February and March 2021 by searching the Pubmed, Scopus, and SciELO databases, using different combinations of the following terms: "vaccines", "clinical trials" , "SARS-CoV-2", "Coronavirus", "COVID-19", "mechanisms of action". Data regarding clinical trials of SARS-CoV-2 vaccines and epidemiological information were also searched. Results: The mechanisms of action included vector-virus, mRNA and inactivated virus vaccines. The vaccines showed positive results in phases 2/3 clinical trials. The efficacy of the mRNA 1273 and of mRNA BNT 162b2 vaccines were 94.1% and 95%, respectively. The effectiveness of the ChAdOx1 nCoV-19 vaccine varied according to the scheme, with an overall value of 70.4%. The Gam-COVID-Vac vaccine had an efficacy of 91.6%. Regarding the Ad26.COV2.S vaccine, 99% or more of seroconversion was observed in all subgroups 29 days after vaccination. The CoronaVac vaccine induced an immune response in 92% of the volunteers receiving 3ug and in 98% with 6ug, in comparison to 3% in the placebo group. Conclusion: Global efforts have resulted in vaccines available in record time, with good safety and immunogenicity profile. However, only long-term studies can provide more information on duration of immunity and the need for additional doses.


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