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Medicine Aug 2016Placebo, defined as "false treatment," is a common gold-standard method to assess the validity of a therapy both in pharmacological trials and manual medicine research... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Placebo, defined as "false treatment," is a common gold-standard method to assess the validity of a therapy both in pharmacological trials and manual medicine research where placebo is also referred to as "sham therapy." In the medical literature, guidelines have been proposed on how to conduct robust placebo-controlled trials, but mainly in a drug-based scenario. In contrast, there are not precise guidelines on how to conduct a placebo-controlled in manual medicine trials (particularly osteopathy). The aim of the present systematic review was to report how and what type of sham methods, dosage, operator characteristics, and patient types were used in osteopathic clinical trials and, eventually, assess sham clinical effectiveness.
METHODS
A systematic Cochrane-based review was conducted by analyzing the osteopathic trials that used both manual and nonmanual placebo control. Searches were conducted on 8 databases from journal inception to December 2015 using a pragmatic literature search approach. Two independent reviewers conducted the study selection and data extraction for each study. The risk of bias was evaluated according to the Cochrane methods.
RESULTS
A total of 64 studies were eligible for analysis collecting a total of 5024 participants. More than half (43 studies) used a manual placebo; 9 studies used a nonmanual placebo; and 12 studies used both manual and nonmanual placebo. Data showed lack of reporting sham therapy information across studies. Risk of bias analysis demonstrated a high risk of bias for allocation, blinding of personnel and participants, selective, and other bias. To explore the clinical effects of sham therapies used, a quantitative analysis was planned. However, due to the high heterogeneity of sham approaches used no further analyses were performed.
CONCLUSION
High heterogeneity regarding placebo used between studies, lack of reporting information on placebo methods and within-study variability between sham and real treatment procedures suggest prudence in reading and interpreting study findings in manual osteopathic randomized controlled trials (RCTs). Efforts must be made to promote guidelines to design the most reliable placebo for manual RCTs as a means of increasing the internal validity and improve external validity of findings.
Topics: Controlled Clinical Trials as Topic; Humans; Osteopathic Medicine; Placebo Effect
PubMed: 27583913
DOI: 10.1097/MD.0000000000004728 -
Journal of Advanced Veterinary and... Jun 2023Recent clinical studies suggest that oxidative stress is one of the key players in the pathogenesis of coronavirus disease 2019 (COVID-19), and N-acetylcysteine (NAC), a...
OBJECTIVES
Recent clinical studies suggest that oxidative stress is one of the key players in the pathogenesis of coronavirus disease 2019 (COVID-19), and N-acetylcysteine (NAC), a potent antioxidant, has been shown to improve clinical outcomes in COVID-19 patients. We conducted a systematic review and meta-analysis of the literature published on the therapeutic intervention of NAC on COVID-19 infection.
METHODS
We searched PubMed, Google Scholar, and Science Direct. We identified and screened eight studies with 20,503 participants, including 2,852 in the NAC-treated group and 17,651 in the placebo group, which reported the effect of NAC on COVID-19 infection. A meta-analysis was performed using forest plots under fixed effect estimates based on the standardized mean difference (SMD) and risk ratio (RR).
RESULTS
Pooled analysis showed that NAC was associated with lower mortality in patients with COVID-19 compared with the placebo group [RR, 0.65; (95% CI: 0.56 to 0.75); < 0.0001]. Similarly, C-reactive protein (CRP) [SMD, -0.32; (95% CI: -56 to -0.09); = 0.0070] and D-dimer [SMD, -0.35, (95% CI: -0.59 to -0.10; 0.0062] levels were significantly decreased, and the oxygenation marker, PaO/FiO ratio, was increased in the NAC-treated group compared with the placebo group [SMD, 0.76; (95% CI: 0.48 to 1.03); < 0.0001].
CONCLUSION
Although the number of included studies was minimal, this meta-analysis suggests that NAC may have a positive effect on COVID-19 outcomes, specifically, a significant decrease in CRP and D-dimer levels and a significant increase in oxygen saturation, which decreased mortality. We have also presented a comprehensive review of the role and mechanisms of NAC in patients with COVID-19.
PubMed: 37534078
DOI: 10.5455/javar.2023.j665 -
The Cochrane Database of Systematic... Nov 2022Antidepressants may be useful in the treatment of abnormal crying associated with stroke. This is an update of a Cochrane Review first published in 2004 and last updated... (Review)
Review
BACKGROUND
Antidepressants may be useful in the treatment of abnormal crying associated with stroke. This is an update of a Cochrane Review first published in 2004 and last updated in 2019.
OBJECTIVES
To evaluate the benefits and harms of pharmaceutical treatment in people with emotionalism after stroke.
SEARCH METHODS
We searched the Cochrane Stroke Group Register, CENTRAL, MEDLINE, Embase, four other databases, and three trials registers (May 2022).
SELECTION CRITERIA
We included randomised controlled trials (RCTs) and quasi-RCTs comparing psychotropic medication to placebo in people with stroke and emotionalism (also known as emotional lability, pathological crying or laughing, emotional incontinence, involuntary emotional expression disorder, and pseudobulbar affect).
DATA COLLECTION AND ANALYSIS
Two review authors independently selected trials, assessed risk of bias, extracted data from all included trials, and used GRADE to assess the certainty of the body of evidence. We calculated the mean difference (MD) or standardised mean difference (SMD) for continuous data and the risk ratio (RR) for dichotomous data, with 95% confidence intervals (CIs). We assessed heterogeneity using the I statistic. The primary emotionalism measures were the proportion of participants achieving at least a 50% reduction in abnormal emotional behaviour at the end of treatment, improved score on the Center for Neurologic Study - Lability Scale (CNS-LS) or Clinician Interview-Based Impression of Change (CIBIC), or diminished tearfulness.
MAIN RESULTS
We did not identify any new trials for this update. We included seven trials with a total of 239 participants. Two trials had a cross-over design, but outcome data were not available from the first phase (precross-over) in an appropriate format for inclusion as a parallel randomised controlled trial (RCT). Thus, the results of the review are based on five trials with a total of 213 participants. It is uncertain whether fluoxetine increases the number of people who have a 50% reduction in emotionalism when compared to placebo (risk ratio (RR) 0.26, 95% CI 0.09 to 0.77; P = 0.02; 1 trial, 19 participants) because the certainty of evidence is very low. Sertraline may lead to little to no difference in Center for Neurologic Study - Lability Scale (CNS-LS) scores and Clinician Interview-Based Impression of Change (CIBIC) scores when compared to placebo (RR 0.20, 95% CI 0.03 to 1.50; P = 0.12; 1 trial, 28 participants; low-certainty evidence). Antidepressants probably increase the number of people who experience a reduction in tearfulness (RR 0.32, 95% CI 0.12 to 0.86; P = 0.02; 3 trials, 164 participants; moderate-certainty evidence). No trials were found that evaluated the impact of other pharmaceutical interventions. Only two trial authors systematically recorded and reported adverse events, resulting in limited data on the potential harms of treatment. Six trials reported death as an adverse event and found no difference between the groups (antidepressants versus placebo) in the number of deaths reported (RR 0.59, 95% CI 0.08 to 4.50; P = 0.61; 172 participants; moderate-certainty evidence). This review provides very low- to moderate-certainty evidence that antidepressants may reduce the frequency and severity of emotionalism. The included trials were small and had some degree of bias.
AUTHORS' CONCLUSIONS
Antidepressants may reduce the frequency and severity of crying or laughing episodes when compared to placebo, based on very low-certainty evidence. Our conclusions must be qualified by several methodological deficiencies in the trials and interpreted with caution despite the effect being very large. The effect does not seem specific to one drug or class of drugs. More reliable data are required before appropriate conclusions can be made about the treatment of post-stroke emotionalism. Future trialists investigating the effect of antidepressants in people with emotionalism after stroke should consider developing and using a standardised method to diagnose emotionalism, determine severity, and assess change over time; provide treatment for a sufficient duration and follow-up to better assess rates of relapse or maintenance; and include careful assessment and complete reporting of adverse events.
Topics: Humans; Stroke; Crying; Emotions; Antidepressive Agents; Pharmaceutical Preparations; Randomized Controlled Trials as Topic
PubMed: 36394565
DOI: 10.1002/14651858.CD003690.pub5 -
The Cochrane Database of Systematic... Jun 2023Premenstrual syndrome (PMS) is a common problem. Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome. Combined oral contraceptives (COC),... (Review)
Review
BACKGROUND
Premenstrual syndrome (PMS) is a common problem. Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome. Combined oral contraceptives (COC), which provide both progestin and oestrogen, have been examined for their ability to relieve premenstrual symptoms. A combined oral contraceptive containing drospirenone and a low oestrogen dose has been approved for treating PMDD in women who choose combined oral contraceptives for contraception.
OBJECTIVES
To evaluate the effectiveness and safety of COCs containing drospirenone in women with PMS.
SEARCH METHODS
We searched the Cochrane Gynaecology and Fertility Group trial register, CENTRAL (now containing output from two trials registers and CINAHL), MEDLINE, Embase, PsycINFO, LILACS, Google Scholar, and Epistemonikos on 29 June 2022. We checked included studies' reference lists and contacted study authors and experts in the field to identify additional studies.
SELECTION CRITERIA
We included randomised controlled trials (RCT) that compared COCs containing drospirenone with placebo or with another COC for treatment of women with PMS.
DATA COLLECTION AND ANALYSIS
We used standard methodological procedures recommended by Cochrane. The primary review outcomes were effects on premenstrual symptoms that were prospectively recorded, and withdrawal due to adverse events. Secondary outcomes included effects on mood, adverse events, and response rate to study medications.
MAIN RESULTS
We included five RCTs (858 women analysed, most diagnosed with PMDD). The evidence was very low to moderate quality; the main limitations were serious risk of bias due to poor reporting of study methods, and serious inconsistency and imprecision. COCs containing drospirenone and ethinylestradiol (EE) versus placebo COCs containing drospirenone and EE may improve overall premenstrual symptoms (standardised mean difference (SMD) -0.41, 95% confidence interval (CI) -0.59 to -0.24; 2 RCTs, N = 514; I = 64%; low-quality evidence); and functional impairment due to premenstrual symptoms in terms of productivity (mean difference (MD) -0.31, 95% CI -0.55 to -0.08; 2 RCTs, N = 432; I = 47%; low-quality evidence), social activities (MD -0.29, 95% CI -0.54 to -0.04; 2 RCTs, N = 432; I = 53%; low-quality evidence), and relationships (MD -0.30, 95% CI -0.54 to -0.06; 2 RCTs, N = 432; I = 45%; low-quality evidence). The effects from COCs containing drospirenone may be small to moderate. COCs containing drospirenone and EE may increase withdrawal from trials due to adverse effects (odds ratio (OR) 3.41, 95% CI 2.01 to 5.78; 4 RCT, N = 776; I = 0%; low-quality evidence). This suggests that if you assume the risk of withdrawal due to adverse effects from placebo is 3%, the risk from drospirenone plus EE will be between 6% and 16%. We are uncertain of the effect of drospirenone plus EE on premenstrual mood symptoms, when measured by validated tools that were not developed to assess premenstrual symptoms. COCs containing drospirenone may lead to more adverse effects in total (OR 2.31, 95% CI 1.71 to 3.11; 3 RCT, N = 739; I = 0%; low-quality evidence). This suggests that if you assume the risk of having adverse effects from placebo is 28%, the risk from drospirenone plus EE will be between 40% and 54%. It probably leads to more breast pain, and may lead to more nausea, intermenstrual bleeding, and menstrual disorder. Its effect on nervousness, headache, asthenia, and pain is uncertain. There was no report of any rare but serious adverse effects, such as venous thromboembolism in any of the included studies. COCs containing drospirenone may improve response rate (OR 1.65, 95% CI 1.13 to 2.40; 1 RCT, N = 449; I not applicable; low-quality evidence). This suggests that if you assume the response rate from placebo is 36%, the risk from drospirenone plus EE will be between 39% and 58%. We did not identify any studies that compared COCs containing drospirenone with other COCs.
AUTHORS' CONCLUSIONS
COCs containing drospirenone and EE may improve premenstrual symptoms that result in functional impairments in women with PMDD. The placebo also had a significant effect. COCs containing drospirenone and EE may lead to more adverse effects compared to placebo. We do not know whether it works after three cycles, helps women with less severe symptoms, or is better than other combined oral contraceptives that contain a different progestogen.
Topics: Female; Humans; Contraceptives, Oral, Combined; Drug-Related Side Effects and Adverse Reactions; Estrogens; Premenstrual Dysphoric Disorder; Premenstrual Syndrome; Progestins
PubMed: 37365881
DOI: 10.1002/14651858.CD006586.pub5 -
The Cochrane Database of Systematic... Jun 2022Respiratory disease is the main cause of morbidity and mortality in cystic fibrosis (CF), and many different therapies are used by people with CF in the management of... (Review)
Review
BACKGROUND
Respiratory disease is the main cause of morbidity and mortality in cystic fibrosis (CF), and many different therapies are used by people with CF in the management of respiratory problems. Bronchodilator therapy is used to relieve symptoms of shortness of breath and to open the airways to allow clearance of mucus. Despite the widespread use of inhaled bronchodilators in CF, there is little objective evidence of their efficacy. A Cochrane Review looking at both short- and long-acting inhaled bronchodilators for CF was withdrawn from the Cochrane Library in 2016. That review has been replaced by two separate Cochrane Reviews: one on long-acting inhaled bronchodilators for CF, and this review on short-acting inhaled bronchodilators for CF. For this review 'inhaled' includes the use of pressurised metered dose inhalers (MDIs), with or without a spacer, dry powder devices and nebulisers.
OBJECTIVES
To evaluate short-acting inhaled bronchodilators in children and adults with CF in terms of clinical outcomes and safety.
SEARCH METHODS
We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books on 28 March 2022 and searched trial registries for any new or ongoing trials on 12 April 2022. We also searched the reference lists of relevant articles and reviews.
SELECTION CRITERIA
We searched for randomised controlled trials (RCTs) or quasi-RCTs that looked at the effect of any short-acting inhaled bronchodilator delivered by any device, at any dose, at any frequency and for any duration compared to either placebo or another short-acting inhaled bronchodilator in people with CF. We screened references as per standard Cochrane methodology.
DATA COLLECTION AND ANALYSIS
Two review authors extracted data and assessed risk of bias using the Cochrane RoB 1 tool. Where we were not able to enter data into our analyses we reported results directly from the papers. We assessed the certainty of evidence using GRADE.
MAIN RESULTS
We included 11 trials from our systematic search, with 191 participants meeting our inclusion criteria; three of these trials had three treatment arms. Eight trials compared short-acting inhaled beta-2 agonists to placebo and four trials compared short-acting inhaled muscarinic antagonists to placebo. Three trials compared short-acting inhaled beta-2 agonists to short-acting inhaled muscarinic antagonists. All were cross-over trials with only small numbers of participants. We were only able to enter data into the analysis from three trials comparing short-acting inhaled beta-2 agonists to placebo. Short-acting inhaled beta-2 agonists versus placebo All eight trials (six single-dose trials and two longer-term trials) reporting on this comparison reported on forced expiratory volume in 1 second (FEV), either as per cent predicted (% predicted) or L. We were able to combine the data from two trials in a meta-analysis which showed a greater per cent change from baseline in FEV L after beta-2 agonists compared to placebo (mean difference (MD) 6.95%, 95% confidence interval (CI) 1.88 to 12.02; 2 trials, 82 participants). Only one of the longer-term trials reported on exacerbations, as measured by hospitalisations and courses of antibiotics. Only the second longer-term trial presented results for participant-reported outcomes. Three trials narratively reported adverse events, and these were all mild. Three single-dose trials and the two longer trials reported on forced vital capacity (FVC), and five trials reported on peak expiratory flow, i.e. forced expiratory flow between 25% and 75% (FEF). One trial reported on airway clearance in terms of sputum weight. We judged the certainty of evidence for each of these outcomes to be very low, meaning we are very uncertain about the effect of short-acting inhaled beta-2 agonists on any of the outcomes we assessed. Short-acting inhaled muscarinic antagonists versus placebo All four trials reporting on this comparison looked at the effects of ipratropium bromide, but in different doses and via different delivery methods. One trial reported FEV % predicted; three trials measured this in L. Two trials reported adverse events, but these were few and mild. One trial reported FVC and three trials reported FEF. None of the trials reported on quality of life, exacerbations or airway clearance. We judged the certainty of evidence for each of these outcomes to be very low, meaning we are very uncertain about the effect of short-acting inhaled muscarinic antagonists on any of the outcomes we assessed. Short-acting inhaled beta-2 agonists versus short-acting inhaled muscarinic antagonists None of the three single-dose trials reporting on this comparison provided data we could analyse. The original papers from three trials report that both treatments lead to an improvement in FEV L. Only one trial reported on adverse events; but none were experienced by any participant. No trial reported on any of our other outcomes. We judged the certainty of evidence to be very low, meaning we are very uncertain about the effect of short-acting inhaled beta-2 agonists compared to short-acting inhaled muscarinic antagonists on any of the outcomes we assessed.
AUTHORS' CONCLUSIONS
All included trials in this review are small and of a cross-over design. Most trials looked at very short-term effects of inhaled bronchodilators, and therefore did not measure longer-term outcomes. The certainty of evidence across all outcomes was very low, and therefore we have been unable to describe any effects with certainty.
Topics: Administration, Inhalation; Adult; Bronchodilator Agents; Child; Cystic Fibrosis; Forced Expiratory Volume; Humans; Muscarinic Antagonists
PubMed: 35749226
DOI: 10.1002/14651858.CD013666.pub2 -
The Cochrane Database of Systematic... Nov 2021Asthma is a chronic disease in which inflammation of the airways causes symptomatic wheezing, coughing and difficult breathing. Macrolides are antibiotics with... (Review)
Review
BACKGROUND
Asthma is a chronic disease in which inflammation of the airways causes symptomatic wheezing, coughing and difficult breathing. Macrolides are antibiotics with antimicrobial and anti-inflammatory activities that have been explored for the long-term control of asthma symptoms.
OBJECTIVES
To assess the effects of macrolides compared with placebo for managing chronic asthma.
SEARCH METHODS
We searched the Cochrane Airways Group Specialised Register up to March 2021. We also manually searched bibliographies of previously published reviews and conference proceedings and contacted study authors. We included records published in any language in the search.
SELECTION CRITERIA
We included randomised controlled clinical trials (RCTs) involving both children and adults with asthma treated with macrolides versus placebo for four or more weeks. Primary outcomes were exacerbation requiring hospitalisation, severe exacerbations (exacerbations requiring emergency department (ED) visits or systemic steroids, or both), symptom scales, asthma control questionnaire (ACQ, score from 0 totally controlled, to 6 severely uncontrolled), Asthma Quality of Life Questionnaire (AQLQ, with score from 1 to 7 with higher scores indicating better QoL), rescue medication puffs per day, morning and evening peak expiratory flow (PEF; litres per minutes), forced expiratory volume in one second (FEV; litres), bronchial hyperresponsiveness, and oral corticosteroid dose. Secondary outcomes were adverse events (including mortality), withdrawal, blood eosinophils, sputum eosinophils, eosinophil cationic protein (ECP) in serum, and ECP in sputum.
DATA COLLECTION AND ANALYSIS
Two review authors independently examined all records identified in the searches then reviewed the full text of all potentially relevant articles before extracting data in duplicate from all included studies. As per protocol, we used a fixed-effect model. We conducted a sensitivity analysis for analyses with high heterogeneity (I greater than 30%). GRADE was used to assess the certainty of the body of evidence.
MAIN RESULTS
Twenty-five studies met the inclusion criteria, randomising 1973 participants to receive macrolide or placebo for at least four weeks. Most of the included studies reported data from adults (mean age 21 to 61 years) with persistent or severe asthma, while four studies included children. All participants were recruited in outpatient settings. Inclusion criteria, interventions and outcomes were highly variable. The evidence suggests macrolides probably deliver a moderately sized reduction in exacerbations requiring hospitalisations compared to placebo (odds ratio (OR) 0.47, 95% confidence interval (CI) 0.20 to 1.12; studies = 2, participants = 529; moderate-certainty evidence). Macrolides probably reduce exacerbations requiring ED visits and/or treatment with systemic steroids (rate ratio (RaR) 0.65, 95% CI 0.53 to 0.80; studies = 4, participants = 640; moderate-certainty evidence). Macrolides may reduce symptoms (as measured on symptom scales) (standardised mean difference (SMD) -0.46, 95% CI -0.81 to -0.11; studies = 4, participants = 136 ; very low-certainty evidence). Macrolides may result in a little improvement in ACQ (SMD -0.17, 95% CI -0.31 to -0.03; studies = 5, participants = 773; low-certainty evidence). Macrolides may have little to no effect on AQLQ (mean difference (MD) 0.24, 95% CI 0.12 to 0.35; studies = 6, participants = 802; very low-certainty evidence). For both the ACQ and the AQLQ the suggested effect of macrolides versus placebo did not reach a minimal clinically important difference (MCID, 0.5 for ACQ and AQLQ) (ACQ: low-certainty evidence; AQLQ: very low-certainty evidence). Due to high heterogeneity (I > 30%), we conducted sensitivity analyses on the above results, which reduced the size of the suggested effects by reducing the weighting on the large, high quality studies. Macrolides may result in a small effect compared to placebo in reducing need for rescue medication (MD -0.43 puffs/day, 95% CI -0.81 to -0.04; studies = 4, participants = 314; low-certainty evidence). Macrolides may increase FEV, but the effect is almost certainly below a level discernible to patients (MD 0.04 L, 95% CI 0 to 0.08; studies = 10, participants = 1046; low-certainty evidence). It was not possible to pool outcomes for non-specific bronchial hyperresponsiveness or lowest tolerated oral corticosteroid dose (in people requiring oral corticosteroids at baseline). There was no evidence of a difference in severe adverse events (including mortality), although less than half of the studies reported the outcome (OR 0.80, 95% CI 0.49 to 1.31; studies = 8, participants = 854; low-certainty evidence). Reporting of specific adverse effects was too inconsistent across studies for a meaningful analysis.
AUTHORS' CONCLUSIONS
Existing evidence suggests an effect of macrolides compared with placebo on the rate of exacerbations requiring hospitalisation. Macrolides probably reduce severe exacerbations (requiring ED visit and/or treatment with systemic steroids) and may reduce symptoms. However, we cannot rule out the possibility of other benefits or harms because the evidence is of very low quality due to heterogeneity among patients and interventions, imprecision and reporting biases. The results were mostly driven by a well-designed, well powered RCT, indicating that azithromycin may reduce exacerbation rate and improve symptom scores in severe asthma. The review highlights the need for researchers to report outcomes accurately and according to standard definitions. Macrolides can reduce exacerbation rate in people with severe asthma. Future trials could evaluate if this effect is sustained across all the severe asthma phenotypes, the comparison with newer biological drugs, whether effects persist or wane after treatment cessation and whether effects are associated with infection biomarkers.
Topics: Adult; Anti-Bacterial Agents; Asthma; Disease Progression; Humans; Macrolides; Middle Aged; Quality of Life; Young Adult
PubMed: 34807989
DOI: 10.1002/14651858.CD002997.pub5 -
Defining and evaluating the Hawthorne effect in primary care, a systematic review and meta-analysis.Frontiers in Medicine 2022In 2015, we conducted a randomized controlled trial (RCT) in primary care to evaluate if posters and pamphlets dispensed in general practice waiting rooms enhanced...
In 2015, we conducted a randomized controlled trial (RCT) in primary care to evaluate if posters and pamphlets dispensed in general practice waiting rooms enhanced vaccination uptake for seasonal influenza. Unexpectedly, vaccination uptake rose in both arms of the RCT whereas public health data indicated a decrease. We wondered if the design of the trial had led to a Hawthorne effect (HE). Searching the literature, we noticed that the definition of the HE was unclear if stated. Our objectives were to refine a definition of the HE for primary care, to evaluate its size, and to draw consequences for primary care research. We designed a Preferred Reporting Items for Systematic reviews and Meta-Analyses review and meta-analysis between January 2012 and March 2022. We included original reports defining the HE and reports measuring it without setting limitations. Definitions of the HE were collected and summarized. Main published outcomes were extracted and measures were analyzed to evaluate odds ratios (ORs) in primary care. The search led to 180 records, reduced on review to 74 for definition and 15 for quantification. Our definition of HE is "an aware or unconscious complex behavior change in a study environment, related to the complex interaction of four biases affecting the study subjects and investigators: selection bias, commitment and congruence bias, conformity and social desirability bias and observation and measurement bias." Its size varies in time and depends on the education and professional position of the investigators and subjects, the study environment, and the outcome. There are overlap areas between the HE, placebo effect, and regression to the mean. In binary outcomes, the overall OR of the HE computed in primary care was 1.41 (95% CI: [1.13; 1.75]; = 97%), but the significance of the HE disappears in well-designed studies. We conclude that the HE results from a complex system of interacting phenomena and appears to some degree in all experimental research, but its size can considerably be reduced by refining study designs.
PubMed: 36425097
DOI: 10.3389/fmed.2022.1033486 -
British Journal of Clinical Pharmacology Aug 2022The placebo effect and the specific effect are often thought to add up (additive model). Whether additivity holds can dramatically influence the external validity of a... (Review)
Review
AIM
The placebo effect and the specific effect are often thought to add up (additive model). Whether additivity holds can dramatically influence the external validity of a trial. This assumption of additivity was tested by Kleijnen et al in 1994 but the data produced since then have not been synthetized. In this review, we aimed to systematically review the literature to determine whether additivity held.
METHODS
We searched Medline and PsychInfo up to 10 January 2019. Studies using the balanced placebo design (BPD), testing two different strengths of placebos, were included. The presence of interaction was evaluated by comparing each group in the BPD with analysis of variance or covariance.
RESULTS
Thirty studies were included and the overall risk of bias was high: four found evidence of additivity and 16 studies found evidence of interaction (seven had evidence of positive additivity).
CONCLUSION
Evidence of additivity between placebo and specific features of treatments was rare in included studies. We suggest interventions for placebo-sensitive ailments should be tested in trials designed to take interactions seriously once an exploratory RCTs has proven their efficacy with sufficient internal validity.
Topics: Humans; Placebo Effect
PubMed: 35384004
DOI: 10.1111/bcp.15345 -
Frontiers in Pharmacology 2024Accumulating evidence suggests that hyperuricemia is a pathological factor in the development and progression of chronic kidney disease. However, the potential benefit...
Accumulating evidence suggests that hyperuricemia is a pathological factor in the development and progression of chronic kidney disease. However, the potential benefit afforded by the control of uric acid (UA) is controversial. Individual studies show discrepant results, and most existing meta-analysis, especially those including the larger number of studies, lack a placebo or control group as they aim to compare efficacy between drugs. On these grounds, we performed a me-ta-analysis restricted to studies including the action of any anti-gout therapies referenced to a control or placebo arm. This approach allows for a clearer association between UA reduction and renal effect. Of the twenty-nine papers included, most used allopurinol and febuxostat and, therefore, solid conclusions could only be obtained for these drugs. Both were very effective in reducing UA, but only allopurinol was able to significantly improve glomerular filtration rate (GFR), although not in a dose-dependent manner. These results raised doubts as to whether it is the hypouricemic effect of anti-gout drugs, or a pleiotropic effect, what provides protection of kidney function. Accordingly, in a correlation study that we next performed between UA reduction and GFR improvement, no association was found, which suggests that additional mechanisms may be involved. Of note, most trials show large inter-individual response variability, probably because they included patients with heterogeneous phenotypes and pathological characteristics, including different stages of CKD and comorbidities. This highlights the need to sub classify the effect of UA-lowering therapies according to the pathological scenario, in order to identify those CKD patients that may benefit most from them. CRD42022306646 https://www.crd.york.ac.uk/prospero/.
PubMed: 38601468
DOI: 10.3389/fphar.2024.1373258