-
Respiratory Care Nov 2023Studies can be observational or experimental. With an observational study, the investigator does not determine the assignment of subjects, and there might not be a...
Studies can be observational or experimental. With an observational study, the investigator does not determine the assignment of subjects, and there might not be a control group. If there is a control group, assignment of the independent variable (exposure or intervention) is not under the control of the investigator. Observational studies can be rigorously conducted, but the lack of random assignment of the exposure/intervention introduces confounding and bias. Thus, the quality of evidence resulting from observational studies is lower than that of experimental randomized controlled trials (RCTs). An observational study might be performed if an RCT is unethical, impractical, or outside the control of the investigator. There are many types of prospective and retrospective observational study designs. However, an observational study design should be avoided if an experimental study is possible. Sophisticated statistical approaches can be used, but this does not elevate an observational study to the level of an RCT. Regardless of quality, an observational study cannot establish causality.
Topics: Research Design; Observational Studies as Topic
PubMed: 37339891
DOI: 10.4187/respcare.11170 -
Clinical and Experimental Medicine Jul 2023Chronic COVID syndrome is characterized by chronic fatigue, myalgia, depression and sleep disturbances, similar to chronic fatigue syndrome (CFS) and fibromyalgia... (Review)
Review
Chronic COVID syndrome is characterized by chronic fatigue, myalgia, depression and sleep disturbances, similar to chronic fatigue syndrome (CFS) and fibromyalgia syndrome. Implementations of mitochondrial nutrients (MNs) with diet are important for the clinical effects antioxidant. We examined if use of an association of coenzyme Q10 and alpha lipoic acid (Requpero®) could reduce chronic covid symptoms. The Requpero study is a prospective observational study in which 174 patients, who had developed chronic-covid syndrome, were divided in two groups: The first one (116 patients) received coenzyme Q10 + alpha lipoic acid, and the second one (58 patients) did not receive any treatment. Primary outcome was reduction in Fatigue Severity Scale (FSS) in treatment group compared with control group. complete FSS response was reached most frequently in treatment group than in control group. A FSS complete response was reached in 62 (53.5%) patients in treatment group and in two (3.5%) patients in control group. A reduction in FSS core < 20% from baseline at T1 (non-response) was observed in 11 patients in the treatment group (9.5%) and in 15 patients in the control group (25.9%) (p < 0.0001). To date, this is the first study that tests the efficacy of coenzyme Q10 and alpha lipoic acid in chronic Covid syndrome. Primary and secondary outcomes were met. These results have to be confirmed through a double blind placebo controlled trial of longer duration.
Topics: Humans; Thioctic Acid; Post-Acute COVID-19 Syndrome; COVID-19; Prospective Studies; Observational Studies as Topic; Randomized Controlled Trials as Topic
PubMed: 35994177
DOI: 10.1007/s10238-022-00871-8 -
Journal of the American Society of... Aug 2023Target trial emulation has drastically improved the quality of observational studies investigating the effects of interventions. Its ability to prevent avoidable biases... (Review)
Review
Target trial emulation has drastically improved the quality of observational studies investigating the effects of interventions. Its ability to prevent avoidable biases that have plagued many observational analyses has contributed to its recent popularity. This review explains what target trial emulation is, why it should be the standard approach for causal observational studies that investigate interventions, and how to do a target trial emulation analysis. We discuss the merits of target trial emulation compared with often used, but biased analyses, as well as potential caveats, and provide clinicians and researchers with the tools to better interpret results from observational studies investigating the effects of interventions.
Topics: Causality; Observational Studies as Topic
PubMed: 37131279
DOI: 10.1681/ASN.0000000000000152 -
Internal Medicine Journal Aug 2023Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) reduce elevated blood glucose levels and induce weight loss. Multiple GLP-1 RAs and one combined... (Meta-Analysis)
Meta-Analysis Review
Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) reduce elevated blood glucose levels and induce weight loss. Multiple GLP-1 RAs and one combined GLP-1/glucose-dependent insulinotropic polypeptide agonist are currently available. This review was conducted with the aim of summarising direct comparisons between subcutaneous semaglutide and other GLP-1 RAs in individuals with type 2 diabetes (T2D), particularly with respect to efficacy for inducing weight loss and improving other markers of metabolic health. This systematic review of PubMed and Embase from inception to early 2022 was registered on PROSPERO and was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-Analysis of Observational Studies in Epidemiology guidelines. Of the 740 records identified in the search, five studies fulfilled the inclusion criteria. Comparators included liraglutide, exenatide, dulaglutide and tirzepatide. In the identified studies, multiple dosing regimens were utilised for semaglutide. Randomised trials support the superior efficacy of semaglutide over other GLP-1 RAs with respect to weight loss in T2D, but tirzepatide is more effective than semaglutide.
Topics: Humans; Diabetes Mellitus, Type 2; Hypoglycemic Agents; Glucagon-Like Peptide 1; Weight Loss; Observational Studies as Topic
PubMed: 37189293
DOI: 10.1111/imj.16126 -
NEJM Evidence Mar 2024Contemporary data collection strategies, storage capabilities, and modern statistical methodology have made retrospective analyses of observational databases...
Contemporary data collection strategies, storage capabilities, and modern statistical methodology have made retrospective analyses of observational databases commonplace. Such databases afford opportunities to learn about the effectiveness and risks of interventions or health behaviors that generally cannot be randomized. In this issue of , Cho et al. assemble survey data and cohort data from four countries to quantify the association between age-sex-specific smoking cessation and mortality. The authors conclude that smoking cessation at any age is associated with lower excess overall mortality risk and lower death from diseases made more common by smoking. It is difficult to argue with this conclusion - to question the magnitude of the associations is not.
Topics: Female; Humans; Male; Data Collection; Databases, Factual; Health Behavior; Learning; Retrospective Studies; Observational Studies as Topic
PubMed: 38411452
DOI: 10.1056/EVIDe2300324 -
Indian Heart Journal Mar 2024Evidence from the existing literature suggests that exercise has positive effects for prevention and treatment of cardiovascular diseases by reducing risk factors such... (Review)
Review
Evidence from the existing literature suggests that exercise has positive effects for prevention and treatment of cardiovascular diseases by reducing risk factors such as elevated blood lipids. Based on clinical and observational clinical trials, it is well established that increased physical activity and regular exercise has a favourable impact on blood lipids and lipoprotein profiles. Exercise training significantly decreases blood triglycerides concentration and increases high density lipoprotein cholesterol levels. Though the Indian data depicting the effect of exercise on lipids is scarce, exercise directly improves "atherogenic dyslipidaemia" which is frequently present among Indians i.e. HDL-C is increased, TG is reduced and LDL-C particle size is improved. While drug therapy is key to the treatment of dyslipidaemia, lifestyle alterations such as exercise should continue to be actively promoted and encouraged by clinicians. Exercise is a low cost, non pharmacological therapeutic lifestyle change that is of value to lipid metabolism and cardiovascular fitness.
Topics: Humans; Cholesterol, HDL; Dyslipidemias; Exercise; Lipids; Lipoproteins; Triglycerides; Clinical Trials as Topic; Observational Studies as Topic
PubMed: 38599728
DOI: 10.1016/j.ihj.2023.11.270 -
The Lancet. Gastroenterology &... Jul 2023Rome criteria differentiate distinct types of disorders of gut-brain interaction (DGBI); also known as functional gastrointestinal disorders. Overlap of symptom... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Rome criteria differentiate distinct types of disorders of gut-brain interaction (DGBI); also known as functional gastrointestinal disorders. Overlap of symptom categories frequently occurs. This systematic review and meta-analysis aimed to define the prevalence of DGBI overlap and compare overlap in population-based, primary care or tertiary care health settings. Furthermore, we aimed to compare symptom severity of psychological comorbidities in DGBI with and without overlap.
METHODS
For this systematic review and meta-analysis we searched MEDLINE (PubMed) and Embase electronic databases from inception until March 1, 2022, for original articles and conference abstracts of observational cross-sectional, case-controlled, or cohort design studies that reported the prevalence of DGBI overlap in adult participants (aged ≥18 years). We included only those studies where the diagnosis of DGBI was based on clinical assessment, questionnaire data, or specific symptom-based criteria. Studies were excluded if reporting on mixed populations of DGBI and organic diseases. Aggregate patient data were extracted from eligible published studies. The prevalence of DGBI overlap in all studies was pooled using the DerSimonian and Laird random effects model, and further analysis stratified by subgroups (care setting, diagnostic criteria, geographic region, and gross domestic product per capita). We also assessed the relationship between DGBI overlap with anxiety, depression, and quality of life symptom scores. This study was registered with PROSPERO (CRD42022311101).
FINDINGS
46 of 1268 screened studies, reporting on 75 682 adult DGBI participants, were eligible for inclusion in this systematic review and meta-analysis. Overall, 24 424 (pooled prevalence 36·5% [95% CI 30·7 to 42·6]) participants had a DGBI overlap, with considerable between-study heterogeneity (I=99·51, p=0·0001). In the tertiary health-care setting, overlap among participants with DGBI was more prevalent (8373 of 22 617, pooled prevalence 47·3% [95% CI 33·2 to 61·7]) compared with population-based cohorts (11 332 of 39 749, pooled prevalence 26·5% [95% CI 20·5 to 33·4]; odds ratio 2·50 [95% CI 1·28 to 4·87]; p=0·0084). Quality of life physical component scores were significantly lower in participants with DGBI overlap compared with participants without overlap (standardised mean difference -0·47 [95% CI -0·80 to -0·14]; p=0·025). Participants with DGBI overlap had both increased symptom scores for anxiety (0·39 [95% CI 0·24 to 0·54]; p=0·0001) and depression (0·41 [0·30 to 0·51]; p=0·0001).
INTERPRETATION
Overlap of DGBI subtypes is frequent, and is more prevalent in tertiary care settings and associated with more severe symptom manifestations or psychological comorbidities. Despite the large sample size, the comparative analyses revealed substantial heterogeneity, and the results should be interpreted with caution.
FUNDING
National Health and Medical Research Council and Centre for Research Excellence.
Topics: Adult; Humans; Adolescent; Cross-Sectional Studies; Quality of Life; Anxiety; Comorbidity; Brain; Observational Studies as Topic
PubMed: 37211024
DOI: 10.1016/S2468-1253(23)00102-4 -
JAMA Network Open Sep 2023Observational (nonexperimental) studies that aim to emulate a randomized trial (ie, the target trial) are increasingly informing medical and policy decision-making, but...
IMPORTANCE
Observational (nonexperimental) studies that aim to emulate a randomized trial (ie, the target trial) are increasingly informing medical and policy decision-making, but it is unclear how these studies are reported in the literature. Consistent reporting is essential for quality appraisal, evidence synthesis, and translation of evidence to policy and practice.
OBJECTIVE
To assess the reporting of observational studies that explicitly aimed to emulate a target trial.
EVIDENCE REVIEW
We searched Medline, Embase, PsycINFO, and Web of Science for observational studies published between March 2012 and October 2022 that explicitly aimed to emulate a target trial of a health or medical intervention. Two reviewers double-screened and -extracted data on study characteristics, key predefined components of the target trial protocol and its emulation (eligibility criteria, treatment strategies, treatment assignment, outcome[s], follow-up, causal contrast[s], and analysis plan), and other items related to the target trial emulation.
FINDINGS
A total of 200 studies that explicitly aimed to emulate a target trial were included. These studies included 26 subfields of medicine, and 168 (84%) were published from January 2020 to October 2022. The aim to emulate a target trial was explicit in 70 study titles (35%). Forty-three studies (22%) reported use of a published reporting guideline (eg, Strengthening the Reporting of Observational Studies in Epidemiology). Eighty-five studies (43%) did not describe all key items of how the target trial was emulated and 113 (57%) did not describe the protocol of the target trial and its emulation.
CONCLUSION AND RELEVANCE
In this systematic review of 200 studies that explicitly aimed to emulate a target trial, reporting of how the target trial was emulated was inconsistent. A reporting guideline for studies explicitly aiming to emulate a target trial may improve the reporting of the target trial protocols and other aspects of these emulation attempts.
Topics: Randomized Controlled Trials as Topic; Observational Studies as Topic
PubMed: 37755828
DOI: 10.1001/jamanetworkopen.2023.36023 -
BMC Medical Research Methodology Aug 2023When conducting randomised controlled trials is impractical, an alternative is to carry out an observational study. However, making valid causal inferences from... (Review)
Review
BACKGROUND
When conducting randomised controlled trials is impractical, an alternative is to carry out an observational study. However, making valid causal inferences from observational data is challenging because of the risk of several statistical biases. In 2016 Hernán and Robins put forward the 'target trial framework' as a guide to best design and analyse observational studies whilst preventing the most common biases. This framework consists of (1) clearly defining a causal question about an intervention, (2) specifying the protocol of the hypothetical trial, and (3) explaining how the observational data will be used to emulate it.
METHODS
The aim of this scoping review was to identify and review all explicit attempts of trial emulation studies across all medical fields. Embase, Medline and Web of Science were searched for trial emulation studies published in English from database inception to February 25, 2021. The following information was extracted from studies that were deemed eligible for review: the subject area, the type of observational data that they leveraged, and the statistical methods they used to address the following biases: (A) confounding bias, (B) immortal time bias, and (C) selection bias.
RESULTS
The search resulted in 617 studies, 38 of which we deemed eligible for review. Of those 38 studies, most focused on cardiology, infectious diseases or oncology and the majority used electronic health records/electronic medical records data and cohort studies data. Different statistical methods were used to address confounding at baseline and selection bias, predominantly conditioning on the confounders (N = 18/49, 37%) and inverse probability of censoring weighting (N = 7/20, 35%) respectively. Different approaches were used to address immortal time bias, assigning individuals to treatment strategies at start of follow-up based on their data available at that specific time (N = 21, 55%), using the sequential trial emulations approach (N = 11, 29%) or the cloning approach (N = 6, 16%).
CONCLUSION
Different methods can be leveraged to address (A) confounding bias, (B) immortal time bias, and (C) selection bias. When working with observational data, and if possible, the 'target trial' framework should be used as it provides a structured conceptual approach to observational research.
Topics: Humans; Biomedical Research; Selection Bias; Databases, Factual; MEDLINE; Medical Oncology; Observational Studies as Topic
PubMed: 37587484
DOI: 10.1186/s12874-023-02000-9 -
BMJ Open Aug 2023The purpose of TheShinISS-Vax|Flu study is to examine the association between influenza vaccines and adverse events requiring hospital admission or emergency care during...
INTRODUCTION
The purpose of TheShinISS-Vax|Flu study is to examine the association between influenza vaccines and adverse events requiring hospital admission or emergency care during the influenza vaccination campaigns 2021/2022 and 2022/2023 in Italy.
METHODS AND ANALYSIS
This is a Self-Controlled Case Series multiregional study using linked routinely collected data from regional healthcare databases of the participating regions. Study participants will be persons aged ≥6 months, unvaccinated or who have received influenza vaccine during the influenza vaccination campaigns in the seasons 2021/2022 and 2022/2023 in Italy and who have experienced the outcome of interest for the first time during the study period (1 September 2021-30 June 2022 and 1 September 2022-30 June 2023 for the first and second vaccination campaigns, respectively). Risk periods will be specifically defined for each outcome and further subdivided into periods of 7 days. The exposures will be the first or second dose of the influenza vaccines administered during the two vaccination campaigns. Statistical analysis will be conducted separately for the data of the two campaigns. Exposure risk period will be compared with baseline risk period defined as any time of observation out of the risk periods. The modified SCCS method will be applied to handle event-dependent exposure and mortality and fitted using unbiased estimating equations to estimate relative incidences and excess of cases per 100 000 vaccinated by dose, age, sex and type of vaccine. Calendar period will be included as time-varying confounder in the model, where appropriate.
ETHICS AND DISSEMINATION
The study received the approval from the National ethics committee for clinical trials of public research bodies and other national public institutions (PRE BIO CE n.0036723, 23/09/2022). Results will be published in peer-reviewed journals and reports in accordance with the publication policies of the Italian National Institute of Health and of the Italian Medicines Agency.
Topics: Humans; Influenza Vaccines; Influenza, Human; Vaccination; Immunization Programs; Italy; Observational Studies as Topic
PubMed: 37550029
DOI: 10.1136/bmjopen-2022-069858