scholarly journals Design and Analysis of Observational Studies

2014 ◽  
Vol 5 (2) ◽  
pp. 33-39 ◽  
Author(s):  
KP Suresh ◽  
MR Gajendragad ◽  
H Rahman
Keyword(s):  
Observational Study ◽  
Study Design ◽  
Observational Studies ◽  
Research Question ◽  
Validity And Reliability ◽  
Current Review ◽  
Valid Result ◽  
Methods And Techniques ◽  
H Design

ABSTRACT Appropriate study design forms the basis of any successful organized research. Irrespective of the underlying rationale of the research question, inappropriate design of an experiment or execution of a study may not give a valid result. As defined, the research should have the following characteristics: it should be undertaken within the framework of a set of philosophies, should have an unbiased objective and a design comprising of methods and techniques that have been tested for their validity and reliability. These principles of research clearly emphasize the need for an appropriate study design. The current review focuses on the planning and analysis of an observational study to obtain significant and accurate findings. How to cite this article Suresh KP, Gajendragad MR, Rahman H. Design and Analysis of Observational Studies. Int J Infertil Fetal Med 2014;5(2):33-39.

Trial designs, including observational to interventional

2020 ◽  
pp. 57-64
Author(s):  
Edo Richard
Keyword(s):  
Study Design ◽  
Treatment Effect ◽  
Clinical Relevance ◽  
Observational Studies ◽  
Research Question ◽  
Sample Size Calculation ◽  
Target Population ◽  
Ethical Considerations ◽  
Neuropsychiatric Diseases ◽  
The Right

Observational studies have taught us a lot about the origin of neurological and neuropsychiatric diseases. This chapter describes how we can translate this knowledge into action. Before engaging in a large RCT, several steps have to be taken. First, the potential for a treatment effect has to be compelling. The target population in the RCT has to resemble the population in which observational studies described an association. Second, the outcome of an RCT has to be chosen, and has to have clinical relevance or at least have the potential of clinical relevance in the future. Third, the right study design has to be decided on. Each research question will require a specific study design with accompanying sample size calculation. Lastly, specific ethical considerations have to be taken into account when designing and executing an intervention study. This chapter presents an overview of these issues.

scholarly journals Observational Study Design in Veterinary Pathology, Part 1: Study Design

2018 ◽  
Vol 55 (5) ◽  
pp. 607-621 ◽  
Author(s):  
Jeff L. Caswell ◽  
Laura L. Bassel ◽  
Jamie L. Rothenburger ◽  
Andrea Gröne ◽  
Jan M. Sargeant ◽  
...  
Keyword(s):  
Observational Study ◽  
Study Design ◽  
Observational Studies ◽  
Daily Practice ◽  
Temporal Relationships ◽  
Different Types ◽  
Observational Study Design ◽  
Veterinary Pathology ◽  
Incident Cases ◽  
Selection Of

Observational studies are the basis for much of our knowledge of veterinary pathology and are highly relevant to the daily practice of pathology. However, recommendations for conducting pathology-based observational studies are not readily available. In part 1 of this series, we offer advice on planning and conducting an observational study with examples from the veterinary pathology literature. Investigators should recognize the importance of creativity, insight, and innovation in devising studies that solve problems and fill important gaps in knowledge. Studies should focus on specific and testable hypotheses, questions, or objectives. The methodology is developed to support these goals. We consider the merits and limitations of different types of analytic and descriptive studies, as well as of prospective vs retrospective enrollment. Investigators should define clear inclusion and exclusion criteria and select adequate numbers of study subjects, including careful selection of the most appropriate controls. Studies of causality must consider the temporal relationships between variables and the advantages of measuring incident cases rather than prevalent cases. Investigators must consider unique aspects of studies based on archived laboratory case material and take particular care to consider and mitigate the potential for selection bias and information bias. We close by discussing approaches to adding value and impact to observational studies. Part 2 of the series focuses on methodology and validation of methods.

scholarly journals Assessing risk of bias: a proposal for a unified framework for observational studies and randomized trials

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Hendrika J. Luijendijk ◽  
Matthew J. Page ◽  
Huibert Burger ◽  
Xander Koolman
Keyword(s):  
Study Design ◽  
Subject Matter ◽  
Health Care Professionals ◽  
Observational Studies ◽  
Randomized Trials ◽  
Outcome Measurement ◽  
Research Question ◽  
Subject Matter Knowledge ◽  
Unified Framework ◽  
Causal Diagrams

Abstract Background Evidence based medicine aims to integrate scientific evidence, clinical experience, and patient values and preferences. Individual health care professionals need to appraise the evidence from randomized trials and observational studies when guidelines are not yet available. To date, tools for assessment of bias and terminologies for bias are specific for each study design. Moreover, most tools appeal only to methodological knowledge to detect bias, not to subject matter knowledge, i.e. in-depth medical knowledge about a topic. We propose a unified framework that enables the coherent assessment of bias across designs. Methods Epidemiologists traditionally distinguish between three types of bias in observational studies: confounding, information bias, and selection bias. These biases result from a common cause, systematic error in the measurement or common effect of the intervention and outcome respectively. We applied this conceptual framework to randomized trials and show how it can be used to identify bias. The three sources of bias were illustrated with graphs that visually represent researchers’ assumptions about the relationships between the investigated variables (causal diagrams). Results Critical appraisal of evidence started with the definition of the research question in terms of the population of interest, the compared interventions and the main outcome. Next, we used causal diagrams to illustrate how each source of bias can lead to over- or underestimated treatment effects. Then, we discussed how randomization, blinded outcome measurement and intention-to-treat analysis minimize bias in trials. Finally, we identified study aspects that can only be appraised with subject matter knowledge, irrespective of study design. Conclusions The unified framework encompassed the three main sources of bias for the effect of an assigned intervention on an outcome. It facilitated the integration of methodological and subject matter knowledge in the assessment of bias. We hope that graphical diagrams will help clarify debate among professionals by reducing misunderstandings based on different terminology for bias.

scholarly journals Study design: what’s in a name?

2020 ◽  
Vol 183 (6) ◽  
pp. E11-E13
Author(s):  
Olaf M Dekkers ◽  
Rolf H H Groenwold
Keyword(s):  
Observational Study ◽  
Study Design ◽  
Observational Studies ◽  
Case Control Study ◽  
Case Control ◽  
Short Paper ◽  
Cross Sectional ◽  
Trial Intervention ◽  
Control Study

The name of the study should properly reflect the actual conduct and analysis of the study. This short paper provides guidance on how to properly name the study design. The first distinction is between a trial (intervention given to patients to study its effect) and an observational study. For observational studies, it should further be decided whether it is cross-sectional or whether follow-up time is taken into account (cohort or case–control study). The distinction prospective-retrospective has two disadvantages: prospective is often seen as marker of higher quality, which is not necessarily true; there is no unifying definition that makes a proper distinction between retrospective and prospective possible.

scholarly journals Cost comparison of asthma treatments in 12-week study: caution about matching and short observational follow-up

2016 ◽  
Vol 11 ◽  
Author(s):  
David B. Price ◽  
Job F.M. Van Boven ◽  
Lisa M. Law ◽  
Alessandra Cifra ◽  
R. Brett McQueen
Keyword(s):  
Observational Study ◽  
Cost Analysis ◽  
Study Design ◽  
Observational Studies ◽  
The Other ◽  
Cost Comparison ◽  
Treatment Groups ◽  
Matching Methods ◽  
Key Characteristics

In the absence of randomisation, observational studies must take extra care to create treatment groups that are comparable in terms of key characteristics. Various matching methods exist which can create sound comparisons, minimising confounding where possible. A recent observational study by Dal Negro et al. carried out a cost analysis comparing two asthma medications. They report strong conclusions which favour one treatment over the other, however they include little discussion on the limitations of their study. The purpose of this letter is to comment on the weaknesses of the study design, including the level of matching used, and to urge readers to consider these issues alongside the interpretation of results.

scholarly journals Depletion-of-susceptibles bias in influenza vaccine waning studies: how to ensure robust results

2019 ◽  
Author(s):  
M. Lipsitch ◽  
E. Goldstein ◽  
G.T. Ray ◽  
B. Fireman
Keyword(s):  
Observational Study ◽  
Influenza Vaccine ◽  
Randomized Trial ◽  
Study Design ◽  
Null Hypothesis ◽  
Influenza Season ◽  
Calendar Time ◽  
Future Studies ◽  
Biased Estimates ◽  
Induced Immunity

SUMMARYVaccine effectiveness (VE) studies are subject to biases due to depletion of at-risk persons or of highly susceptible persons at different rates from different groups (depletion-of-susceptibles bias), a problem that can also lead to biased estimates of waning effectiveness, including spurious inference of waning when none exists. An alternative study design to identify waning is to study only vaccinated persons, and compare for each day the incidence in persons with earlier or later dates of vaccination. Prior studies suggested under what conditions this alternative would yield correct estimates of waning. Here we define the depletion-of-susceptibles process formally and show mathematically that for influenza vaccine waning studies, a randomized trial or corresponding observational study that compares incidence at a specific calendar time among individuals vaccinated at different times before the influenza season begins will not be vulnerable depletion-of-susceptibles bias in its inference of waning under the null hypothesis that none exists, and will – if waning does actually occur – underestimate the extent of waning. Such a design is thus robust in the sense that a finding of waning in that inference framework reflects actual waning of vaccine-induced immunity. We recommend such a design for future studies of waning, whether observational or randomized.

scholarly journals Methodological diversity in Russian sociology: An analysis of research on values

2021 ◽  
Vol 14 (2) ◽  
pp. 107-123
Author(s):  
Marina A. Kashina ◽  
◽  
Sergey Tkach ◽  
Keyword(s):  
Scientific Knowledge ◽  
Research Question ◽  
Quantitative Methodology ◽  
Outer Contour ◽  
Qualitative Design ◽  
External Contour ◽  
Empirical Base ◽  
Methods And Techniques ◽  
Highly Cited Articles ◽  
Highly Cited

Methodological diversity is a condition for the development of sociology since the complexity of social reality does not allow adhering to one universal scientific paradigm. At the same time, the nature of methodological diversity in research is an indicator of the alignment of forces of agents in the field of science. Hence the research question arises — how is the influence of the external contour of science (business, public organizations, media, politicians, etc.) manifested in the methodology used by the authors of highly cited articles on values? The work is of qualitative design and the empirical base was formed by the texts of 42 of the most cited Russian articles on the issues of values posted on the RSCI platform in 2016–2019 and indexed by international scientometric databases (Scopus, Wos CC). The choice of articles on the study of values as an empirical object for assessing the nature of methodological diversity in sociology is explained by the complexity and multilevel nature of this phenomenon, and the existence of various approaches to its study, which provides ample opportunities for various methods and techniques. The research optics was the structuralist concept of the inner and outer contours of science. Analysis of the texts of articles showed that the quantitative methodology dominates (29 out of 42). In these studies, the signs of the pressure of the outer contour of science are most pronounced. The least pressure is experienced by authors of works in qualitative design, but there are very few studies in the sample of highly cited articles (2 out of 42), and the topic of values in them is optional. Promising areas for the continuation of the research are related to the analysis of the phenomenon of imitation in the process of producing scientific knowledge and its impact on methodological diversity.

scholarly journals Assessment of Medication Adherence Using a Medical App Among Patients With Multiple Sclerosis Treated With Interferon Beta-1b: Pilot Digital Observational Study (PROmyBETAapp)

10.2196/14373 ◽  
2019 ◽  
Vol 21 (7) ◽  
pp. e14373 ◽  
Author(s):  
Volker Limmroth ◽  
Klaus Hechenbichler ◽  
Christian Müller ◽  
Markus Schürks
Keyword(s):  
Multiple Sclerosis ◽  
Medication Adherence ◽  
Observational Study ◽  
Observational Studies ◽  
Interferon Beta ◽  
Apparent Difference ◽  
Process Data ◽  
Medication Usage ◽  
Medical App ◽  
Mean Compliance

Background Accurate measurement of medication adherence using classical observational studies typically depends on patient self-reporting and is often costly and slow. In contrast, digital observational studies that collect data directly from the patient may pose minimal burden to patients while facilitating accurate, timely, and cost-efficient collection of real-world data. In Germany, ~80% of patients with multiple sclerosis (MS) treated with interferon beta 1b (Betaferon) use an electronic autoinjector (BETACONNECT), which automatically records every injection. Patients may also choose to use a medical app (myBETAapp) to document injection data and their well-being (using a “wellness tracker” feature). Objective The goal of this pilot study was to establish a digital study process that allows the collection of medication usage data and to assess medication usage among patients with MS treated with interferon beta-1b who use myBETAapp. Methods The PROmyBETAapp digital observational study was a mixed prospective and retrospective, noninterventional, cohort study conducted among users of myBETAapp in Germany (as of December 2017: registered accounts N=1334; actively used accounts N=522). Between September and December 2017, users received two invitations on their app asking them to participate. Interested patients were provided detailed information and completed an electronic consent process. Data from consenting patients’ devices were collected retrospectively starting from the first day of usage if historical data were available in the database and collected prospectively following consent attainment. In total, 6 months of data on medication usage behavior were collected along with 3 months of wellness tracker data. Descriptive statistics were used to analyze persistence, compliance, and adherence to therapy. Results Of the 1334 registered accounts, 96 patients (7.2%) provided informed consent to participate in the study. Of these, one patient withdrew consent later. For another patient, injection data could not be recorded during the study period. Follow-up of the remaining 94 patients ended in May 2018. The mean age of participants was 46.6 years, and 50 (53%) were female. Over the 6-month study period, persistence with myBETAapp usage was 96% (90/94), mean compliance was 94% of injections completed, and adherence (persistence and ≥80% compliance) was 89% (84/94). There was no apparent difference between male and female participants and no trend across age groups. The wellness tracker was used by 21% of participants (20/94), with a mean of 3.1 entries per user. Conclusions This study provides important information on medication usage among patients with MS treated with interferon beta-1b and on consenting behavior of patients in digital studies. In future studies, this approach may allow patients’ feedback to be rapidly implemented in existing digital solutions. Trial Registration ClinicalTrials.gov NCT03134573; https://clinicaltrials.gov/ct2/show/NCT03134573

Management of composite defects of the nose, cheek, eyelids and upper lip

2009 ◽  
Vol 123 (S32) ◽  
pp. 1-38 ◽  
Author(s):  
N S Jones ◽  
U Raghavan
Keyword(s):  
Observational Study ◽  
Study Design ◽  
Retrospective Observational Study ◽  
Tissue Loss ◽  
Upper Lip ◽  
Facial Skeleton ◽  
Alar Base ◽  
The Aesthetic

AbstractAim:To assess the results of reconstruction of composite defects involving the nose which extend to involve the cheeks, eyelids or upper lip.Study design:Retrospective observational study.Material:Sixteen patients with defects of the nose extending to the adjoining cheek, upper lip or eyelid.Method:A combination of flaps and grafts were needed to reconstruct these defects so that the aesthetic subunits were replaced and joined at their junctions wherever possible.Results:Where the defect required three or four flaps, there was some unpredictable cicatrisation at their junction that resulted in some asymmetry. This problem primarily occurred at the alar base, and was compounded if there was tissue loss of the premaxilla or maxilla.Conclusion:If a defect that involves the nose, cheek and upper lip is repaired with a combination of cheek advancement, nasolabial, paramedian forehead and/or septal flaps, there can be unpredictable cicatrisation at their junction, particularly at the alar base. In these circumstances, we recommend replacing the nasal and other defects with a slightly more generous amount of tissue than would be taken to repair a similar, but solitary, defect. It is important to replace any loss of the facial skeleton, in order to provide support for overlying flaps.

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