Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Bias in Epidemiological Studies01:29

Bias in Epidemiological Studies

96
Biases can arise at various stages of research, from study design and data collection to analysis and interpretation. Recognizing and addressing these biases is essential to ensure the validity and reliability of epidemiological findings.Broadly speaking, biases in epidemiology fall into three main categories: selection bias, information bias, and confounding. A more detailed description of possible biases is:  
96
Regression Toward the Mean01:52

Regression Toward the Mean

6.2K
Regression toward the mean (“RTM”) is a phenomenon in which extremely high or low values—for example, and individual’s blood pressure at a particular moment—appear closer to a group’s average upon remeasuring. Although this statistical peculiarity is the result of random error and chance, it has been problematic across various medical, scientific, financial and psychological applications. In particular, RTM, if not taken into account, can interfere when...
6.2K
Obesity01:24

Obesity

338
The Body Mass Index (BMI) is a numerical value derived from a person's weight and height, used to categorize individuals into weight ranges. It is calculated using the formula: weight in kilograms divided by height in meters squared. Obesity is a health condition characterized by excessive accumulation of adipose tissue that poses health risks, often diagnosed with a BMI ≥ 30. This excess fat storage occurs when surplus dietary calories are converted into triglycerides and stored in...
338
Study Designs in Epidemiology01:20

Study Designs in Epidemiology

139
Epidemiological study designs are fundamental tools for investigating the distribution, determinants, and control of health conditions in populations. They help researchers understand the relationships between exposures and outcomes, and they broadly fall into two categories: "observational" and "experimental" studies.
Observational studies are those where the researcher does not intervene but rather observes natural variations. They include cross-sectional, cohort, and...
139
Bias01:22

Bias

3.7K
Bias refers to any tendency that prevents a question from being considered unprejudiced. In research, bias occurs when one outcome or answer is selected or encouraged over others in sampling or testing. Bias can occur during any research phase, including study design, data collection, analysis, and publication.
In statistics, a sampling bias is created when a sample is collected from a population, and some members of the population are not as likely to be chosen as others (remember, each member...
3.7K
Longitudinal Research02:20

Longitudinal Research

11.8K
Sometimes we want to see how people change over time, as in studies of human development and lifespan. When we test the same group of individuals repeatedly over an extended period of time, we are conducting longitudinal research. Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time. For example, we may survey a group of individuals about their dietary habits at age 20, retest them a decade later at age 30, and then again...
11.8K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Familial hypercholesterolaemia in children and adolescents: a European Atherosclerosis Society consensus statement.

European heart journal·2026
Same author

ADAR1 Controls Macrophage Scavenging and Lipid-Buffering Programs in Metabolic Tissues.

European journal of immunology·2026
Same author

Renin-Aldosterone Profiles and Cardiorenal Outcomes in Hypertension: A Nationwide Cohort Study.

Journal of the American College of Cardiology·2026
Same author

Obstructive Sleep Apnea Following Bariatric Surgery: 20 Year Outcomes From the Swedish Obese Subjects Study.

Obesity (Silver Spring, Md.)·2026
Same author

Sex-specific associations between surgery-induced weight loss and cancer outcomes: A post hoc analysis of the prospective, controlled Swedish Obese Subjects study.

PLoS medicine·2026
Same author

Occurrence and Patient Characteristics of Aldosterone Dysregulation in Routine Clinical Care: A Population-Based Study.

JACC. Advances·2025
Same journal

Neonatal vitamin D levels and autoimmune disorders: a Danish population-based cohort study.

European journal of epidemiology·2026
Same journal

Re: "Does tattoo exposure increase the risk of cutaneous melanoma? A population-based case-control study".

European journal of epidemiology·2026
Same journal

Separability and identifiability as primary obstacles to substantively useful mediation analysis.

European journal of epidemiology·2026
Same journal

Intergenerational income mobility and psychotropic drug dispensation in a 1953 Stockholm cohort: a diagonal reference model approach.

European journal of epidemiology·2026
Same journal

Genetic risk score to enhance glaucoma case detection: a prospective double-blind screening study (EyeLife) in the population-based Lifelines cohort.

European journal of epidemiology·2026
Same journal

Different risks, same causes: educational attainment influences when, not from what, we die.

European journal of epidemiology·2026
See all related articles

Related Experiment Video

Updated: May 13, 2025

Sample Preparation to Bioinformatics Analysis of DNA Methylation: Association Strategy for Obesity and Related Trait Studies
14:56

Sample Preparation to Bioinformatics Analysis of DNA Methylation: Association Strategy for Obesity and Related Trait Studies

Published on: May 6, 2022

4.3K

Possible selection bias in register-based obesity studies.

Lena Ms Carlsson1, Markku Peltonen2, Peter Jacobson1

  • 1Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

European Journal of Epidemiology
|May 12, 2025
PubMed
Summary
This summary is machine-generated.

Control groups in obesity studies may skew results. Those with a prior obesity diagnosis in registers showed higher mortality than those without, impacting bariatric surgery survival benefit estimations.

Keywords:
Life expectancyObesity diagnosisRegister-based studies

More Related Videos

Assessment of Child Anthropometry in a Large Epidemiologic Study
09:36

Assessment of Child Anthropometry in a Large Epidemiologic Study

Published on: February 2, 2017

26.9K
Palatable Western-style Cafeteria Diet as a Reliable Method for Modeling Diet-induced Obesity in Rodents
09:10

Palatable Western-style Cafeteria Diet as a Reliable Method for Modeling Diet-induced Obesity in Rodents

Published on: November 1, 2019

10.5K

Related Experiment Videos

Last Updated: May 13, 2025

Sample Preparation to Bioinformatics Analysis of DNA Methylation: Association Strategy for Obesity and Related Trait Studies
14:56

Sample Preparation to Bioinformatics Analysis of DNA Methylation: Association Strategy for Obesity and Related Trait Studies

Published on: May 6, 2022

4.3K
Assessment of Child Anthropometry in a Large Epidemiologic Study
09:36

Assessment of Child Anthropometry in a Large Epidemiologic Study

Published on: February 2, 2017

26.9K
Palatable Western-style Cafeteria Diet as a Reliable Method for Modeling Diet-induced Obesity in Rodents
09:10

Palatable Western-style Cafeteria Diet as a Reliable Method for Modeling Diet-induced Obesity in Rodents

Published on: November 1, 2019

10.5K

Area of Science:

  • Bariatric surgery outcomes
  • Obesity research methodology
  • Epidemiology

Background:

  • Studies on obesity treatments often use control groups from real-world registers.
  • These control groups may not accurately represent the general population with obesity.
  • This can potentially bias the assessment of treatment efficacy.

Purpose of the Study:

  • To evaluate the impact of control group selection on obesity treatment outcome studies.
  • To investigate differences in mortality rates between obese individuals with and without a prior diagnosis in a national patient register.
  • To assess potential selection bias in bariatric surgery research.

Main Methods:

  • Analysis of the SOS study cohort, comparing bariatric surgery patients (n=2,007) with matched controls (n=2,040).
  • Subdivision of the control group based on obesity diagnosis status in the Swedish National Patient Register.
  • Long-term mortality assessment over a median follow-up of 26 years, confirmed in a separate cohort (n=2,759).

Main Results:

  • Controls with a prior obesity diagnosis exhibited a higher mortality rate (19.7 deaths/1000 person-years) compared to those without (14.4 deaths/1000 person-years).
  • This translated to a hazard ratio of 1.45 (p=0.005) and a 3.4-year shorter life expectancy for controls with a prior diagnosis.
  • Similar findings were observed in a second cohort, indicating a hazard ratio of 1.82 (p<0.001) and a 6.1-year shorter life expectancy.

Conclusions:

  • Real-world control groups, particularly those identified by a prior obesity diagnosis, may represent individuals in poorer health.
  • Using such controls in obesity treatment research can lead to an overestimation of treatment benefits, such as survival advantages post-bariatric surgery.
  • Careful consideration of control group selection and health status is crucial for accurate research findings in obesity and bariatric surgery studies.