ArticleClinical epidemiology2018
Sampling strategies for selecting general population comparison cohorts.
Article in Clinical epidemiology, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 63 papers.
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63 citing papers in PubMed.
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- Increased Early Post-Discharge Mortality in Patients With Acute Pancreatitis.United European gastroenterology journal · 2025Article
- Healthcare use in 12-18-year-old adolescents vaccinated against SARS-CoV-2 versus unvaccinated in a national register-based Danish cohort.Nature human behaviour · 2025Observational
- Cardiovascular risk and mortality in men receiving testosterone replacement therapy for Klinefelter syndrome in Denmark: a retrospective cohort study.The Lancet regional health. Europe · 2025Article
- Risk of type 2 diabetes after breast cancer treatment: a population-based cohort study in Denmark.Journal of the National Cancer Institute · 2025Article
- Comparison of Mortality Rates Between Patients With Diffuse Large B Cell Lymphoma Surviving 5 Years After Initial Diagnosis and a Matched General Population Cohort.Cancer medicine · 2025Article
- Patterns of Medical Diagnoses Before and After a Diagnosis of Anorexia Nervosa: A Danish Nationwide Cohort Study.The International journal of eating disorders · 2025Article
- Obstructive sleep apnoea and risk of dementia: a Danish population-based cohort study.BMJ neurology open · 2025Article
- Adverse health outcomes in offspring of parents with alcohol-related liver disease: Nationwide Danish cohort study.PLoS medicine · 2024Article
3 more citing papers are in PubMed but not listed here.
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5 authors.
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Abstract
backgroundFor a patient cohort, access to linkable population-based registries permits sampling of a comparison cohort from the general population, thereby contributing to the understanding of the disease in a population context. However, sampling without replacement in random order can lead to immortal time bias by conditioning on the future.
aimWe compared the following strategies for sampling comparison cohorts in matched cohort studies with respect to time to ischemic stroke and mortality: sampling without replacement in random order; sampling with replacement; and sampling without replacement in chronological order.
methodsWe constructed index cohorts of individuals from the Danish general population with no particular trait, except being alive and without ischemic stroke on the index date. We also constructed index cohorts of persons aged >50 years from the general population. We then applied the sampling strategies to sample comparison cohorts (5:1 or 1:1) from the Danish general population and compared outcome risks between the index and comparison cohorts. Finally, we sampled comparison cohorts for a heart failure cohort using each strategy.
resultsWe observed increased outcome risks in comparison cohorts sampled 5:1 without replacement in random order compared to the index cohorts. However, these increases were minuscule unless index persons were aged >50 years. In this setting, sampling without replacement in chronological order failed to sample a sufficient number of comparators, and the mortality risks in these comparison cohorts were lower than in the index cohorts. Sampling 1:1 showed no systematic difference between comparison and index cohorts. When we sampled comparison cohorts for the heart failure patients, we observed a pattern similar to when index persons were aged >50 years.
conclusionWhen index persons were aged >50 years, ie, had high outcome risks, sampling 5:1 without replacement introduced bias. Sampling with replacement or 1:1 did not introduce bias.
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