Sampling strategies for selecting general population comparison cohorts
Uffe Heide-Jørgensen, Kasper Adelborg, Johnny Kahlert, Henrik Toft Sørensen, Lars Pedersen Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark Background: For a patient cohort, access to linkable population-based registries permits sampling of a com...
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| Format: | Article |
| Language: | English |
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Dove Medical Press
2018-09-01
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| Series: | Clinical Epidemiology |
| Subjects: | |
| Online Access: | https://www.dovepress.com/sampling-strategies-for-selecting-general-population-comparison-cohort-peer-reviewed-article-CLEP |
| _version_ | 1818937014952656896 |
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| author | Heide-Jørgensen U Adelborg K Kahlert J Sørensen HT Pedersen L |
| author_facet | Heide-Jørgensen U Adelborg K Kahlert J Sørensen HT Pedersen L |
| author_sort | Heide-Jørgensen U |
| collection | DOAJ |
| description | Uffe Heide-Jørgensen, Kasper Adelborg, Johnny Kahlert, Henrik Toft Sørensen, Lars Pedersen Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark Background: For 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.Aim: We 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.Methods: We 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.Results: We 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.Conclusion: When 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. Keywords: matched cohort study, survival analysis, population-based registry, observational study |
| first_indexed | 2024-12-20T05:45:14Z |
| format | Article |
| id | doaj.art-22e11084b564472481793a059a41f87c |
| institution | Directory Open Access Journal |
| issn | 1179-1349 |
| language | English |
| last_indexed | 2024-12-20T05:45:14Z |
| publishDate | 2018-09-01 |
| publisher | Dove Medical Press |
| record_format | Article |
| series | Clinical Epidemiology |
| spelling | doaj.art-22e11084b564472481793a059a41f87c2022-12-21T19:51:20ZengDove Medical PressClinical Epidemiology1179-13492018-09-01Volume 101325133740866Sampling strategies for selecting general population comparison cohortsHeide-Jørgensen UAdelborg KKahlert JSørensen HTPedersen LUffe Heide-Jørgensen, Kasper Adelborg, Johnny Kahlert, Henrik Toft Sørensen, Lars Pedersen Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark Background: For 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.Aim: We 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.Methods: We 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.Results: We 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.Conclusion: When 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. Keywords: matched cohort study, survival analysis, population-based registry, observational studyhttps://www.dovepress.com/sampling-strategies-for-selecting-general-population-comparison-cohort-peer-reviewed-article-CLEPmatched cohort studysurvival analysispopulation-based registryobservational study |
| spellingShingle | Heide-Jørgensen U Adelborg K Kahlert J Sørensen HT Pedersen L Sampling strategies for selecting general population comparison cohorts Clinical Epidemiology matched cohort study survival analysis population-based registry observational study |
| title | Sampling strategies for selecting general population comparison cohorts |
| title_full | Sampling strategies for selecting general population comparison cohorts |
| title_fullStr | Sampling strategies for selecting general population comparison cohorts |
| title_full_unstemmed | Sampling strategies for selecting general population comparison cohorts |
| title_short | Sampling strategies for selecting general population comparison cohorts |
| title_sort | sampling strategies for selecting general population comparison cohorts |
| topic | matched cohort study survival analysis population-based registry observational study |
| url | https://www.dovepress.com/sampling-strategies-for-selecting-general-population-comparison-cohort-peer-reviewed-article-CLEP |
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