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Comparability of Control and Comparison Groups in Studies Assessing Long COVID
1University of California San Francisco, San Francisco.
The American Journal of Medicine
|January 28, 2023
Summary
Studies on long COVID often lack adequate comparison groups and control for confounders. This review highlights the need to re-evaluate current long COVID definitions for objectivity and reliability.
Area of Science:
- Medical Research
- Public Health
- Epidemiology
Background:
- Long COVID awareness grew via media, leading to varied definitions.
- Initial definitions were based on methodologies of inconsistent quality.
- Characterizing comparison groups in long COVID studies is crucial.
Purpose of the Study:
- To characterize comparison groups in long COVID research.
- To evaluate the comparability of different groups within long COVID studies.
- To assess the methodological rigor of existing long COVID research.
Main Methods:
- Searched Embase, Web of Science, and PubMed for high-impact original research.
- Included studies on human patients with long COVID outcomes.
- Abstracted study and long COVID characteristics, focusing on comparison groups and confounder control.
Main Results:
- Of 83 studies, 96.4% were observational, focusing on incidence, prevalence, and risk factors.
- Only 56.2% of observational studies used a control group, and 43.8% lacked one.
- Many studies failed to adjust for covariates (48.8%) or match participants (26.5% overall).
Conclusions:
- Long COVID studies frequently lack adequate comparison groups and confounder control.
- Current definitions of long COVID may be based on uncontrolled and potentially biased data.
- Standardized definitions require review to ensure they are based on objective evidence.
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