USING CASE-CASE STUDY DESIGN: WHICH CAN BE THE PERFORMANCE?
Abstract
The case-case studies compare groups of patients classified by the subtype of the disease they present, to identify specific risk factors for the sub-category of patients with a characteristic of interest. Material and methods: This analysis brings attention to the main characteristics of case-case studies, with the aim of facilitating the understanding of methodology and the adequate way of implementing it, and the interpretation of the obtained results. Results: Specifically, this study design identifies the differences regarding risk factors between disease’s subtypes, reflecting their etiological heterogeneity. However, the association for potential risk factors that are common to comparison sub-groups cannot be identified and the risk revealed does not represent the risk level in the general population. One conducting a case-case study must consider both the characteristics of the chronic or infectious diseases category and the advantages and the limitation of this type of study. Conclusions: As advantages, the case-case study design helps minimizing the selection and recall bias and can be carried out for a shorter period of time, with fewer resources than conventional studies. Selection or information bias may persist, and caution is needed for the interpretation of results.
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