• Maria Irina BRUMBOIU “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania
  • Irina IARU “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania


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.

Author Biographies

Maria Irina BRUMBOIU, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania

Faculty of Medicine
Department of Epidemiology

Irina IARU, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania

Faculty of Pharmacy
Department of Pharmacology, Physiology and Physiopathology


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