Comparison of advantages and limitations relevant to the collection of biological specimens and data interpretation in molecular epidemiology study designs (adapted from Garcia-Closas et al, 200649)
| Study design | Advantages | Limitations |
| Cross-sectional | Facilitates intense collection and timely processing of specimens (eg, freshly frozen samples, cryopreserved lymphocytes) Allows detailed collection of exposure and confounder information | Relevance of intermediate endpoints altered by current exposures in healthy individuals not always clear |
| Hospital-based case control | Facilitates intense collection and timely processing of specimens (eg, freshly frozen samples, cryopreserved lymphocytes) Participation rates for biological collections might be enhanced Facilitates follow-up of cases for treatment response and survival | More prone to selection and differential biases than other designs Some biomarkers might be affected by disease process or hospital stay |
| Population-based case control | Less subject to biases (eg, selection, exposure misclassification) than hospital-based studies | Some biomarkers might be affected by disease process May be more difficult to obtain high participation rates for biological collection than hospital-based designs |
Implementation of intense, specialised blood and tumour collection and processing protocols can be challenging | ||
| Prospective cohort | Allows study of multiple disease endpoints Allows study of transient biomarkers and biomarkers affected by disease status Selection bias and differential misclassification are avoided: non-differential misclassification might be reduced for some exposures Nested case-control or case-cohort studies can be used to improve efficiency of the design | Implementation of intense, specialised collection and processing protocols for the entire cohort can be challenging Obtaining tissue samples and following cases for treatment response and survival can be challenging in many cohorts |