University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

447

Pages:

2
Author:

Mariam A. A.

Descriptive studies • First foray into an area of inquiry • Documents health or illness of populations • Prelude to more rigorous studies, gives suggestive findings • Traditional descriptive epidemiology: person, place and time. Who? What? When? and Where? • Types: case reports/case series, cross-sectional studies, ecological studies, use of routine data • Use: trend analysis, service planning (i.e. resources, utilisation), clues about case and generation of hypothesis • Common pitfalls: o Absence of a clear, specific and reproducible case definition o Interpretations that overstep the data o No comparison group – do not allow conclusions about cause 39 Cross sectional studies (descriptive) • Measure prevalence of exposure and disease at the same time • Rate of exposure is correlated with rate of disease frequency (or other health outcome) Case reports/case series • Case report o Detailed description of an unusual disease or association o Rare disease, or common disease in unusual person • Case series o Aggregates individual cases into one report o May include hypothesis as to the cause o Weak evidence, but may prompt further investigations with more rigorous study designs • Advantages o May be the only means of surveillance for rare clinical events o Provides source of ideas for hypotheses • Disadvantages o No comparison made with another group o Are not able to test hypotheses o Highly susceptible to bias o Not able to generalise or make conclusions about causality Ecological studies • ‘Correlational’ or ‘aggregate’ studies • Relate exposure and outcome in populations or groups NOT individuals • Can compare populations in different geographic areas or with similar characteristics, at same point in time • Can compare same population at different points in time • May use published routine data sources • Advantages o Quick, cheap and easy to do o Use of routine data o May suggest associations between exposure and outcomes, hypothesis generating • Disadvantages o Doesn’t link exposure to outcome in the same person o ‘Ecological fallacy’ – other (individual) differences might explain observed effects o Use of proxy measures