Incidence is determined by?

Appeared in: P.CHO-2019

Explanation

Incidence is the number of new cases of a disease in a population over a period of time.
Prospective (cohort) studies follow disease-free individuals over time to observe new cases.
This design allows direct calculation of incidence rates.
Prospective studies are also called incidence studies or longitudinal studies.

Option B: Case control studies start with people who already have the disease (cases) and compare them to controls without the disease. They look backward to assess exposure, so they cannot measure incidence directly.
Option C: Cross-sectional studies provide a snapshot of a population at a single point in time, measuring both exposure and disease status simultaneously. They measure prevalence, not incidence.
Option D: Retrospective studies usually refer to case-control studies, which cannot measure incidence. Only retrospective cohort studies (not specified here) can measure incidence, but the generic term 'retrospective study' does not guarantee this design.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Ability to identify which study design measures incidence (new cases) in epidemiology as background academic context rather than a clinical decision trigger.
Nurses and public health professionals use incidence data to identify emerging health problems and evaluate the effectiveness of interventions.
Incidence helps in planning preventive strategies and allocating resources for new cases.
What if? If a cross-sectional study is used instead, only prevalence (existing cases) can be measured, not the rate of new cases.

How to Approach the Question

Identify what is being measured: incidence (new cases) or prevalence (existing cases).
Recall that only studies with follow-up of disease-free individuals can measure incidence.
Eliminate options that start with cases (case-control) or measure at a single point in time (cross-sectional).
Remember that 'prospective' or 'cohort' studies are designed to measure incidence.
Be cautious with the term 'retrospective study'—only a retrospective cohort can measure incidence, not all retrospective studies.

Concept Tested & Keywords

Concept Tested: Ability to identify which study design measures incidence (new cases) in epidemiology.
Stem keywords: Incidence, determined by, study design
Lead-in keywords: determined by

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) pp. 69-71, 55-57

E6 NursingResearch Suresh Sharma 5e Part 1 p. 182-184

Practise the full P.CHO-2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.