Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 7: Gathering Evidence for Practice

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter Highlights Epidemiologic research defined Descriptive versus analytical research Strengths and limitations of epidemiologic research methodology Applying epidemiologic research to practice

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement True or False? In descriptive studies, the researcher relies on comparisons between groups to determine the role of various risk factors in causing the problem.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False Rationale: In analytical studies, the researcher relies on comparisons between groups to determine the role of various risk factors in causing the problem. In descriptive studies, the researcher collects information to characterize and summarize the health event or problem.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Epidemiologic Research Identify community/public health problems Describe natural history and etiology of diseases

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Observational Studies In descriptive studies, the researcher collects information to characterize and summarize the health event or problem. In analytical studies, the researcher relies on comparisons between groups to determine the role of various risk factors in causing the problem.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement True or False? Cohort studies involve an in-depth analysis of an individual, group, or social institution.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False Rationale: Case studies involve an in-depth analysis of an individual, group, or social institution. Cohort studies, sometimes referred to as prospective studies, are longitudinal studies, which monitor subjects over time to find associations between risk factors and health outcomes.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Descriptive Studies Case studies involve an in-depth analysis of an individual, group, or social institution Cross sectional studies are those in which a sample of persons from a population is enrolled and their exposures and health outcomes are measured simultaneously.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement True or False? Case–control studies, also known as prospective studies, work backward from the effect to the suspected cause.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False Rationale: Case–control studies, also known as retrospective studies, work backward from the effect to the suspected cause. Cohort studies, sometimes referred to as prospective studies, are longitudinal studies, monitor subjects over time to find associations between risk factors and health outcomes.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Analytical Studies Cohort studies, sometimes referred to as prospective studies, are longitudinal studies, which monitor subjects over time to find associations between risk factors and health outcomes. RR =Incidence rate of people exposed Incidence rate of people not exposed Causality—relationship between two variables in which the presence or absence of one variable (the “cause”) determines the presence or absence of the other (the “effect”)

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Analytical Studies (cont.) Case–control studies, also known as retrospective studies, work backward from the effect to the suspected cause. Subjects are selected on the basis of the presence or absence of the disease or outcome in question—one group of people (case-subjects) with the health problem and another group without the health problem (controls) The relationship between exposure and outcome in a case-control study is quantified by calculating the odds ratio (OR). The OR is an estimate of RR that is interpreted in the same manner as RR.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Advantages of Case–Control Studies Allow for the examination of multiple exposures for a single outcome Are suitable for studying rare diseases and those with long latency periods Require fewer case-subjects Are generally quicker and less expensive to conduct than cohort studies, making them well suited for an outbreak investigation

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Disadvantages of Case–Control Studies They are not appropriate for studying rare exposures. They are subject to bias because of the method used to select controls. They do not allow the direct measure of the incidence of disease.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement True or False? Intervention study is the epidemiologic investigation designed to test a hypothesized relationship by modifying an identified factor in a population. The study is preventive.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False Rationale:Intervention study is the epidemiologic investigation designed to test a hypothesized relationship by modifying an identified factor in a population. Studies may be therapeutic (clinical) or preventive.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Intervention (Experimental) Studies Intervention study—epidemiologic investigation designed to test a hypothesized relationship by modifying an identified factor in a population. –Preventive trial—study where the investigator provides a specific preventive measure to the group under study and follows the group to determine the effects of the intervention –Therapeutic trial—clinical trial where the investigator provides a specific treatment (therapy) to the group under study and follows the group to determine the effects of the treatment

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Statistics P value, generally at.05, to ensure that the study results are not due to chance alone and to avoid committing a type I error. A type I error occurs when the null hypothesis (H 0, a theory that has been put forward, either because it is believed to be true or because it is to be used as a basis for argument) is rejected when it is true. A type II error occurs when one rejects the alternative hypothesis (H a ) (fails to reject the null hypothesis) when the alternative hypothesis is true.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement True or False? The “gold standard” for research design is the randomized, experimental group design.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False Rationale: The “gold standard” for research design is the randomized, control group design.

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Community Health Nurses Consumers of health-related research, which is used to inform and educate the public Having a basic understanding of research methods allows nurses to interpret and critically analyze studies described in newspapers, magazines, and scientific journals, as well as on the Internet Allows nurses to generate research questions related to problems identified in their practice