A review of cohort study design for cardiovascular nursing research

Cohort Studies

Editor's note: This is the seventh article in a series on clinical research by nurses. The series is designed to give nurses the knowledge and skills they need to participate in research, step by step. Each column will present the concepts that underpin evidence-based practice-from research design to data interpretation. The articles will be accompanied by a podcast offering more insight and context from the authors. To see all the articles in the series, go to http://links.lww.com/AJN/A204.

Schizophrenia, cognition, and aging: cognitive deficits and the relationship between test performance and aging

Most measures of cognitive function decline with age during adulthood. Research indicates that people with schizophrenia experience considerable cognitive deficits. These deficits appear to become more troublesome with increasing age, but this has been debated. The aim of this research was to better understand the age related cognitive deficits of Icelandic subjects with schizophrenia in comparison to healthy individuals. Cognition of individuals 18 to 64 years of age was evaluated with 10 neuropsychological tests. People with schizophrenia performed significantly worse on all tests, as expected, indicating widespread cognitive deficits compared to healthy individuals, independent of age. Furthermore, the results suggest that people with schizophrenia follow a similar age-related trajectory of cognitive decline as healthy individuals. Overall, we conclude that the cognitive difficulties often experienced by older people with schizophrenia are better explained by lower cognitive function at the time of diagnosis than by faster cognitive decline with increasing age.

Cohort Research in "Omics" and Preventive Medicine

Cohort studies are observational studies in which the investigator determines the exposure status of subjects and then follows them for subsequent outcomes. The incidence of outcomes is observed in the exposed group and compared with that in a nonexposed group. Recently, new epidemiologic strategies have encouraged cohort research information exchange and cooperation to improve the cognition of disease etiology, such as case-cohort design and nested case-control study, which is available for "omics" data. Meanwhile, large-scale cohort studies using a prospective multiple design and long follow-ups have explored some of the challenges in preventive medicine. Cohort study can bridge the gap between the micro and macro research.This chapter is divided into three parts: 1. Basic knowledge of cohort study, which included the definition of cohort study and different types of cohort study, how to design the cohort study, data analysis for the cohort study, sources of bias in cohort studies, tools and software for cohort studies, and strengths and limitations of cohort study 2. Cohort study for "omics" data analysis, which introduced three related methodologically distinct study designs, case-cohort design for genomic cohort study, nested case-control design for transcriptomics cohort data, and population-based design for integrative "omics" cohort 3. Perspectives on cohort study including data-driven medicine and cohort research, cohort research for healthcare medicine, and cohort research for preventive medicine.

Effectiveness of an emergency nurse practitioner service for adults presenting to rural hospitals with chest pain: protocol for a multicentre, longitudinal nested cohort study

INTRODUCTION

Chest pain is common in emergency department (ED) patients and represents a considerable burden for rural health services. Health services reforms to improve access to care need appropriately skilled and supported clinicians in the delivery of safe and effective care, including the use of emergency nurse practitioners (ENPs). Despite increasing use of ENPs, little is known about the safety and quality of the service in the rural ED context. The aims of this study are (1) to examine the safety and quality of the ENP service model in the provision of care in the rural environment and (2) to evaluate the effectiveness of the service in the management of patients presenting with undifferentiated chest pain.

METHODS AND ANALYSIS

This is the protocol for a prospective longitudinal nested cohort study to compare the effectiveness of ENP service with that of standard care. Adults presenting to three rural EDs in Queensland, Australia with a primary presenting complaint of atraumatic chest pain will be eligible for enrolment. We will measure (1) clinician's use of evidence-based guidelines (2) diagnostic accuracy of ECG interpretation for the management of patients with suspected or confirmed ACS (3) service indicators of waiting times, length-of-stay and did-not-wait rates and (4) clinician's diagnostic accuracy as measured by rates of unplanned representation within 7 days (5) satisfaction with care, (6) quality-of-life and (7) functional status. To assess these outcomes we will use a combination of measures collected from routinely collected data, medical record review and questionnaires (with 30-day follow-up).

ETHICS AND DISSEMINATION

Queensland Health Human Research Ethics Committee (HREC) has approved this protocol. The results will be published in peer-reviewed scientific journals and presented at one or more scientific conferences.

An overview of cohort study designs and their advantages and disadvantages

Background

Cohort studies are analytical observational research studies which follow groups (cohorts) of subjects forward in time from an exposure to an outcome/s. Rigorous cohort studies provide the best scientific evidence of all the observational research designs.

Contents

This paper provides an overview of the definition, design, analysis, interpretation, advantages and disadvantages of cohort studies. Readers should appreciate the strengths, weaknesses and potential pitfalls of cohort studies when interpreting and applying results to clinical practice.

Conclusions

Cohort study designs should be considered when RCT are not possible or practical for ethical, logistical, or financial reasons. When properly designed and interpreted, links between exposures and outcomes (including an indication of causality) can be made.