Health Science Research

A handbook of quantitative methods

Jennifer K Peat, Katrina Williams, Wei Xuan, Craig Mellis

• Publisher: Routledge
• Year: 2020
• eBook ISBN:
  9781000256703
• Topic: Medicine
• Subtopic: Biostatistics

This is an excellent book, which will be of value to all those health professionals seeking to demystify the sometimes intimidating area of research. Well organised, comprehensive, and clearly written, it is indeed a 'handbook'; it has a clear, step by step approach with many practical examples. It is suitable for researchers across the range of health disciplines, and the authors are to be congratulated for what will become an important resource.

Professor Frank Oberklaid, Director, Centre for Community Child Health

University of Melbourne/Royal Children's Hospital

This book will clearly be a great help to young, and to some extent, experienced research workers focusing on epidemiological and clinical questions framed either in terms of the broad community or patient groups. I recommend it warmly.

Professor Stephen Leeder, Dean, Faculty of Medicine, University of Sydney

High quality clinical research is a cornerstone of effective health care and much good research is undertaken by clinicians. Yet many of the resources available on research methods are highly theoretical and inaccessible.

Written in a user-friendly style by a team of experienced clinical researchers, Health Science Research guides readers through the fundamentals of clinical inquiry. It outlines the steps needed to plan a study, recruit and select subjects, gather and analyse data, and report on results. The authors also explain how to deal ethically with interviewees, and how to prepare a grant application.

Health Science Research is an indispensable guide for anyone who needs to undertake a clinical study, including physicians, nurses, allied health workers, scientists and research assistants.

Jennifer Peat is Hospital Statistician in the Clinical Epidemiology Unit at the New Children's Hospital, Westmead, and Associate Professor in the Department of Paediatrics and Child Health at the University of Sydney. Katrina Williams and Professor Craig Mellis are from the same Hospital and Department, and Wei Xuan is from the Department of Medicine, University of Sydney.

1
REVIEWING THE LITERATURE

Reviewing the literature

Reviewing the literature

The objectives of this chapter are to understand:

• how critical appraisal is used;
• the role of systematic reviews;
• the process of Cochrane reviews; and
• how to facilitate evidence-based practice.

Improving health care delivery

Critical appraisal

Scientific merit

Using critical appraisal to prioritise research

Critical appraisal checklist

Systematic reviews

Narrative and systematic reviews

Cochrane collaboration

Cochrane library

Cochrane review groups

Undertaking a Cochrane review

Evidence-based practice

Procedures for evidence-based practice

Benefits of evidence-based practice

Improving health care delivery

Two essential components in the process of delivering high quality health care are the availability of scientifically valid research studies and the practice of good critical appraisal skills in order to select the most appropriate evidence. Critical appraisal skills are essential for helping to decide whether published research is of a sufficiently high quality to indicate that changes in health practice are required. In this process, the disciplines of critical appraisal and research methods both complement and overlap one another because critical appraisal is a process that helps to identify and foster research studies that use methods of the highest scientific integrity.

Glossary

Term	Meaning
Critical appraisal	Application of rules of scientific evidence to assess the validity of the results of a study
Systematic review	Procedure to select and combine the evidence from the most rigorous scientific studies
Evidence-based practice	Patient care based on the evidence from the best available studies

High quality evidence of health care practices can only be acquired through the implementation of accurate research methods at all stages of a research study, especially the critical stages of study design, data collection and data management, statistical analyses and the interpretation and presentation of the findings. The fundamental issues that must be considered in collecting accurate research data are shown Table 1.1.

Table 1.1 Fundamental issues in research design

Study methods merit—type of study accuracy—differential and non-differential bias randomisation and allocation concealment blinding—single or double confounding—control in design or analyses precision—validity and repeatability of tools stopping rules—reducing type I errors sample size—statistical power and accuracy

Analysis data management interim analyses statistical and reporting methods

Interpretation generalisability clinical importance level of evidence

Critical appraisal

Scientific merit

Critical appraisal, which is the process used to evaluate the scientific merit of a study, has become an essential clinical tool. The fundamental skills of appraisal are to ask questions about whether a reported association between an intervention or exposure and a health outcome is causal or can be explained by other factors such as chance, bias or confounding. This approach is essential because we can only have confidence in results that could not have arisen by chance, are not affected by bias or confounding, and are not influenced by the statistical methods chosen to analyse the data.

Critical appraisal skills are essential for making decisions about whether to change clinical practice on the basis of the published literature, and for making decisions about the most important directions for future research. In judging an article as valuable evidence, the conclusions reached must be justified in terms of the appropriateness of the study methods used and the validity of the results reported. Judging these merits comes from a sound understanding of the limitations and the benefits of different research methods.

Using critical appraisal to prioritise research

A valuable aspect of critical appraisal is that the process can help to prior-itise new research by highlighting gaps in knowledge and inadequacies in existing studies. This is important because, at best, poor studies cannot provide answers to questions about the effectiveness of practices but, at worst, they can be misleading. The process of critical appraisal can also provide a formalised system of peer review before published results are considered for incorporation into clinical practice. By highlighting clinical practices for which the evidence of efficacy or effectiveness is poor, the process of critical appraisal also helps to identifiy questions that can only be answered by conducting research studies that are more rigorous than those previously undertaken. The steps for undertaking the critical appraisal of a study that has been designed to address a health care question are shown in Table 1.2.

Table 1.2 Steps for critical appraisal

❑ Identify hypothesis ❑ Identify study design ❑ Note criteria for subject selection and sample size ❑ Identify sources of bias ❑ Consider possible effects of confounding ❑ Appraise statistical methods ❑ Consider whether results are statistically significant and/or magnitude is of clinical importance ❑ List strengths and weaknesses ❑ Decide whether conclusion is warranted

Critical appraisal checklist

When reviewing an article, it is often useful to have a checklist to help evaluate scientific merit. The checklist shown in Table 1.3 provides a short list of questions to ask when reviewing a journal article for research purposes. Other critical appraisal checklists for more specialised purposes are available. For example, an evaluation method has been developed that ranks studies into five levels of evidence according to the risk of bias.1 Many journals also provide their own checklists and formats that have to be followed when submitting or reviewing articles and the British Medical Journal has excellent checklists for writers, statisticians and reviewers that can be accessed through its website. In addition, other question lists2, 3 and check lists4–9 provide specific questions that should be asked when deciding whether the evidence reported in an article should be applied in a specific clinical practice.

Table 1.3 Checklist of questions for critical appraisal

Introduction ❑ What does this study add to current knowledge? ❑ What are the study aims or what hypotheses are being tested? Study design ❑ What type of study design has been used? ❑ What are the inherent strengths and weaknesses of this design? ❑ Are the methods described in enough detail to repeat the study? Subjects ❑ Are the characteristics of the study sample described in detail? ❑ What are the selection methods, including the exclusion/inclusion criteria? ❑ Are the subject numbers adequate to test the hypothesis? ❑ What is the generalisability of the results? Measurements ❑ Are the validity and repeatability of the measurements described? ❑ Are the outcome measurements clinically relevant? Minimisation of bias ❑ What was the response rate? ❑ What is the profile of the refusers or non-responders? ❑ Were the cases and controls sampled from similar populations? ❑ Were all subjects studied using exactly the same protocol? ❑ Could there be any recall or reporting bias? ❑ Was double blinding in place? Control of confounding ❑ How was the randomisation and allocation concealment carried out? ❑ Have confounders been measured accurately and taken into account? ❑ Were the study groups comparable at baseline? Results ❑ What are the outcomes (dependent) and explanatory (independent) variables? ❑ Do the results answer the study question? Reporting bias ❑ Are the statistical analyses appropriate? ❑ Are all of the subjects included in the analyses? ❑ Are confidence intervals and P values given? ❑ Could any results be false positive (type I) or false negative (type II) errors? Discussion ❑ Did the choice of subjects influence the size of the treatment effect? ❑ Are the critical limitations and potential biases discussed? ❑ Can the results be explained by chance, bias or confounding? ❑ Are the conclusions justified from the results presented? ❑ Do the results have implications for cli...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Foreword
• Contents
• Contributors
• Introduction
• 1 Reviewing the literature
• 2 Planning the study
• 3 Choosing the measurements
• 4 Calculating the sample size
• 5 Conducting the study
• 6 Analysing the data
• 7 Reporting the results
• 8 Appraising research protocols
• References
• Index