Prevalence and Diagnostic Accuracy of Red Flag Questions

187 Pages·2016·3.77 MB·English

Serious Pathologies in the Lumbar Spine:
Prevalence and Diagnostic Accuracy of Red Flag Questions

Kathryn J. Street

A thesis submitted to Auckland University of Technology in fulfilment of the requirements
for the degree of Masters of Health Science (MHSc)

2016

School of Physiotherapy

Supervisors
Steven G. White
Associate Professor Alain C. Vandal
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Contents
List of Figures ................................................................................................................... 4
List of Tables..................................................................................................................... 5
List of Abbreviations......................................................................................................... 6
Glossary ............................................................................................................................ 7
Attestation of Authorship .................................................................................................. 8
Research Outputs Resulting from this Thesis ................................................................... 9
Acknowledgements ......................................................................................................... 10
Ethics ............................................................................................................................... 11
Abstract ........................................................................................................................... 12
Chapter 1 Introduction .................................................................................................... 15
1.1 The Problem ....................................................................................................... 15
1.1.1 Summary of the problem ............................................................................. 17
1.2 Thesis Aims ........................................................................................................ 18
1.3 Overview of the Thesis ...................................................................................... 18
1.4 Significance of the research ............................................................................... 19
Chapter 2 Systematic Review of the Literature .............................................................. 21
2.1 Introduction ........................................................................................................ 21
2.1.1 Prevalence and incidence ............................................................................ 21
2.1.2 Index tests ................................................................................................... 22
2.1.3 Reference standard ...................................................................................... 22
2.1.4 Objectives .................................................................................................... 23
2.2 Target Condition: Vertebral Fracture ................................................................. 23
2.2.1 Background ................................................................................................. 23
2.2.2 Objectives .................................................................................................... 28
2.2.3 Methods ....................................................................................................... 28
2.2.4 Results ......................................................................................................... 32
2.2.5 Discussion ................................................................................................... 44
2.3 Target Condition: Spinal Malignancy ................................................................ 49
2.3.1 Background ................................................................................................. 49
2.3.2 Objectives .................................................................................................... 53
2.3.3 Methods ....................................................................................................... 53
2.3.4 Results ......................................................................................................... 55
2.3.5 Discussion ................................................................................................... 65
2.4 Target Condition: Cauda Equina Syndrome ...................................................... 68
2.4.1 Background ................................................................................................. 68
2.4.2 Objectives .................................................................................................... 72
2.4.3 Methods ....................................................................................................... 72
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2.4.4 Results ......................................................................................................... 74
2.4.5 Discussion ................................................................................................... 76
2.5 Target Condition: Spinal Infection ..................................................................... 78
2.5.1 Background ................................................................................................. 78
2.5.2 Objectives .................................................................................................... 83
2.5.3 Methods ....................................................................................................... 84
2.5.4 Results ......................................................................................................... 85
2.5.5 Discussion ................................................................................................... 89
Chapter 3 Clinical Prevalence and Population Incidence of Serious Pathologies
Amongst Patients Undergoing Magnetic Resonance Imaging for Low Back Pain ........ 91
3.1 Introduction ........................................................................................................ 91
3.1.1 Study aims ................................................................................................... 93
3.1.2 Methodological considerations ................................................................... 93
3.2 Study Methods ................................................................................................... 94
3.2.1 Ethics ........................................................................................................... 94
3.2.2 Study design ................................................................................................ 94
3.2.3 Participants .................................................................................................. 94
3.2.4 Test methods ............................................................................................... 94
3.2.1 Data analysis ............................................................................................... 96
3.3 Results ................................................................................................................ 97
3.3.1 Participants .................................................................................................. 97
3.3.1 Prevalence ................................................................................................... 98
3.3.2 Incidence ................................................................................................... 100
3.3.3 Discussion ................................................................................................. 107
3.3.4 Limitations ................................................................................................ 111
3.3.5 Conclusion ................................................................................................ 111
Chapter 4 Diagnostic Accuracy of Red Flag Questions to Screen for Serious Pathologies
Amongst Patients Referred for Magnetic Resonance Imaging for Low Back Pain ...... 113
4.1 Introduction ...................................................................................................... 113
4.1.1 Diagnostic accuracy .................................................................................. 113
4.1.2 Study Aims ................................................................................................ 115
4.1.3 Methodological considerations ................................................................. 115
4.2 Study Methods ................................................................................................. 116
4.2.1 Ethics ......................................................................................................... 117
4.2.2 Study design .............................................................................................. 117
4.2.3 Participants ................................................................................................ 117
4.2.4 Test methods ............................................................................................. 118
4.2.5 Data analysis ............................................................................................. 122
4.3 Results .............................................................................................................. 122
4.3.1 Participants ................................................................................................ 122
4.3.2 Index test results ........................................................................................ 126
4.4 Discussion ........................................................................................................ 136
4.4.1 Limitations ................................................................................................ 141
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4.4.2 Conclusion ................................................................................................ 141
Chapter 5 Summary, Key Findings and Conclusions ................................................... 143
5.1 Summary .......................................................................................................... 143
5.1.1 Key findings .............................................................................................. 143
5.1.2 Directions for future research ................................................................... 145
5.1.3 Clinical implications and conclusions ....................................................... 146
References ..................................................................................................................... 148
Appendix A Ethical Approval ....................................................................................... 168
Appendix B Participant Forms ...................................................................................... 173
Appendix C Search Strategy ......................................................................................... 180
Appendix D Quality Assessment of Diagnostic Accuracy Studies .............................. 183
Appendix E Data Coding .............................................................................................. 186
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List of Figures
Figure 2.1 Search flow chart ……………………………………………………………………….….… 33
Figure 2.2 QUADAS-2 combined study results to illustrate overall risk of bias …………………..….... 36
Figure 2.3 QUADAS-2 combined study results to illustrate overall applicability …………….……..…. 36
Figure 2.4 Combined QUADAS-2 results to illustrate overall risk of bias ………………….….………. 57
Figure 2.5 Combined QUADAS-2 results to illustrate overall applicability …………….….……...…… 57
Figure 4.1 Flow of participants through study in secondary care (SRG) …………..……………….…. 123
Figure 4.2 Flow of participants through study in tertiary care (MMH) ……………..………..….…….. 124
Figure 4.3 ROC Curve for age and with respect to fracture …………………………..………....…….. 127
Figure 4.4 ROC Curve for age and with respect to malignancy ……………………..………….…..…. 127
Figure 4.5 ROC Curve evaluating age and infection ………………………………..……….………… 128
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List of Tables
Table 2.1 Search terms for prevalence of and screening for vertebral fracture in the lumbar spine ……. 33
Table 2.2 Assessment of study quality for fracture using the QUADAS-2 ……………………………... 35
Table 2.3 Study characteristics for fracture…………………………………………………….………... 38
Table 2.4 Clinical signs and diagnostic accuracy data extracted from eligible studies for fracture …….. 42
Table 2.5 Assessment of study quality for malignancy using the QUADAS-2 ……………………….… 56
Table 2.6 Study characteristics for malignancy ………………………………………………….……… 59
Table 2.7 Clinical signs and diagnostic accuracy data extracted from eligible studies for malignancy … 63
Table 2.8 Assessment of study quality for cauda equina syndrome using the QUADAS-2 ……….…… 74
Table 2.9 Study Characteristics for cauda equina syndrome (CES) ………..………………………...…. 75
Table 2.10 Clinical signs and diagnostic accuracy data extracted from eligible studies for CES …...….. 75
Table 2.11 Assessment of study quality for spinal infection using the QUADAS-2 ................................ 86
Table 2.12 Study characteristics for spinal infection ………………………………………….………… 88
Table 2.13 Clinical signs and diagnostic accuracy data extracted from eligible studies for infection ….. 88
Table 3.1 Baseline characteristics ……………………………………………………………………….. 98
Table 3.2 Prevalence of serious pathology in secondary and tertiary care ………………...……………. 99
Table 3.3 Incidence table (per 100,000 person-years) for serious pathologies in Counties Manukau … 102
Table 3.4 Incidence table (per 100,000 person-years) for vertebral fractures in Counties Manukau ..… 103
Table 3.5 Incidence table (per 100,000 person-years) for malignancy in Counties Manukau ………… 104
Table 3.6 Incidence table (per 100,000 person-years) cauda equina syndrome in Counties Manukau ... 105
Table 3.7 Incidence table (per 100,000 person-years) for spinal infection in Counties Manukau …..… 106
Table 4.1 Baseline characteristics ………………………………………………………….…………... 125
Table 4.2 Baseline characteristics and prevalence of serious pathologies between groups …………… 126
Table 4.3 Diagnostic accuracy of red flag questions for vertebral fracture ……………………………. 131
Table 4.4 Diagnostic accuracy of red flag questions for malignancy ………………………..………… 132
Table 4.5 Diagnostic accuracy of red flag questions for cauda equina compression ………………….. 133
Table 4.6 Diagnostic accuracy of red flag questions for spinal infection ……………………………… 134
Table 4.7 ACC red flags for any serious pathology ……………………………………………………. 135
Table 4.8 Henschke diagnostic rule for vertebral fracture …………………………...………………… 135
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List of Abbreviations
AIDS Acquired Immune Deficiency Syndrome
CT Computed Tomography
CES Cauda Equina Syndrome
DEXA Dual-energy X-ray absorptiometry
HIV Human Immunodeficiency Virus
LBP Low Back Pain
LR+ Positive Likelihood Ratio
LR- Negative Likelihood Ratio
MRI Magnetic Resonance Imaging
NZD New Zealand Dollar
PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses
QUADAS Quality Assessment of Diagnostic Accuracy Studies
SPECT Single Photon Emission Computed Tomography
STARD Standards for Reporting of Diagnostic Accuracy Studies
Sn Sensitivity
Sp Specificity
95% CI 95% Confidence Interval
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Glossary
Diagnostic Accuracy – Expresses the test’s ability to discriminate between patients with
and without the target condition
Diagnostic utility – Refers to the intended use of the test, i.e. whether the test is used for
diagnosis, screening, staging, monitoring, surveillance, prediction, prognosis, or other
reasons
Incidence – The number of new cases of a condition during a specific time period in a
given population
Index test – The test under evaluation
Likelihood Ratio – The likelihood that a given test result would be predicted in a patient
with the target condition compared to the likelihood of the same result in a patient
without the target condition
Prevalence – The baseline risk of a condition within the population of interest
Point Prevalence – The proportion of a population that has the condition at a specific
point in time
Period Prevalence – The proportion of a population that has the condition at some time
during a given period (e.g. 12 months), and includes people who have the condition at
the start of the study period as well as those who acquire it during that period
Sensitivity – Proportion of those with the target condition who test positive with the
index test
Specificity – Proportion of those without the target condition who test negative with the
index test
Target condition – The disease or condition that the index test is expected to detect
Reference standard – The best available method for establishing the presence or absence
of the target condition; a gold standard would be an error-free reference standard
Receiver Operating Characteristic (ROC) Curve – A ROC curve plots the sensitivity in
function of the false positive rate (1- specificity)
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Attestation of Authorship
I hereby declare that this submission is my own work and that, to the best of my
knowledge and belief, it contains no material previously published or written by another
person (except where explicitly defined in the acknowledgements), nor material which
to a substantial extent has been submitted for the award of any other degree or diploma
of a university or other institution of higher learning.

Signed:

Dated: 10.05.2016
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Research Outputs Resulting from this Thesis
National conference presentations
Street, K., Mistry, D., White, S., & Vandal, A. (2014). Red flags in the spine. Invited
workshop presentation: General Practice Conference and Medical Exhibition, Rotorua,
NZ.
Street, K., Mistry, D., White, S., & Vandal, A. (2016). Red flags in the spine - updated.
Invited workshop presentation: General Practice Conference and Medical Exhibition,
Rotorua, NZ.
Local presentations
Street, K., White, S., & Vandal, A. (2015). Screening for serious pathologies in the
lumbar spine. Invited oral presentation: Middlemore Hospital, Auckland, NZ.
Street, K., White, S., & Vandal, A. (2015). Red flags in the lumbar spine. Invited oral
presentation: Auckland Physiotherapy, Auckland, NZ.
Planned poster presentations
Middlemore Science Fair (2016).
Other contributions
Advisory board for the development of a clinical pathway for acute low back pain
(2015). This pathway was developed in conjunction with local experts for use in general
practice, district health boards, and by St John Ambulance Services. Contributions
included a lead role in the pathway development, preparation of proposals, and
presentation to district health board managers.