Chiropractic Care and Risk For Acute Lumbar Disc Herniation

199 Pages·2015·9.34 MB·English

Chiropractic Care and Risk For Acute Lumbar Disc
Herniation: A Mixed Methods Approach
by
Cesar Alberto Hincapié
A thesis submitted in conformity with the requirements
for the degree of Doctor of Philosophy
Dalla Lana School of Public Health
Division of Epidemiology
University of Toronto
© Copyright by Cesar Alberto Hincapié, 2015
Chiropractic Care and Risk For Acute Lumbar Disc Herniation:
A Mixed Methods Approach
Cesar Alberto Hincapié
Doctor of Philosophy
Dalla Lana School of Public Health
Division of Epidemiology
University of Toronto
2015
Abstract
Objective: To advance knowledge of the risk for acute lumbar disc herniation (LDH)
following chiropractic care. The objectives were to: (1) synthesize current evidence on
the incidence and determinants of LDH with radiculopathy in adults; (2) determine
clinicians’ beliefs regarding the risk for acute LDH associated with chiropractic spinal
manipulation treatment (SMT); and, (3) investigate associations between both
chiropractic and primary care physician (PCP) care, and acute LDH with incident early
surgery.
Methods: (1) Systematic review of the literature. (2) Belief elicitation interviews with 47
chiropractors, family physicians and spine surgeons. Probability distributions for the
relative risk (RR) for acute LDH associated with chiropractic SMT were derived. (3) Self-
controlled case series study using Ontario administrative health data. Incidence ratios
for acute LDH with early surgery in exposed periods after chiropractic visits relative to
unexposed periods were estimated within individuals, and compared with incidence
ratios following PCP visits.
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Results: (1) The annual incidence of LDH with radiculopathy ranges between 0.1% and
10%, and varies with the case definition. Risk factors included individual, behavioural
and work-related characteristics. (2) In the belief elicitation study, chiropractors
expressed the most optimistic belief (median RR, 0.56; IQR, 0.39-1.03); family
physicians, a neutral belief (median RR, 0.97; IQR, 0.64-1.21); and spine surgeons, a
more pessimistic belief (median RR, 1.07; IQR, 0.95-1.29). (3) The self-controlled case
series study found positive associations between both chiropractic and PCP visits, and
surgically managed acute LDH. There was no more risk associated with visits to
chiropractors than with visits to PCPs.
Conclusions: (1) The best evidence synthesis shows the varying quality and
heterogeneity of the epidemiologic literature on LDH with radiculopathy. There is a need
to develop standardized case definitions that validly classify the clinical spectrum. (2)
Clinicians’ beliefs about the risk for acute LDH associated with chiropractic SMT varied
systematically across professions. The derived probability distributions can serve as
prior probabilities in Bayesian analyses of this exposure-outcome association. (3)
Patients with prodromal back pain related to a developing disc herniation may seek
healthcare from both chiropractors and PCPs before full clinical expression of acute
LDH that is subsequently surgically managed.
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Acknowledgments
First, I would like to acknowledge my parents, Juan Manuel and Lilia Hincapié; my
brother, Juan Carlos Hincapié, and sister, Maria Cristina Choy (née Hincapié); and the
rest of my family, for all their love, support and encouragement. Má y Pá, soy quien
soy, en gran parte por tu ejemplo único de amor, sacrificio y esfuerzo. Gracias con toda
alma, vida y corazón!
I would like to express my sincere gratitude and appreciation to my supervisor, J. David
Cassidy, for giving me the opportunity to undertake this PhD under your great
mentorship and for providing many learning and research opportunities throughout the
process. Your dedication, excellence and leadership have burned a bright path for so
many others to follow, and I am truly honoured and blessed to count you as a mentor,
colleague and friend.
A heart-felt thanks to all of my advisory committee members: Pierre Côté, Alejandro
Jadad, George Tomlinson, Raj Rampersaud and Eleanor Boyle, for their enthusiasm,
support and guidance with this thesis. This work and I have been enriched by each of
your brilliant minds and many contributions along the way. A special thanks goes to
George, for your incredible generosity with both your time and sharp analytical mind,
and for your friendship. I will remember with great fondness the many hours of
“R-awesome” coding and analysis that we shared.
I thank my doctoral program director, Nancy Kreiger, and the support staff in the
Division of Epidemiology, at the Dalla Lana School of Public Health, for their helpful
administrative support and guidance throughout the program.
I would like to acknowledge the Canadian Institutes of Health Research and the
Canadian Chiropractic Research Foundation, for their interest and funding of this work.
A special mention goes to Allan Gotlib, for your tireless effort and enthusiasm for the
development of Canadian chiropractic clinician-scientists; thank you, Allan.
Many thanks to my chiropractic and epi research friends: Maja Stupar, Carol
Cancelliere, James Donovan, Heather Shearer, Craig Jacobs, Mana Rezai, Darren
iv
Brenner, Paul Arora, Beth Rachlis, Nancy Carnide and Silje Mæland, for the memorable
times shared and many insightful clinical, epidemiologic and personal discussions along
the way. Silje, a special thanks to you and Ketil (and Sunniva, Gustav and Wilhelm), for
your friendship and encouragement, and the great times our families shared.
Thank you to my beautiful, supportive and understanding children, Maia Liliana, Julia
Marie, Daniel Joseph and Michael Juan Hincapié. You are the most precious gift and
blessing in my life, and I give God thanks for allowing me to share in your lives.
Finally, thank you to my wonderful and amazing wife, Barb Hincapié (née Kral). Amor,
there are no words to express my love and gratitude for you and all that you do for our
family. You are a shining beacon of love, dedication and giving. Thank you for your
support, patience, kindness and encouragement. I look forward to continuing on life’s
journey together!

v
Table of Contents
Acknowledgements iv
Table of Contents vi
List of Tables vii
List of Figures viii
List of Appendices ix
List of Abbreviations x
Thesis Overview xii

Chapter 1 General introduction and outline 1
Chapter 2 Incidence and determinants of lumbar disc herniation with 22
radiculopathy in adults: a systematic review
In preparation for submission, 2015
Chapter 3 Chiropractic spinal manipulation treatment and the risk for acute 65
lumbar disc herniation: a belief elicitation study
In preparation for submission, 2015
Chapter 4 Chiropractic care and risk for acute lumbar disc herniation: a 87
population-based self-controlled case series study
In preparation for submission, 2015
Chapter 5 Summary and synthesis 115
Chapter 6 Appendices 131

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List of Tables
Table 1.1. Low risk of bias RCTs on spinal manipulation for lumbar disc herniation
with radiculopathy
Table 2.1. Characteristics of eligible studies examining the incidence of and/or risk
factors for lumbar disc herniation with radiculopathy in adults
Table 2.2. Summary of eligible studies examining the incidence of and/or risk factors
for lumbar disc herniation with radiculopathy in adults
Table 3.1. Characteristics of belief elicitation study participants
Table 3.2. Clinicians’ beliefs about the risk for acute lumbar disc herniation and
surgically managed acute lumbar disc herniation associated with
chiropractic spinal manipulation treatment
Table 3.3. Characteristics of clinicians with optimistic versus pessimistic beliefs about
the risk for acute lumbar disc herniation and surgically managed acute
lumbar disc herniation associated with chiropractic spinal manipulation
treatment
Table 4.1. Characteristics of study participants at the time of the recording of an
acute lumbar disc herniation with incident early surgery
Table 4.2. Distribution of chiropractor and primary care physician visits before the
event index date for all cases and stratified by event fiscal year
Table 4.3. Incidence rate ratios for an acute lumbar disc herniation with first early
surgery event in exposed periods following chiropractic and primary care
physician visits
Table 4.4. Results of sensitivity analyses compared to primary analysis of an acute
lumbar disc herniation with first early surgery event in risk periods 0 to 7
days after chiropractor and primary care physician visits
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List of Figures
Figure 1.1. The case-crossover and self-controlled case series designs
Figure 2.1. Flow diagram of information through phases of the systematic review
Figure 3.1. Beliefs regarding the risk for acute lumbar disc herniation associated with
chiropractic spinal manipulation treatment: a. among all clinicians, b.
among clinician groups, c. among optimistic versus pessimistic clinicians
Figure 3.2. Beliefs regarding the risk for acute lumbar disc herniation associated with
chiropractic spinal manipulation treatment: a. by gender, b. by age group,
c. by clinical experience
Figure 4.1. Representation of the self-controlled case series design
Figure 4.2. Case definition flow diagram
Figure 4.3. Bootstrap incidence rate ratios for primary analysis of any visit exposure
with a risk period of 0-7 days following chiropractic versus primary care
physician care
Figure 4.4. Kernel density estimate of the ratio of bootstrap incidence rate ratios for
chiropractic versus primary care physician care
Figure 5.1. Preliminary Bayesian triplots of risk for acute lumbar disc herniation with
early surgery associated with chiropractic care

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List of Appendices
Appendix A. Risk of bias assessment summary (Chapter 1)
Appendix B. Comparison of the case-crossover (CCO) and self-controlled case series
(SCCS) designs (Chapter 1)
Appendix C. Systematic review search strategies (Chapter 2)
Appendix D. Detailed evidence tables for systematic review (Chapter 2)
Appendix E. Belief elicitation questionnaire (Chapter 3)
Appendix F. Belief elicitation script (Chapter 3)
Appendix G. Belief elicitation computer protocol (Chapter 3)
Appendix H. Case and exposure definition tables for self-controlled case series study
(Chapter 4)
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List of Abbreviations
CCO Case-crossover
CI Confidence interval
CT Computerized tomography
DAD Discharge Abstract Database
DC Doctor of chiropractic
ED Emergency department
HEA Home exercise and advice
HNP Herniated nucleus pulposus
HRR Hazard rate ratio
ICD International classification of diseases
IQR Interquartile range
IRR Incidence rate ratio
LBP Low back pain
LDH Lumbar disc herniation
MRI Magnetic resonance imaging
MSK Musculoskeletal
N Number
NACRS National Ambulatory Care Reporting System
ND No data
NR Not reported
NRS Numerical rating scale
NSAID Nonsteroidal anti-inflammatory drug
OHIP Ontario Health Insurance Plan
OR Odds ratio
PCP Primary care physician
PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses
PROSPERO International prospective register of systematic reviews
QTFSD Quebec Task Force on Spinal Disorders
R R project for statistical computing
RCT Randomized controlled trial
x