J. David Cassidy

University of Toronto | U of T · Dalla Lana School of Public Health

Background Lumbar disc herniation (LDH) with radiculopathy is associated with greater pain, disability, healthcare use, and costs compared with nonspecific low back pain. Reliable information about its incidence and risk factors were lacking. Questions (1) What is the incidence of lumbar disc herniation (LDH) with radiculopathy in adults? (2) What...

Determining whether repetitive head impacts (RHI) cause the development of chronic traumatic encephalopathy (CTE)-neuropathological change (NC) and whether pathological changes cause clinical syndromes are topics of considerable interest to the global sports medicine community. In 2022, an article was published that used the Bradford Hill criteria...

Objectives: To assess all-cause mortality and suicides after pediatric traumatic brain injury (pTBI). Study design: We conducted population-based historical cohort study using three nationwide registers from 1998 to 2018 in Finland. All patients that were the age of 0e17 at the time of the pTBI were included. The reference group consisted of childr...

This prospective, community-based, active surveillance study aimed to report the incidence of moderate, severe, and serious adverse events (AEs) after chiropractic (n = 100) / physiotherapist (n = 50) visit in offices throughout North America between October-2015 and December-2017. Three content-validated questionnaires were used to collect AE info...

Objective Few clinical prediction models are available to clinicians to predict the recovery of patients with post-collision neck pain and associated disorders. We aimed to develop evidence-based clinical prediction models to predict (1) self-reported recovery and (2) insurance claim closure from neck pain and associated disorders (NAD) caused or a...

Objective Concern exists about possible problems with later-in-life brain health, such as cognitive impairment, mental health problems and neurological diseases, in former athletes. We examined the future risk for adverse health effects associated with sport-related concussion, or exposure to repetitive head impacts, in former athletes. Design Sys...

The purpose of this paper is to summarise the consensus methodology that was used to inform the International Consensus Statement on Concussion in Sport (Amsterdam 2022). Building on a Delphi process to inform the questions and outcomes from the 5th International Conference on Concussion in Sport, the Scientific Committee identified key questions,...

Studies investigating long-term symptoms and disability after mild traumatic brain injury (mTBI) have yielded mixed results. This systematic review and meta-analysis aimed to determine the prevalence of self-reported post-concussion symptoms (PCS) and disability following mTBI. We systematically searched MEDLINE, Embase, CINAHL, CENTRAL, and PsycIn...

An amendment to this paper has been published and can be accessed via the original article.

Purpose: The inter-rater reliability of the Quebec Task Force (QTF) classification system for Whiplash-Associated Disorders (WAD) remains unknown. Our objective was to determine the inter-rater reliability of the WAD classification between an experienced chiropractic clinician and two chiropractic residents. Methods: We conducted an inter-rater...

Importance: The management of traffic injuries is challenging for clinicians. Knowledge about predictors of nonrecovery from traffic injuries may help to improve patient care. Objective: To develop a prediction model for self-reported overall nonrecovery from traffic injuries six months post-collision in adults with incident traffic injuries inc...

Objectives To develop an evidence‐based guideline for the non‐invasive management of soft tissue disorders of the shoulder (shoulder pain), excluding major pathology. Methods This guideline is based on high‐quality evidence from seven systematic reviews. Multidisciplinary experts considered the evidence of effectiveness, safety, cost‐effectiveness...

Importance Claims that spinal manipulative therapy (SMT) can improve immune function have increased substantially during the COVID-19 pandemic and may have contributed to the rapid spread of both accurate and inaccurate information (referred to as an infodemic by the World Health Organization). Objective To identify, appraise, and synthesize the s...

Background A small proportion of chiropractors, osteopaths, and other manual medicine providers use spinal manipulative therapy (SMT) to manage non-musculoskeletal disorders. However, the efficacy and effectiveness of these interventions to prevent or treat non-musculoskeletal disorders remain controversial. Objectives We convened a Global Summit...

Background: In the midst of the coronavirus pandemic, the International Chiropractors Association (ICA) posted reports claiming that chiropractic care can impact the immune system. These claims clash with recommendations from the World Health Organization and World Federation of Chiropractic. We discuss the scientific validity of the claims made i...

Importance The prognosis of post-traumatic headache is poorly understood. Objective To develop and validate a prognostic model to predict the presence of post-traumatic headache six months after a traffic collision in adults with incident post-traumatic headache. Design Secondary analyses of adults with incident post-traumatic headache injured in...

Background: Prognostic research has many important purposes, including (i) describing the natural history and clinical course of health conditions, (ii) investigating variables associated with health outcomes of interest, (iii) estimating an individual's probability of developing different outcomes, (iv) investigating the clinical application of p...

Background: In occupational rehabilitation programs, return-to-work is a key outcome measure; however, the studies either used different definitions for return-to-work or do not provide their definition. In order to provide a solution to this issue, we developed a self-report return-to-work measure. Objective: We investigated the reliability and...

Objectives To develop an evidence‐based guideline for the non‐pharmacological management of persistent headaches associated with neck pain (i.e., tension‐type or cervicogenic). Methods This guideline is based on systematic reviews of high‐quality studies. A multidisciplinary expert panel considered the evidence of clinical benefits, cost‐effective...

Objective To evaluate the effectiveness of a government-regulated rehabilitation guideline compared with education and activation by general practitioners, and to a preferred-provider insurance-based rehabilitation programme on self-reported global recovery from acute whiplash-associated disorders (WAD) grade I–II. Design Pragmatic randomised clin...

Objectives: To: 1) develop/adapt and validate an instrument to measure patient safety attitudes and opinions of community-based spinal manipulative therapy (SMT) providers; 2) implement the instrument; and 3) compare results among healthcare professions. Methods: A review of the literature and content validation were used for the survey developm...

Purpose: Chiropractic spinal manipulation treatment (SMT) is common for back pain and has been reported to increase the risk for lumbar disc herniation (LDH), but there is no high quality evidence about this. In the absence of good evidence, clinicians can have knowledge and beliefs about the risk. Our purpose was to determine clinicians' beliefs...

Purpose: Chiropractic care is popular for low back pain, but may increase the risk for acute lumbar disc herniation (LDH). Low back pain is a common early (prodromal) symptom of LDH and commonly precedes LDH diagnosis. Our objective was to investigate the association between chiropractic care and acute LDH with early surgical intervention, and con...

Purpose: This population-based cohort study investigated the association between a lifetime history of a low back injury in a motor vehicle collision (MVC) and future troublesome low back pain. Participants with a history of a low back injury in a motor vehicle collision who had recovered (no or mild low back pain) were compared to those without a...

Objectives: Various definitions for concussion have been proposed, each having its strengths and weaknesses. We reviewed and compared current definitions and identified criteria necessary for an operational definition of sports-related concussion (SRC) in preparation of the 5th Concussion Consensus Conference (Berlin, Germany). We also assessed th...

Objective and background: Sleep stage disruption in persons with mild traumatic brain injury (mTBI) has received little research attention. We examined deviations in sleep stage distribution in persons with mTBI relative to population age- and sex-specific normative data and the relationships between such deviations and brain injury-related, medic...

Pain is an unpleasant, complex, and perceived experience that places a significant burden on patients and clinicians. Its severity may be mediated by emotion, attitude, and environmental influences, and pain may be expressed differently in males and females. Traumatic brain injury (TBI) is frequently associated with chronic pain. This diagnostic mo...

ABSTRACT Objective: Fatigue, alertness and daytime sleepiness are complex perceived states with significant implications for health and safety. These states are not diagnostically specific, and they may, or may not share interrelated features. Potential commonality or discordance is challenging in clinical situations, especially in controversial ne...

Objective: Fatigue, alertness and daytime sleepiness are complex perceived states with significant implications for health and safety. These states are not diagnostically specific, and they may, or may not share interrelated features. Potential commonality or discordance is challenging in clinical situations, especially in controversial neurologic...

Background Work disability is a major personal, financial and public health burden. Predicting future work success is a major focus of research. Objectives To identify common prognostic factors for return-to-work across different health and injury conditions and to describe their association with return-to-work outcomes. Methods Medline, Embase, Ps...

Objective/Background: Sleep stage disruption in persons with mild traumatic brain injury (mTBI) has received little research attention. We examined deviations in sleep stage distribution in persons with mTBI relative to population age- and sex-normative data, as well as the relationships between such deviations and brain injury-related, medical/psy...

Background Presenteeism is a growing problem in developed countries mostly due to an aging workforce. The economic costs related to presenteeism exceed those of absenteeism and employer health costs. Employers are implementing workplace health promotion and wellness programs to improve health among workers and reduce presenteeism. How best to desig...

Background: Chiropractic manipulation is a popular treatment for neck pain and headache, but may increase the risk of cervical artery dissection and stroke. Patients with carotid artery dissection can present with neck pain and/or headache before experiencing a stroke. These are common symptoms seen by both chiropractors and primary care physician...

A BSTRACT We examine the effect of a Danish reform in 2002 that increased compensation for permanent loss of earnings capacity and extended the period when whiplash claimants could get compensation for temporary loss of earnings. The first is subject to extensive state verification by the government while the second is not. Using weekly data about...

Purpose: To develop an evidence-based guideline for the management of grades I-III neck pain and associated disorders (NAD). Methods: This guideline is based on recent systematic reviews of high-quality studies. A multidisciplinary expert panel considered the evidence of effectiveness, safety, cost-effectiveness, societal and ethical values, and...

Background: Work-related traumatic brain injury (wrTBI) comprises up to 24% of TBIs, yet relatively little is known about it even though wrTBI incurs high costs to employers, insurers, and injured. Objectives: To compare demographic, clinical, and occupation-related factors following mild-to-moderate TBI of those who successfully returned to wor...

Purpose: The purpose of this study was to determine if time to claim closure was similar to time to self-reported recovery in a no fault motor vehicle collision insurance system. Method: A prospective cohort of traffic injured adults with a whiplash-associated disorder (WAD) was assembled. We excluded participants who applied for benefits after...

Background and objective: Despite being common early in life and affecting individuals' quality of life to the same degree as neck and low back pain, research into epidemiological aspects of mid-back pain (MBP) has been scarce. The purpose of our systematic review was therefore to describe the incidence and prognosis of MBP in the general populati...

Objective: The purpose of the study was to determine the prevalence and factors associated with injury in professional ballet and modern dancers, and assess if dancers are reporting their injuries and explore reasons for not reporting injuries. Design: Cross-sectional study. Setting: Participants were recruited from nine professional ballet an...

Objective: To determine whether the results from previous research suggesting that early intensive health care delays recovery from whiplash-associated disorders (WAD), was confounded by expectations of recovery and whether the association between early health care intensity and time-to-recovery varies across patterns of health care. Design: A p...

Objective: The purpose of this study was to determine the test-retest reliability and the Minimal Detectable Change (MDC) of the Whiplash Disability Questionnaire (WDQ) in individuals with acute whiplash-associated disorders (WADs). Methods: We performed a test-retest reliability study. We included insurance claimants from Ontario who were at le...

Background: Delayed recovery in persons after mild traumatic brain injury (mTBI) is poorly understood. Community integration (CI) is endorsed by persons with neurological disorders as an important outcome. We aimed to describe CI and its associated factors in insured Ontario workers with delayed recovery following mTBI. Methods: A cross-sectiona...

Aim/background: The principal aim of this study was to, for the first time, examine the relationship between insomnia and perceived disability among workers with mild traumatic brain injury (mTBI)/concussion. Patients/methods: A cross-sectional study was conducted at the Workplace Safety and Insurance Board Clinic of the largest rehabilitation t...

Study design: A cross-sectional survey. Objective: The purpose of this study was to identify characteristics of Canadian doctors of chiropractic (DCs) associated with their number of workers’ compensation patients. Summary of background data: It has been previously hypothesized that DCs that treat a relatively high volume of workers’ compensation c...

To explore how individuals with work-related mild traumatic brain injury (wrMTBI) experience return-to-work (RTW) processes when returning to the workplace where the injury occurred. RTW experiences were explored using in-depth interviews and an inductive analytic approach. Qualitative analysis guided by the research question moved through phases o...

To identify spinal injuries in Canadian ice hockey from 2006 to 2011 and to discuss data from 1943 to 2011 and impact of injury prevention programs. Data about spinal injuries with and without spinal cord injury in ice hockey have been collected by ThinkFirst's (now Parachute Canada) Canadian Ice Hockey Spinal Injuries Registry since 1981 through q...

Abstract Purpose This population-based cohort study investigated the association between a lifetime history of a work-related low back injury, in those who had recovered to have no or mild low back pain, and the development of troublesome low back pain (LBP). A secondary analysis explored the possible effects of misclassification of the exposure by...

Few instruments are available to measure disability associated with Whiplash-associated disorders (WAD). The Whiplash Disability Questionnaire (WDQ) was developed to measure disability resulting from WAD, but its validity is unknown for acute WAD. To determine the structural and construct validity of the WDQ in individuals with acute WAD. Cohort st...

Abstract Objective The purpose of this study was to identify characteristics of Canadian doctors of chiropractic (DCs) associated with the number of patients referred by medical doctors (MDs). Methods Secondary data analyses were performed on the 2011 cross-sectional survey of the Canadian Chiropractic Resources Databank. The Canadian Chiroprac...

Introduction: Insomnia is a common complaint among persons with mild traumatic brain injury (mTBI). However, its impact on recovery after mTBI/concussion has not been characterized. Clarifying the association between insomnia and self-perceived disability may serve the vital role in understanding rehabilitation outcomes, including return to work af...

Over the past two decades, clinical research within the chiropractic profession has focused on the spine and spinal conditions, specifically neck and low back pain. However, there is now a small group of chiropractors with clinical research training that are shifting their focus away from traditional research pursuits towards new and innovative are...

To determine sex differences in the recovery and prognosis after MTBI in adults and children. We analyzed all scientifically admissible primary studies in the World Health Organization (WHO) (n=120) and International Collaboration on Mild Traumatic Brain Injury Prognosis (ICoMP) (n=101) systematic reviews regarding prognosis of MTBI for sex-stratif...

Background Traffic collisions often result in a wide range of symptoms included in the umbrella term whiplash-associated disorders. Mid-back pain (MBP) is one of these symptoms. The incidence and prognosis of different traffic injuries and their related conditions (e.g. neck pain, low back pain, depression or others) has been investigated previousl...

Summary of Background Data Current evidence suggests that neck pain is negatively associated with health related quality of life (HRQoL). However, these studies are cross-sectional and do not inform the association between neck pain and future HRQoL. Purpose The purpose of this study was to investigate the association between increasing grades of...

The purpose of this study was to identify characteristics of Canadian doctors of chiropractic (DCs) associated with the number of patients referred by medical doctors (MDs). Secondary data analyses were performed on the 2011 cross-sectional survey of the Canadian Chiropractic Resources Databank. The Canadian Chiropractic Resources Databank survey i...

Purpose The purpose of this study was to investigate the impact of low back pain (LBP) on future health-related quality of life (HRQoL). Current evidence suggests that individuals with LBP have poorer HRQoL than those without LBP. However, most of the evidence comes from cross-sectional studies where LBP and HRQoL are determined at the same time....

In 2004, the WHO Collaborating Centre for Neurotrauma, Prevention, Management and Rehabilitation Task Force published the first large systematic review and best evidence synthesis on the clinical course and prognosis for recovery after MTBI. Ten years later, the International Collaboration on Mild Traumatic Brain Injury Prognosis (ICoMP) formed to...

Background: Fatigue is common after traumatic brain injury (TBI). Its risk factors, natural history and consequences are uncertain. Best-evidence synthesis was used to address the gaps. Methods: Five databases were searched for relevant peer-reviewed studies. Of the 33 articles appraised, 22 longitudinal studies were selected. Results were repor...

In 2004, the WHO Collaborating Centre for Neurotrauma, Prevention, Management and Rehabilitation Task Force published the first large systematic review and best evidence synthesis on the clinical course and prognosis for recovery after MTBI. Ten years later, the International Collaboration on Mild Traumatic Brain Injury Prognosis (ICoMP) formed to...

The objective of this study was to gain an understanding of workers' experiences with returning to work, the challenges they experienced, and the supports they found most beneficial when returning to work after a workplace electrical injury. Thirteen semistructured qualitative telephone interviews were conducted with individuals who experienced an...