Research Review By Dr. Jeff Muir©

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Date Posted:

June 2020

Study Title:

Exposure to a motor vehicle collision and the risk of future back pain: A systematic review and meta-analysis

Authors:

Nolet PS, Emary PC, Kristman VL, Murnaghan K, Zeegers MP, Freeman MD

Author's Affiliations:

Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands; Department of Graduate Education and Research, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada; School of Kinesiology, Lakehead University, Thunder Bay, Ontario, Canada; Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Ontario, Canada; Department of Health Sciences, Lakehead University, Thunder Bay, Ontario, Canada; Division of Human Sciences, Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, Canada; and Institute for Work and Health, Toronto, Ontario, Canada

Publication Information:

Accident Analysis and Prevention 2020; 142: 105546.

Background Information:

Low back pain (LBP) remains one of the most common conditions in the general population and is the leading cause of years lived with disability (1). LBP maintains an annual incidence of 18.6% (2) in the general population and is associated with high rates of both persistence (40.2%) and recurrence at six months (28.7%) (2).

LBP following a motor vehicle collision (MVC) has been documented in several studies, with the Insurance Research Council reporting a 58% rate of LBP after MVC (second only to neck pain) (4). Recovery from MVC-related LBP is slow and incomplete, with 31% reporting ongoing LBP 12 months after the collision (3). The likelihood of an MVC-related injury being responsible for LBP is an important question for clinicians, insurers and courts alike, although no studies investigating this predictive relationship are currently available. As such, the authors sought to complete a systematic review and meta-analysis to estimate the difference in risk of future LBP in patients having been involved in an MVC when compared to those who had not.

Pertinent Results:

Study Characteristics

From an initial pool of 1310 citations, 3 studies met the inclusion criteria. These studies were generated from insurance/injury databases (n = 2) and a general population survey (n = 1). The duration since MVC varied from unknown to five years to seven years. Exposure to injury was alternately defined within these cohort studies as: exposure to a rear-end collision 1) without injury, 2) with neck/shoulder and low back injury, 3) with whiplash injury and 4) with only low back injury. Exposure to an MVC was confirmed via either self-reporting, physician diagnosis or insurance report. Outcomes were measured via either self-reported or validated questionnaires. Using the Task Force on Neck Pain and Its Associated Disorders phases, each of the 3 phases (hypothesis generation, exploratory and confirmatory studies) were represented by the 3 eligible studies.

Risk of Bias Assessment:

Risk of bias (RoB) was evaluated based on 6 domains: study participation, study attrition, MVC exposure, neck pain measurement, study confounding and statistical analysis/reporting. One study was rated as having low RoB in all domains. Further limitations were noted as follows: one study had moderate risk in study attrition; two studies had moderate risk in LBP measurement; one study had moderate risk when controlling for confounding factors; and one study had high risk due to not controlling for confounding factors.

Summary of Evidence:

Exposure to an injury in MVC:
One study (5) found a positive association between a neck injury in an MVC and future back pain (odds ratio [OR] = 2.28 (95% CI: 1.15−4.54) and absolute risk difference [ARD] = 7.7% (95% CI: 1.5%–13.9%)). They also noted a graded response according to the Quebec classification of injury between grade I (OR = 1.92 [95% CI: 0.76−4.89]) and grade II (OR = 3.35 [95% CI: 1.60−7.01) injuries.

One study (6) found a positive association between a low back injury in a rear-end collision and future LBP 7 years later (adjusted relative risk [RR] = 2.9 [95% CI: 1.6−5.2] and ARD =22.6% [95% CI: 6.0%–39.1%]).

One study (7) found a positive association between a low back injury in an MVC and future LBP when compared to non-injured controls (Hazard Rate Ratio [HRR] = 2.25 [95% CI: 1.11−4.56] and ARD =15.5% [95% CI: 6.6%–17.9%]).

Meta-analysis (random effects method) of the pooled results found a positive association between injury in an MVC and future LBP (RR = 2.7 [95% CI: 1.9–3.8], p = 0.001). An attributable risk (AR) of 63% for patients with ongoing LBP who had a previous MVC was also noted (explained further below).

Exposure to an MVC:
One study (5) did not find an association between exposure to a rear-end collision without injury (i.e. no claim submitted to insurer) and future low back pain when compared with controls (RR = 0.9 [95% CI: 0.5−1.6]).

Clinical Application & Conclusions:

Data from three studies indicate that there is an increased risk of future LBP in individuals who have been exposed to prior injury in an MVC, with an attributable risk of 63% (that is, “for an individual presenting with chronic LBP that has had a past history of an acute MVC-related back injury with no intervening injury, 63% of the LBP is attributable to the index crash.”). There is no evidence, however, to support an association between future LBP and exposure to an MVC where no injury was reported. While these findings are important for clinicians to consider, the relatively low number of available studies should also be considered when applying these findings to clinical decision-making.

Study Methods:

Several databases were searched: PUBMED, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, SPORTDISCUS, and MEDLINE (EBSCO).

Eligibility for Study Inclusion:
2 authors independently screened relevant articles, with a third reviewer independently screening citations where consensus could not be reached. Specific eligibility criteria included:
  • Studies with participants aged 16+ who were involved in an MVC and included an appropriate comparator group,
  • English language, published since 1998, in a peer-reviewed journal,
  • Examining the association between MVC-related injury and future low back pain, and
  • Use a case-control or cohort design.
Excluded were: book chapters, commentaries, conference proceedings, guidelines, consensus statements and editorials; systematic reviews, cross-sectional or case studies; studies with fewer than 20 participants; or LBP related to fracture, dislocation, infection, inflammatory joint disease or tumour.

Data Extraction:
One reviewer created evidence tables while a second screened the tables for accuracy.

Methodological Quality:
Risk of bias was assessed by 2 reviewers using the Quality in Prognosis Studies (QUIPS) appraisal tool modified for risk studies.

Data Synthesis and Analysis:
Between group/intervention differences were determined for each outcome. When possible, data was pooled for meta-analysis, using standard meta-analytic tests for heterogeneity (Q-value and I2 statistic).

Study Strengths / Weaknesses:

Strengths:
  • Very strong, comprehensive search criteria designed by health science librarian.
  • Inclusion of several varied databases.
  • Independent reviewers screened eligible studies.
  • Critical appraisal via the QUIPS assessment tool was used.
Weaknesses:
  • Studies limited to English language only.
  • Studies limited to those published after 1998.
  • Only 3 studies were ultimately included (their analogous neck pain study included 8 studies by comparison).
  • Heterogeneity amongst studies may limit the strength of the conclusions.

Additional References:

  1. Vos T, Flaxman AD, Naghavi M, et al. Years lived with disability (YLD’s) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the global burden of disease study 2010. Lancet. 2012; 380: 2163-2196.
  2. Cassidy JD, Côté P, Carroll LJ, Kristman V. Incidence and course of low back pain episodes in the general population. Spine 2005; 30(24): 2817–2823.
  3. Cassidy JD, Carroll LJ, Côté P, Berglund A., Nygren, Å. Low back pain after traffic collisions: a population-based cohort study. Spine 2003; 28(10): 1002–1009.
  4. Insurance Research Council, 2008. Trends in Auto Injury Claims: Countrywide Patterns in Treatment, Cost, and Compensation. Malvern, Pa, USA Edition.
  5. Tournier C, Hours M, Charnay P, Chossegros L, Tardy H. Five years after the accident, whiplash casualties still have poorer quality of life in the physical domain than other mildly injured casualties: analysis of the ESPARR cohort. BMC Public Health 2016; 16: 13.
  6. Berglund A, Alfredsson L, Jensen I, Cassidy JD, Nygren A. The association between exposure to a rear-end collision and future health complaints. J Clin Epidemiol 2001; 54(8): 851–856.
  7. Nolet PS, Kristman VL, Côté P, Cassidy JD, Carroll LJ. The association between a lifetime history of low back injury in a motor vehicle collision and future low back pain: a population-based cohort study. Eur Spine J 2018; 27(1): 136–144.