Hand-arm Vibration and the Risk of Vascular and Neurological Diseases – A Systematic Review and Meta-analysis.
Tohr Nilsson, Jens Wahlstrom, Lage Burstrom
PLoS ONE 2017;12(7):e0180795 / https://doi.org/10.1371/journal.pone.0180795
Copyright: 2017 Nilsson et al. (Open access article)
JACO Editorial Reviewer: Steven G. Yeomans, DC, FACO
Published: March 2018
Journal of the Academy of Chiropractic Orthopedists
March 2018, Volume 15, Issue 1
The original article copyright belongs to the original publisher. This review is available from: http://www.dcorthoacademy.com
© 2018 Yeomans and the Academy of Chiropractic Orthopedists. This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: Increased occurrence of Raynaud’s phenomenon, neurosensory injury and carpal tunnel syndrome has been reported for more than 100 years in association with work with vibrating machines. The current risk prediction modelling (ISO-5349) for ªRaynaud’s phenomenonº is based on a few studies published 70 to 40 years ago. There are no corresponding risk prediction models for neurosensory injury or carpal tunnel syndrome, nor any systematic reviews comprising a statistical synthesis (meta-analysis) of the evidence.
Objectives: Our aim was to provide a systematic review of the literature on the association between Raynaud’s phenomenon, neurosensory injuries and carpal tunnel syndrome and hand-arm vibration (HAV) exposure. Moreover the aim was to estimate the magnitude of such an association using meta-analysis.
Methods: This systematic review covers the scientific literature up to January 2016. The databases used for the literature search were PubMed and Science Direct. We found a total of 4,335 abstracts, which were read and whose validity was assessed according to pre-established criteria. 294 articles were examined in their entirety to determine whether each article met the inclusion criteria. The possible risk of bias was assessed for each article. 52 articles finally met the pre-established criteria for inclusion in the systematic review.
Results: The results show that workers who are exposed to HAV have an increased risk of vascular and neurological diseases compared to non-vibration exposed groups. The crude estimate of the risk increase is approximately 4±5 fold. The estimated effect size (odds ratio) is 6.9 for the studies of Raynaud’s phenomenon when including only the studies judged to have a low risk of bias. The corresponding risk of neurosensory injury is 7.4 and the equivalent of carpal tunnel syndrome is 2.9.
Conclusion: At equal exposures, neurosensory injury occurs with a 3-time factor shorter latency than Raynaud’s phenomenon. Which is why preventive measures should address this vibration health hazard with greater attention.
JACO Editorial Summary:
- This article was written by authors from the Occupational and Environmental Medicine, Department of Public Health & Clinical Medicine, Umea University, Umea, Sweden.
- The purpose was to reevaluate the association between Raynaud’s phenomenon, neurosensory injury and carpal tunnel syndrome (CTS) by providing a systematic literature review including risk of bias and, to estimate the risk exposure of vibratory tool use based on meta-analysis.
- Relevant literature published from 1945-2016 resulted in 4335 abstracts, 294 articles, with 52 making the final selection as only those including relative risk (odds ratio) were included. This was further reduced to 24 articles included to complete the meta-analysis portion of the study.
- Hand-arm-vibration syndrome (HAVS) is the internationally acknowledged condition describing the symptom complex that occurs to the peripheral neurological, vascular and musculoskeletal systems when prolonged, extensive power tool vibration exposure occurs in manual work environments.
- The vascular component of HAVS includes vasospasm in the digital capillaries (causing “white finger”/Raynaud’s Phenomenon).
- The neurological component includes both a diffuse peripheral neurosensory injury and median nerve entrapment at the wrist (causing CTS)
- Skeletal injuries in HAVS include osteoarthritis and development of muscular dysfunction (such as tendonopathies, tenosynovitis, fibrosis/Duputren’s contracture).
- The vascular and nerve manifestations in HAVS can occur together or separately.
- Workers who are exposed to HAV have a crude estimate of 4-5 fold increased risk of developing vascular and/or neurological disease.
- The estimated effect size (odds ratio) of 6.9 for Raynaud’s phenomenon, 7.4 for neurosensory injury, and 2.9 for CTS when utilizing only the low risk of bias studies (but the number of CTS studies were few making the risk estimate for CTS less precise/more sensitive to bias).
- Comparing and contrasting high vs. low exposure to vibration groups resulted in a pooled risk estimate that varies between 2.5 and 5 for both Raynaud’s phenomenon and neuro-sensory injury. There were too few studies found to calculate this for CTS.
- Possible outcome bias included shifts or changes in diagnostic approaches used in early vs. more recent studies as early studies included collectively many “sub-categories” that were reported in later studies (like large vs. small fibre neuropathy and entrapment syndromes like CTS).
- Also, between 1945 and 2016, testing protocols changed (lab tests, electro-diagnostic tests and various cold provocation tests are examples) as well as diagnostic precision. This may be why earlier studies found more vascular injuries vs. a shift to more nerve injuries found in the more recent studies.
- Further bias regarding the effect size was noted between the studies determined to have low vs. high risk of bias. The corresponding effect size for Raynaud’s phenomenon was 6.8 vs. 3.6, and for neuro-sensory impairment 7.8 vs. 3.3, respectively.
- Possible exposure bias (how long the person was exposed to vibration) is an issue as well, as differences in defining the degree of exposure was not consistent between the studies reviewed.
- Risk of developing HAVS is also affected by co-morbidities (other concurrent health conditions) as well as medication effects (such as BP meds). Interactions between different diseases/comorbidities, medication effects as well as sleep, fitness and age-related factors are currently lacking in these studies.
- With all the potential for bias described above, it remains clear that workers exposed to vibration/HAV have an increased risk of developing vascular and neurological diseases compared to non-vibration-exposed groups.
- At equal exposures, neurosensory injury occurs with a 3-time factor shorter latency than Raynaud’s phenomenon.
- More preventive measures are needed to aggressively address the tool vibration health hazard.
This study describes the history of HAVS, compares and contrasts the early from the later studies (1945-2016), reports odds ratios using both the studies with low risk of bias only vs. those that have high risk of bias and, discuss in great detail the potential for other biases that should be considered. This high level of transparency is commended and appreciated. In the end, it remains clear that prevention must be aggressively addressed as it is key to minimizing the risk of developing neurological and/or vascular injury caused by tool-induced vibration exposure.