Elsevier

The Spine Journal

Volume 10, Issue 7, July 2010, Pages 639-651
The Spine Journal

Review Article
Causal assessment of workplace manual handling or assisting patients and low back pain: results of a systematic review

https://doi.org/10.1016/j.spinee.2010.04.028Get rights and content

Abstract

Background Context

Low back pain (LBP) is a common musculoskeletal disorder associated with a considerable social and economic burden within the working-age population. Despite an unclear etiology, numerous physical activities are suspected of leading to LBP. Declaring a causal relationship between occupational activities and LBP remains challenging and requires a methodologically rigorous approach.

Purpose

To conduct a systematic review focused on assessing the potentially causal relationship between workplace manual handling or assisting patients and LBP.

Study Design

Systematic review of the literature.

Samples

Studies reporting an association between workplace manual handling or assisting patients and LBP.

Outcome Measures

Numerical association between different levels of exposure to manual handling or assisting patients, and the presence or severity of LBP.

Methods

A systematic review was conducted using Medline, EMBASE, CINAHL, Cochrane Library, and Occupational Safety and Health database, gray literature, hand-searching occupational health journals, reference lists of included studies, and content experts. The methodological quality of each study was assessed using a modified Newcastle-Ottawa Scale (NOS) for observational studies. The overall level of evidence supporting various Bradford-Hill criteria for causality for each category of manual handling or assisting patients and type of LBP was then evaluated. Studies were deemed of higher quality if they received a score of five or more on the modified NOS and used appropriate statistical analysis methods.

Results

This search yielded 2,766 citations, and 32 studies met the eligibility criteria. Three high-quality studies reported on manual handling and LBP, including two prospective cohorts and one cross-sectional design. None demonstrated a significant association in most of their multivariate risk estimates. One study was able to assess dose-response and temporality, but its results did not support these criteria. Only one study discussed the biological plausibility of this association. Four high-quality studies evaluated assisting patients and LBP, including two case-controls, one cross-sectional, and one prospective cohort design. These studies were consistent in reporting no significant association. Two studies demonstrated a nonsignificant dose-response trend, and two studies discussed the biological plausibility of this association. No studies were able to demonstrate the temporality or experiment criteria.

Conclusions

The studies reviewed did not support a causal association between workplace manual handling or assisting patients and LBP in a Bradford-Hill framework. Conflicting evidence in specific subcategories of assisting patients was identified, suggesting that tasks such as assisting patients with ambulation may possibly contribute to LBP. It appears unlikely that workplace manual handling or assisting patients is independently causative of LBP in the populations of workers studied.

Introduction

Low back pain (LBP) is generally considered to be mechanical in nature, which indicates that any mechanical stress placed on the muscles, ligaments, bones, and supportive tissues of the spine may exacerbate symptoms [1]. The precise nature of injuries or pathological processes leading to mechanical LBP is rarely known. LBP is characterized by symptoms such as pain, muscle tension, stiffness, weakness in the legs or feet, or a tingling or burning sensation traveling down the legs [2], [3]. Approximately 85% of all people will experience some form of LBP during their lifetime [4]; 60% of whom still report symptoms after 5 years [5], [6]. In the working-age population, the social and economic impact of LBP is enormous: LBP is the second most frequently reported reason for visiting a doctor, the fifth most frequent cause of hospitalization, and the third most frequent reason for surgery [7]. To effectuate meaningful changes in work-related LBP, it is necessary to improve our understanding of the etiology of LBP as it relates to physical activities frequently performed in the workplace.

Manual handling is common within the construction, manufacturing, mining, retail, and agricultural industries and may involve specific tasks such as using power tools above shoulder level [8], laying brick on uneven surfaces [9], or erecting building site scaffolding [10]. Assisting patients, defined as patient-oriented manual handling, is common within hospital and nursing-home settings and often involves specific activities, such as feeding patients [11], positioning patients on beds [12], and transporting patients between a chair and commode [13]. Both manual handling and assisting patients can involve repetitive and often simultaneous performance of bending, twisting, carrying or lifting movements, each of which may have the potential to cause LBP because of excessive lumbar flexion, ligament strain, and compression forces [14], [15], [16]. It was reported in the United Kingdom that manual handling is responsible for more than one-third of musculoskeletal workplace injuries reported each year [17].

Cross-sectional studies have suggested that manual handling and assisting patients may have a causal relationship with LBP [18], [19], [20], [21], [22], [23], [24], [25], [26].. However, the strength and consistency of these results have varied. Declaring that a causal relationship may exist between specific risk factors and LBP has proven complex and unreliable when based on single studies [27], [28]. A systematic review, on the other hand, can help assess any such relationship more clearly by summarizing all available evidence in light of the many criteria that have been proposed to determine causation (eg, Bradford-Hill) [27], [28]. Fundamental to this process is a critical appraisal of the methodological quality of the studies to establish their potential for bias or confounding [29], [30].

The purpose of this study was to identify, evaluate, and summarize the best available evidence regarding manual handling or assisting patients and LBP in workers, using the Bradford-Hill [31] framework to assess causation. This knowledge is required to help establish safe parameters for exposure to workplace manual handling or assisting patients and to provide guidance to stakeholders involved in the adjudication of work-related LBP claims involving these activities.

Section snippets

Literature search

An electronic search of Medline (1966 to November 2007; updated in August 2008), EMBASE (1980 to November 2007), and CINAHL (1982 to November 2007) was conducted to identify relevant articles using a comprehensive strategy combining indexed terms and free text with three main components: 1) setting (ie, work related); 2) etiology (ie, manual handling or assisting patients); and 3) outcome (ie, LBP) (Note: full search strategy details and results are available from the primary author on

Results

Overall, the electronic and manual search strategies yielded a total of 2,766 citations, of which 275 were deemed potentially relevant. On review of the full-text copies of the 275 articles, 32 satisfied all of the specific study inclusion/exclusion criteria. Figure summarizes the results of the searching, Level 1 and 2 screening, data abstraction, quality appraisal, and summary evaluation of evidence for causation. A total of 25 studies were considered of low methodological quality, and 7

Discussion

Manual handling is a common activity within many workplaces, whereas assisting patients is an everyday task undertaken by nurses, nurse aides, and home care providers. Previous studies have indicated that repetitive performance of strenuous physical activities constituting manual handling or assisting patients can contribute toward LBP and related work absenteeism [18], [19], [20], [21], [22], [23], [24], [25], [26].. Results from this systematic review contradict these findings and suggest

Conclusions

This systematic review did not identify any high-quality evidence to support the Bradford-Hill criteria to establish overall causality for workplace manual handling or assisting patients and LBP. However, because of the presence of a combination of strong and conflicting evidence, it is possible that specific categories of assisting patients could contribute to LBP. In particular, results suggest that assisting patients to ambulate could possibly be associated with disabling types of LBP in

References (63)

  • L. Manchikanti et al.

    Evidence-based practice guidelines for interventional techniques in the management of chronic spinal pain

    Pain Physician

    (2003)
  • P. Enthoven et al.

    Clinical course in patients seeking primary care for back or neck pain: a prospective 5-year follow-up of outcome and health care consumption with subgroup analysis

    Spine

    (2004)
  • D.G. Borenstein et al.

    Low back pain medical diagnosis and comprehensive management

    (1995)
  • E.B. Holmstrom et al.

    Low back and neck/shoulder pain in construction workers: occupational workload and psychosocial risk factors. Part 1: Relationship to low back pain

    Spine

    (1992)
  • U. Latza et al.

    Impact of repetitive manual materials handling and psychosocial work factors on the future prevalence of chronic low-back pain among construction workers

    Scand J Work Environ Health

    (2002)
  • U. Latza et al.

    Cohort study of occupational risk factors of low back pain in construction workers

    Occup Environ Med

    (2000)
  • S. Ando et al.

    Associations of self estimated workloads with musculoskeletal symptoms among hospital nurses

    Occup Environ Med

    (2000)
  • J. Smedley et al.

    Epidemiological differences between back pain of sudden and gradual onset

    J Rheumatol

    (2005)
  • V.Y. Yip

    New low back pain in nurses: work activities, work stress and sedentary lifestyle

    J Adv Nurs

    (2004)
  • A. Garg et al.

    Epidemiology of low-back pain in industry

    Occup Med

    (1992)
  • L.M. Straker et al.

    A comparison of risk assessment of single and combination manual handling tasks: 1. maximum acceptable weight measures

    Ergonomics

    (1996)
  • E.R. Vieira et al.

    Safety analysis of patient transfers and handling tasks

    Qual Saf Health Care

    (2009)
  • HSE

    Getting to grips with manual handling: a short guide

    (2009)
  • C.K. Feng et al.

    Prevalence of and risk factors for different measures of low back pain among female nursing aides in Taiwanese nursing homes

    BMC Musculoskelet Disord

    (2007)
  • Y.B. Yip

    A study of work stress, patient handling activities and the risk of low back pain among nurses in Hong Kong

    J Adv Nurs

    (2001)
  • J. Alcouffe et al.

    Analysis by sex of low back pain among workers from small companies in the Paris area: severity and occupational consequences

    Occup Environ Med

    (1999)
  • L.A.M. Elders et al.

    Interrelations of risk factors and low back pain in scaffolders

    Occup Environ Med

    (2001)
  • E.F. Harkness et al.

    Risk factors for new-onset low back pain amongst cohorts of newly employed workers

    Rheumatology (Oxford)

    (2003)
  • J.F. Kraus et al.

    Epidemiology of acute low back injury in employees of a large home improvement retail company

    Am J Epidemiol

    (1997)
  • J. Smedley et al.

    Manual handling activities and risk of low back pain in nurses

    Occup Envrion Med

    (1995)
  • J. Smedley et al.

    Prospective cohort study of predictors of incident low back pain in nurses

    BMJ

    (1997)
  • Cited by (0)

    FDA device/drug status: not applicable.

    Author disclosures: BKK (consulting, Medtronic); SD (consulting, Palladian Health; scientific advisory board, Palladian Health).

    This study was funded by a peer-review grant provided to Drs Wai, Bishop, Kwon, and Dagenais by the Workers Compensation Board of British Columbia.

    View full text