The burden of back pain and scope of this review

Back pain may be considered a symptom that is usually not attributable to a specific pathology such as infection, tumour, osteoporosis, fracture, structural deformity, inflammatory disorder, radicular syndrome or cauda equina syndrome . In about 90% of cases of back pain, the pathogenesis is unknown, and it is considered non-specific back pain. Because the pain is mostly felt in the lower part of the back, it is also termed ‘low back pain (LBP)’. However, there is no specific additional value of this adjective, as pain higher in the back does not seem to be different from LBP. LBP is reported four times more frequently than mid-back pain .

Most people will experience one or more episodes of LBP in their lives. For most, these episodes are self-limiting, and they will require no medical care . The majority of patients attending their general practitioner in connection with LBP also recover fairly quickly without specific treatment with a median recovery period of 7 weeks. After 12 weeks, only 35% of these patients attending their general practitioner still have symptoms, although relapses are common with 60–75% relapsing within 1 year . According to some researchers, LBP should actually be considered a recurrent condition rather than a self-limiting one . A truly ‘initial’ episode of LBP is probably rare in adults, as many children and adolescents have also experienced significant LBP episodes . In only a minority of subjects (10%), LBP becomes a manifest chronic problem, and it persists even after 1 year leading to disability and sickness absence or even loss of employment over time. Long periods out of work are associated with two to three times increased risk of poor general health, two to three times increased risk of mental health problems and even 20% excess mortality risk . Prolonged sickness absence can result in permanent disability, even without serious illness, as patients become depressed, inactive, develop catastrophic beliefs and become fixated on their disability.

The burden from LBP is very high throughout the world. Out of the 291 conditions studied in the global burden of diseases in 2010, LBP was found to have the sixth highest burden. LBP caused more disability globally than any other condition . Based on systematic reviews about the prevalence and incidence of LBP, Hoy et al. calculated a global point prevalence of 9.4% (95% confidence interval (CI): 9.0–9.8) with prevalence peaks in older age groups . With the prospect that future populations all over the world will continue to grow and age, the burden from LBP will further expand at the same time.

A difficulty in estimating the prevalence of LBP is that this depends on the definition used . If LBP is defined as requiring sickness absence, then prevalence in the previous 6 months is estimated to be around 8%; if LBP is defined as pain lasting at least a day, then 6-month prevalence is estimated to be around 45% . In 2002, a uniform definition of LBP episodes was proposed stating that an episode of LBP is a period of pain in the lower back lasting for >24 h, preceded and followed by a period of at least 1 month without LBP. An episode of sickness absence due to LBP is a period of sickness absence due to LBP, preceded and followed by a period of at least 1 day at work . The pooled estimate for the occurrence of sickness absence in workers with chronic or recurrent LBP is estimated to be around 15.5% in studies with follow-up periods up to 6 months . The economic costs associated with LBP are high mainly due to productivity losses . These productivity losses related to LBP are a result of either being less productive while being sick at work (i.e., presenteeism), of sickness absence (i.e., absenteeism), of being work disabled, or even of exit from the labour market by early retirement. For most individuals with work disability or with early retirement, there will be direct consequences for their personal income . For the government, both situations will also place a burden because of the lost income taxation revenue and the increase in government benefit payments to the retired individuals . With the increasing proportion of the 45–64-year-old group in the working population, this matter will probably need even more attention in the future . Not only productivity losses but also health-care utility plays a considerable part in the financial burden of LBP as well . Despite existing professional guidelines, requests for a routine diagnostic imaging and referral to a specialist care due to acute episodes of LBP are still a normal daily practice . Currently, it remains a huge challenge for practitioners to change patient expectations regarding LBP management and to avoid unnecessary referrals to a specialist care .

This article will provide a brief overview about effective interventions to prevent incident, or to reduce recurrent or chronic back pain in the workplace with or without sickness absence, remaining challenges and optional new research roads to consider aiming to decrease the global burden of LBP among workers.

Prevention of back pain in the workplace: what are the work-related risk factors?

In general, the aetiology of LBP is multifactorial: genetic, environmental and biological determinants probably all play a role . Regarding environmental factors, it has been estimated that worldwide 37% of LBP may be attributable to work-related risk factors. This fraction varies among different regions in the world, and it is higher in areas with lower health status in general, mostly due to the relatively high proportion of physical labour . Overall, the attributable risk fraction is higher for males than for females, probably largely because of men’s higher participation in the labour force and in occupations with heavy lifting and whole body vibration. Which structures in the body exactly cause the pain remains rather unclear, and, as a consequence, the relationship between overload, damage and back pain is still not fully clarified . Many work-related risk factors have been studied extensively over the past few decades. Physical factors such as manual material handling (mainly manual lifting) and whole body vibration are considered work-related factors for which there is a strong evidence base for the attribution of incident LBP . Recently, the impact of lifting during work on the incidence of LBP was assessed; meta-analyses were used to quantify relationships between different exposure measures regarding manual lifting and the occurrence of LBP . Subsequently, in a health impact assessment, it was estimated that lifting loads >25 kg and lifting at a frequency of >25 lifts per day will increase the annual incidence of LBP by 4.3% and 3.5%, respectively, added to the annual incidence of 18.4% among those not being exposed to lifting . These are relative increases of 23.5% and 19.0%, respectively. The authors concluded that exposure–response relationships show that lifting heavy loads may have a substantial impact on the musculoskeletal health of the working population .

For other work-related physical factors, such as patient handling, awkward posture or bending and twisting of the trunk, the evidence base for an association with incident LBP is also considered strong, although it remains difficult to calculate a dose–response effect in daily practice . However, a series of eight systematic reviews and a summary of these reviews concluded that none of the work-related physical factors were causally related to LBP . These conclusions were heavily disputed in scientific literature . For other physical risk factors, such as standing or walking, and prolonged sitting at work, the existing evidence does provide some reason for debate . Notably, however, for all of these work-related physical factors, including for instance manual lifting and whole body vibration, only relatively small effect sizes were measured, and this is possibly one of the main reasons why interventions focusing on these risk factors at the workplace have only resulted in a rather disappointing effect on the primary prevention of LBP.

The evidence for work-related psychosocial risk factors for LBP is even more difficult to interpret as it has been somewhat contradictory up to now, and it has been mainly based on older systematic reviews . Although some reviews reported evidence for a relationship between LBP incidence and low social support, job dissatisfaction or high job demands or workload, others reported no evidence for any association between LBP incidence and perception of work or organizational aspects of work or social support at work . Most likely, many of these work-related psychosocial factors will probably not be the direct cause for incident LBP, but they will indirectly contribute through associated increases in exposure to work-related physical factors or changes in the perception of and response to symptoms. Work-related psychosocial factors could also be an important factor for diminished recovery of LBP or for sickness absence due to LBP .

Prevention of back pain in the workplace: what are the work-related risk factors?

In general, the aetiology of LBP is multifactorial: genetic, environmental and biological determinants probably all play a role . Regarding environmental factors, it has been estimated that worldwide 37% of LBP may be attributable to work-related risk factors. This fraction varies among different regions in the world, and it is higher in areas with lower health status in general, mostly due to the relatively high proportion of physical labour . Overall, the attributable risk fraction is higher for males than for females, probably largely because of men’s higher participation in the labour force and in occupations with heavy lifting and whole body vibration. Which structures in the body exactly cause the pain remains rather unclear, and, as a consequence, the relationship between overload, damage and back pain is still not fully clarified . Many work-related risk factors have been studied extensively over the past few decades. Physical factors such as manual material handling (mainly manual lifting) and whole body vibration are considered work-related factors for which there is a strong evidence base for the attribution of incident LBP . Recently, the impact of lifting during work on the incidence of LBP was assessed; meta-analyses were used to quantify relationships between different exposure measures regarding manual lifting and the occurrence of LBP . Subsequently, in a health impact assessment, it was estimated that lifting loads >25 kg and lifting at a frequency of >25 lifts per day will increase the annual incidence of LBP by 4.3% and 3.5%, respectively, added to the annual incidence of 18.4% among those not being exposed to lifting . These are relative increases of 23.5% and 19.0%, respectively. The authors concluded that exposure–response relationships show that lifting heavy loads may have a substantial impact on the musculoskeletal health of the working population .

For other work-related physical factors, such as patient handling, awkward posture or bending and twisting of the trunk, the evidence base for an association with incident LBP is also considered strong, although it remains difficult to calculate a dose–response effect in daily practice . However, a series of eight systematic reviews and a summary of these reviews concluded that none of the work-related physical factors were causally related to LBP . These conclusions were heavily disputed in scientific literature . For other physical risk factors, such as standing or walking, and prolonged sitting at work, the existing evidence does provide some reason for debate . Notably, however, for all of these work-related physical factors, including for instance manual lifting and whole body vibration, only relatively small effect sizes were measured, and this is possibly one of the main reasons why interventions focusing on these risk factors at the workplace have only resulted in a rather disappointing effect on the primary prevention of LBP.

The evidence for work-related psychosocial risk factors for LBP is even more difficult to interpret as it has been somewhat contradictory up to now, and it has been mainly based on older systematic reviews . Although some reviews reported evidence for a relationship between LBP incidence and low social support, job dissatisfaction or high job demands or workload, others reported no evidence for any association between LBP incidence and perception of work or organizational aspects of work or social support at work . Most likely, many of these work-related psychosocial factors will probably not be the direct cause for incident LBP, but they will indirectly contribute through associated increases in exposure to work-related physical factors or changes in the perception of and response to symptoms. Work-related psychosocial factors could also be an important factor for diminished recovery of LBP or for sickness absence due to LBP .

Prevention of back pain in the workplace: what are the effective interventions?

If manual lifting at work is an important risk factor for LBP, then it makes sense to try to reduce spinal load by setting maximum permissible limits . The National Institute of Occupational Safety and Health (NIOSH) in the USA has developed a risk assessment tool that can be used to assess a ‘recommended weight limit’. The maximum recommended weight limit is 23 kg. The lifting conditions, such as the vertical and horizontal distances of the load from the body and the degree of trunk rotation, have to be specified and entered into a formula, which provides a recommended weight limit for these conditions . There are no controlled trials published evaluating the effect of this NIOSH tool in reducing the incidence of LBP.

Exposure to whole body vibrations has also been regulated by setting limits. Exposure during an 8-h workday beyond an intensity of 0.25 m/s ² is considered potentially dangerous, and, beyond 0.50 m/s ² , it is required to take action to remediate the danger of exposure. It should be pointed out that the current design of cars, trucks and other road vehicles has already reduced vibration exposure below levels at which LBP effects are expected, except for vehicles such as forklift trucks driven on an uneven surface or earth movers riding on a bumpy terrain. There are some studies that have evaluated the effectiveness of measures to reduce whole body vibration when the exposure was above the standard, but they could not show a decrease in exposure .

Management of back pain

It is customary to distinguish between acute LBP with a duration up to 6 weeks, subacute LBP with a duration between 6 and 12 weeks and chronic LBP with a duration of >12 weeks . However, in this article, we will particularly focus on risk factors and the management of LBP with and without sickness absence to prevent long-term work disability.

Working-age patients with an episode of LBP often consult different types of health-care providers, such as the general practitioner, chiropractor, physical therapist or even a medical specialist . In many countries, patients are legally required to obtain a medical certification for sickness absence, or clearance to return to work (RTW), and for this they often need to visit their general practitioner. In some other countries, occupational physicians play this gatekeeper role. All health professionals have an important secondary preventive role when making recommendations to patients with regard to work restrictions and participation . Whether or not the LBP episode is a result of occupational exposure, there is always a risk of a serious pathology for LBP. It is therefore important to differentiate at an early stage between non-specific LBP, radicular syndrome and specific LBP .

Many common treatments for individuals with episodes of acute LBP, such as exercise, work hardening or spinal manipulative therapy, do not seem to be effective . This lack of evidence for the effect of treatments for acute LBP has been reflected in clinical practice guidelines published in recent years . These guidelines generally emphasize an approach of watchful waiting rather than specific interventions during the first few weeks after the onset of LBP. For example, in The Netherlands, general practitioners are recommended to provide assurance to patients with acute LBP and to advise them to remain active within the limits of pain as long as there is no evidence of underlying serious pathology . General practitioners should also enquire about any work-related risk factors, and if necessary they should seek contact with the occupational physician or a case manager related to the workplace. Adherence to these recommendations of clinical practice guidelines for LBP has been associated with improved clinical outcomes and decreased costs . However, despite the existing clinical practice guidelines for LBP management, most practitioners do not fully adhere to these guidelines, and they still prefer to refer LBP patients for (early) diagnostic imaging or for specialist treatment with the risk of stimulating medicalization, chronicity and work disability . In fact, patients still report poor communication and collaboration between health-care providers, despite the advice in their national guidelines, sometimes leading to conflicting treatment advice and poor coordination of care .

In conclusion, there still remains an enormous challenge to convince clinicians and general practitioners to widen their perspective when treating the individual with LBP in such a way that unnecessary referrals are limited as much as possible. On the other hand, it seems plausible that not all patients with LBP visiting their general practitioner only need reassurance. Some patients may be at a higher risk of a prolonged episode involving also sickness absence, and identifying these subgroups of patients at the earliest moment possible may indeed be a promising way to handle LBP . This way, interventions can be more effectively tailored to particular risk factors related to the individual or related to the courses of the disease or disability . Recently, studies using a stratification strategy for LBP management according to the individual patient’s risks (low, medium or high risk), or according to particular underlying mechanisms of the LBP showed better clinical and economic outcomes compared to current best practice .

Management of back pain in the workplace: what are the risk factors for sickness absence?

Not all workers with an episode of LBP will also have sickness absence. Whether someone does call in sick will depend on many factors related to the individual and to the workplace. First of all, it is generally known that a previous episode of sickness absence is the strongest predictor for future sick listing . This also holds true for sickness absence due to LBP. Personal factors, such as older age and an individual’s beliefs about back pain, play a major role in reporting sick or becoming disabled . Workplace factors that play an important role in the duration of sickness absence and or receiving benefits are co-worker support, organizational support and psychosocial job demands . A prediction model for RTW in LBP patients, both initially and after 1 year, found only two relevant clinical factors: pain score and slide flexion, and four psychosocial factors: ‘bodily distress’, ‘low expectations of RTW’, ‘blaming the work for pain’ and ‘no home ownership’, and one lifestyle factor, ‘drinking alcohol less than once/month’ . Interestingly, also shorter job tenure seems to have an association with becoming work disabled due to LBP . Self-reported high physical workload is another important work-related factor that has an influence on sickness absence due to LBP . Results of these studies all point in the direction that more involvement of the workplace is essential in effective RTW management. This is in line with the paradigm shift of recent years that solely medical treatment will not be the solution to prevent sickness absence and work disability due to medical problems such as LBP .