The Global Burden of Musculoskeletal Pain

The Global Burden of Musculoskeletal Pain—Where to From Here? – free full-text /PMC6301413/ – Am J Public Health. 2019 January

This article makes it clear that our chronic musculoskeletal pain is a serious burden, not just for us, but for all of society too. It itemizes reasons why chronic pain is so often regarded as a mere nuisance and isn’t taken as seriously as other health concerns.

In the 2010 Global Burden of Disease Study (GBD), which broadened the scope of musculoskeletal conditions that were included over previous rounds, low back pain imposed the highest disability burden of all specific conditions assessed, and subsequent GBD reports further reinforce the size of this burden.

Over the past decade, the GBD has produced compelling evidence of the leading contribution of musculoskeletal pain conditions to the global burden of disability, but this has not translated into global health policy initiatives.  

There is a mismatch between the burden of musculoskeletal pain conditions and appropriate health policy response and planning internationally that can be addressed with an integrated research and policy agenda.

Although musculoskeletal conditions comprise about 150 discrete conditions, the GBD specifically reports on health estimates for hip and knee osteoarthritis, rheumatoid arthritis, back and neck pain, gout, and a group of other musculoskeletal conditions. The category of “other” refers to a wide range of autoimmune, inflammatory, joint, ligament, tendon, and muscle disorders that vary across epidemiologic studies

Across all these conditions, pain and its sequelae (e.g., activity limitation, participation restriction) are unifying features. Musculoskeletal conditions included in the GBD, therefore, provide an important, albeit not exhaustive, insight into the global burden of pain, which is otherwise not measured as a condition in its own right.

Recent GBD 2016 estimates showed that low back pain was the leading cause of years lived with disability in most countries and territories, and musculoskeletal conditions as a group were a main driver of noncommunicable disease (NCD)-related disability burden

Two key long-term drivers of contemporary burden of disease estimates are the

1. age structure of populations and
2. their longevity.

In simple terms, demographic dynamics related to changes in fertility rates, migration rates, and mortality rates have led to rapid global aging to the extent that soon, for the first time in recorded history, the proportion of the global population 65 years and older will exceed the proportion of those younger than 5 years.

Because most painful musculoskeletal conditions increase with age and because there is an increase in multimorbidity, NCDs, and reduced physical activity associated with musculoskeletal pain, the global burden related to pain will also rise substantially.

Global life expectancy has been rising, but the extent to which the increase in longevity is matched by gain in healthy life-years is unclear on the basis of current evidence and depends in part on whether healthy aging is defined using a disease-based approach or a functional ability approach

Nevertheless, people are now living longer and experiencing chronic diseases to an extent not seen before, and multimorbidity is the norm rather than the exception; musculoskeletal conditions feature prominently.

Musculoskeletal conditions contribute to a substantial proportion of global disability, second only to mental health conditions, and commonly occur in multimorbid presentations

As population aging is so fundamental to the global burden of nonfatal conditions, there will be continuing debate about the most appropriate way to measure the morbidity burden in older people and the extent to which increased longevity is lived with or without morbidity burden

UNDERESTIMATION OF BURDEN OF DISEASE

Despite evidence for the very significant burden of musculoskeletal conditions associated with pain, current estimates are likely to be an underestimate of both true prevalence and burden.

Specifically, the calculation of DALYs (disability adjusted life year) related to musculoskeletal pain likely underestimates both

1. the mortality (years of life lost) as well as
2. the morbidity (years lived with disability) components.

The main contributors to this underestimation include the following:

1. Case definitions for most musculoskeletal conditions have not been universally standardized or applied consistently in population-based studies, and in particular with inconsistency between low-, middle- and high-income settings. 
2. Reliable and validated self-report measures are not available for each of the 150 or more painful musculoskeletal conditions, making large-scale population-based studies logistically difficult and costly, rendering impact data limited in volume and scope.
3. Because of the discordance between clinical features that help define a case (e.g., rheumatoid factor for rheumatoid arthritis, x-ray change for osteoarthritis, hyperuricemia for gout) and the clinical manifestations of the diseases (e.g., levels of pain and loss of function or activity limitation), simple biomarkers of musculoskeletal pain are not available for routine use in disease surveillance, nor are they appropriate for capturing the multidimensional impact of a pain experience.
4. Reporting pain and the resulting impact of musculoskeletal conditions can fluctuate widely, and there can be transition between many health states for the 1 condition throughout a person’s life
5. Harms associated with treatment, including medication-based interventions (notably long-term opioids, corticosteroids, and nonsteroidal and immunosuppressive therapies) and surgical interventions, are not captured in the estimation of burden.
6. Many musculoskeletal conditions are nonspecific with no defined tissue-based cause and, although they may have a low level of associated disability, they are extremely common and the associated pain burden has previously been underestimated or not measured (e.g., the pain and loss of function associated with arthritis in hands and feet was not measured in GBD).
7. Even the wider range of musculoskeletal conditions (e.g., such as other musculoskeletal, rheumatoid arthritis, osteoarthritis, and gout) that have pain as a key feature in the lay health state descriptors but not in the title are not immediately recognized as contributing to global pain burden, limiting the awareness of the magnitude of this burden.
8. Numerous other health conditions have musculoskeletal pain as a key factor contributing to overall morbidity and mortality that will not always be acknowledged or attributed to pain or musculoskeletal burden. It is also likely that a considerable proportion of both the years of life lost and years lived with disability burden that is attributed to injury, mental health, and substance abuse and neurologic disorders is related to musculoskeletal and other acute and chronic pain conditions.
9. Although the chronic nature of the majority of musculoskeletal pain conditions means that most people do not die from their condition, the condition may contribute to premature mortality through the effect of associated comorbidities related to the disease and treatments. 

It’s this last one that seems to underlie the whole issue: people don’t die of pain by itself (though the comorbidities can be fatal).

Our healthcare system regards the preservation of life as the pinnacle of achievement, while the quality of that life is too often ignored. Only countable and verifiable values are respected.

This is the problem of subjective evaluations versus measurable outcomes.

We can easily determine (in most cases) whether someone is dead or alive, but it’s impossible to objectively measure the quality of that life.

There is an ongoing debate about the extent to which the relative importance of physical versus cognitive function in health state valuations vary by culture, age, education, and socioeconomic status. Cultural heterogeneity related to pain is an important consideration in this context.

The problems related to underestimation of musculoskeletal pain burden should also be seen in the broader context of pain burden. Chronic pain of neuropathic or mixed origin is a common and enduring consequence of other diseases and injuries, for example, painful diabetic neuropathy, spinal cord injury-related neuropathic pain, HIV-related painful neuropathies, and persistent postsurgical pain.

CONCLUSIONS

Current estimates of the global burden of musculoskeletal pain, although they underestimate the burden, are grounded on a systematic, rigorously evaluated evidence base that was defined for the GBD 2010. Despite the underestimation of total burden, the data remain essential to our understanding and the urgency to address musculoskeletal pain at a global level.

The size of the problem clearly requires a significantly accelerated and globally elevated policy response commensurate with the magnitude of the musculoskeletal pain burden.

System-level reform initiatives, such as changes or enhancements to policy, governance, and health financing, are likely to have the most impactful and sustainable effect on improving population-level musculoskeletal health and system efficiencies.

At a systems level, pain and musculoskeletal health are inadequately integrated with other NCDs in the context of health policy and system financing

Health systems have traditionally been oriented toward prevention and measurement of mortality, rather than the long-term health and social care for people with disabilities

At a service delivery level, the lack of recognition that musculoskeletal pain may be affecting other health conditions is also problematic.

For example, musculoskeletal pain limits mobility in older people, culminating in increased cognitive decline, sarcopenia, frailty, loss of independence

Until musculoskeletal pain is recognized as a major reason for lack of adherence to, or uptake of, healthy behaviors and rehabilitation, suboptimal health states will prevail

Such a shift requires a transformation in the way health services are delivered to a more integrated care model underpinned by a biopsychosocial approach to care

The impact of pain and musculoskeletal diseases on functional ability should be more explicitly assessed and documented in planning health resources and delivering care interventions aimed at improving functional outcomes.