Osteoarthritis: an overlooked target for health improvement

The burden of osteoarthritis (OA) in primary care constitutes a significant proportion of the workloads of GPs, physiotherapists and pharmacists alike.  While it makes no contribution to national mortality statistics, the morbidity generated by OA – a condition primarily managed in contemporary general practice – is of sufficient proportion to render the condition a significant public health problem worthy of urgent preventative intervention.

OA is a progressive, mechanical, non-inflammatory, chronic disorder of synovial joints that causes pain, stiffness and disability.  While any joint can be affected by OA, the hips and knees are most commonly involved and, at the condition’s end-stage, may necessitate artificial joint replacement.  Although the precise cause of OA is not fully understood, this complex and multifactorial condition is known to include substantial genetic, biological, and biomechanical components.  While increasing age and female sex constitute strong risk factors for the development of OA, clinical obesity is the most prevalent modifiable risk factor (OA is up to six times more likely in obese individuals than in those of a healthy weight).¹  While it is primarily managed in contemporary general practice, without adequate intervention, OA may lead to significant joint deformity, functional impairment and profound disability that significantly impacts on social life, occupational duties, and activities of daily living, along with increasing the risk of falls, chronic pain, and severe psychological harms.  Existing therapies only serve to manage the symptoms of OA (such as pharmacological analgesia and artificial joint replacement) or delay its further deterioration (such as attainment of healthy body weight), while none are able to reverse the condition or provide definitive cure.  As such, preventative measures that promote healthy weight attainment offer the most effective means by which to minimise OA morbidity (moderate weight loss in obese individuals reduces the risk of knee OA by up to 33%).²

The total burden of OA is substantial, both in the UK and on the global scale.  Between 2000 and 2010 in England, 16.1 general practice consultations per 1,000 people in the over 45 years old population occurred annually for OA complaints.³  In 2017 there were about 303.1 million prevalent cases of hip and knee OA worldwide, and an age-standardised prevalence of 3,754.2 per 100,000 people, signifying a 9.3% increase in age-standardised global prevalence since 1990.  Also in the same year, OA accounted for 14.9 million incident cases worldwide, and an age-standardised incidence rate of 181.2 per 100,000 people, an increase in age-standardised incidence of 8.2% from 1990.  Also in 2017, 9.6 million years lived with disability (YLD) were due to OA, and an age-standardised rate of 118.8 YLDs per 100 000 people, an increase in age-standardised YLD of 9.6% from 1990.  The recent increase in the global burden of OA revealed by these metrics is associated with, and may be at least partially causative of, the simultaneous rise in global levels of overweight and obesity, which are recognised risk factors for the development of OA (this is also suggested by the regional variation in age-standardised prevalence of OA, which in 2017 was highest in high-income North America [5,923.9 per 100,000 people] where obesity rates are high, and lowest in Western Sub-Saharan Africa [2,678.3 per 100,000 people] where obesity rates are low).⁴

The economic costs of OA to individuals (such as health insurance coverage, unrealised wages, and out-of-pocket payments), health systems (such as hospital stays, theatre time, and physician consultations) and national economies (such as productivity losses, absenteeism and healthcare expenditure) are substantial and increasing.⁵  The combined economic costs for certain high-income countries have been estimated to account for up to 1-2.5% of the gross national product of the UK, USA, Canada, France and Australia, and is comparable to that of diabetes mellitus.⁶  Specifically in the UK, musculoskeletal conditions, of which osteoarthritis is the most common disorder, account for the third largest area of NHS spend, amounting to approximately £5 billion annually,⁷ while musculoskeletal conditions are responsible for one in five episodes of absenteeism and result in the loss of some 28.2 million working days each year.

Accordingly, the prevalence, severity, and economic impact of OA, combined with the inability to cure this progressive condition, render the prevention of OA a pressing problem for population health and primary healthcare.  Since weight loss in those who are obese is one of the few, and seemingly the most tractable, reversable causes of OA, health improvement campaigns to promote healthy weight attainment should highlight the enormous benefits to health and wellbeing that would be successfully realised by the avoidance of OA.  While such campaigns often focus on the potential to reduce the risks of certain cancers, heart disease, and diabetes mellitus, they often overlook the significant burden of avoidable suffering generated by OA.  By emphasising the avoidance of pain, disability and socioeconomic costs through the loss of excess body weight (through healthy eating and physical exercise) to prevent OA, the effectiveness of health promotion campaigns to stimulate behaviour change may be substantially enhanced.  It must be ensured, however, that excessive physical exercise is not encouraged, especially in those who are not obese, since weight loss in such people may paradoxically promote OA.

While it makes no contribution to mortality statistics, the morbidity, economic cost and primary care workload generated by OA is of sufficient proportion to render the condition a significant public health problem worthy of urgent investment of resources.  Happily, these resources need not be costly, since health improvement campaigns that prioritise prevention are inherently cheaper than their curative counterparts.  In the first instance, these campaigns should promote the benefits of preventing OA through healthy weight attainment and lifelong maintenance, which would accrue to individuals, workplaces, health systems, and national economies alike.

References

1. D Coggon, I Reading, P Croft, M McLaren, D Barrett, and Cooper. Knee osteoarthritis and obesity. International Journal of Obesity and Related Metabolic Disorders May 2001; 25(5): 622-7. DOI: 10.1038/sj.ijo.0801585
2. KS Thomas, KR Muir, M Doherty, AC Jones, SC O’Reilly, and EC Bassey. Home based exercise programme for knee pain and knee osteoarthritis: randomised controlled trial. British Medical Journal 05 October 2002; 325(7367): 752. DOI: 10.1136/bmj.325.7367.752
3. D Yu, G Peat, J Bedson, et al. Annual consultation incidence of osteoarthritis estimated from population-based health care data in England. Rheumatology November 2015; 54(11): 2051-2060. DOI: 10.1093/rheumatology/kev231
4. S Safiri, A Kolahi, E Smith, C Hill, D Bettampadi, MA Mansournia, et al. Global, regional and national burden of osteoarthritis 1990-2017: a systematic analysis of the Global Burden of Disease Study 2017. Annals of the Rheumatic Diseases May 2020; 79: 819-828. DOI: 10.1136/annrheumdis-2019-216515
5. DJ Hunter, D Schofield, and E Callander. The individual and socioeconomic impact of osteoarthritis. Nature Reviews RheumatologyJuly 2014; 10(7): 437-441. DOI: 10.1038/nrrheum.2014.44
6. LM March and CJM Bachmeier. Economics of osteoarthritis: a global perspective. Baillière’s Clinical Rheumatology 1997; 11(4): 817-834. DOI: 10.1016/S0950-3579(97)80011-8
7. Versus Arthritis. Versus Arthritis representation to the Budget. January 2021. https://www.versusarthritis.org/media/23185/representation-to-the-budget-jan-21.pdf [accessed 25 August 2022]

Featured photo by De an Sun on Unsplash