Burden of Musculoskeletal Disease
Musculoskeletal conditions are the most common cause of chronic disability around the world. The importance of musculoskeletal conditions as a cause of mortality and morbidity has been recognized by the designation of 2000-10 as the Bone and Joint Decade (Hazes and Woolf 2000) by the United Nations, World Health Organization (WHO), and more than 60 countries around the world. WHO (2003,2004) has highlighted the burden of musculoskeletal conditions. Estimates of the global burden of these conditions have increased 25 percent over the past decade (WHO 2000). Conditions considered under this rubric include osteoarthritis (OA); inflammatory arthritis (rheumatoid arthritis and the seronegative spondyloarthropathies); back pain; musculoskeletal injuries, including sports injuries; crystal arthritis (gout and calcium pyrophosphate disease), and metabolic bone disease, principally osteoporosis (OP).
Back pain is extremely common in both industrial and developing countries, with up to 50 percent of workers suffering an episode each year. Back pain causes 0.8 million disability-adjusted life years (DALYs) each year and is a major cause of absence from work and of correspondingly high economic losses. Nearly 40 percent of back pain is due to occupational risk factors, and many of these factors can be prevented with the cooperation of labor, management, industrial engineers, ergonomists, and health workers.
OA is increasing among the world's aging populations and is the sixth leading cause of years lost because of disability globally. It accounts for nearly 3 percent of the total global years lost to disability, and 10 percent of men and 18 percent of women over the age of 60 have OA. Table 51.1 provides an estimate of the contribution of musculoskeletal conditions to the global burden of disease, including a disaggregation by gender and between the developed and developing world. The proportions presented in the second and third panels are the most noteworthy data in table 51.1. First, the second panel shows that musculoskeletal conditions account for approximately 1.7 and 2.4 percent of the burden of disease experienced by males and females, respectively, or, across both genders, approximately 2 percent of the global burden of disease. The disaggregation by developing and developed regions, however, shows that while musculoskeletal conditions account for around 3.4 percent of the total burden of disease in the developed world, they account for 1.7 percent in the developing world. The data also show that, of the set of musculoskeletal conditions, OA accounts for the largest burden, approximately 52 percent of the total in developing regions and 61 percent in developed regions.
[Table .]
Table 51.2 provides a further disaggregation of the estimated burden of musculoskeletal conditions by developing region and mortality stratum. Note that the burden of disease caused by musculoskeletal conditions varies considerably by region: in Africa, mortality stratum D, musculoskeletal conditions account for less than 1 percent of the burden from all causes, while in the Western Pacific, mortality stratum B, they account for more than 3 percent of the total burden of disease. Similarly, the relative importance of rheumatoid arthritis (RA) and OA varies considerably by region. In the African regions, where the prevalence of RA is low, only 12 percent of the burden created by musculoskeletal diseases is due to RA; in the Americas, however, that proportion is approximately 24 to 27 percent.
[Table .]
RA has a prevalence of 0.7 to 0.1 percent worldwide and results in significant work disability and long-term treatment costs. In addition, OP is increasing with the aging of populations: one in three people over the age of 50 suffers a fracture because of OP. Back pain, OA, trauma, and RA account for 32,948,765 DALYs, or 2.15 percent of the global total for 2000.
A recent review of the prevalence of rheumatic disorders in Sub-Saharan Africa suggests that the frequency of RA is increasing in East, Central, and South Africa but is rare in West Africa (McGill and Oyoo 2002). Gout is also prevalent throughout the continent, and the HIV epidemic has spawned a variety of associated spondyloarthropathies among the aging population. Countries such as Thailand are also recognizing an increasing burden of disease caused by arthritis and trauma (Jitapunkul and others 2003).
