THE EPIDEMIOLOGY OF LOW-BACK-PAIN IN THE REST OF THE WORLD - A REVIEWOF SURVEYS IN LOW-INCOME AND MIDDLE-INCOME COUNTRIES

Study Design, A criteria-based review of the literature. Summary of Ba ckground Data. The literature on the epidemiology of low back pain is accumulating, but for the most part studies are restricted to high-inc ome countries, which comprise less than 15% of the world's population. Little is known about the epidemiology of low back pain in the rest o f the world. Objectives. To address the imbalance in the literature an d to review the relatively few studies on the epidemiology of low back pain in low- and middle-income countries. Rates from these studies ar e contrasted with rates from selected high-income countries. In review ing the literature, a hypothesis is tested: low back pain rates are hi gher in low-income countries than in high-income countries, not only b ecause hard physical labor is more prevalent in low-income countries, but also because, unlike high-income countries, hard physical labor fo r older workers in low-income countries often is unavoidable. Methods. Among other sources, articles for the review come from a search of th e MEDLINE bibliographic database, with ''back pain'' and individual lo w- and middle-income countries entered as key words. To avoid recall b iases, findings specifically on point prevalence are reviewed. Results . Within the categories of low-income and high-income countries, low b ack pain rates vary twofold or more. In comparisons between these cate gories of countries, rates on the whole are higher among the general p opulations of selected high-income countries than among rural low-inco me populations; specifically, rates are 2-4 times higher among Swedish , German, and Belgium general populations than among Nigerian, souther n Chinese, Indonesian, and Filipino farmers. Within low-income countri es, rates are higher among urban populations than among rural populati ons and still higher among workers in particular worksites, referred t o as ''enclosed workshops.'' Conclusions, The disparity in low back pa in rates within categories of countries, high-income and low-income, c alls attention to the high proportion of studies on the epidemiology o f low back pain that are methodologically questionable. Recommendation s are offered to improve the methodologic quality of this type of stud y. Conclusions may be drawn from comparisons between studies, although , in the absence of set methodologic standards, they are tentative. Th e considerably lower rates among populations of low-income farmers com pared with rates of the affluent populations of selected northern Euro pean countries indicate that, contrary to the hypothesis proposed here , hard physical labor itself is not necessarily related to low back pa in. The higher rates in urban low-income populations as compared with rates in rural low-income populations and the sharply higher rates amo ng workers in enclosed workshops of low-income countries suggest a dis turbing trend: low back pain prevalence may be on the rise among vast numbers of workers as urbanization and rapid industrialization proceed .