Supplements Current Treatment Options for Osteoarthritis
The Economic Burden of Osteoarthritis
As the most common form of joint disease, osteoarthritis (OA) is associated with an extremely high economic burden. This burden is largely attributable to the effects of disability, comorbid disease, and the expense of treatment. Although typically associated with less severe effects on quality of life and per capita expenditures than rheumatoid arthritis, OA is nevertheless a more costly disease in economic terms because of its far higher prevalence. At the same time, the burden of OA is increasing. While direct and indirect per capita costs for OA have stabilized in recent years, the escalating prevalence of the disease-partly a function of the rapid increase in 2 major risk factors: aging and obesity-has led to much higher overall spending for OA. Approximately one-third of direct OA expenditures are allocated for medications, much of which goes toward pain-related agents. Hospitalization costs comprise nearly half of direct costs, although these expenditures are consumed by only 5% of OA patients who undergo knee or hip replacement surgery. However, while these surgeries are costly, they also appear to be quite cost-effective in the long term. Indirect costs for OA are also high, largely a result of work-related losses and home-care costs. Despite the need for wide-ranging and up-to-date data on the economics of OA treatment to clarify the most effective treatments and the best use of resources, this area of study has received insufficient research attention.
(Am J Manag Care. 2009;15:S230-S235)
Osteoarthritis (OA) is a degenerative joint disease characterized by joint pain and dysfunction caused by a progressive and irreversible loss of articular cartilage.1 OA is the most common form of arthritis, affecting nearly 27 million Americans or 12.1% of the adult population of the United States.2 This compares to slightly less than 1.3 million Americans with rheumatoid arthritis representing 0.6% of the adult population.3 A study conducted by the Centers for Disease Control and Prevention in cooperation with the Harvard School of Public Health found that OA is the fifth leading cause of disability in older Americans after cardiovascular, cerebrovascular, and pulmonary diseases.4
Although OA is both a common and highly burdensome disease, the study of costs associated with OA has been neglected to a surprising degree. This stems, in part, from the fact that OA has often been lumped in with other diseases under the rubric "musculoskeletal conditions" and cost-related studies frequently fail to separate the expenditures associated with OA.5 The present article will attempt to clarify the direct and indirect costs of OA based on the available published data.
Increased age is the primary risk factor for OA, but there are other important risk factors for the disease including obesity, injuries to joint areas, and rigorous physical activity such as engagement in intensive sports.6 As the US population ages, and as the well-known obesity epidemic in this country continues to unfold, the prevalence and burden of OA has been steadily increasing. From 1995 to 2005, the number of adults with OA increased by approximately 6 million people.2,7 This increase is paralleled by similar growth in the larger population suffering from arthritic and rheumatoid conditions which has increased from 36.8 million adults in 1997 (18.7% of US adults) to 46.1 million in 2003 (21.5% of US adults), a notably large proportional increase over a period of just 6 years.8 This larger population consists of condition A, condition B, and related conditions, in addition to OA and rheumatoid arthritis. Indeed, the number of adults in the United States with clinically diagnosed arthritic conditions is expected to reach nearly 67 million people, or 25% of the adult population, by 2030 (Figure 1).9 Twenty-five million of these, 9.3% of US adults, are projected to experience activity limitations as a result of their arthritis.9 The consequent burden, in both quality-of-life and economic terms, great as they are now, can be expected to be very substantial indeed.
Cost of Care
A 1997 analysis of the economic costs of musculoskeletal disorders in 5 industrialized countries (Australia, Canada, France, United Kingdom, and United States), in which OA was the most common of these disorders, found a rising trend of costs that had, by then, reached between 1% and 2.5% of the gross national product of these countries.10 A continued upward trend is reflected in data from the United States in which, in 1997, the total medical expenditures for arthritis and other rheumatic conditions were $233.5 billion.8 By 2003, these costs had increased to $321.8 billion after factoring in inflation. A substantial part of these costs are specific to OA. One estimate, by Leigh et al, put the total annual costs of OA at $89.1 billion.11 They further estimated that between $3.4 billion and $13.2 billion of that expenditure was due solely to job-related OA, making job-related OA more costly than asthma and pulmonary diseases, and also more than renal and neurologic diseases combined.11
Indirect Costs Analyses
The indirect cost burden discussed below refers to those costs incurred not as a result of medical management of the disease but rather of other incurred losses such as lost wages, lost productivity, and expenditures resulting from the need for home care and child care that would otherwise not be incurred. Taken together, these costs can be quite substantial. A Canadian study estimated the annual indirect costs for OA at US$1760 per person (compared with US$3952 direct annual costs).12 A more recent analysis, based on a claims database comprising 5 million privately insured individuals, put the indirect costs of OA at $4603 per person annually.13 An analysis of costs related to OA compared with patients without OA or rheumatoid arthritis, but who might have other illnesses, found that patients with OA required 3 more days of medical care per year than controls and experienced significantly greater costs for issues such as home care, child care, medical equipment, and home remodeling necessary to address disability.14 In addition, 9.4% of OA patients were unable to acquire jobs as a result of their illness compared with 5.2% of nonarthritic patients.
The impact of arthritic diseases on earnings has increased on aggregate in recent years, with $108 billion of earnings being lost in 2003 to people with arthritic conditions, an increase of $9 billion from 1997.8 However, the amount of estimated lost wages on a per capita basis, although still highly significant, fell between 1997 and 2003 from $4551 to $3613 per person.
Costs of Comorbid Disease. The economic impact of comorbid disease may be defined as indirect to the extent that such costs are not directly related to the treatment of OA. The influence of comorbidities is underscored by results from a study based on the Olmsted County, in Minnesota Health Care Utilization and Expenditures database showing that people with OA incur costs at a much higher rate than all other body systems (ie, excluding the musculoskeletal system) compared with nonarthritic controls. These included respiratory, cardiovascular, gastrointestinal, neurological, endocrine, psychiatric, renal and digestive systems (P <.0001 for all systems, OA vs controls).15 These data also underscore the fact that OA patients incur statistically significantly more costs for diagnostic and therapeutic procedures, in-hospital care, imaging studies, physician services, equipment, and laboratory studies compared with nonarthritic patients.15 Furthermore, OA patients experience significantly higher rates of work disability compared with controls.16
An analysis of medical claims from a major third-party payer, which sought to determine the contribution of comorbidities to the cost of OA treatment, found that OA patients cost between 1.5 and 2.6 times more to treat than nonarthritic matched patients.17 These results are supported by a survey of OA patients from 1999/2000 which observed a more than doubling in costs of treatment for patients with 3 comorbidities compared with those with no comorbidities.12
Direct Costs Analyses
Results from studies conducted to determine the direct costs of OA are somewhat heterogeneous, a result, in part, of different patient populations, different payers, different variables calculated, and different treatment locales. The Canadian study noted earlier found that direct costs for OA patients were US$3952 per person per year based on 1999 and 2000 data from a government health plan from the province of Ontario.12 A study of claims filed with a US managed care plan between 1991 and 1993 compared the medical costs of OA patents with non-OA patients and subtracted the latter from the former to arrive at a figure of additional costs attributable to OA. This study also divided patients in 2 age groups: <65 years and >65 years. For the <65 years age group total annual costs were $5294, which was $2827 more than non-OA patients. OA patients 65 years or older had overall annual costs of $5704, which were $1963 higher.18 Taken together, these data suggest OA costs are roughly double those of non-OA patients.
A study using data from a managed care organization over the course of 1 year starting in mid-1993 (but this time using Medicare reimbursement schedules to calculate costs) reckoned direct costs as a combination of medication use, ambulatory care, and hospital care. The annual figure for OA patients was just $543, nearly half (46%) of which was for hospital care and a third (32%) for medications.19 Most of the hospitalization costs went to knee and hip replacements, and although they constituted a large proportion of total costs, they represented resources used by only 5% of the OA patients.19 Medication costs, which amounted to $173 per person per year, were mainly split between nonsteroidal anti-inflammatory drugs (NSAIDs) and antiulcer drugs. OA patients used 3.3 office visits each year, 1.2 of which were for physical therapy. Interestingly, the same study found per patient costs for rheumatoid arthritis almost 5 times greater than per patient OA costs ($2612 vs $543), and yet total costs to the plan for OA patients were nearly 7 times as high due to the much higher prevalence of OA.19