Many cross-sectional studies have demonstrated a substantial relationship between arthritis and functional limitations and disability, a selection of which are highlighted here. Fewer studies address the contribution of osteoarthritis to disability.
Research indicates that the impact of arthritis on disability is greater on physical functional limitations than on more complex social and role activities. [22
] Verbrugge et al. compared levels of functional limitation and disability for those with and without arthritis in a nationally representative sample living in the United States using data from the Supplement on Aging of the 1984 National Health Interview Survey. [21
] This study investigated the relationship between over 20 indicators of functional limitation and disability including walking, “motions and strength” (e.g. reaching, lifting, standing), personal care and household activities among those with a range of arthritic conditions. Across all of these measures members of this sample with arthritis experienced more disability than those who did not, and that the impact of arthritis was greater on functional limitations than on disability, represented by more complex social role activities. Comparing the impact of various health conditions, Results from the Women’s Health and Aging Study also have revealed that women reporting “a physician with a diagnosis of arthritis” were significantly more likely to report difficulty in 13 of 15 functional tasks and activities.[23
Employing the World Health Organization’s Disability Assessment Schedule, and the National Comorbidity Survey Replication, Merikangas et al. used regression analysis to estimate the effect of specific conditions on disability days. Arthritis more generally accounted for the third largest number of disability days (374.6 million days per year), following back/neck pain (1167.8 million days per year) and major depressive disorder (386.6 million days per year). [24
Verbrugge et al. provided detail to the emerging picture of the contribution of arthritis to functional limitations and disability by analyzing the 1994-95 National Health Interview’s Disability Supplement Phase I.[25
] In this “profile of arthritis disability,” arthritis (including osteo, rheumatoid, spinal, and other arthropathies). Those with arthritis had a slower progression of milder disabilities than persons with disabilities from other conditions. This “profile of arthritis disability” is consistent with Ferrucci et al.’s concept of “progressive disability” characterized by a slower, more progressive course as compared to more rapid onset seen in “catastrophic disability.
A second profile of arthritis disability used the National Health Interview’s Disability Supplement Phase II to compare a range of functional limitations and disability for persons who attributed their disability to arthritis (including osteo, rheumatoid, spinal, and other arthropathies) against those with disability attributed to other conditions.[9
] They reported that those with arthritis were more likely to be older, and female, and to be less likely to be working than those with other disabling conditions, and to report that they are unable to work due to their health. Overall, ”arthritis-disabled“ persons experienced more disability across a wider range of activities than ”other-disabled“ persons. In regard to participation in social activities, arthritis-disabled persons reported traveling long distances less often, using a vehicle for transportation less often, going out fewer days per week, and were less likely to report working at a job. This study provided new knowledge about the functional course for those with arthritis in middle age, and revealed that they experienced functional limitations and disability earlier than those without arthritis.
In longitudinal research, Song et al. estimated the population impact of arthritis using data from the nationally representative National Health and Retirement Survey.[8
] Arthritis was identified when respondents answered yes to the question, ”Have you ever had or has a doctor ever told you that you have arthritis or rheumatism?“ Investigators used multiple logistic regression analysis to compare the incidence of new functional limitation or disability (preparing meals, grocery shopping, managing money, taking medications, using the telephone). Consistent with prior studies, investigators noted that risk factors for incident disability among persons 65 years and older were: demographic factors, age, comorbid conditions, physical limitations, health behaviors (tobacco and alcohol use, and physical activity), and socioeconomic factors, and they adjusted for them in the analysis. Song et al. conclude from their findings, ”Almost 1 in every 4 new cases of ADL disability was due to arthritis (adjusted population attributable fraction 23.7%).“[8
] In is editorial comment, Covinsky wrote, ”Although Song et al. demonstrated that in a statistical sense almost 25% of disability is attributable to arthritis, it would not be correct to claim that arthritis is the cause of disability in 1 of 4 individuals with ADL dependence. In contrast, a conclusion stating that arthritis is the contributing cause in 75% of patients with ADL disability, and on average accounts for one-third of the disability is clinically very plausible.“[1
A recent longitudinal study with 10 year follow-up from the Health and Retirement Study addressed the need to investigate the role of arthritis (as defined by the response to the same general arthritis question used in Song et al. above) earlier in life in the later development of functional limitations (walking and climbing stairs) or disability (bathing, dressing, transfers, eating and toileting). [2
] The baseline results indicated that those with arthritis were significantly more likely to be older, female, of lower socioeconomic status, and have comorbid conditions (e.g. hypertension, depressive symptoms, cancer, or diabetes). After adjusting for age, sex, socioeconomic status, comorbid conditions, body mass index, smoking, depression, physical activity, difficulty jogging one mile, and difficulty climbing stairs, investigators found that those with arthritis demonstrated significantly higher risk of developing functional limitations (30% vs 16%) or difficulty with ADL function (13% vs 5% ) over 10 years. The adjusted odds ratio for ”mobility or ADL difficulty“ for those with arthritis compared to those without arthritis was 1.63 (1.43-1.86). Investigators also calculated odds ratios for those with arthritis only and those without arthritis and at least one other condition compared to those with no arthritis or other conditions. The adjusted odds ratios for those with arthritis and those with at least one other condition were 1.91(1.59-2.44) and 1.74 (1.46-2.08) respectively. This study provided new knowledge about the course of functional limitations and disability over a long period in those who experience arthritis in middle age.