Several measures have been proposed to capture summaries of disability, particularly to make comparisons across conditions and populations. One of the most frequently cited measure, the DALY, has been especially promoted in the multiple iterations of the Global Burden of Disease (GBD) Study (Murray et al., 2012). DALYs themselves are somewhat of a summary measure as they are derived by summing a measure of years of life lost (YLLs) and years lived with disability (YLDs) (Murray et al., 2012). Given the gargantuan undertaking of the GBD, it is understandable that only three (osteoarthritis, rheumatoid arthritis, and gout) of the more than 100 conditions that comprise “arthritis” are examined and reported. In the most recent analysis, the examined musculoskeletal conditions comprised 6.8 % of total DALYs, of which osteoarthritis alone accounted for 10 % (Murray et al., 2012). Estimates for 2010 indicated that gout, rheumatoid arthritis, and osteoarthritis globally produced 2 (95 % CI = 1–2), 70 (54–88), and 249 (172–352) DALYs per 100,000, respectively (Murray et al., 2012). (For some context, these values were 174 (167–184) for breast cancer and 222 (186–268) for hypertensive heart disease (Murray et al., 2012)).

Activities of daily living (ADLs) and instrumental activities of daily living (IADLs) actually represent summary measures of function and activity limitations and, for some IADLs, participation restriction, as defined by the ICF. ADLs are broadly defined as “basic tasks of everyday life” and represent activities such as bathing, dressing, transferring, using the toilet, continence, and eating; IADLs were subsequently developed to incorporate more activities necessary for independent community living and include managing personal finances, preparing meals, shopping, getting around outside the home, doing housework, using a telephone, and taking medication (Wiener, Hanley, Clark, & Van Nostrand, 1990).

Most population-based US studies measuring ADLs or IADLs among people with arthritis have focused on older adults (Martin & Schoeni, 2014; Song, Chang, & Dunlop, 2006). Song et al. found that, even after adjusting for other risk factors, older adults (age ≥65 years) with arthritis at baseline had higher incidence of ADL disability compared with those without arthritis (9.3 % vs. 4.5 %) over two years of follow-up, and that approximately 1-in-4 new cases of ADL disability in the population were due to arthritis, with an adjusted population-attributable fraction of 23.7 % (Song et al., 2006). Another study examining causes of ADL and IADL disability in US adults between 1997 and 2010 found that arthritis/rheumatism ranked second (behind back/neck problem) among adults ages 40–64 and first among adults ≥65 years; importantly, in the younger group limitations increased over the study period (Martin & Schoeni, 2014). A recent Dutch study had very similar findings in terms of ADL disability, including the greater emphasis on arthritis vs. back pain as a cause among older adults, and reported that high prevalence, moderately disabling conditions, specifically arthritis, make the greatest contributions to population disability among older adults (Klijs, Nusselder, Looman, & Mackenbach, 2011).

There has been some criticism of ADLs/IADLs as being too focused on narrow functional limitations at the expense of other important areas of life that may have more meaning to some individuals (such as personal relationships), and broader evaluation of disability in advanced or valued activities beyond activities that are necessary for survival or self-sufficiency have been suggested (Katz, 2004).

Another source of general disability surveillance in the USA has been the Survey of Income and Program Participation (SIPP) . Over a period of 15 years, three independent cross-sectional ascertainments of the prevalence and causes of disability among US adults were conducted through the SIPP by the U.S. Census Bureau. Each of these analyses demonstrated that arthritis or rheumatism is the most common cause of disability, and, in the most recent of these analyses, the top three most common causes of disability were found to be (1) arthritis or rheumatism (8.6 million), (2) back or spine problems (7.6 million), and (3) heart trouble (3.0 million) (Brault, Hootman, Helmick, Theis, & Armour, 2009).

SIPP used a broad and comprehensive set of questions to identify disability. Because of the breadth of the scope of disability as defined by SIPP, it is not possible to classify this measure in one of the ICF categories; the SIPP definition includes impairments, activity limitations, and participation restrictions, making it a thorough definition for surveillance and planning purposes. Respondents were classified as having a disability if they answered “yes” to at least one of the queried limitation categories: (1) use of an assistive aid (cane, crutches, walker, or wheelchair), (2) difficulty performing activities of daily living (getting around inside the home, getting in/out of a bed/chair, bathing, dressing, eating, and toileting) or instrumental activities of daily living (getting around outside the home, taking care of money/bills, preparing meals, doing light housework, managing prescriptions, and using the telephone), or specified functional activities (seeing letters/words in newsprint, hearing normal conversation, having speech understood, walking three city blocks, climbing a flight of stairs, grasping objects, lifting/carrying 10 lb), (3) one or more selected impairments (learning disability, mental retardation, other developmental disability, Alzheimer’s disease/senility/dementia, or other emotional/mental disability), or (4) limitation in the ability to work around the house or at a job or business. Effects of temporary conditions (less than 5 months duration) were excluded. Individuals who reported any of these limitations (except those with only “use of an assistive aid” or “selective impairments”) were also asked “Which condition or conditions cause these difficulties?” and shown a list of 30 conditions from which they were asked to identify the cause of their disability. Respondents indicating more than one condition were asked to identify a main condition.

Arthritis or rheumatism was cited as the main cause of disability most often overall (19.0 %, 95 % CI = 18.0–20.0), for men (11.5 %, 95 % CI = 10.3–12.7), and for women (24.3, 95 % CI = 22.9–25.7) (Brault et al., 2009). Back or spine problems was the next most common cause of disability, cited by 16.8 %, which was statistically significantly lower than for arthritis or rheumatism. The same is true for all remaining mutually exclusive reported causes, which ranged in prevalence from 0.2 % (AIDS or AIDS-related condition and, separately, speech disorder) to 12.9 % (other) to sum to 100 % (Brault et al., 2009).

Surveillance of nine specific functional limitations is also conducted in the USA through the National Health Interview Survey (NHIS) , which is an ongoing multistage, probability sample survey conducted by in-person interview representative of the civilian, non-institutionalized population (National Center for Health Statistics, 2009). These functional limitations would be considered activity limitations in the ICF framework and are useful clinical targets for intervention as many of them represent critical capacities for independent living. The prevalence of functional limitations is high among people with arthritis. When the root question “By yourself, and without using any special equipment, how difficult is it for you to …” was queried with a 5-point scale ((1) Not at all difficult, (2) Only a little difficult, (3) Somewhat difficult, (4) Very difficult, (5) Can’t do at all) among respondents with self-reported, doctor-diagnosed arthritis, limitations restricted to responses of “very difficult” and “can’t do at all” ranged from 5.5 % (grasp/handle small objects) to 27.3 % (stand or be on feet for about 2 h) (Theis, Murphy, Hootman, & Wilkie, 2013). The remaining functional limitations were stoop, bend, or kneel (27.2 %), walk a quarter of a mile or three city blocks (21.0 %), push/pull large objects (e.g., living room chair) (18.2 %), climb up ten steps without resting (15.3 %), carry/lift something as heavy as 10 lb (e.g., bag of groceries) (12.4 %), reach up over head (7.0 %), and sit for 2 h (9.8 %) (Theis et al., 2013). Findings from this study also indicated that slightly greater than 2-in-5 (43 %) adults with arthritis report at least one functional limitation (Theis et al., 2013). The range of prevalence of functional limitations among people with arthritis, from 1-in-20 to 2-in-5, suggests substantial disability in many basic and necessary activities for everyday life.

Mental health impacts are important components of disease consequences and the study of disability because of the complex relationship between mental and physical conditions, coping ability, pain perception, and interference with compliance and responsiveness to treatment and self-management behaviors, such as physical activity (Burnett, Coverdale, Pickens, & Dyer, 2006; Dimatteo, Lepper, & Croghan, 2000; Graves, Scott, Lempp, & Weinmann, 2009; Lowe et al., 2004; McFarlane & Brooks, 1988; Parker & Wright, 1995; Rosemann, Laux, & Kuehlein, 2007; Scopaz, Piva, Wisniewski, & Fitzgerald, 2009; Soderlin, Hakala, & Nieminen, 2000). Specifically, functional disabilities among people with arthritis can be worsened by depression (Rosemann et al., 2007), and impaired mental health itself can increase disability and decrease quality-of-life and physical function (Crotty et al., 1994; Lowe et al., 2004; McFarlane & Brooks, 1988; Parker & Wright, 1995; Rupp, Boshuizen, Dinant, Jacobi, & van den Bos, 2006).

For people with arthritis, symptoms often affect mood, and negative mental health impacts are common. For example, a nationally representative US study found that both serious psychological distress (as measured by the K-6 (Kessler et al., 2002) and frequent anxiety or depression were significantly and substantially higher in adults with arthritis compared with those without (5.6 % vs. 1.8 % and 26.2 % vs. 10.7 %, respectively) (Shih, Hootman, Strine, Chapman, & Brady, 2006). The K-6, which measures non-specific serious psychological distress in populations and has been shown to discriminate DSM-IV cases from non-cases (Kessler et al., 2010), uses a six-question scale to assess how often in the past 30 days respondents felt each of: sad, worthless, nervous, restless, hopeless, and that everything was an effort (Kessler et al., 2002). Frequent anxiety or depression in this study was defined as a “yes” response to: “During the past 12 months have you been frequently depressed or anxious?” (Shih et al., 2006). Shih et al. also found that, among adults with arthritis, younger age, recurrent pain, physical inactivity, functional or social limitations, comorbid medical conditions, lower socioeconomic status, and divorce/separation were significantly associated with serious psychological distress. In fact, serious psychological distress was 6.5 times more prevalent in adults ages 18–44 years compared with those 65 years or older (Shih et al., 2006). Because this study was cross-sectional in nature, the temporal sequence between functional or social limitations and serious psychological distress could not be assessed, but the strong, significant relationship between them was established (Shih et al., 2006).

Another nationally representative US study of adults with arthritis ages 45 or older found that one-third of respondents reported at least one episode of anxiety or depression, anxiety was significantly more common than depression (31 % vs. 18 %), and that most respondents with depression (84 %) also reported anxiety (Murphy, Sacks, Brady, Hootman, & Chapman, 2012). This study used the Arthritis Impact Measurement Scales to assess anxiety and depression separately (Meenan, Mason, Anderson, Guccione, & Kazis, 1992). Importantly, conclusions from this study indicated that, despite greater focus on depression among people with arthritis, anxiety is almost twice as common; due to the lack of a distinct profile of people with arthritis reporting anxiety and/or depression that all people with arthritis should be screened and treated for both conditions; and low prevalence of help-seeking for mental health among people with arthritis suggests unmet treatment need in this area (Murphy et al., 2012).

Health-Related Quality-of-Life (HRQOL) , while not strictly a measure of disability, is a useful reflection of how overall health states, and the absence of acceptable levels of health, influence perceived physical and mental health. Among adults ages 18 years or older, those with arthritis report fair/poor health, mean numbers of physically unhealthy, mentally unhealthy, and activity-limited days in the past month substantially and significantly more often than those without arthritis (Furner, Hootman, Helmick, Bolen, & Zack, 2011). For fair/poor health, 27 % of US adults with arthritis report this outcome compared with only 12 % of those without arthritis (Furner et al., 2011). For mean numbers of mentally unhealthy days (5.4 vs. 2.8), physically unhealthy days (6.6 vs. 2.5), and activity-limited days (4.3 vs. 1.4) adults with arthritis report 1.9, 2.6, and 3.0 times more affected days, respectively, than their non-arthritis counterparts (Furner et al., 2011).

An important Healthy People 2020 arthritis objective is to “reduce the proportion of people with doctor-diagnosed arthritis who are limited in their ability to work for pay due to arthritis” (U.S. Department of Health and Human Services, 2013). Arthritis-attributable work limitation (AAWL) is defined for Healthy People 2020 and U.S. public health surveillance purposes as a “yes” to “In this next question, we are referring to work for pay. Do arthritis or joint symptoms now affect whether you work, the type of work you do, or the amount of work you do?” Nationally, the prevalence of AAWL is 30 % among working-age (18–64 year old) adults with arthritis, which equates to 1-in-20 or 5 % of the entire US working-age population (Theis, Murphy, Hootman, Helmick, & Yelin, 2007).

Holding a job has valuable benefits in terms of identity, status, and feelings of self-worth and self-esteem, while both a person’s economic situation and mental health can be adversely affected by joblessness (Prady et al., 1998). Workforce participation provides opportunities to contribute productively to society and to remain financially independent (ABS, 2005). As described by Armstrong and Wilkie, workforce participation is necessary for individual prosperity and full participation in society as well as being “central to identity, social roles, and social status” (Armstrong & Wilkie, 2009). On the other hand, being outside the labor force may have a negative impact on a person’s health (ABS, 2005). Burgard et al. established via analysis of two longitudinal datasets that involuntary job loss is associated with significantly poorer overall self-rated health and more depressive symptoms; moreover, among involuntary job losers whose job loss was for health-related reasons, the declines in health are even more severe (Burgard, Brand, & House, 2007). Job loss also represents more than the loss of wage and non-wage economic benefits. It is the loss of a major social role and of on-the-job social networks (Burgard et al., 2007; Hayes & Nutman, 1981). In addition, being unemployed is a stigmatized condition in many countries, which brings the potential of anxiety, insecurity, shame, and the worsening of psychological symptoms such as depression (Burgard et al., 2007; Gallo, Bradley, Siegel, & Kasl, 2000). The high prevalence of AAWL among adults with arthritis puts them at greater risk for these negative outcomes and provides an important target population for intervention.

Volunteering can be a meaningful personal pursuit; particularly for older adults, volunteering can also be a meaningful social role. Increased life satisfaction, as well as positive changes in psychological and physical well-being, has been demonstrated to be associated with volunteering in longitudinal studies (Meier & Stutzer, 2004; Musick & Wilson, 2003; Pilliavin & Siegel, 2007; van Willigen, 2000). Some evidence suggests that “volunteering may be more beneficial to older adults with functional limitations” (Morrow-Howell, Hinterlong, Rozario, & Tang, 2003). Taken together, this evidence suggests that limitations in the ability to volunteer, particularly due to arthritis, may be a consequential marker of participation restriction, as defined by the ICF, in a population that already experiences excess disability and functional and activity limitations. It is also true that volunteers contribute substantially to the economy, with some estimates of volunteer output equal to 0.8–1.3 % of the gross domestic product (Pho, 2004), making volunteering a valuable social and economic good beyond personal benefits.