Chapter 1: Life with arthritis in Canada: a personal and public health challenge – What is arthritis and how common is it?

Chapter One: What is arthritis and how common is it?

• Introduction
• What is arthritis?
• How common is arthritis?
• Prevalence by age and sex
• Geographic variations in prevalence
  • Provinces and Territories
  • Urban and rural areas
  • Health regions
  • Socio-demographic and socio-economic characteristics
• Projections of arthritis prevalence
• Summary

Introduction

This chapter addresses two key questions: "What is arthritis?" and "How common is it?" The first section describes arthritis in general and its different types. The second section presents the prevalence of arthritis in the Canadian population according to personal characteristics, place of residence and projects the prevalence of arthritis into the future.

What is arthritis?

Put simply, arthritis means "joint inflammation" and encompasses more than 100 rheumatic diseases and conditions that affect the joints, the tissues that surround the joint and other connective tissue. The most familiar types of arthritis are osteoarthritis (OA), rheumatoid arthritis (RA), systemic lupus erythematosus, childhood or juvenile idiopathic arthritis (JIA), and gout (Table 1-1). For further information about the different types of arthritis see the Glossary.

Most types of arthritis are characterized by pain, aching, stiffness and swelling in and around joints or elsewhere in the musculoskeletal system.^{Footnote 1} They can affect the structure and functioning of the joints, leading to increased pain, disability and difficulty in performing everyday tasks and activities.^{Footnote 1 Footnote 2 Footnote 3 Footnote 4 Footnote 5}

Arthritis affects people of all ages. Although it is most prevalent among seniors, arthritis also affects babies, toddlers and people in the prime of their working lives, and can cause lifelong, permanent disability.

At the present time there is no known cure for arthritis, but appropriate treatment and management can prevent disability, maintain function and reduce pain.^{Footnote 1 Footnote 3 Footnote 4 Footnote 5} While treatments vary according to the type of arthritis, general management and rehabilitation interventions are similar for all types. It includes pain management, self-management education, maintenance of healthy weight, medication and minimization of the impact of arthritis via rehabilitation interventions, such as adapted exercises and the use of assistive devices.

How common is arthritis?

Arthritis is one of the most common chronic health conditions in Canada and a major cause of morbidity, disability and health care utilization.^{Footnote 2 Footnote 6 Footnote 7}

Data from the Canadian Community Health Survey (CCHS) 2007-2008 were used for this chapter.^{Footnote 1a *} The CCHS asked respondents about the presence of chronic conditions with the question "Do you have any of the following long-term conditions that have been diagnosed by a health professional?" "Arthritis, excluding fibromyalgia" was one of the options from which respondents could choose. The CCHS defined a long-term condition as lasting or expected to last six months or longer. Data for people aged 15 years and over were included in this chapter.

Between 2005 and 2007-2008, the wording of the question on arthritis was changed. In 2001, 2003 and 2005, the question included the term "rheumatism", whereas in 2007-2008, this term was removed from the question. Consequently, the estimated prevalence of arthritis cannot be directly compared over time and the estimates presented in this chapter may appear lower than in the previous years. The change in the wording must be taken into account when interpreting and comparing current estimates to those of previous years.

Prevalence by age and sex

In 2007-2008, arthritis as a long-term health condition affected more than 4.2 million Canadians aged 15 years and older — or 16% of this population. Arthritis was the second and third most common chronic condition reported by women and men, respectively (Figure 1-1).

Figure 1-1: Self-reported prevalence of specific chronic conditions by sex, household population aged 15 years and older, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

The prevalence of arthritis increased with increasing age (Figure 1-2). In all age groups, prevalence of arthritis was higher among women than men. Overall, nearly two-thirds (64%) of those affected with arthritis were women, among whom the prevalence was 19%. Prevalence among men was 13%.

Several factors, such as longer life expectancy, hormones and lower socio-economic status, may explain the higher prevalence of arthritis among women.^{Footnote 8 Footnote 9}

Figure 1-2: Self-reported prevalence and number of individuals with arthritis by age and sex, household population aged 15 years and older, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada.
E – Interpret with caution.

Although arthritis is perceived as a disease of the elderly, nearly 3 in 5 people (58%) who reported having arthritis in 2007-2008 were younger than 65 years of age (Figure 1-3).

Figure 1-3: Proportion of total number of individuals with arthritis by age group, household population aged 15 years and older, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

Geographic variations in prevalence

This section presents crude and age-standardized prevalence of arthritis by province/territory. It also shows age-standardized prevalence of arthritis by urban/rural areas and health regions. Crude prevalence is defined as the number of events (in this case, the number of people with arthritis) over a specified period of time, divided by the total population. Age – standardization serves to diminish the effect of differences in the age compositions of the various geographic areas and permit direct comparison with the overall Canadian prevalence.

Provinces and Territories

The crude prevalence of arthritis varied considerably across Canada in 2007-2008 (Figure 1-4 and Table 1-2). The highest percentage of individuals who reported having arthritis was found in Nova Scotia (23%), followed by Newfoundland and Labrador (21%), and New Brunswick and Prince Edward Island (20% and 19% respectively). The province of Quebec (12%) and the Territories (Yukon, Northwest Territories and Nunavut) (11%) had the lowest percentage of individuals who reported having arthritis.

Provinces and territories have different age compositions so age-standardized prevalence estimates were calculated to identify if the differences remained after adjusting for these age differences. Newfoundland and Labrador and Nova Scotia were significantly higher (1.1-1.3 times) than the national prevalence, whereas Quebec and British Columbia were significantly lower (0.6-0.9 times) (Table 1-2). This pattern has been consistently reported over time.^{Footnote 2 Footnote 10} Differences in obesity rates and demographic and socio-economic factors (e.g. variations in ethnic composition, rural/urban, education, income levels, etc) might explain the provincial variations in the prevalence of self-reported arthritis.^{Footnote 10}

Figure 1-4: Crude self-reported prevalence of arthritis, by province/territory, household population aged 15 years and older, Canada, 2007-2008 (see Table 1-2 in the report for data)

Source: Public Health Agency of Canada, using Canadian Community Health Survey, 2007-2008, Statistics Canada and 1991 Census population for age-standardization.

Urban and rural areas

Both men and women residing in rural areas reported statistically higher rates of arthritis compared to those residing in urban areas (Figure 1-5). In both rural and urban settings, prevalence of arthritis was higher among women than men. The highest prevalence of arthritis was among women living in rural settings (18%). Higher obesity rates and higher (paid or unpaid) work-related injury rates are consistent with the higher prevalence of arthritis among rural Canadians.^{Footnote 11 Footnote 12 Footnote 13 Footnote 14} Agricultural occupations, such as farming, have been found to be associated with higher prevalence of musculoskeletal conditions, particularly osteoarthritis of the hip and knee.^{Footnote 12 Footnote 13 Footnote 14}

Figure 1-5: Age-standardized self-reported prevalence of arthritis, by rural and urban place of residence and sex, household population aged 15 years and older, Canada 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

Health regions

The age-standardized prevalence of arthritis varied considerably across Canadian health regions (Figure 1-6). The highest prevalence of arthritis in the country was reported in Ontario's Hastings and Prince Edward counties (27%) and the lowest was reported in Richmond, British Columbia (7%).^{Footnote 1c *} Regional variations in socio-economic status, body mass index and ethnic composition could contribute to the observed variations.^{Footnote 1}

Figure 1-6: Age standardized self-reported prevalence of arthritis, by health regions, household population aged 15 years and older, Canada 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

Socio-demographic and socio-economic characteristics

Age-standardized prevalence rates are reported in this section. This was done to enable the comparison of rates between groups with different age structure.

The health benefits of relationships like marriage within society are well known.^{Footnote 51 Footnote 16} For example, married adults are generally found to be healthier than single or divorced adults.^{Footnote 15 Footnote 16} In keeping with this, the age-standardized prevalence of arthritis was significantly lower among men and women who were married/common law, compared to those who were widowed/separated/divorced (Figure 1-7). The higher rates of arthritis among separated and divorced people could result from the direct effect of arthritis on family dynamics or reduced family income, or from the higher rates of stress-related disability, job loss, and depression among those with arthritis, each of which could put stress on a marriage and lead to separation or divorce.

Figure 1-7: Age-standardized self-reported prevalence of arthritis, by marital status and sex, household population aged 15 years and older, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

Ethnicity has been identified as a factor associated with arthritis. The age-standardized prevalence of arthritis for Caucasian, Black, Asian and other ethnic groups is illustrated in Figure 1-8. The prevalence rates of arthritis among people from Asian origins were statistically lower than in people of Caucasian origin.

For information about arthritis among First Nations, Inuit and Métis populations, see Chapter 4.

Figure 1-8: Age-standardized self-reported prevalence of arthritis for Caucasian, Black, Asian and other ethnic groups by sex, household population aged 15 years and over, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada.
E – interpret with caution.
‘Other’ category – excludes First Nations, Inuit and Metis populations.

Men and women with less than secondary school education were more likely to report having arthritis compared to all other levels of education (Figure 1-9).

Figure 1-9: Age-standardized self-reported prevalence of arthritis, by level of education and sex, household population aged 15 years and over, Canada 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

The prevalence of arthritis was significantly higher among women and men with low / low middle income compared to all other income levels (Figure 1-10).

The association between self-reported arthritis and individual level of education and socio-economic status is well established. However, whether arthritis primarily affects those of low socio-economic status or leads to a lower socio-economic status is unknown.^{Footnote 9 Footnote 17 Footnote 18} These findings may result from differences in the prevalence of risk factors, as a lower socioeconomic status has been linked with inactivity and obesity, both established risk factors for certain types of arthritis. As well, disability associated with arthritis may reduce the opportunities for higher education and employment.

Figure 1-10: Age-standardized self-reported prevalence of arthritis, by income and sex, household population aged 15 years and over, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

The age-standardized prevalence of arthritis was significantly lower among immigrants than among people who were Canadian-born (Figure 1-11). This may be partly due to the healthy immigrant effect^{Footnote 1b*}. Women reported a higher prevalence than men in both immigrant (14% versus 9%) and non-immigrant populations (17% versus 12%).

Figure 1-12 illustrates the impact of time since immigration on the prevalence of arthritis among immigrants. The age-standardized prevalence of arthritis was much lower among recent immigrants (less than 15 years since immigration) than those who immigrated 15 years ago or more. The more time since immigration the more similar the prevalence rates of arthritis became to non-immigrant, particularly among women. These findings are consistent with results from the Canadian literature.^{Footnote 9} Studies reported a narrowing of the health status gap in Canada between individuals who are native born and immigrants as their years in Canada increase — a worsening of immigrant health over time. Some researchers hypothesize that convergence in health outcomes might arise from a process of acculturation, in which recent immigrants gradually take on the characteristics of their "new" society.^{Footnote 9}

Figure 1-11: Age-standardized self-reported prevalence of arthritis, by immigration status and sex, household population aged 15 years and over, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

Figure 1-12: Age-standardized self-reported prevalence of arthritis, by time since immigration and sex, household population aged 15 years and over, Canada, 2007-2008

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada
E – interpret with caution.

Projections of arthritis prevalence

As previously shown (Figure 1-2), the prevalence of arthritis in Canada increases with age. Given the aging of the Canadian population, this pattern has significant implications for the future impact of arthritis in Canada. Canada's population is aging so quickly that in approximately a decade senior citizens will outnumber children.^{Footnote 19}

The prevalence of arthritis is projected to increase by nearly one percentage point every five years over the next quarter century. By 2031, the prevalence of arthritis is projected to be 20% (Table 1-3), which would represent an increase of approximately 38% from 2007. It is estimated that by 2031, 6.7 million Canadians aged 15 years and older will have arthritis, with the largest increases in the older age groups, particularly among those aged 65 years and older due to an increasing number of older people (Figure 1-13). An increase is also noted in the working-age population (35-64 years of age), particularly among those aged 55-64 years.

While these prevalence projections show similar trends to previously published estimates, a change in the arthritis question in the 2007 CCHS, as compared to previous surveys, resulted in slightly lower overall estimates, as expected.^{Footnote 2} Furthermore, these projections may, in fact, be conservative due to the assumptions made regarding the stability of the age- and sex-specific prevalence estimates as well as of the prevalence of associated risk factors, such as obesity, over time.

Figure 1-13: Number of people projected to have arthritis, by year and age group, Canada 2007-2031

Source: Public Health Agency of Canada using Canadian Community Health Survey, 2007-2008, Statistics Canada

Summary

• The word “arthritis” is used to describe more than 100 rheumatic diseases and conditions that affect a joint or joints, causing pain, swelling and stiffness which often lead to disability.
• Common types of arthritis include osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, psori- atic arthritis, systemic lupus erythematosus, gout, and childhood or juvenile idiopathic arthritis.
• In 2007-2008, over 4.2 million Canadians (16%) aged 15 years and older reported to have arthritis.
• On the basis of current projections, 1 million more Canadians will have arthritis within 10 years. In 20 years, the prevalence of arthritis may reach one in five Canadians.
• Close to three in five people (58%) with arthritis are under 65 years. Loss of both work and productivity are frequent and occur early, due to disability. This may impact participation in the labour force.
• The crude prevalence of arthritis varied considerably across Canada ranging from 23% in Nova Scotia to 12% in Quebec and 11% in the Territories (Yukon, Northwest Territories and Nunavut). Age-standardized prevalence estimates for Newfoundland and Labrador and Nova Scotia were significantly higher (1.1-1.3 times) than the national prevalence whereas, Quebec and British Columbia were significantly lower (0.6-0.9 times). Variations in socio-economic status, body mass index and ethnic composition could contribute to the observed differences between the provinces and territories.
• Prevalence of arthritis was higher among people who have lower formal education levels and report low income levels.
• The age-standardized prevalence of arthritis was significantly lower among immigrants compared to Canadian-born people. However, the age- standardized prevalence of arthritis was much lower among recent immigrants (less than 15 years since immigration) than those who immigrated 15 years ago or more. The more time since immigration the more similar the prevalence rates of arthritis became to non-immigrant, particularly among women.