Why was this study done?
Arthritis is one the most common causes of work disability in the United States. Research has consistently shown a link between arthritis and difficulties finding work and staying at work. People with arthritis are also more likely to live with depression compared to people without the condition. Yet few studies have examined the role of depression in the employment of those living with arthritis, and whether differences exist across different age groups.
How was the study done?
The research team used five years of data (2013-2017) from the National Health Interview Survey (NHIS), a nationally representative survey conducted by the U.S. National Center for Health Statistics. The team focused on participants of traditional working age (18 to 64) who had been diagnosed with arthritis, rheumatoid arthritis, gout, lupus or fibromyalgia. The total sample size was 11,380.
The team examined answers to survey questions about work (“What were you doing last week?” and “What is the main reason you did not work last week?”) and depression (“How often do you feel depressed?” and “Thinking about the last time you felt depressed, how depressed did you feel?”).
Participants were grouped into three age categories: young (aged 18 to 34 years), middle-aged (35 to 54) and older (55 to 64). In addition to demographic factors such as age, sex and race, the team also took into account education, income (accounting for family size), health factors such as obesity, anxiety and other co-occurring health conditions, social activity limitations due to arthritis, physical activity levels, access to and use of heath services and insurance coverage.
What did the researchers find?
Among working-age adults with arthritis in the U.S., about 13 per cent reported depressive symptoms. This is higher than the prevalence of depressive symptoms among adults without arthritis (a prevalence of five per cent, according to research elsewhere). When comparing people with arthritis and depressive symptoms to people with arthritis but no depressive symptoms, researchers found lower employment levels among those who: were male (27 versus 72 per cent), were poor (15 versus 36 per cent), reported limitations in their social activities (10 versus 17 per cent), rated their health poorly (16 versus 36 per cent), were obese (29 versus 63 per cent), had three or more co-morbid conditions (16 versus 40 per cent) and had limitations due to arthritis (19 versus 46 per cent).
Looking across the age groups among people with arthritis and depressive symptoms, the study found higher levels of employment in young people (40 per cent) than in middle-aged people (32 per cent) and older working-age adults (25 per cent). When controlling for all other variables, the researchers found the effect of having depressive symptoms was strongest among middle-aged adults, who were 17 per cent less likely to work than their peers without depressive symptoms. A borderline difference was found among younger adults, while no statistically significant difference was found among older adults.
What are the implications of the study?
Because the NHIS sample is nationally representative, the findings of prevalence in this study can be considered a true picture of the patterns of work disability among U.S. working-age adults with arthritis. Although the links between depressive symptoms and work disability are well-known, studies have also shown that people with arthritis use fewer mental health services than people without arthritis. Providing mental health care along with clinical care to people with arthritis may be a needed strategy to reduce work disability in this population.
What are some strengths and weaknesses of the study?
A strength of this study is its use of a large, nationally representative sample of working-age adults across different age groups and with a range of arthritic conditions.
A weakness of the study is its cross-sectional or snapshot-in-time design. This design does not allow researchers to conclude whether people’s difficulties finding work and remaining at work lead to depressive symptoms, or vice versa. Understanding the direction of such a cause-and-effect relationship would require a longitudinal or follow-up study design.