This study showed that having both back problems and arthritis is associated with a greater likelihood of being not currently employed and being out of the labor force, than having either condition alone. To date most of the literature on labor force participation and back problems has not considered the impact of co-occurring arthritis. Our findings give a new perspective on the emphasis on back problems as a major cause of work disability. They suggest that interventions to maintain work participation in those with back problems need to take into account the possibility of co-occurring arthritis. The findings may also help partially explain why interventions to reduce back pain related impact on functioning and absences at work have only met with limited success [38, 39]. Common interventions include educational or exercise components that usually focus on biomechanical aspects such as lifting techniques, with the implication that much of low back pain is related to biomechanical factors and injury . If there is indeed a sub-category of back problems involving comorbidity with arthritis that is associated with loss of labor force participation, this may need to be taken into account in the development of preventive strategies. For those with back problems and arthritis, interventions may need to consider that other joints, most likely the knees, hands, feet and hip, might also be affected. In this instance, biomechanical-focused back pain preventive strategies such as bending from the knees rather than the back when lifting may be inappropriate for individuals with knee symptoms. Instead, strategies related to osteoarthritis management, such as self-management, physical activity and, if appropriate, muscle strengthening exercises and weight loss might be needed.
While it is not clear what the back problems and arthritis group represents, the similarity to the arthritis only group in terms of risks of not being in the labor force as well as the profile of socio-demographic and lifestyle characteristics tentatively suggests that a portion of the back problems and arthritis group might represent a contribution from arthritis with spinal involvement, such as osteoarthritis [29, 41]. The profile of characteristics of the back problems only group is similar to that for chronic non-specific low back pain .
This study supports previous findings on the impact of chronic diseases on labor force participation [2, 14, 15, 42], and suggests that particular attention needs to be paid to back problems and arthritis. Our findings extend previous analyses which showed that the combination of back problems and arthritis was more highly associated with pain and activity limitation and having poor self-rated heath than either condition alone, even after controlling for the effect of other chronic health conditions . It is likely that these higher levels of pain and disability are contributory reasons for the increased risk for individuals with both back problems and arthritis of not being employed or being out of the labor force. The population impact of back problems and arthritis is not trivial as their combined prevalence (29.2%) in the working age population exceeds that of all other chronic conditions taken together (24.8%). Furthermore, the prevalence of co-occuring arthritis and back problem, the group with the highest risk for being not employed or being out of the labor force, is 5.8%, which is comparable to the prevalence of diabetes in our study population (5.1%).
There were some noteworthy differences between the sexes. Generally, the risks of non-participation in the labor force associated with chronic diseases were higher for men than for women. In addition, there was a gendered pattern of associations between employment status and living arrangements, where living with a partner and/or living with dependent children was associated with a higher likelihood of not being currently employed for women but a lower likelihood for men. This was consistent with earlier findings [30, 31] and may reflect the effect of a proportion of women being not employed due to child-care and other domestic responsibilities. On the other hand, both men and women were less likely to report being out of the labor force when they also report living with a partner and/or living with dependent children. This could reflect support from those at home to facilitate being able to work.
A possible confounder not accounted for in our study was type of occupation. Back problems and/or arthritis could differentially affect that risk of not being in the labor force for those with physically demanding jobs . Data on type of occupation in the CCHS were only available for individuals who were currently working and were therefore not available for our analyses. However, descriptive analyses stratified by age showed no clear pattern of occupation type by disease condition [data provided in Additional file 2].
A major strength of this study is the use of data from a national population-based study with broad coverage and a large, representative sample. There are also a number of limitations. First, chronic conditions were ascertained by self-report of health professional diagnoses and was not validated; however, validation studies have shown that self-reported questions about arthritis are a reasonably reliable and economic means to estimate population prevalence of arthritis and other chronic conditions [44, 45]. Second, the outcome of “not currently employed” relates to a long-standing absence from the workforce of a year or more. This means this study does not capture short time sickness absence from the workforce, and thus underestimates the impact of chronic conditions on work loss. Third, the questions about back and arthritis problems in the survey referred to chronic problems which had lasted or were expected to last six months or more. This means that acute and/or episodic back problems from which the respondent expected rapid recovery may not have been captured. This may mean that the impact of back problems on work loss may be underestimated in this study. It is feasible that the impact of back problems in particular is greater for shorter work absences . Fourth, individual with back problems and arthritis could also have other chronic conditions which could contribute to their employment status. In a study using data collected from Australians aged 45 to 64, Schofield and colleagues found that among individuals reporting back problems, increasing number of comorbid conditions reported was associated with increasing risk of being out of the labor force . When we controlled for comorbidities in a sensitivity analysis, the risks for being out of the labour force and not being currently employed associated with back problems and arthritis were attenuated in comparison to the primary analysis, but remained statistically significant [see Additional file 3]. This showed that while the number of comorbid conditions is an important predictor of employment status, the specific combination of back problems and arthritis poses a heightened risk for negative employment outcomes. Fifth, employment status was self-reported and was not validated against any formal employment records. Finally we included those who were away from work in the previous week in the in the labor force category. If some of these absences were due to back problems, arthritis, or other chronic conditions we may have underestimated the impact of these conditions on labor force participation.