There were several significant differences in the socioeconomic characteristics of farmers and nonfarmers with CBD (Table 2). Farmers with back pain were significantly older than nonfarmers with back pain, a difference that persisted after adjusting for confounders (65+ age group OR 4.01, 95% CI = 1.92-8.35; Table 4). This may indicate that the inverted-U-shaped effect of age on back disorders is shifted among farmers. Although increasing age has been linked with remission of back pain in the general population, it may be that in farming occupations, older age is no longer associated with a protective effect. This may also be a reflection that the agricultural workforce is older and aging. In the United States, the average age of farmers increased from 54 to 57 years between 1997 and 2007. Similar trends are seen in Canada, with the proportion of farmers over 55 increasing from 32% in 1991 to 48% in 2011. Farmers also continue to work beyond typical retirement age, extending their exposure to occupational hazards.[14, 39] The trend of increasing farmer age has implications for health care planning for CBD in this group, as well as being informative for clinicians who may otherwise anticipate fewer work hours, less exposure to occupational risk factors, and a protective effect of age among older individuals.
A far larger proportion of the farmer CBD group is male than nonfarmers with CBD (OR 1.87, 95% CI = 1.23-2.83; Table 4). In general, back disorders are more common in women than in men.40,41 Farming is male-dominated; surveys show most of those doing full- and part-time farm work are male.[15, 42] Gender may have an impact on how health promotion materials are designed and disseminated, as well as health policies, service provision and health care utilization. Women are more likely than men to use health care for back pain, take more sick days from work, have a poor outcome after a single episode of low back pain, and develop persistent, chronic pain lasting more than 3 months. Being married has been found to increase the odds of low back pain, but after adjusting for confounders there were no significant differences in marital status between farmers and nonfarmers with CBD.
Nonfarmers with CBD were more likely to have some or completed postsecondary graduation than were farmers, although only the latter difference remained after adjusting for confounders (OR 0.49; 95% CI = 0.28-0.85; Table 4). As farming is a “blue-collar” occupation, one might expect a difference when compared with a mixed occupational group. Like many “blue-collar” occupations, farming is potentially hazardous and associated with several physical and psychosocial risk factors that can be associated with CBD. Among the many physical hazards are lifting and carrying heavy loads,[15, 18] working with the trunk in flexed or awkward positions,[15, 18, 20, 21] high work pace and workload, exposure to WBV from farm vehicles,[18, 19] risk of trips and falls on slippery and uneven ground, accidents caused by the sudden unpredictable actions of livestock, or motor vehicle accidents. Low educational attainment has been shown to be related to increased odds of low back pain, suggesting it may be acting as a surrogate measure of the physical exposures of these occupations. Although the reasons for a disparity in education may be intuitive, more important are the implications this has for outreach and health promotion in this group. Adjustment for confounders aside, it is important to consider the communication needs and socio-cultural context of a less-educated target audience whenever prevention or rehabilitation information is disseminated.
Although 28.5% of farmers in this study resided in cities or strongly influenced areas, farmers were far more likely to live in rural areas (ie, those areas with moderate or weak MIZ), even after adjusting for confounders (weak MIZ OR 8.89, 95% CI = 6.93-23.86; Table 4). It is not surprising that an occupation which in most cases requires access to arable or pastureland would be more often located in rural areas. Rural residence has been found to be associated with back pain, and regardless of farming occupation, rural people may have decreased access to health care services to help them cope with back pain and return to productivity. It may be more difficult to access health services, there may be less preventive information available in a self-employment situation, and it may be harder to get preventive or early stage care, although a study using CCHS data found this was not the case for mental health services. A study of dementia care reported that those in rural areas travel up to 500 km round-trip for diagnostic services, resulting in substantial costs once the time and expense of food, travel, and overnight accommodations for patients and accompanying family members are taken into account. The issue of rurality has important implications for interpretation of CBD prevalence and appropriate strategies for prevention. Clearly, rural residence is also an important consideration for health services planning and should be the subject of future research on CBD.
Back disorders have been found to be more common among Caucasians than individuals of African descent, and they are associated with smoking41,48 and obesity.[36, 41, 48] However, smoking, BMI, and ethnicity were not found to be significantly different between farmers and nonfarmers in this study (Table 4).
The presence of other chronic health conditions is common among people with CBD. These other co-morbidities are important to consider within the CBD population as it may signal additional health care needs of individuals with CBD and may represent clusters of symptoms that could or should be addressed in tandem, particularly for folks with time or geographical barriers to health care access. However, there were few significant differences between farmers and nonfarmers with respect to health status (Table 3). Farmers were more likely than nonfarmers to also have arthritis, and they were less likely than nonfarmers to report also having migraine headaches, although neither of these relationships persisted after adjusting for potential confounders such as age, sex, area of residence, and education. There were also no significant differences between farmers and nonfarmers with respect to the number of co-morbidities, high blood pressure, asthma, mood disorders, depression, self-rated stress, self-rated mental health, and self-rated work stress (Table 4). Mental health status has been shown to be closely linked to back pain; the presence of anxiety, and depression predict both disability and number of health care contacts. Symptom remission is less likely among those with depressive symptoms or low self-rated health. Anxiety, depression, somatisation symptoms, stressful responsibility, and mental stress at work are related to higher risk of back disorders, with mixed results for high work pace, high job demands, and low job control. Farmers in particular have been found previously to have increased depression and job stress as a risk factor for low back disorders. Although mental and emotional sequelae have been shown to be important in treating low back disorders and returning patients to function, the results of this study do not suggest a disproportionate coincidence of mental health issues in famers with CBD.
Self-rated pain and function are related to the ability to participate in activities of daily living and fulfill one's goals. The degree of “disability” depends on the demands one is asked to fulfill.52,53 Productivity loss is similar in that the degree of disability is related to the demands of the job; for example, clerical work may be possible to perform with back pain, whereas heavy lifting may not. A differential in work ability could have a severe impact on a farmer's economic status; farm income is lower when operators have musculoskeletal-related disability. A survey of Iowa farmers showed they had double the risk of low back pain as compared to the general working population, and they were 8 times more likely to make major changes in their work activities as a result of low back pain. Despite an anticipated differential, there were no statistically significant differences between farmers and nonfarmers with CBD with respect to self-rated overall health, pain and function index, and loss of productivity (Table 4).
Strengths and Limitations
The CCHS dataset is a nationally representative sample of Canadians, allowing us to complete the first study known to the authors that investigates CBD and includes a Canada-wide population of farmers. Careful survey design, large sample size, and postweighting based on Census and other Statistics Canada data ensure the survey is representative of the target population. The CCHS is representative of approximately 98% of the Canadian population 12 years or older; exclusions include persons living on reserves and other aboriginal settlements, or in institutions.
This study also includes a broad range of sociodemographic and other health factors, which are not available in most studies of back disorders. The CCHS also experienced a relatively high participation rate, which has become rare in population-based studies in recent years. This reduces the potential bias and improves the generalizability of results.
However, there are some limitations. As a broad health survey, information on all possible confounders, occupational exposures, and the nature of back pain itself was not available in the CCHS. Farming status is determined through open-ended questions with follow-ups by the surveyor to determine the specific occupational code. However, no specific definitions are given in the CCHS question guidebook, so respondents are left to interpret the term “farmer” as a representation of a heterogeneous occupational group spanning many different commodities, cultivation methods, work tasks, activities, and occupational exposures. Similarly, the survey section on chronic disorders directs respondents thus: “We are interested in ‘long-term conditions’ which are expected to last or have already lasted 6 months or more and that have been diagnosed be a health professional.” Although back pain is often associated with episodic and recurrent manifestations, a consistent definition is problematic; it is not clear what the case definition should be54 as there are no definitive diagnostic tests and most patients have few objective physical findings.[1, 5]