Chronic headache(s), characterized by recurrent headaches, and including migraine, tension headache, and cluster headache, are among the most common disorders of the nervous system . Globally, the prevalence of chronic headache(s) has been estimated at 46% for headache in general, 11% for migraine, 42% for tension-type headache, and 3% for chronic daily headache . Where studies have often focused on migraine, other types of headaches have received less attention . Chronic headache(s) are most prevalent in the age group 18–50, and as such affect the working population .
Concerning the impact of headache on work, headaches have been associated with various indicators of reduced work ability. In a population-based study in Sweden, frequent headache was associated with poor mental and physical work ability, but unrelated to sickness absence . In other studies headaches have been shown to relate to both higher absenteeism and reduced productivity at work [2, 5]. Migraine, as a specific headache disorder, was responsible for an average loss of 4.6 h of work productivity per week . A review study on the impact of migraine on work productivity in the United States estimated that an employee with migraine loses on average four workdays per year due to headaches . Illustrative of the high impact of chronic headache(s) were the findings of The Global Burden of Disease Study  identifying chronic headache(s) third among the worldwide causes of disability, measured in years of life lost to disability.
Given the reduced work ability in employees with chronic headache(s), it is important to determine in which way work ability in these employees can be optimized. The current study examined the relationship between psychosocial job characteristics and work ability indicators in a sample of employees with chronic headaches, in order to identify those job characteristics that could be targeted to improve and maintain work ability in these employees.
The psychosocial characteristics of a job have been widely studied as determinants of employees’ job related well-being and functioning [9,10,11]. Two of the main models in this regard, the Job Demands–Control–Support (JDCS) model and the Job Demands–Resources (JDR) model, discern two types of job characteristics [12,13,14,15]. The first type includes the job demands, which are considered to exert their influence on well-being and functioning through an energy depleting pathway. Job demands include the quantitative, emotional, and cognitive demands the job poses on the employee. The second type of job characteristics includes the job resources, which are expected to have a positive effect on functioning through a motivational pathway . Job resources are positive job aspects that are functional in achieving work goals, reduce job demands and the associated costs, and stimulate personal growth, learning, and development. The resources most commonly studied are autonomy, and social support from colleagues and supervisor. Research has related job demands and job resources to various indicators of work ability (see e.g., ). High job resources were associated with high employability , high engagement, and low burnout . In contrast, high demands impeded work ability , and were related to burnout and low engagement . In a longitudinal study, Airila et al.  found high job resources to be predictive for work engagement and future work ability. Furthermore, changes in job demands and resources have shown to have an impact on burnout, work engagement, and sickness absenteeism .
The current study examined whether job demands are negatively, and job resources are positively associated with indicators of work ability in employees with chronic headaches as is proposed in the JDR model. The following outcomes were included as indicators of work ability: emotional exhaustion, work engagement, employability, and sick leave.
In employees with chronic headaches, higher (quantitative, emotional, and cognitive) job demands are associated with reduced work ability.
In employees with chronic headaches, higher job resources (i.e. autonomy, and social support from supervisor and colleagues) are associated with higher work ability.
Furthermore, it was examined whether these associations are stronger for employees with chronic headaches than for employees without a chronic condition. Limited research has thus far addressed this issue. A cross-sectional study on university employees analyzing relationships between job characteristics and fatigue, exhaustion, and health complaints found overall comparable relationships for employees with and without chronic disease . Only unpleasant treatment (i.e. experiencing discrimination) proved to be a stronger correlate of outcomes for the employees with chronic disease, and there were indications that social support from superiors was a more important resource for employees with chronic disease. The latter is in line with the findings from a study on employees with diverse chronic illnesses .
Focusing on employees with chronic headaches, we expected that high job demands have a stronger impact on their work ability, as their (working) capacity is already taxed by their health status. Furthermore, one would expect high job demands to contribute to the severity and frequency of headache episodes. Longitudinal research has found a strong association between experienced stress and the frequency and intensity of tension headache , and there is also, though more limited, evidence linking migraine to stress . More specific for work-related stress, Christensen and Knardahl found higher quantitative demands, higher role conflict, and low job control to be prospectively related to more severe headache at follow-up .
On the other hand, we expected employees with chronic headache to benefit more from the job resources autonomy and social support than employees without chronic conditions do. High levels of autonomy would enable employees to adapt their work schedule and workload to their condition on a daily basis. Job control furthermore has been shown to act as a buffer in the association between decreased work ability and productivity loss . We expected social support from supervisor and colleagues to be a more valuable resource for employees with chronic headache, providing them with understanding and support in periods of reduced capacity due to recurrent headaches. The importance of a good social climate for work ability of chronically ill employees has been well documented [23, 24, 29].
Quantitative, emotional, and cognitive job demands will be more strongly negatively associated with work ability in employees with chronic headaches than in employees without a chronic condition.
Job resources (autonomy and social support) will be more strongly positively associated with work ability in employees with chronic headaches than in employees without a chronic condition.
Summarizing, the current study examined in a representative sample of employees with chronic headache which psychosocial job characteristics predicted work ability, and determined whether the work ability in this group was more hampered by job demands and more enhanced by job resources in comparison to employees without chronic condition. The results of this study indicate whether it would be a fruitful avenue to focus on enhancing (specific) job characteristics in order to improve work ability in employees with chronic headaches.