Researchers have identified anxiety as a more important risk factor in long-term sick leave than previously thought.
Common mental disorders such as anxiety and depression will affect 1 of 3 of us at some point in our lives. The core symptoms of mental disorders affect a person’s emotional, cognitive and social functioning, which can impact on working ability.
Previous studies have found a link between mental disorders and sick leave, though they have been uncertain as to whether mental disorder increases the risk of sick leave, or the other way around.
Prolonged absence from the workplace can contribute to avoidance behaviour, especially in those with anxiety, which can make it even harder for these individuals to get fully back to work.
It is therefore important to examine the long-term associations between common mental disorders and sick leave in order to help plan more effective interventions aimed to prevent and reduce sick leave among individuals with common mental disorders.
This study by researchers at the Norwegian Institute of Public Health, in collaboration with Australian and British institutes examined anxiety and depression levels among 13 436 participants in the Hordaland Health Study. Common mental disorders were assessed at the start of the study with the Hospital Anxiety and Depression Scale.
Participants were then followed for up to 6 years, retrieving information on sick leave of 16 days or more from the official Norwegian registry over state paid sick leave benefits. Information on other possible causal factors such as socioeconomic status and physical health was also obtained from the health study.
The study has several findings that have not been previously shown in similar studies. Firstly, it shows that common mental disorders increase the risk of very prolonged absence (over 90 days) and repeated episodes of sick leave.
Secondly, it shows that the risk of these outcomes is highest among those with both anxiety and depression simultaneously. Thirdly, the results indicate that anxiety may be more important than depression.
“Surprisingly, we found that anxiety alone is a stronger risk factor for prolonged and frequent sick leave than depression alone. Further, anxiety seems to be a relatively stable risk factor for sick leave, as we found an increased risk of sickness absence up to six years after the anxiety level was assessed,” Ann Kristin Knudsen, lead author of the study, said.
A number of risk factors can simultaneously influence long-term sick leave. In particular, pain was found to have a considerable impact on the association between common mental disorders and sick leave: adjusting for pain.
“Adjusting for pain may have given us artificially low effect sizes, since pain, anxiety and depression are closely related and may reflect the same underlying health condition,” Knudsen said.
In other words, the association between common mental disorders and sick leave may actually be stronger.