Gender and age differences in the recurrence of sickness absence due to common mental disorders

Background: Common mental disorders (CMDs) are an important cause of sickness absence and long-term work disability. Although CMDs are known to have high recurrence rates, little is known about the recurrence of sickness absence due to CMDs. The aim of this study was to investigate the recurrence of sickness absence due to CMDs, including distress, adjustment disorders, depressive disorders and anxiety disorders, according to age, in male and female employees in the Netherlands. Methods: Data on sickness absence episodes due to CMDs were obtained for 137,172 employees working in the Dutch Post and Telecommunication companies between 2001 and 2007. The incidence density (ID) and recurrence density (RD) of sickness absence due to CMDs was calculated per 1000 person-years in men and women in the age-groups of < 35 years, 35-44 years, 45-54 years, and ≥ 55 years. Results: The ID of one episode of CMDs sickness absence was 25.0 per 1000 person-years, and the RD was 76.7 per 1000 person-years. Sickness absence due to psychiatric disorders (anxiety and depression) does not have a higher recurrence density of sickness absence due to any CMDs as compared to stress-related disorders (distress and adjustment disorders): 81.6 versus 76.0 per 1000 person-years. The ID of sickness absence due to CMDs was higher in women than in men, but the RD was similar. Recurrences were more frequent in women < 35 years and in women between 35 and 44 years of age. We observed no differences between age groups in men. Recurrences among employees with recurrent episodes occurred within 3 years in 90% of cases and the median time-to-onset of recurrence was 11 (10-13) months in men and 10 (9-12) months in women. Conclusions: Employees who have been absent from work due to CMDs are at increased risk of recurrent sickness absence due to CMDs and should be monitored after they return to work. The RD was similar in men and in women. In women < 45 years the RD was higher than in women ≥ 45 years. In men no age differences were observed. Background Mental disorders are common in the general population, particularly among women between 25 and 45 years of age [1-4], and there is a high risk of recurrence. For depressive disorders, recurrences have been reported in 50-85% of patients, and very few demographic or clinical characteristics have been found to predict a recurrence after recovery from a major depressive disorder [5,6]. Recently, it has been reported that the more recurrences of depressive episodes, the higher the likelihood of a subsequent episode [7]. Depressive episodes remit but may leave psychological scars, such as negative cognitive patterns which were not present prior to the episode [8]. Such cognitive scars can also be caused by anxiety disorders, and may contribute to the recurrence of mental disorders [9-11]. Patients with two or more lifetime episodes of mental disorders, are at risk for long-term pharmacotherapy, especially if they have comorbid disorders, report psychosocial stressors, poor symptom * Correspondence: petra.koopmans@arboned.nl ArboNed Occupational Health Services, Statistics, Groningen, The Netherlands Koopmans et al. BMC Public Health 2010, 10:426 http://www.biomedcentral.com/1471-2458/10/426 © 2010 Koopmans et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. control, or severe symptoms [12]. Despite pharmacotherapy, a chronic clinical course with low rates of recovery and a high probability of recurrence is found in the majority of patients suffering from anxiety disorders [13,14]. Common mental disorders (CMDs) include criteriabased psychiatric disorders, mostly mild to moderate depressive disorders and anxiety disorders, as well as ‘subtreshhold’syndromes such as distress and adjustment disorders. CMDs are the second most frequent cause of sickness absence after musculoskeletal disorders [15-19]. In Scandinavian countries, the incidence of sickness absence due to CMDs is increasing when compared to sickness absence due to other diagnoses [17,18]. In the Netherlands a quadratic trend was observed: the 12month incidence of sickness absence due to CMDs was 2.2% in 2001, increased to 2.7% in 2004 and decreased thereafter to 2.0% in 2007 [19]. Sickness absence due to CMDs has been associated with long-term work disability resulting in high social and economic costs [20-25]. Research on sickness absence among employees with psychiatric diagnoses has focused on the duration of the episodes of sickness absence and the risk of a disability pension. Vaez et al. found that 65% of those who returned to work after being absent due to mental disorders had high levels of all cause sickness absence in the following three years [21]. We assume that there is a high risk of recurrent sickness absence due to CMDs in employees who have returned to work after a previous episode of absence due to CMDs. Although mental disorders are known to have high recurrence rates [5,6,14], the recurrence of sickness absence due to CMDs by gender and age has not been investigated yet. With regard to gender and sickness absence due to mental disorders contradictory findings are reported [26]. Women show higher sickness absence and are more frequently sick-listed due to mental disorders than men [27]. Although mental disorders are more common among women, sickness absence seems to be longer among male employees with mental disorders than among female employees with mental disorders [28,29]. However, Koopmans et al. [30] found a longer duration of absence due to depression in women than in men. Men and women had an equal duration until return to work (RTW), but women did report a longer time until lasting return to work than men after a long-term absence due to mental disorders [31]. Lasting return to work was defined as return to work without recurrence during the period in which the study was conducted. In the Netherlands the incidence of CMDs is higher in people aged 18-45 years than in those older than 45 years [2,32-34]. In the present study, the recurrence of sickness absence due to CMD will be examined, thereby stratifying by gender and age. In addition, the time-to-onset of recurrent episodes of sickness absence due to CMDs will be investigated. We hypothesize that the risk of recurrent sickness absence due to CMDs increases after a previous episode of sickness absence due to CMDs. We further hypothesize that women and employees < 45 years have a higher risk of recurrence than men and employees > 45 years.