The occupational physicians classify mental disorders according to the Dutch Guidelines for Mental Disorders (Van der Klink and van AZD2281 concentration Dijk 2003) based on the 10th International Classification of Diseases (ICD-10) as follows:

distress symptoms (ICD-10 code R45), stress-related disorders (ICD-10 code F43 including acute stress reactions and adjustment disorders), depressive disorders (ICD-10 code F32), anxiety disorders (ICD-10 code F40 and F41) and other psychiatric disorders, such as psychoses, bipolar affective disorders, and disorders caused by psychoactive substances. Although distress symptoms (R45) are not a psychiatric code, we included it in our study because it is a frequently encountered CMD in the occupational health practice. selleck compound sickness absence on the organizational level is computed as the number of calendar days of sickness absence in a year, adjusted for partial selleck chemicals return to work divided by 365 × mean number

of person-years in that year. Adjustment for partial return to work means that when an employee starts to work part-time, the number of days of sickness absence is adjusted by the percentage of work. The frequency of sickness absence is defined as the number of incident episodes of sickness absence in a year, divided by the mean number of person-years in that year. On the individual level, the recurrence density (RD) of sickness absence due to CMDs was computed by dividing the number of employees with recurrent episodes of sickness absence due to CMDs by the person-years of those with a previous episode of sickness absence due to CMDs. Employees with more than one recurrence were counted once in the nominator. The person-years at risk for RD were based on the total time of employment in the

observation period after an earlier episode of sickness Guanylate cyclase 2C absence due to CMDs. A recurrence is defined as the start of a new episode of sickness absence due to CMDs after a recovery period of at least 28 days. The 28-day interval was chosen, because in the Netherlands episodes of sickness absence with an interval of less than 28 days between them are regarded as one episode. The person-years were counted from the moment of the first absence episode due to CMDs until the end of employment, or the end of the observation period, or 1 year of sickness absence, depending on which came first. The person-years had a cutoff point after 1 year of sickness absence (irrespective of diagnosis), because an employee was granted a disability pension after 1 year of work incapacity in the Netherlands. Absence episodes were not subtracted from the person-years at risk, with the exception of absence longer than 1 year. Figure 1 shows the periods at risk for recurrence in different situations. In situation (a) there is one episode of CMD and no recurrent episode.