The workers in the study had "moderate" levels of workaholism overall. Workaholics showed evidence of high job strain, with physical and mental symptoms such as digestive, memory, and sleep problems.
In turn, high strain was associated with worse job performance, thus workaholism led indirectly to decreased performance, via increased mental and physical strain. After accounting for strain, there was no direct link between workaholism and job performance.
There was a similar indirect effect on absenteeism, with high job strain leading to increased absences. But this was partly offset by a negative direct effect- perhaps reflecting workaholics' reluctance to miss any work time, even when ill. Since the direct effect was stronger, workaholics tended to have fewer absences, on balance.
The study is published in Journal of Occupational and Environmental Medicine.