Reliability and Factor Structure of the 10-item Kessler Psychological Distress Scale (K10) among Portuguese adults.

The 10-item Kessler Psychological Distress Scale (K10) has been presented as a valid measure to assess psychological distress levels in population surveys but its dimensional structure was not consensual. Our main objective was to provide a Portuguese version of the K10 exploring the reliability and factor structure of this measure. This cross-sectional study included 694 adults collected from a web-based survey and in training entities. Results showed that 37.9% of the individuals reported significant distress symptoms. A good internal consistency of the K10 scale (α=.91) and strong inter-item correlation (ranges from .350 to .659) were found in our study but the original one-dimensional structure was not confirmed. A two-factor model considering anxiety and depression as two latent, independent but correlated factors shows a good fit with the data even across two data collection methods. The K10 tool was sensitive to sociodemographic variables. Participants aged 40 or over and belonging to the general working class presented higher distress levels. Our data indicates the Portuguese version of K10 as a reliable tool with a factor structure to assess psychological distress.