General population normative data from seven European countries for the K10 and K6 scales for psychological distress

The 10-item Kessler Psychological Distress scale (K10) and its 6-item short-form version (K6) measure psychological distress, particularly anxiety or depressive symptoms. While these questionnaire scales are widely used in various settings and populations, general population normative data are rarely available. To facilitate the interpretation of K10 and K6 scores, we provide normative general population data from seven European countries. We used an online survey to collect K10 data from general population samples in Austria, Italy, Germany, France, the Netherlands, Poland and Spain. We calculated the age- and sex-specific normative values separately for each country. For more specific estimates of K10 and K6 scores for individuals or groups, we also established a multivariable regression model based on socio-demographic and health data. In total, N=7,087 adults participated in our study (51.6% women; mean age, 49.6 years). The mean K10 score in the total sample was 8.5 points (standard deviation, 7.3) on 0-40 points metric, with mean scores in individual countries ranging from 6.9 (the Netherlands) to 9.9 (Spain). Women showed higher scores than men and younger participants scored higher than older participants. Our study is the first to present normative K10 and K6 data from several European countries using a consistent sampling approach. These reference values will facilitate the interpretation of K10 and K6 scores in clinical research and practice and also highlight the variation in psychological distress levels across countries and groups according to their socio-demographic and health characteristics.