Distress in the previous 4 weeks was measured using the distress screener (three items scored on a three-point scale), which is based on a four-dimensional symptom questionnaire (4DSQ) [14, 30]. This is a self-rating questionnaire and is used as a convenient tool to assess common psychosocial symptoms. An example of a question is ‘Have you recently felt tense?’. Possible answers are no (0 points), sometimes (1 point), regularly (2 points) or (very) often (2 points). The 4DSQ, has been validated in several populations and languages including English, French and Spanish (internal consistency: 0.6–0.7; test–retest coefficients: ≥0.9; criterion-related validity: area under ROC curve ≥0.8) [14, 30]. A total score ranging from 0 to 6 was obtained by summing up the answers on the three items, a score of 4 or more indicating the presence of distress [14, 30].