QoL factors grouped in the vitality category correspond to ‘alertness’ (slow in responses, Q2), ‘energy’ (Q7), ‘motivation’ (Q8) factors of the additional QoL questionnaire, and the ‘feeling tired’ symptom factor (Q11) from the WURSS-21 questionnaire. The score range of the vitality category was calculated by adding the maximum score for each factor resulting in a range of 0–28, where higher scores indicate higher severity.