Table 3.

Item to total correlations and Cronbach’s alpha for the CHQ scale

Scale/Items	Corrected item to total correlation	Cronbach’s alpha
Restriction of ADL		0.91
Avoided leaving the house	0.67
Avoided making plans due to unpredictability of CH e.g., holidays	0.66
Felt unable to complete duties at work	0.70
Had difficulty in getting involved in leisure activities e.g., cinema, theatre, etc.?	0.78
Avoided crowded and noisy places e.g., public transport, pubs, etc.	0.63
Felt that the severity of cluster headache affected your daily activities	0.68
Been less involved in family affairs eg interaction with children,planning holidays	0.67
Been unable to socialise/spend time with friends and family	0.73
Been unable to achieve your daily goals and carry out routines and chores	0.69
Impact on mood and interpersonal relationships		0.90
Felt less respected by others	0.72
Had problems with close personal relationship	0.71
Felt you were a burden on family and friends	0.73
Felt self-conscious and uncomfortable about your appearance after a cluster headache attack (eg swelling/redness of eyes and facial sweating, etc.)	0.65
Felt that others are dismissive of your cluster headaches	0.50
Felt aggressive	0.59
Felt bad about yourself, lost self-confidence or felt worthless	0.63
Felt like harming yourself or suicidal	0.59
Been irritable, impatient or less tolerant	0.63
Been forgetful e.g., missed appointments	0.58
Been unable to take care of your appearance (eg take a bath, put make-up on, change clothes etc.)	0.55
Felt isolated, lonely or vulnerable	0.71
Pain and anxiety		0.52
Found your pain is unbearable if untreated	0.37
Dreaded that the headache would not go away	0.37
Lack of vitality		0.85
Felt lacking in energy and constantly tired	0.69
Felt sleepy, worn out or less able to concentrate due to nocturnal attacks of CH	0.61
Had problems concentrating e.g., reading paper, watching TV, etc.	0.64
Been unable to think clearly	0.70
Felt tense or anxious	0.66