Table 5.

Differential item functioning of the Romanian ThyPRO (85-item) questionnaire

Abbreviated items wording	Significance of DIF	Variance explained by DIF	Direction of DIF
Goitre Symptoms scale
Visible swelling in front of neck	<0.0001	2.9%	Romanian patients report more visible swelling
Sense of suffocating	<0.0001	2.9%	Romanian patients report less sense of suffocating
Hyperthyroid Symptoms scale
Increased appetite*	0.0004	2.1%	Romanian patients report more appetite with few hyperthyroid symptoms but less increased appetite with more hyperthyroid symptoms
Anxiety scale
Nervous*	0.0006	2.0%	Romanian patients report more nervousness, mostly at low levels of anxiety
Depressivity scale
Happy*	<0.0001	11.3%	Romanian patients report being more happy at low level of depressivity and less happy at high levels of depressivity; i.e. they have a more exaggerated response
Self confident*	<0.0001	9.9%	Romanian patients report being more self-confident at low levels of Depressivity and less self-confidence at high levels of Depressivity; i.e. they have a more exaggerated response
Emotional Susceptibility
In control*	<0.0001	13.1%	Romanian patients report being more in control at low levels of emotional susceptibility and less in control at high levels of emotional susceptibility; i.e. they have a more exaggerated response
In balance*	<0.0001	14.5%	Romanian patients report being more in balance at low levels of emotional susceptibility and less in balance at high levels of emotional susceptibility; i.e. they have a more exaggerated response
Impaired Daily Life
Difficult getting around	<0.0001	2.4%	Romanian patients report greater difficulty getting around

^*Non-uniform DIF.