No validated scales exist specifically for measuring quality of life (QoL)

and functioning level in patients with thoracic outlet syndrome (TOS). This

cross-sectional survey examined whether some items adopted from validated

quality of life scales could be suitable for patients with TOS. To find an optimal

Thoracic Outlet Syndrome Index (TOSI), a panel of 14 specialists experienced

in treating TOS evaluated independently the relevance of 19 items adopted

from scales used in other upper extremity syndromes. After their undergoing

surgery for TOS, 52 patients rated the relevance of those items found by experts

to be relevant. Content validity was measured by a content validity index, a

content validity ratio, and a modified kappa. The internal consistency of 15

retained items was assessed with Cronbach`s α and its construct validity by an

exploratory factor analysis. Of the 19 items, 15 were considered relevant for TOS

by the panelists with an overall test CVI (S-CVI) of 0.93. The internal consistency

of these 15 items was excellent. The exploratory factor analysis accompanied

by a parallel analysis confirmed the uni-dimensionality of TOSI. All our 15 items

that the panelists considered relevant were also ones that the patients marked

with scores over 7 on an 11-point scale of relevancy. The internally consistent,

face and content valid TOSI scale is proposed for use in evaluating specifically the QoL in TOS as well as to improve future longitudinal studies comparing

functioning before and after interventions or spontaneous recovery of TOS