335symptoms severity domain correlated signifi cantly with the functional ability score,
indicating more functional impairment as pain is increased [ 36 ]. Moreover, the
mean baseline symptoms severity and functional status scores were reported to be
signifi cantly higher for patients who later (1 year follow-up) had carpal tunnel
decompression, indicating strong predictive validity. In concordance, responsive-
ness has been demonstrated for both dimension of the BCTQ after carpal tunnel
release surgery [ 23 ]. In another study [ 37 ], both symptom severity and functional
status domains of the BCTQ were found to be 2–4 times more responsive to clinical
improvement than measures of neuromuscular impairment.
However, the questionnaire was criticized for two main points. The fi rst one
(bearing in mind the questionnaire was developed in 1993) is that, whilst the func-
tional status scale covers activities usually performed by a broad range of CTS
patients, it does not include other items of relevance to specifi c groups such as
workers or computer/gadget-related activities, which have been recently reported as
the commonest causes for CTS symptoms. Secondly, Atroshi et al. [ 38 ] reported
that the BCTQ scales were initially developed without assessing the questionnaire
item structure such as for factor analysis. This was supported by the results of a
study [ 39 ] investigating the symptom severity and functional status scales using
modern measurement methodology in a stepwise process. Results revealed that four
items did not fi t well in the symptom severity scale whereas it was possible to merge
two other items in that scale.
The Modifi ed Boston Carpal Tunnel Questionnaire
The modifi ed BCTQ was developed in 2006 aiming at enclosure of the missing
items relevant to specifi c groups such as workers or computer/gadget-related activi-
ties [ 40 ] (Appendix 1). It was developed specifi cally to assess functional ability in
CTS patients. Two questions were added to the original BCTQ [ 31 ] that represent
the current most common forms of repetitive stress injury (computer work/typing
and driving). The questionnaire contains ten items that rate the degree of functional
ability on a 5-point scale. The fi nal score (sum of individual scores divided by num-
ber of items) ranges from 1 to 5, with a higher score indicating greater disability.
The modifi ed BCTQ can be self-, interview-, or telephone-administered.
The modifi ed questionnaire was tested in the original study [ 40 ] for internal con-
sistency, reliability, and construct validity by correlating the yield of the question-
naire with other disease testings, namely the Boston carpal tunnel severity
self-administered questionnaire, nerve conduction study, and ultrasonography of
the carpal tunnel fi ndings. Appropriateness of the two added items was evaluated by
principal component analysis in comparison to the correlation of the other eight
items with the principal component. Test–retest analysis showed strong reliability
with high percentage of agreement and high rates for kappa (0.94–0.981). Internal
consistency showed a high value for standardized alpha (Cronbach) 0.973. The
modifi ed questionnaire has shown a strong validity on correlating its results with
13 PROMs for Carpal Tunnel Syndrome