Psychometric Properties of the Pain Numeric Rating Scale When Applied to Multiple Body Regions among Professional Musicians.
BACKGROUND
Despite the broad popularity of a numeric rating scale (NRS) its psychometric properties are not well known. The objective was to determine if there is any difference in the discrimination ability of the NRS when used for measuring pain severity separately in different body regions.


METHODS
Cross-sectional survey study of 630 professional musicians. Item Response Theory (IRT) was used to define the psychometric properties of the NRS.


RESULTS
The discrimination ability of the pain NRS was dependent on the body area to which it was applied. The discrimination was low 0.5 (95% CI 0.4. to 0.7) for the hand region and perfect for the shoulder and upper part of the neck- 3.2 (95% CI 1.2 to 5.2) and 10.5 (95% CI 10.0 to 10.9), respectively. Both shoulder and neck NRSs showed a great shift towards higher levels of pain severity meaning that the ability of the NRS to discriminate low levels of pain is poor. NRS scores obtained from all other regions did not demonstrate any discrimination ability.


CONCLUSIONS
The pain NRS might have different psychometric properties depending on the body area to which it is applied. Overall, the modest discrimination ability of the pain NRS implies that it should be used in screening questionnaires with some reservations.
Department of Physical and Rehabilitation Medicine, Turku University Hospital, Turku, Finland, and University of Turku, Turku, Finland.
Mikhail
M
Saltychev
Orton Research Institute, Orton Foundation, Helsinki, Finland.
Heidi
H
Vastamäki
Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, Stanford University Hospital & Clinics, Stanford, California, United States of America.
Ryan
R
Mattie
The Rehabilitation Institute of Chicago/Northwestern McGaw Medical Center, Department of Physical Medicine and Rehabilitation, Chicago, Illinois, United States of America.
Zachary
Z
McCormick
Orton Research Institute, Orton Foundation, Helsinki, Finland.
Martti
M
Vastamäki
Department of Physical and Rehabilitation Medicine, Turku University Hospital, Turku, Finland, and University of Turku, Turku, Finland.
Katri
K
Laimi
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007568:Jaw / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009146:Music / Q000523:psychology*; D063806:Myalgia / Q000503:physiopathology* / Q000523:psychology; D010146:Pain / Q000503:physiopathology / Q000523:psychology*; D010147:Pain Measurement; D011594:Psychometrics; D012782:Shoulder / Q000503:physiopathology; D011795:Surveys and Questionnaires