Assessing pain and pain-related fear in acute low back pain: what is the smallest detectable change?
BACKGROUND
The Tampa Scale for Kinesiophobia (TSK) and the Fear-Avoidance Beliefs Questionnaire (FABQ) are frequently used questionnaires for pain-related fear, and the visual analogue scale (VAS) is for pain.


OBJECTIVE
This study aims to determine the smallest detectable change (SDC) of these questionnaires in patients with acute low back pain (LBP), as well as ceiling and/or floor effects.


RESULTS
The SDC for the TSK (scoring range: 17-68) was 9.2 (95% CI: 8.4; 10.3). The estimated SDC was 9.4 (95% CI: 8.5; 10.6) and 12.7 (95% CI: 11.5; 14.1) for the FABQ physical activity subscale (scoring range: 0-24) and/or work subscale (scoring range: 0-42), respectively. For the VAS for pain (0-100 mm), the SDC turned out to be 36.2 mm (95% CI: 32.4; 41.0). The FABQ physical activity subscale and pain (VAS) seem to have considerable problems in detecting improvement and deterioration. The TSK appears to be able to detect improvement as well as deterioration.


CONCLUSIONS
The SDCs of the (subscales of) questionnaires range from 18% to 40%. Floor and/or ceiling effects were detected for most scales, except the TSK total and the TSK activity avoidance subscale. These results should be considered when using these questionnaires as measures of therapeutic change in acute LBP.
Ostelo
Raymond W J G
RW
Institute for Research in Extramural Medicine (EMGO Institute), VU University Medical Center, Amsterdam, The Netherlands. r.ostelo@vumc.nl
Swinkels-Meewisse
Ilse J C M
IJ
Knol
Dirk L
DL
Vlaeyen
Johan W S
JW
de Vet
Henrica C W
HC
D000208:Acute Disease; D000328:Adult; D004056:Differential Threshold; D005239:Fear / Q000523:psychology*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000150:complications / Q000523:psychology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010147:Pain Measurement / Q000379:methods*; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric