Definition of Nonresponse to Analgesic Treatment of Arthritic Pain: An Analytical Literature Review of the Smallest Detectable Difference, the Minimal Detectable Change, and the Minimal Clinically Important Difference on the Pain Visual Analog Scale

Table 2

Minimal clinically important difference on the 0–100 mm pain VAS.

Study	Patients	Anchor			MCID
		Type	Points	Responses	Definition	Points on anchor scale	Units on VAS^a
Pope et al. 2009 [24]	RA	PGA	5	Much worsened, somewhat worsened, same, somewhat improved, much improved	Difference between “same” and “somewhat improved or somewhat worsened”	±1 point	−11.9, +6.8
Tubach et al. 2005 [30]	OA	PGA	5	None, poor, fair, good, excellent	Difference between “none” and “good” response	+3 points	−19.9 (knee); −15.3 (hip)
Hägg et al. 2003 [18]	Back pain	PGA	4	Worse, unchanged, better, much better	Difference between “unchanged’ and “better” or “worse”	±1 point	−18, +8
Ehrich et al. 2000 [26]	OA	PGA	5	None, poor, fair, good, excellent	Difference between “none” and “poor” response on the PGA^b	+1 point	−11.1

MCID; minimal clinically important difference; PGA: patient global assessment of response.
^aNegative values indicate improvement, and positive ones indicate deterioration.
^bDefined as minimal perceptible clinical improvement.