Pain pressure threshold algometry in knee osteoarthritis: intra- and inter-rater reliability

Figures & data

Table 1. Characteristics of the participants.

Gender Women Men	20 (74%) 7 (26%)
Age (min-max)	65.07 (51–79) years
Height	1.71 meter (SD = 0.085)
Unilateral knee osteoarthritis Bilateral knee osteoarthritis	4 persons 23 persons
Bony enlargement	20 knees
Most tender spot in joint line Medial side Lateral side	42 knees 8 knees
Duration of knee pain	73.01 months (SD = 99.18)
KOOS pain	56.88 (SD = 19.59)
Use of analgesics in the previous 7 days	10 persons

KOOS = Knee injury and Osteoarthritis Outcome Score; NSAIDs = Non-Steroidal Anti-Inflammatory Drugs; SD = standard deviation. The KOOS pain scores ranges from 0–100 (higher score is better).

Table 2. Intra- and inter-rater reliability results of PPT algometry in persons with KOA.

Rater	ICC (95% CI)	Mean (N)	95% CI of true value (N)	MDD (N)
Intra-rater reliability
A	0.909 (0.844–0.948)	40.16	±9.79	13.84
B	0.956 (0.924–0.975)	41.81	±6.44	9.11
C	0.914 (0.853–0.950)	39.94	±10.77	15.23
Inter-rater reliability
ABC	0.707 (0.581–0.809)	40.63	±17.68	25.01
AB	0.707 (0.537–0.822)	41.28	±16.79	23.74
AC	0.718 (0.550–0.830)	40.85	±17.91	25.33
BC	0.695 (0.520–0.815)	41.12	±18.31	25.90

CI = Confidence Interval; ICC = Intraclass Correlation Coefficient; MDD = Minimal Detectable Difference; N = Newton.

Figure 1. Level of agreement between rater A’s 2. and 3. measurements.

Note. The values are Newton. The thick horizontal solid line represents the mean difference and the dotted horizontal lines represent the 95% limits of agreement; PPT = Pain Pressure Threshold.

Figure 2. Level of agreement between rater B’s 2. and 3. measurements.

Note. The values are Newton. The thick horizontal solid line represents the mean difference and the dotted horizontal lines represent the 95% limits of agreement; PPT = Pain Pressure Threshold.

Figure 3. Level of agreement between rater C’s 2. and 3. measurements.

Note. The values are Newton. The thick horizontal solid line represents the mean difference and the dotted horizontal lines represent the 95% limits of agreement; PPT = Pain Pressure Threshold.

Figure 4. Level of agreement between rater A’s and B’s 2.-3. measurements.

Note. The values are Newton. The thick horizontal solid line represents the mean difference and the dotted horizontal lines represent the 95% limits of agreement; PPT = Pain Pressure Threshold.

Figure 5. Level of agreement between rater A’s and C’s 2.-3. measurements.

Note. The values are Newton. The thick horizontal solid line represents the mean difference and the dotted horizontal lines represent the 95% limits of agreement; PPT = Pain Pressure Threshold.

Figure 6. Level of agreement between rater B’s and C’s 2.-3. measurements.

Note. The values are Newton. The thick horizontal solid line represents the mean difference and the dotted horizontal lines represent the 95% limits of agreement; PPT = Pain Pressure Threshold.