Table 3.

Reliability of unidimensional pain assessment tools in surgical patients. ∗Average interclass correlation coefficient calculated for 7 days. ^†No separate result for each scale. ^‡Results categorised in 20–44 yr (n=43), 45–59 yr (n=39), 60 yr without cognitive impairment (n=40), ≤60 yr with mild cognitive impairment (n=31). ^¶95% confidence interval. FPS, faces pain scale; n, number of patients; NRS, numerical rating scale; PROM/s, patient-reported outcome measures; SD, standard deviation; VAS, visual analogue scale; VDS, verbal descriptor scale.

First author, year	PROM/s	Pain construct	Reliability
			Type	n	Time interval	Interclass correlation coefficient
Li, 200747	VAS NRS VDS FPS	Current, worst, least, average pain on 7 postoperative days	Scale reliability	173	Every 24 h	0.66∗ 0.76∗ 0.72∗ 0.72∗
Li, 200946	FPS NRS Iowa Pain Thermometer	Current pain and daily retrospective ratings of worst and least pain	Scale reliability	180	Every 24 h	0.95 to 0.97†
Zhou, 201156	VDS NRS FPS Numeric Box-21 Scale Coloured Analogue Scale	Recalled pain and postoperative pain	Test–retest reliability	153	24 h	0.96, 0.88, 0.93, 0.84‡ 0.94, 0.90, 0.91, 0.80‡ 0.93, 0.91, 0.84, 0.80‡ 0.92, 0.91, 0.78, 0.76‡ 0.93, 0.90, 0.88, 0.77¶
Aziato, 201533	NRS FPS Colour Circle Pain Scale	No pain – worst possible pain No pain – worst possible pain No pain – unbearable	Inter-rater reliability	150	5–10 min	0.92 0.93 0.93
Myles, 201748	VAS	Pain unchanged or almost the same	Test–retest reliability	22	Not reported	0.79 (0.49–0.91)¶