Self-assessment using 30-second chair stand test for patients with knee osteoarthritis – an intra- and inter-rater reliability study

Figures & data

Table 1. Reference values for 30 s chair stand test [35,36].

	Age groups^a
Sex	20–59	60–64	65–69	70–74	75–79	80–84	85–89	90–94
Women	22.6	13.8	13.7	12.8	12.5	11.9	10.7	9.2
Men	24.2	14.8	14.0	13.0	12.9	12.4	10.1	9.4

^a Normative values based on McKay et al. for patient group 20–59 years of age. For patients above 60 years, reference values were based on Rikli et al. [35,36].

Table 2. Patient characteristics (n = 114).

	Mean (SD)^aor n (%)^b	Median [25^th to 75^th percentiles]
Age, year	69 (8.7)	70 [63–75]
Gender (females)	66 (58%)
Body Mass Index (BMI)	29 (4.6)	28 [25–31]
Healthy weight ≤24.9	23 (20%)
Overweight ≥ 25–29.9	53 (47%)
Obese ≥ 30	38 (33%)
Origin (born in Sweden)	107 (94%)
Education level
Primary school	38 (33%)
High school	43 (38%)
College/University	32 (28%)
Pain duration (months)	39 (48)	20 [7.3–60]
Number of pain sites	4.1 (3.0)	3.0 [2.0–5.0]
KOA^c diagnosis duration
0–3 months	41 (36%)
3–12 months	27 (24%)
> 12 months	45 (40%)
Other diseases
None	47 (33%)
OA^din other joints	24 (21%)
Heart disease	20 (18%)
Diabetes mellitus	20 (18%)
Rheumatic disease	6 (5.3%)
Mental illness	1 (0.9%)
Other	25 (22%)
ICOAP Knee^e (0–100)	39 (20)	38 [23–52]
Constant pain (0–20)	6.9 (4.2)	7.0 [4.0–9.0]
Intermittent pain (0–24)	10 (4.7)	11 [7.0–13]
KOOS-PS^f (0–100)	59 (14)	60 [52–66]

^a SD: Standard deviation; ^bn: number; ^cKOA: Knee Osteoarthritis; ^dOA: Osteoarthritis; ^eICOAP: Intermittent and Constant Osteoarthritis Pain. The total pain score range between 0–100, where 0 corresponds no pain and 100 extreme pain. The subscales for constant and intermittent pain ranged between 0–20 and 0–24 respectively, where 0 corresponds no pain and 20 or 24 extreme pain. ^fKOOS-PS: Knee injury and Osteoarthritis Outcome Score – Physical function Short form. Results in a score ranging between 0–100, where 0 is major difficulty and 100 no difficulties in knee related activities.

Figure 1. Flow chart of participants and analysis for intra- and inter-rater reliability of 30-second chair stand test (30CST).

Rectangular boxes connected to one another. Step one starts from the top with describing recruitment and step 2 the number of patients included in the analysis. Step 3 the assessment and the results of self-test 1, and then self-test 2 (step 4), and at last physiotherapist assessment (step 5). Step 3 and 4, respectively step 4 and 5, are connected to separate boxes to the right, showing results of the reliability analysis. A big arrow in the upper right of the image include description of excluded patients, and a white box in the lower right contains explanations of abbreviations used in the figure.

Figure 2. (a,b) Receiver operating characteristic (ROC)-curve analysis of 30-second chair stand test (30CST) to classify reduced physical function. (A) self-test 1, (B) self-test 2. Reduced physical function was categorised through normative values [35,36].

Two graphs with sensitivity on the y-axis (0 to 1) and 1-specifity on the x-axis (0 to 1). The curves start from lower left corner and ends in the upper right corner.

Rikli RE, Jones CJ. Development and validation of criterion-referenced clinically relevant fitness standards for maintaining physical independence in later years. Gerontologist. 2013;53(2):255–267. doi:10.1093/geront/gns071.

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McKay MJ, Baldwin JN, Ferreira P, et al. Reference values for developing responsive functional outcome measures across the lifespan. Neurology. 2017;88(16):1512–1519. doi:10.1212/WNL.0000000000003847.

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Data availability statement

Decoded data are available on reasonable request.