Table 5 Subgroup analyses of VAS for pain, WOMAC pian score and WOMAC function score in curcuminoids versus placebo group

Overall analysis

8

 − 1.94 (− 2.65, − 1.22)

86.3% (p < 0.001)

6

 − 1.94 (− 2.91, − 0.97)

79.2% (p < 0.001)

6

 − 6.36 (− 8.94, − 3.77)

79.2% (p < 0.001)

Daily dose of curcuminoids

Dose < 1,000 mg

4

 − 2.16 (− 3.45, − 0.88)

89.9% (p < 0.001)

2

 − 2.84 (− 3.46, − 2.22) ^c

0.0% (p = 0.629)

2

 − 8.74 (− 10.17, − 7.31) ^d

86.2% (p < 0.001)

Dose ≥ 1,000 mg

4

 − 1.31 (− 2.02, − 0.59)

76.1% (p = 0.006)

4

 − 1.25 (− 2.06, − 0.43)

47.2% (p = 0.128)

4

 − 4.47 (− 6.63, − 2.31)

55.3% (p = 0.135)

Total dose of curcuminoids

Dose < 50 g

4

 − 2.37 (− 3.91, − 0.83)

92.3% (p < 0.001)

2

 − 2.84 (− 3.46, − 2.22) ^c

0.0% (p = 0.629)

2

 − 8.74 (− 10.17, − 7.31) ^d

0.0% (p = 0.667)

Dose ≥ 50 g

5

 − 1.29 (− 1.91, − 0.68)

68.1% (p = 0.014)

4

 − 1.25 (− 2.06, − 0.43)

47.2% (p = 0.128)

4

 − 4.47 (− 6.63, − 2.31)

42.7% (p = 0.155)

Follow-up duration

Time < 12 weeks

4

 − 1.47 (− 2.25, − 0.68)

79.2% (p = 0.002)

3

 − 2.83 (− 3.43, − 2.23) ^c

0.0% (p = 0.884)

3

 − 8.83 (− 10.23, − 7.24) ^d

0.0% (p = 0.763)

Time ≥ 12 weeks

4

 − 2.04 (− 3.38, − 0.71)

91.2% (p < 0.001)

3

 − 1.05 (− 1.83, − 0.28)

44.1% (p = 0.167)

3

 − 4.08 (− 5.51, − 2.65)

0.0% (p = 0.372)

Biological optimization

Bio-optimized extracts

5

 − 2.25 (− 3.33, − 1.17)

88.0% (p < 0.001)

4

 − 2.38 (− 3.33, − 1.43) ^c

61.4% (p = 0.051)

4

 − 7.45 (− 11.40, − 3.51) ^d

83.1% (p = 0.001)

Pure extracts

3

 − 1.00 (− 1.54, − 0.46) ^b

55.4% (p = 0.106)

2

 − 1.09 (− 2.45, 0.27) ^a

70.0% (p = 0.068)

2

 − 4.74 (− 6.45, − 3.04)

0.0% (p = 0.925)

Regions

Asia

5

 − 2.32 (− 3.29, − 1.34)

91.5% (p < 0.001)

4

 − 2.19 (− 3.65, − 0.74) ^c

86.5% (p < 0.001)

4

 − 7.80 (− 10.64, − 4.96) ^d

75.1% (p = 0.007)

Non-Asia

3

 − 0.86 (− 1.33, − 0.40) ^b

0.0% ((p = 0.502)

2

 − 1.45 (− 2.25, − 0.65)

0.0% (p = 0.391)

2

 − 3.08 (− 5.32, − 0.85)

0.0% (p = 0.411)