. 2022 Oct 26;34(11):2603–2623. doi: 10.1007/s40520-022-02279-6

Table 3.

Meta-analyses of studies on vitamin D supplementation and knee osteoarthritis

Author	RCT number and sample size	Vit D intervention	Outcome
Gao et al. (2017) [107]	4 RCTs; n = 1136	800–2000 IU daily or 50,000–60,000 IU monthly	↓ WOMAC pain: score − 1.65 (95% CI − 2.16 to − 1.14) with 2000 IU/day
			↑ WOMAC function: score -1.87 (95% CI − 2.58 to − 1.17) with 2000 IU/day
			No effect on WOMAC stiffness and tibia cartilage volume
Diao et al. (2017) [108]	4 RCTs; n = 1136	800–2000 IU daily or 50,000–60,000 IU monthly	↓ WOMAC pain: SDM -0.32 (95% CI − 0.63 to − 0.02)
Diao et al. (2017) [108]	4 RCTs; n = 1136	800–2000 IU daily or 50,000–60,000 IU monthly	No effect on tibia cartilage volume or joint space width, regardless of baseline 25(OH)D levels
Beaudart et al. (2020) [109]	4 RCTs; n = 1136	800–2000 IU daily or 50,000–60,000 IU monthly	↓ WOMAC pain: SDM -0.31 (95% CI − 0.56 to − 0.06)
Beaudart et al. (2020) [109]	4 RCTs; n = 1136	800–2000 IU daily or 50,000–60,000 IU monthly	↑ WOMAC function: SDM -0.30 (95% CI − 0.49 to − 0.11)
Zhao et al. (2021) [110]	6 RCTs; n = 1599	800–2000 IU daily or 50,000–60,000 IU monthly	↓ WOMAC pain: SDM -0.32 (95% CI − 0.63 to − 0.02)
			↑ WOMAC function: SDM -0.34 (95% CI − 0.60 to − 0.08)
			↑ WOMAC stiffness: SDM -0.13 (95% CI − 0.26 to − 0.01)
			No effect on tibia cartilage volume or joint space width
Mathieu et al. (2022) [111]	3 RCTs; n = 662	2000 IU daily or 50,000–60,000 IU monthly	↓ WOMAC pain: SDM -0.20 (95% CI − 0.35 to − 0.04)
Mathieu et al. (2022) [111]	3 RCTs; n = 662	2000 IU daily or 50,000–60,000 IU monthly	↑ WOMAC function: SDM − 0.44 (95% CI − 0.80 to − 0.09)

Bold value indicates statistically significant differences

Vit D vitamin D, RCT randomized controlled trial, SDM standardized mean difference