NAMPT and obesity due to melanocortin 4 receptor deficiency: In patients with knee OA, serum levels of visfatin (22.33 ± 15.66 ng/mL) were higher as compared with the control group, which comprised individuals with different BMIs, including cases with obesity but without OA (17.840 ± 8.563 ng/mL), but the difference was not statistically significant (p < 0.16) (Figure 3).