The results of this study demonstrated that ESR was higher and the MLR was lower in females with nodal hand OA. In a study by Gao et al., it was reported that the MLR could be diagnostic in ppatients with knee OA. Patients with a KL score of grade 3 and 4 were included and the MLR was determined to be statistically significantly higher in patients at KL grade 4 compared to those at grade 3 (11). The current study examined patients with hand OA and KL score of grade 2 and 3, but the greater number of patients with grade 2 could have affected the results. Shi et al. reported that PLR could show inflammation in knee OA (12). In another study, no relationship was determined between NLR and symptomatic knee OA (13). In the current study, no difference was determined between the patients and the control group in respect of NLR and PLR.
In a previous meta-analysis, high-sensitive CRP (hsCRP) levels were determined to be at a moderately high level in patients with OA. A relationship was determined between hsCRP and clinical symptoms such as pain and function loss, but no correlation was determined between hsCRP and the KL score (15).
In another study that included 694 patients with hand OA, no relationship was determined between radiographic OA and inflammatory biomarkers (16). Levels of hsCRP have been determined to be significantly higher in patients with erosive OA compared to patients with non-erosive OA (17). A correlation has been shown between pain and higher body mass index (BMI) in patients with hand OA, and it has been reported that low-grade inflammation measured with hsCRP could be associated with pain in obese patients (18). In a study of patients with advanced stage knee and /or hip OA, the CRP level was reported to be higher in females and elevated CRP was found to be correlated with joint pain (19). Another study reported that ESR and the hsCRP level in patients with knee OA were higher than in patients without knee OA (20). Erosive OA patients were compared with non-erosive OA patients in another study, and ESR and CRP levels were found to be higher in the non-erosive group (21). In the current study, although ESR was found to be higher in the patients than in the control group, no significant difference was determined in respect of CRP. However, most previous studies have used hsCRP, and this difference could be related to that.
There are studies in literature which have aimed to understand the relationship between OA, uric acid, and gout, but this relationship has not yet been clearly explained. The combination of gout and OA is known. It is thought that hyperuricemia could lead to the progression of OA, or there could be a two-way relationship between a predisposition to the development of gout in a joint with OA (22, 23).
Ding et al. reported that there was a relationship between hyperuricemia and osteophytes in females with knee OA (9). In another study of 71 patients with knee OA, more abnormalities were observed on MRI in those with high levels of serum uric acid (10). From a study in which patients with knee OA and no gout were followed up for 24 months, there was observed to be greater narrowing of the joint space in those with a high level of uric acid (24). In another cohort study, no significant relationship was determined between tibiofemoral cartilage loss seen on MRI and serum uric acid level (25). Uric acid can activate NLRP3 (Nacht, leucine-rich repeat and pyrin domain containing protein 3) and as a result, IL-18 and IL-1β levels increase. In a study that analyzed the synovial fluid of patients with knee OA and no gout, increased IL-18 and IL-1β levels were found to be corrrelated with the serum uric acid level. This was determined radiographically and scintigraphically to be related to the severity of knee OA (26). It has been reported that while uric acid at low concentrations is chondroprotective and anti-inflammatory (27), at high levels it can trigger OA. Therefore, it may play an antioxidant or pro-oxidant role (28). In the current study, uric acid was determined at a higher level in the OA patients than in the control group, but the difference was not determined to be statistically significant, and no difference was determined between patients with KL score of 2 and 3.
Limitations of this study can be said to be that it was conducted in a single centre, the number of patients was relatively low, and comorbidities were not reported.
In conclusion, the results of this study demonstrated that the ESR was significantly higher in patients with symptomatic nodal hand OA compared to the control group. However, as hand OA is a heterogenous disease, there is a need for further studies related to uric acid and inflammation parameters.