Dear editor, we read with great interest the paper by Balbaloglu et al. entitled “Evaluation of mean platelet volume (MPV) levels in patients with synovitis associated with knee osteoarthritis” [Citation1]. They have argued that MPV values are related to osteoarthritis with synovitis. Previous studies reported that inflammatory diseases were strongly associated with MPV levels [Citation2]. Their study involved important recent findings about MPV in osteoarthritis patients.
Recently, studies have demonstrated that synovial inflammation can be a significant factor in osteoarthritis pathogenesis [Citation3]. The authors detected lower MPV values in osteoarthritis patients with synovitis. Osteoarthritis was diagnosed according to the American College of Rheumatology criteria. Osteoarthritis was divided into four grades according to XR graphic findings. However, a number of studies have shown that both early and late osteoarthritis are associated with synovitis. If the diagnosis and grading of osteoarthritis was done using only XR, some synovitis cases could have been overlooked in their study group showing an absence of synovitis with osteoarthritis. The gold standard for diagnosis of synovitis is histology. Other diagnostic methods are magnetic resonance imaging, ultrasonography and physical examination findings and symptoms including pain, swelling and stiffness [Citation4]. However, the authors did not fully define the diagnosis of synovitis in the material and methods section. Which method was used for diagnosis of synovitis, such as physical examination or imaging methods?
The second limitation of this study was control subject selection. The authors defined control subjects as those who did not have joint complaints. However, osteoarthritis may not always be symptomatic. The prevalence of asymptomatic osteoarthritis is 10–30% at age 30–60 years [Citation5]. Therefore, we think that the control subject selection criteria are controversial. Was any imaging method in addition to lack of joint complaints used for control subjects?
In conclusion, MPV can be important indicator for synovitis. However, we think that some important questions should be answered.
Declaration of interests
This article involved no financial support, and none of the authors had any competing interests including the execution of a similar study.
References
- Balbaloglu O, Korkmaz M, Yolcu S, Karaaslan F, Beceren NG. Evaluation of mean platelet volume (MPV) levels in patients with synovitis associated with kneeosteoarthritis. Platelets 2013. [Epub ahead of print]
- Gasparyan AY, Ayvazyan L, Mikhailidis DP, Kitas GD. Mean platelet volume: A link between thrombosis and inflammation? Curr Pharm Des 2011;17:47–58
- Liu-Bryan R. Synovium and the innate inflammatory network in osteoarthritis progression. Curr Rheumatol Rep 2013;15:323
- Hayashi D, Guermazi A, Roemer FW. MRI of osteoarthritis: The challenges of definition and quantification. Semin Musculoskelet Radiol 2012;16:419–430
- Felson DT, Nevitt MC. Epidemiologic studies for osteoarthritis: New versus conventional study design approaches. Rheum Dis Clin North Am 2004;30:783–797