NLR and PLR as potential markers of disease activity in patients with ankylosing spondylitis?

Dear Editor,

We read the recently published article entitled ‘Neutrophil/lymphocyte and platelet/ lymphocyte ratios as potential markers of disease activity in patients with Ankylosing spondylitis: a case-control study’ by Al-Osami MH et al. [1] with interest. In the article authors aimed to evaluate the NLR and PLR as potential markers of disease activity in patients with ankylosing spondylitis. At the end of the article, the authors have pointed out that there was a statistically significant difference in the NLR and PLR between the active and inactive ankylosing spondylitis patients. And they concluded that PLR may be used as a useful marker in the assessment and monitoring of disease activity in AS together with acute phase reactants such as the ESR. The availability of this parameters at no additional cost may encourage its utilization in clinical practice. We would like to thank to the authors for their comprehensive contribution.

NLR is a globally available and inexpensive laboratory parameter, which is used to test systemic inflammation. In previous papers, it was shown that chronic hepatitis B and/or C infection, renal failure, diabetes mellitus, valvular heart diseases, acute coronary syndromes, thyroid functional abnormalities, metabolic syndrome, essential hypertension, and many inflammatory diseases may potentially affect the NLR [2, 3]. And also the main limitations of PLR studies are preanalytical faults, inadequate standardization of laboratory measurements, and inappropriate subject selection [4]. Thus, it would be more relevant if Al-Osami MH et al. had mentioned these NLR and PLR-affecting factors while evaluating the relationship between NLR and PLR in patients with ankylosing spondylitis. And also, as an important limitation of study, it would be more objective if a larger number of patients were included in this current research. Moreover, medication may easily alter NLR and PLR, so it would have been useful if the patients were described in greater detail in terms of, anti-inflammatory drugs, antiviral agents, immunosuppressive drugs, and/or other medications. In addition, it would also have been better if the authors indicated the elapsed time between taking the blood samples and measuring NLR and PLR, since waiting period prior to analysis may affect this laboratory parameters [2, 3].

We believe that the findings of Al-Osami MH et al. [1] will lead to further research concerning the relationship between NLR, PLR and ankylosing spondylitis. In addition to that, it should be kept in mind that NLR and PLR may not secure true information about disease activity in patients with ankylosing spondylitis.