Can the delta neutrophil ındex be used as a preliminary biomarker ın the evaluation of periodontal disease: a pilot study

Abstract Objective: Tissue destruction in periodontal diseases is related to inflammatory mediators in the host. However, it is unknown whether a relationship between delta neutrophil index (DNI) and neutrophil-lymphocyte ratio (NLR) in Stage 3 Grade A patients occurs. This cross-sectional study aimed to investigate the relationship between periodontal disease and DNI and NLR. Methodology: The study included 74 systemically healthy, non-smoking adults separated into 3 groups. Group 1: 26 subjects with good periodontal health, Group 2: 26 subjects with gingivitis, and Group 3: 22 subjects with Stage 3 Grade A periodontitis. After determining which group the patient will be included in, a clinical periodontal examination was made of each patient and pocket depth (PD), clinical attachment level (CAL), gingival index (GI), bleeding on probing (BOP) and plaque index (PI) parameters were measured. Venous blood samples were taken and examined with an automatic hematology analyzer for DNI, immature granulocytes (IG), NLR, C-reactive protein (CRP), procalcitonin, neutrophil count and lymphocyte count. Results: DNI, IG, CRP, and neutrophil count were observed to be highest in Group 3, followed by Group 2, and the difference between the groups in these parameters was determined to be statistically significant (p<0.001, p<0.001, p=0.046, p=0.016). DNI, IG, CRP and neutrophil count were observed to be positively correlated with periodontal parameters. Conclusion: The findings of this study support the role of DNI as a new biomarker for periodontal diseases. DNI may better reflect the systemic level of stage 3 grade A periodontitis than traditional inflammatory markers.

Although its levels cannot be determined in health, studies showed that procalcitonin levels increase in inflammatory conditions due to bacterial infections. Therefore, it is considered as a marker. 7 However, none of these are a specific biomarker for periodontitis. 1 The delta neutrophil index (DNI) is the fraction of immature granulocytes determined by subtracting the fraction of mature polymorphonuclear leukocytes and reflects the number of immature neutrophils as a blood biomarker.
It is also defined as the difference between leukocyte differentials generated in the myeloperoxidase (MPO) channel and those measured in the nuclear lobular channel provided by automated cell analyzers. 8 DNI can be easily calculated and reported without any additional cost. 3 Studies previously investigated DNI in diseases such as septic shock, bacteriemia, 9 sudden cardiac arrest, 10 renal cell carcinoma, 11 covid-19, 12 and gestational diabetes. 8  The study size was calculated using the G*Power The sample size was calculated at 95% power and 5% significance level, resulting in a minimum of 19 patients per group to obtain a significant statistical value.
While forming the study population, 146 patients who applied to our clinic were invited for the study. The patients reported the loss of more than 4 teeth because of periodontitis. In the evaluation of the spread and distribution of the disease, these patients had CAL ≥ 5 mm in ≥30% of the teeth. Appropriate measures were taken to ensure that CAL was not due to causes other than periodontitis. To estimate the progression of periodontitis, the degree of bone loss/ age was determined radiographically. 19 Radiographic bone loss was determined from the tooth showing the most severe bone loss as a percentage of root length. 19 As bone loss %/age was <0.25, all patients were evaluated as grade A.  Figure 2 shows the factors related to periodontal parameters.

Serum sampling and study variables
In the ROC analysis, the optimal 0.25 cutoff value for the DNI value in the diagnosis of periodontal disease showed 91% sensitivity and 65% specificity.
DNI showed relation to periodontal parameters in the correlation analysis. Figure 3 shows the sensitivity and specificity values obtained by the ROC analysis.     21 In our study, a statistically significant difference was determined between the groups regarding the DNI level.

Characteristic
Moreover, the half-life of DNI is 3 hours, which is much shorter than the 24-30 hours of procalcitonin. 22 A shorter half-life more easily reflects the infection status of the patient and is useful during follow up for the evaluation of the therapeutic efficacy of the treatment applied. In our study, while a significant difference was determined between the groups in respect of DNI, no significant difference was found for procalcitonin. This suggests that DNI could be a more effective precursor than procalcitonin in reflecting the systemic inflammatory load. In another study that evaluated procalcitonin and DNI as predictive and prognostic biomarkers with ROC curve analysis, it was concluded that DNI had better general diagnostic accuracy. 3 NLR seems to reflect the balance between natural and acquired immune mechanisms. 23  with stage 3 grade A periodontitis, and although we observed increased NLR level in the periodontitis group compared to the other groups, no statistically significant difference was determined. Therefore, it seemed that this parameter is not a sufficiently sensitive and specific biomarker in a patient group with low-level chronic inflammation such as diabetes and periodontitis.
Investigations indicates that CRP is a classic biomarker related to periodontitis. 28 In a previous study that defined the association between inflammation and CRP and other inflammation markers, 3 groups were formed and -according to the results -if CRP was >3, there was no significant difference in the procalcitonin and NLR values. 29 Consistent with these findings, in our study groups, CRP values were >3, and showed no difference in respect of NLR and procalcitonin. 21 In general, literature reported a positive relationship between inflammation severity and periodontal diseases. 1 Our results shows that CRP was highest in Group 3, and the difference from the other groups was statistically significant. In addition, we compared the neutrophil and lymphocyte values between the groups, and consistent with the literature, 4 only the neutrophil count was found to be statistically significantly different between the groups.