Investigation of Mean Platelet Volume as a Prognostic Criterion in Non-Healing Wounds

Objective: We aimed to evaluate if the Mean Platelet Volume (MPV) is an acute phase reactant in non-healing wounds, by analyzing its correlation with Erythrocyte Sedimentation Rate (ESR). Method: Our study was carried out in a descriptive type with the participation of patients with non-healing wounds. The laboratory data and characteristics of the patients were accessed retrospectively, and the obtained data were recorded in the data recording form. Results: The sample group consisted of 92 patients with non-healing wounds. 26.9% of the patients with non-healing wounds had pressure sores, 37.6% of them had diabetic foot wounds, 18.3% had non-healing wounds developed after trauma, and 17.2% had necrotizing fasciitis. The average age of the patients was 53.22±19.13, and the average length of stay in the hospital was 108.98±18.78 (min 3 months, max 6 months) days. The MPV value, which was found to be high in the early stages of non-healing wounds, decreased after the wound was completely healed. When the MPV value was compared to ESR, an acute phase reactant, a positive and strong statistically significant correlation was found between MPV and ESR based on the result of this correlation analysis (r=0.256, p<0.01). Conclusion: MPV can be used as a marker, just like ESR, in the presence of non-healing wounds. MPV value can be measured with blood taken into the complete blood count. However, an extra blood sample and a different tube are required for ESR. Using MPV value instead of ESR will provide savings in terms of cost and labor.


INTRODUCTION
Wound healing includes complex biochemical and cellular processes, and it is affected by many variables such as intracellular components and extracellular matrix [1,2]. In non-healing wounds, the process of new vessel formation (angiogenesis) is often impaired. Due to insufficient blood supply, nutrients and oxygen cannot be transported to the wound [3][4][5]. Non-healing wounds cause low comfort levels, low quality of life and low morale and motivation, loss of work power, loss of function due to the wound, long morbidity period and/or risk of death. This reveals the importance of the issue [1,5]. In addition, depending on the location and size of the wound, periodic maintenance often causes the individual to be unable to perform self-care alone, and this is emotionally and socioeconomically exhausting. If non-healing wounds deepen over time and progress towards the bone, they cause osteomyelitis. Osteomyelitis, which can be defined as bone inflammation, prepares the ground for amputation. Despite the high awareness of the problems caused by non-healing wounds, its management cannot be provided at an optimal level.
Platelets are small and morphotic elements of blood. Platelets are effective at the stage of hemostasis and fibrosis in the optimally smooth and expected wound healing process. In the first stage of the wound healing process, platelets accumulate at the wound site. When antagonists (Thromboxane A2 receptor antagonists, etc.) are activated, cytoplasmic granular content and inflammatory cytokines (interleukin-1 and interleukin-6, and tumor necrosis factor-alpha) are released and aggregated. Thus, fibrosis and inflammatory processes are initiated [6,7]. Platelets play an important role in the pathogenesis of local and systemic inflammation. Interleukin (IL)-6, which increases in the inflammatory process, has a direct effect on megakaryocytes and stimulates thrombopoietin simultaneously [8].
In case of bone damage caused by non-healing wounds, magnetic resonance imaging (MRI) and probe-to-bone (PTB) tests can be applied. Erythrocyte Sedimentation Rate (ESR) guides the applications of care and treatment in all nonhealing wounds. Apart from the cost of MRI and PTB, they fall short of the reliability of ESR in terms of the certainty of their results [28]. ESR is defined as the sedimentation rate of erythrocytes. In the presence of inflammation in the body, some protein structures (fibrinogen, α2, β and γ globulin) combine with erythrocytes, causing erythrocytes to precipitate faster [29].
Debris accumulation in the wound paves the way for bacteria to multiply. Dead cells and cell debris in necrotic tissue reduce host defenses and promote infection. The presence of necrotic tissue creates a mechanical obstacle to wound healing, limiting the epithelization of the wound surface, prolonging the inflammatory process and causing inflammation [1][2][3][4][5]. This creates a non-healing wound.
Acute phase reactants (AFRs) are proteins whose serum concentrations increase (positive AFR) or decrease (negative AFR) by at least 25% in response to inflammation. Positive AFRs include Erythrocyte Sedimentation Rate (ESR), C-reactive protein (CRP), procalcitonin (PCT), serum amyloid A (SAA), ferritin, and so forth. Among these, CRP, PCT and ESR are the most used in the evaluation of infection and inflammation [30]. However, these are laboratory tests that are costly and require a new tube of blood from the patient. It is advantageous to work on MPV with other parameters on complete blood count. In this study, we aimed to investigate the MPV value as a prognostic criterion in non-healing wounds.

MATERIALS AND METHODS
The data of our study were analyzed retrospectively. The research design is descriptive. The sample group consisted of 92 patients with non-healing wounds who were followed up in the Plastic, Reconstructive and Aesthetic Surgery Clinic of Adıyaman University Medical Faculty Hospital between 2014 and 2019. Patients treated in the study were included in the sampling. The purposive sampling method was used in sampling. Patient data were analyzed retrospectively using past computer-based records, patient files and electronic health records, and these data were recorded in a data record form developed by the researcher. Parameters such as sociodemographic characteristics, wound etiology, length of hospital stay, blood values of the patients were recorded.

Statistics
Statistical analysis of the results obtained in the study was performed using IBM SPSS (Statistical Package for the Social Sciences) Statistics 25. Descriptive statistical methods (Frequency, Standard Deviation, Arithmetic Mean) were used in data evaluation. The Kruskal-Wallis test, Wilcoxon signed-rank test, One-way ANOVA and Post hoc test were performed to determine the statistical significance of the differences between the means of the groups. Correlation analysis was used. Kolmogorov-Smirnov and Shapiro-Wilk tests were performed to find normal distribution assumptions. The results were evaluated at 95% confidence interval with a significance level of p<0.05.

Ethics
Prior to the study, the requisite approvals were obtained from Adıyaman University Clinical Research Ethics Committee (Decision No:2015/02-05). After the Ethics Committee Report was issued, access to patient records was provided and patient confidentiality was taken into account, and only health records were accessed, identity information was not examined.

RESULTS
The sample group of this study consisted of 92 patients with non-healing wounds. Non-healing wounds were classified as follows; 26.9% (n=25) of the patients had pressure sores, 37.6% (n=35) of them had diabetic foot wounds, 18.3% (n=17) had non-healing wounds developed after trauma, and 17.2% (n=16) had necrotizing fasciitis. When the characteristics of the patients were examined, the average age of the patients was found as 53.22±19.13 (min 14, max 80) years. 60.2% (n=56) of the sample group was determined as male and 39.8% (n=37) as female. The average length of stay in the hospital was determined as 108.98±18.78 days (min 3 months, max 6 months). The patients were discharged after the recovery of the nonhealing wounds. The average healing time of problematic wounds was determined as 114±24.46 days (min 3 months, max 6 months). Laboratory data of the patients are included in Table 1.
Average blood values were determined as follows; Phosphorus as 3.36±0.93 (min 1.9, max 7.4), Calcium as 9.03±0.53 (min7.  The comparison of MPV and type of non-healing wound was given in Table 3. The difference between the admission and discharge values of MPV value was found to be statistically significant in necrotizing fasciitis and pressure sores (p<0.01).
In the post hoc analysis, the statistical difference between MPV values at the time of admission and discharge in non-healing wounds, from the highest to the lowest, was listed as follows; pressure sores > necrotizing fasciitis > traumatic wound > diabetic foot wound.
In the comparison of sociodemographic data with the types of non-healing wounds, there is a statistically significant difference in the types of wounds depending on gender (p=0.001, t=1214). Decubitus ulcers and traumatic wounds were found to be higher in males than females (p=0.001, KW=11503). The higher rate of the diabetic foot and necrotizing fasciitis in women compared to men was found to be statistically significant (p=0.001, KW=11597). Similarly, there is a strong and negative correlation between Vitamin D and Parathyroid hormone (r=-. 249, p<0.029). Table 5 presents the comparison of the laboratory data with the types of non-healing wounds. Accordingly, a statistically significant correlation was found between the types of non-healing wound and vitamin D, parathyroid hormone and magnesium values. 25-hydroxy vitamin D was found to be the highest in non-healing wounds developed after trauma, and the lowest in necrotizing fasciitis (p=0.009, KW=11600). The parathyroid hormone level was found to be the highest in necrotizing fasciitis and the lowest in pressure sores (p=0.037, KW=8466). Magnesium value was found to be the highest in non-healing wounds developed after trauma and the lowest in pressure sores (p=0.001,

DISCUSSION
The treatment of non-healing wounds aims to reduce morbidity and mortality, to increase the quality of life and comfort, and to provide socioeconomic well-being. In the treatment of non-healing wounds, clinicians usually deal with the wound area. However, the focus should not only be on the wound, but also on laboratory data. In this study, we obtained evidence for evaluating MPV as a prognostic criterion in the presence of problematic wounds. In this study, we obtained evidence for evaluating MPV as a prognostic criterion for non-healing wounds. In our study, the significant difference between MPV values at the time of admission and discharge suggests that MPV may be a prognostic criterion. At the same time, a positive and strong statistically significant relationship (r=0.256, p=0.016) was found between MPV and ESR. This has been a finding that supports our hypothesis. This evidence is promising as it means that MPV can be used instead of ESR.
The sample group of this study consisted of 92 patients with non-healing wounds. Non-healing wounds were classified as follows; 26.9% (n=25) of the patients had pressure sores, 37.6% (n=35) of them had diabetic foot wounds, 18.3% (n=17) had non-healing wounds developed after trauma, and 17.2% (n=16) had necrotizing fasciitis. The average length of stay in the hospital was determined as 108.98±18.78 days (min 3 months, max 6 months). The patients were discharged after the recovery of the non-healing wounds. They were then called to be followed up periodically. The mean treatment period for non-healing wounds was determined as 114±24.46 days (min 3 months, max 6 months).
In the literature, it has been reported that CRP, ESR, platelet and MPV are important biomarkers in determining clinical processes and MPV levels are associated with ESR and CRP levels [31][32][33][34]. In a previous study, 83 patients with ulcerative colitis were examined, and in this study, an increase in ESR, CRP, neutrophil levels and a decrease in MPV were found. In addition, the relationship between MPV level and inflammation has been reported in previous studies [35][36][37]. It is thought that the increasing number and activity of platelets during the inflammation process affects MPV levels [38,39].
Crohn's disease, Hepatitis B, Acute Appendicitis cases are reported to be associated with MPV levels, depending on the inflammation [40,41]. In a previous study, it was reported that the MPV value varied during the remission and relapse periods of inflammatory bowel diseases, increasing during remission and decreasing during relapse periods [42]. Therefore, it is possible that MPV levels may  The increase in MPV in the inflammation is related to the stimulation of thrombopoietin formation by IL-6 and the direct effect of this cytokine on megakaryocytes [43]. MPV acts as an inflammatory marker in many chronic diseases. Thus, it can show the activity of the diseases and the effectiveness of the treatment [44]. In a study investigating the MPV value in diabetic foot wounds, it was found that amputation surgery was more common in patients with high MPV value compared to those with lower MPV value [45].
In our study, the MPV value at the time of admission was found to be high in all four different wound types, including the diabetic foot wound. In addition, when comparing the MPV with the types of non-healing wounds, the difference between the MPV value at the time of admission and discharge was found to be the highest in necrotizing fasciitis and the lowest in diabetic foot wound. The difference between values at the time of admission and discharge was statistically significant in necrotizing fasciitis and pressure sores. In addition, in our study, the ESR value was found 44.15±23.3 at the time of admission and 26.49± 5.51 at the time of discharge (p=0.001). Accordingly, the MPV value was 7.52±1.72 at the time of admission and 6.9±1.65 at the time of discharge (p=0.024). As a prognostic criterion in inflammatory diseases, ESR is an important biomarker, and it increases as a result of inflammatory conditions [46]. In this way, it may be possible to use the ESR value alone for diagnosis because some parameters such as age, gender and the presence of a concomitant secondary infection may also affect the level of ESR. ESR reacts slowly in an inflammatory situation [47]. However, in our study, there is a more remarkable decrease in MPV value compared to ESR. This result can be taken into account as a finding that increases the potency of MPV to be a prognostic criterion.
The data regarding MPV in the literature differ due to the fact that the studies have been conducted in different and independent groups, the reliability of the measurement devices is not known exactly, and the changing approaches of the scientists. In the literature review, no study was found to determine the correlation between non-healing wounds and MPV level. In this regard, our study results can be a basis for the use of MPV as an acute phase reactant in clinical applications in non-healing wounds, as well as guiding clinicians. This study was limited by the nature of its single-center design.

CONCLUSION
In our study, it was found that the MPV value was high in the non-healing wounds prior to the treatment and decreased after the non-healing wounds started to heal. In the literature, no study was found to determine the correlation between ESR and MPV in non-healing wounds. In this regard, this study can be seen as an important source of information. However, some important parameters that may affect MPV could not be evaluated due to the retrospective design of our study. These can be listed as environmental factors, nutrition, alcohol use, smoking and psychological factors.
According to our results, high MPV and ESR values at the same time and a decrease in both values after the healing show the correlation between MPV and ESR levels. Therefore, we recommend that this change in MPV level should be evaluated in larger sample groups. The return of these values to normal after the non-healing wounds are healed is the most important evidence that they increase due to inflammation. We believe that our study will guide clinicians and academics and form a basis for future studies. In addition, if the evidence we have obtained is strengthened, the use of MPV value instead of ESR will save in terms of cost and labor.

Author contribution
Study conception and design: FNT, FD, and AV; data collection: FNT, FD, and AV; analysis and interpretation of results: FNT and FD; draft manuscript preparation FNT, FD, and AV. All authors reviewed the results and approved the final version of the manuscript.

Ethical approval
The study was approved by the Adıyaman University (Protocol no. 02-5/2015).

Funding
The authors declare that the study received no funding.

Conflict of interest
The authors declare that there is no conflict of interest.