1 INTRODUCTION

According to the reports of the World Health Organisation (WHO), American Burn Association, and Centers for Disease Control and Prevention (CDC), 1.1 million people were injured annually due to burns1, 2 and 3500 people died from burn injuries.3

A burn is a trauma requiring the highest level of attention and requires a multidisciplinary approach. The need for erythrocyte transfusion in the acute phase of the burn should be considered simultaneously or immediately after resuscitation, due to symptomatic anaemia and acute blood loss. Increased red cell destruction, decreased erythropoiesis, iron deficiency with resistance to erythropoietin, and frequent phlebotomy lead to the development of anaemia.4, 5

Red cell distribution width (RDW) is the variability of the size of circulating red blood cells and is routinely measured in complete blood count (CBC). RDW is used in the differential diagnosis of many haematological diseases, especially anaemia. RDW is obtained from the red cell histograms. The red blood cell size shows its distribution, namely anisocytosis. Before anaemia occurs, the RDW level is first detected. It is most commonly used in practice to distinguish between iron deficiency anaemia and thalassemia carriage.4-6 RDW is normal in thalassemia carriage and high in anaemia. It is calculated by two different methods. In these methods, the normal value is 14.5% to 15% in the method given as a percentage, and 45 fL in the other method. RDW is found as 15% to 25% in iron deficiency anaemia, 12% to 15% in thalassemia carriage, and 25% to 35% in thalassemia major. The clinical experience suggests that if RDW is 17% to 20% with high mean corpuscular haemoglobin concentration (MCHC), hereditary spherocytosis is likely, but if RDW is in the range of 20% to 25%, congenital dyserythropoietic anaemias (CDA) come to mind.6 If the RDW is higher than 25% in unresolved severe microcytic anaemias, sideroblastic anaemia may be considered in the differential diagnosis.

One of the noteworthy points in fluid resuscitation in burns is the “use of colloids”. Increased capillary permeability is seen more and over a longer period of time in burned tissues while simultaneously occurring at a lower degree and in a shorter time in undamaged tissue.7, 8 In this context, clinicians emphasised that the most appropriate solution to reduce capillary permeability is the use of colloid, namely albumin, for both reducing oedema and increasing oncotic pressure, but it should be performed simultaneously with fluid.9, 10 However, current studies have been conducted on the intensive care patient group and do not include burn patients.9, 10

Erythrocyte transfusion is a routine practice in major burn injuries. Red cell transfusion is required due to blood loss, postoperative bleeding, red cell destruction that begins during the acute burn process and continues during the recovery period, and reduced red cell production.11 One of the most important complications in burn cases is infection and hypoalbuminemia, which significantly affects survival. We think that RDW, like albumin, may be a prognostic criterion in predicting the clinical condition of the patient in severe burns. In this study, we aimed to examine the red cell distribution width as a prognostic criterion in severe burns.

2 MATERIAL AND METHOD

Patients exposed to severe burn trauma and treated in the Burn Unit of Diyarbakır Dicle University Medical Faculty Hospital from 2010 to 2020 were included in the sample. Stratified sampling method was used in sample selection. Half of the total n = 120 severe burn patient sample consisted of severe burn patients with albumin level less than 2.5 gram/decilitre (g/dL) and RDW value greater than 15% after burn, and the other half with severe burn patients above these values.

Inclusion criteria were as follows: Not having any chronic disease/comorbidity before the burn. Being over the age of 18. Not having any blood disorders before the burn. Not exposed to any trauma during the burn. Exclusion criteria were as follows: Before burn comorbidity/chronic disease presence (renal, lung and liver failure, malignancy, etc.). Presence of trauma other than burns, falling from height, hitting, accident or any other reason. Being under the age of 18. Presence of thalassemia, anaemia or similar haematological disease in the past.

Patient data were analysed retrospectively using past computer records, patient files and burn unit records, and recorded in a data form developed by the researchers. Parameters such as sociodemographic characteristics, burn aetiology, mortality rates, intervention, hospitalisation period, blood values of the patients were recorded.

Statistical analysis of the results obtained in the study was performed with IBM SPSS (Statistical Package for the Social Sciences) Statistics 25. Descriptive statistics (frequency, standard deviation, mean) were used in data evaluation. Independent samples t test, analysis of variance (ANOVA) and post hoc analysis were performed in order to determine the statistical significance of the differences between the means of the groups. Correlation and regression analyses were implemented. Kolmogorov-Smirnov and Shapiro-Wilk tests were performed to find the normal distribution assumptions. The results were evaluated at 95% confidence interval and P < 0.05 significance level. Ethical approval prior to the start of the study, the requisite legal approvals will be obtained from Diyarbakir Dicle University Ethics Committee (Decision No: 04.02.2021–103).

3 RESULTS 3.1 Burn patient information form

The characteristics of burn patients are shown in Table 1 in terms of number and percentage. Exactly 38.33% of burn patients are between the age of 65 and 80, and 51.67% of them are male patients. It was determined that 92.5% of the patients had third-degree burns, 81.7% of them had a burn percentage of 41% to 50%. When the burn areas were examined, 83.3% of the patients developed left upper extremity, 66.66% right lower extremity and 67.5% left lower extremity burn.

TABLE 1. Distribution of burn patients by descriptive characteristics (n = 120) Features n % Age 31-45 32 26.67 46-64 34 28.33 65-80 46 38.33 81 and above 8 6.67 Age (Mean ± SD) 59.04 ± 15.55 (min 34, max 88) Gender Female 58 48.33 Male 62 51.67 Type of burn Hot liquid 60 50 Electrical 24 20 Flame 32 26.66 Contact 4 3.34 Degree of burn Second degree 9 7.5 Third degree 111 92.5 Percentage of burn 21%-40% 20 16.67 41%-50% 98 81.7 51% and above 2 1.7 Location of burn Head-neck 16 13.33 Anterior trunk 52 43.33 Posterior trunk 52 43.33 Right upper extremity 79 65.83 Left upper extremity 100 83.33 Right lower extremity 80 66.66 Left lower extremity 81 67.5 Intervention applied Operation 93 77.5 Medical treatment 27 22.5 Neuropsychiatric symptom Yes 23 19.16 No 97 80.84 Result Discharged 107 89.17 Death 13 10.83 3.2 Clinical outcomes of burn patients

The minimum, maximum and mean values of the clinical outcomes of burn patients are shown in Table 2.

TABLE 2. The Minimum, maximum and mean values of clinical outcomes of burn patients (n = 120) Clinical Outcomes Mean ± SD Min Max Albumin (g/dL) 2.39 ± 0.34 1.8 3.10 Haemoglobin (g/dL) 9.91 ± 1.01 8.5 13.38 Haematocrit (%) 30.23 ± 2.71 25.5 40.64 Red blood cell (million/μL) 3.68 ± 0.51 2.6 4.8 Red cell distribution (%) 18.47 ± 6.15 11.29 29 Length of stay in intensive care unit (days) 13.45 ± 7.83 3 33 Number of days spent in clinic 9.26 ± 7.83 0 46 Number of albumin or FFP transfusion 1.85 ± 0.88 0 4 Number of red blood cell transfusions 3.76 ± 2.35 0 9 Duration of antibiotic therapy in days 16.72 ± 9.34 5 48 Duration of analgesic use in days 15.91 ± 8.01 5 48 Duration of Foley Catheter use in days 15.55 ± 7.67 3 38 Duration of central venous catheter use in days 23.41 ± 8.25 7 44

In this study, serum albumin value was 2.39 ± 0.34 g/dL (min 1.8, max 3.10), haemoglobin (HGB) level obtained in CBC was 9.91 ± 1.01 (min 8.5, max 13.38), and haematocrit (HCT) value was 30.23% ± 2.71% (min 25.5, max 40.64). In addition, RDW was found to be 18.47% ± 6.15% (min 11.29, max 29), red blood cell (RBC) 3.68 ± 0.51 million/μL (min 2.6, max 4.8). It was determined that the length of stay in the intensive care unit was 13.45 ± 7.83 (min 3, max 33) days, the length of stay in the clinic was 9.26 ± 7.83 (min 0, max 46) days, the duration of Foley catheter use was 15.55 ± 7.67 (min 3, max 38) days, the duration of central venous catheter use was 23.41 ± 8.25 (min 7, max 44) days. Transfusion was determined as 1.85 ± 0.88 (min 0, max 4) for albumin or fresh frozen plasma (FFP) and 3.76 ± 2.35 (min 0, max 9) for erythrocyte suspension. The duration of days was found to be 16.72 ± 9.34 (min 5, max 48) for antibiotic therapy and 15.91 ± 8.01 (min 5, max 48) for analgesic use. In addition, the mean age of the patients was determined as 59.04 ± 15.55 (min 34, max 88).

3.3 Comparisons of blood test parameters, clinical results and descriptive characteristics

In Table 3, the descriptive characteristics of burn patients and the comparisons of their clinical results are shown.

TABLE 3. Comparison of laboratory data, clinical results and descriptive characteristics (n = 120) Features N Laboratory data RDW related laboratory data RDW (%) Albumin (g/dL) HGB (g/dL) RBC (million/μL) HCT (%) Age Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD 31-45 32 16.85 ± 5.25 2.42 ± 0.29 10.48 ± 1 3.74 ± 0.47 31.73 ± 2.43 46-64 34 16.45 ± 4.44 2.42 ± 0.37 9.78 ± 0.99 3.88 ± 0.36 30.32 ± 2.87 65-80 46 19.42 ± 6.63 2.35 ± 0.29 9.79 ± 0.91 3.60 ± 0.55 29.83 ± 2.17 81 and above 8 28.14 ± 0.86 2.27 ± 9.51 8.82 ± 0.2 3.03 ± 0.28 26.25 ± 0.59 F 11.214 0.610 8.045 0.014 11.929 P 0.000** 0.610 0.000** 0.0989 0.000** Post hoc 4 > 1, 2 and 3 (P = 0.000**) - 4 > 3 > 2 and 1 (P = 0.000**) - 4 > 3 > 2 and 1 (P = 0.000**) Gender Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Female 58 18.05 ± 6.23 2.47 ± 0.35 9.91 ± 0.78 3.74 ± 0.43 39.65 ± 1.84 Male 62 18.87 ± 6.09 2.31 ± 0.32 9.9 ± 1.19 3.62 ± 0.57 29.85 ± 3.30 T −0.730 2.717 0.021 1.207 1.629 P 0.467 0.008** 0.983 0.230 0.106 Type of burn Hot liquid 60 18.55 ± 6.37 2.34 ± 0.36 9.94 ± 0.93 3.72 ± 0.53 30.06 ± 2.85 Electrical 24 17.60 ± 5.76 2.40 ± 0.31 10.36 ± 0.90 3.64 ± 0.47 31.14 ± 2.34 Flame 32 18.96 ± 6.08 2.43 ± 0.30 9.42 ± 1.08 3.66 ± 0.48 29.76 ± 2.69 Contact 4 18.69 ± 7.43 2.72 ± 0.35 10.6 ± 0.69 3.51 ± 0.66 31.24 ± 1.98 F 0.229 1.899 5.095 0.304 1.499 P 0.876 0.134 0.002** 0.823 0.219 Post hoc - - 3 and 4 > 1 and 2 (P = 0.012*) - - Burn level Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Second degree 9 14.08 ± 2.40 2.39 ± 0.35 10.72 ± 1.85 4.10 ± 0.52 32.90 ± 4.74 Third degree 111 18.83 ± 6.23 2.30 ± 0.29 9.84 ± 0.89 3.64 ± 0.49 30.02 ± 2.39 T −2.265 −0.801 2.544 2.660 3.172 P 0.000* 0.425 0.012* 0.009** 0.002** Percentage of burn Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD 21%-40% 20 18.55 ± 6.37 2.38 ± 0.39 10.43 ± 1.44 3.72 ± 0.56 31.27 ± 3.74 41%-50% 98 18.41 ± 5.9 2.39 ± 0.33 9.8 ± 0.88 3.67 ± 0.5 30.02 ± 2.45 51% and above 2 27.70 ± 1.27 2.51 ± 0.77 9.87 ± 1.76 3.51 ± 0.21 30.40 ± 1.85 F 2.448 0.211 3.330 0.171 1.792 P 0.091 0.810 0.039* 0.843 0.171 Post hoc - - 2, 3 > 1 (P = 0.021*) - - Location of burn Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Head-neck 16 17.45 ± 4.95 2.52 ± 0.34 10.1 ± 1.26 3.7 ± 0.6 31 ± 3.40 Anterior trunk 52 17.88 ± 5.54 2.37 ± 0.32 10.02 ± 0.85 3.71 ± 0.43 30.64 ± 2.18 Posterior trunk 52 18.39 ± 6.06 2.53 ± 0.38 10.11 ± 0.78 3.71 ± 0.44 30.36 ± 2.12 Right upper extremity 79 18.27 ± 6.08 2.38 ± 0.35 10.07 ± 1.03 3.68 ± 0.51 30.80 ± 2.51 Left upper extremity 100 18 ± 5.76 2.35 ± 0.30 9.86 ± 1.02 3.67 ± 0.52 30.23 ± 2.61 Right lower extremity 80 19.59 ± 6.72 2.42 ± 0.39 9.89 ± 0.99 3.66 ± 0.47 30.56 ± 2.47 Left lower extremity 81 18.97 ± 6.38 2.43 ± 0.37 9.72 ± 0.94 3.64 ± 0.56 29.79 ± 2.64 F 0.016 2.621 0.632 0.183 4.756 P 0.900 0.108 0.428 0.989 0.031* Intervention applied Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Operation 93 18.41 ± 5.92 2.40 ± 0.35 9.93 ± 0.94 3.68 ± 0.51 29.95 ± 2.62 Medical treatment 27 18.69 ± 6.98 2.36 ± 0.31 9.81 ± 1.24 3.68 ± 0.49 31.22 ± 2.83 T 0.203 0.480 0.558 −0.014 −2.181 P 0.839 0.900 0.634 0.989 0.031* Neuropsychiatric symptom Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Yes 23 23.12 ± 6.09 2.28 ± 0.44 9.68 ± 0.98 3.29 ± 0.47 29.29 ± 3.13 No 97 17.37 ± 5.66 2.40 ± 0.32 9.96 ± 1.02 3.09 ± 0.31 30.46 ± 2.57 T 4.310 −0.550 −1.229 −4.418 −1.874 P 0.000** 0.583 0.229 0.000 0.063 Result Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Discharged 107 17.52 ± 5.62 2.42 ± 0.35 10.01 ± 1.01 3.75 ± 0.48 30.62 ± 2.56 Death 13 26.33 ± 4.56 2.15 ± 0.43 9.07 ± 0.56