This observational study is an ongoing study conducted in a tertiary care teaching hospital and currently the data for a period of two years is being analysed. All the patients undergoing elective surgery for nodular thyroid goitre with FNAC Bethesda III, IV & V in this center during this period were recruited in the study after taking written informed consent. Permission for the study was granted from the Institutional Ethics Committee. Bethesda class II & VI were not considered as sensitivity and specificity of FNAC is very high. Patients with thyroid enlargements due to other causes like thyroiditis and those with systemic diseases such as active or chronic infections, diabetes mellitus, autoimmune disease, renal and liver disease were excluded. Similarly, patients on anticoagulants including aspirin, steroids or h/o alcohol intake and smoking were not included.
Sample size calculation: A total of 15 patients of each group were recruited in the pilot study for sample size calculations. Mean NLR (µ1) was calculated for patients with benign nodule. Similarly mean NLR (µ2) was calculated for other group of patients that is with malignant nodules based on the post-operative histopathology report. Standard deviation SD1 and SD2 was calculated for each mean NLR. From pilot data of patients µ1 = 2.21, µ2 = 1.86, SD1 = 0.58, SD2 = 0.52. Taking α as 1% and power as 80%, the required sample came out as 38 patients each for Benign thyroid Nodule and Malignant Thyroid Nodule. Hence, a sample size of 40 in each group was decided.
Method: All the patients undergoing elective surgery for nodular thyroid goitre with FNAC III, IV, V in this center during this period were recruited in the study after written informed consent. The phlebotomy samples for hemoglobin, complete blood counts, absolute neutrophil count, absolute lymphocyte count, differential leucocyte count, TSH and free T4 were collected and analyzed in the hospital laboratory. The blood samples were collected in the admission ward itself by the study surgical resident in a single prick phlebotomy on the day of surgery between 0800 to 0900 hours. At least 4 ml of blood samples were collected for all patients in a EDTA bottle for evaluation of complete blood counts, absolute neutrophil count, absolute lymphocyte count and differential leucocyte count. Samples in sterile bottles with at least 4 ml in the bottle were collected for TSH and free T4. The automatic hematology analyzer Beckman Coulter Hematology Analyzer LH 750 (Beckman Coulter Inc., CA, USA) was used to assess the blood counts. The levels of TSH and free T4 were obtained by Beckman Coulter DX1800 Immunoassay Analyser (Beckman Coulter Inc., CA, USA).
The NLR was calculated by dividing absolute neutrophil count by absolute lymphocyte count and the values obtained were recorded and plotted on a graph. The final diagnosis was confirmed in the post-operative final pathology sample. The Patients were grouped in two different groups Group A with benign HPE and Group B with malignant HPE results. NLR values in both groups were collected and analysed. The patient groups were compared with regards to the age of patients, gender, thyroid function tests, neutrophil, lymphocyte, and NLR. The primary end point for the study was evaluation of pre-operative NLR correlation with thyroid carcinoma and establishing the range of NLR values in benign and malignant nodule in Nodular goitre. In this study we had recruited 107 patients with thyroid nodule (Bethesda III,IV,V). We recruited more patients as we required 40 in each group. Remaining 27 patients were excluded for this study, however will be recruiting them later for further subgroup analysis as this is an ongoing study.
Data analysis: The data generated noted on a pre-designed proforma was entered in a excel sheet to statistically analyze the set using the SPSS Ver. 22 software (IBM Inc.). The numerical variables were expressed as mean ± standard deviation (SD). Categorical variables were presented as absolute values or percentage/ proportions. The two-sample t-test (Student’s t) was used for analyzing the quantitative variables with normal distribution. The Chi (χ2) square test was used for skewed distribution and for categorical variables. In comparisons using Student’s t test, 80% confidence intervals for the mean difference in response provided a range of likely values to assess clinical significance. Receiver operating characteristics (ROC) curve analysis was used to define optimal cut-offs of NLR, for which specificities, positive and negative predictive values (PPV, NPV) and overall accuracies were calculated. For all tests of significance, p-values less than 0.05 were considered statistically significant.