Comparison of Tzanakis and Alvarado Scoring System in Diagnosis of Acute Appendicitis, with Histopathology as Gold Standard

of Tzanakis and Alvarado Scoring System in Diagnosis of Acute Appendicitis, with Histopathology as Gold Standard


Introduction
Appendicitis is a common surgical emergency requiring surgery. 1 It has a lifetime prevalence of 8%. 2 Therefore, its diagnosis is a continuous surgical challenge. The final diagnosis is usually made at surgery or sometime after Histopathology. 2,3 Its diagnosis is made after a carefully taken history and clinical examination, aided by some important laboratory investigations. 2,4 Despite all these, a negative appendectomy rate of 15 to 40% is reported in the literature. 2 To outcome this, different scoring systems are available like Alvarado, Tzanakis, RIPASA, and Ohman. 5,6 Due to its simplicity, the Alvarado scoring system is widely used to reduce the rise in the negative appendectomy rate. 2 The Tzanakis scoring combines clinical examination, USG, and leucocyte count. 7 A recent article has reported that Tzanakis scoring has a sensitivity of 86.0% and specificity of 75.5%, a positive predictive value of 33.3%, a negative predictive value of 33.3% whereas the Alvarado scoring system has a sensitivity of 76.0%, specificity of 75.0%, positive predictivity 97.2%, and negative predictivity of 21.3%. 7 The diagnosis of acute appendicitis in young females of their reproductive age is very tricky. Gynecological and Obstetrical diseases can mimic acute appendicitis 13 , for example, PID, Tubal Pregnancy, Ovarian cyst, etc. The advent of USG has greatly helped in correctly diagnosing acute appendicitis in these female patients. 14 Similarly, acute appendicitis diagnosis is quite challenging in elderly patients. Establishing the diagnosis of inflammation of appendicitis can be a real challenge. The delay in the treatment of acute appendicitis can lead to very serious consequences and increase both morbidity and mortality in some cases due to the perforation of an inflamed appendix. These facts lead to justifying high rates of negative appendectomy which range from 14 to 75%. 23 Therefore, many clinical scoring systems have been devised to diagnose acute appendicitis. These use symptoms, signs, and laboratory values to diagnose acute appendicitis. The most widely cited system had been Alvarado Scoring System. 23 Similarly Pediatric appendicitis score or Samuel Score is used most of the time for children. 24 Objective: To determine the diagnostic accuracy of Tzanakis and Alvarado's score for the diagnosis of acute appendicitis taking histopathology as the gold standard.

Materials and Methods
This cross-sectional validation study was conducted at the emergency department of Rawalpindi Medical University allied hospital Rawalpindi. The study was completed in eighteen months from dated 1 st May 2020 to 30 th November 2020. The sample size was estimated as 420 from WHO calculators. Non-probably consecutive sampling Patients aged 10 to 40 years of either gender presented with suspicion of acute appendicitis within seven days of onset of symptoms. Excluded Patients include those with suspected appendicular perforation, appendicular mass, appendicular abscess, and any patient who had given analgesia or sedation before clinical evaluation of acute appendicitis. After getting approval from the ethical committee of Rawalpindi medical university, 420 patients, fulfilling the inclusion criteria, were included in the study after getting their written informed consent. The demographic profile of patients was taken on a proforma and their Alvarado and Tzanakis score was calculated at the time of hospital induction. An appendicular specimen was sent for histopathology in the hospital laboratory. The final decision on acute appendicitis was based on histopathologist findings. All the data was entered into the software and different calculations were obtained. Data Analysis: SPSS version 20 was used to analyse data. And variables like age, Alvarado, and Tzanakis score were measured as frequency and percentages. 2x2 tables were constructed to calculate the diagnostic accuracy of the Alvarado and Tzanakis score. Likelihood ratio and ROC were measured. The diagnostic accuracy of both of these scoring systems was compared by the chi-square test. P value <_ 0.05 was significant.

Results
Out of the total of 420 patients, 51.9% were males and the mean age of patients was 20.15±7.13 years with minimum and maximum ages of 10 years and 39 years respectively. The mean Alvarado score was recorded as 7.22±1.58 with the lowest and highest scores of 1.00 and 10.00 respectively. (Table 1)        Using ROC, we found the optimum cut-off value for Alvarado Score as 6.5, whereas we obtained sensitivity and specificity of 88.6% and 92.5% respectively. Moreover for Tzanakis Score, the optimum cut of value is 8.5 which results in higher sensitivity and specificity of 82.3% and 92.5% respectively.

Discussion
An appendix is a hollow muscular tube at the junction of the ileum and caecum. The inflammation of this apparently vestigial structure is called appendicitis which is a very common cause of acute abdomen in our daily life in the accident and emergency department, and a significant number of such patients require surgery. 28 The patients suffering from right lower quadrant abdominal pain have a wide spectrum of symptoms and sometimes diagnosis of acute appendicitis can be a really difficult task even by a senior surgeon. 29 A prompt diagnosis of the condition is very important to reduce the morbidity and mortality associated with this condtion 28 due to associated perforation. Over the years, certain noninvasive scoring systems like Alvarado and Tzanakis scoring system have evolved which help in making a diagnosis and thus preventing unnecessary operations in these patients. Of the two, the Alvarado scoring system is most commonly used worldwide although it has certain weaknesses. On the other hand, the Tzanakis scoring system is considered better than Alvarado's as it combines clinical examination, assisted by the laboratory as well as ultrasonography in making a final diagnosis of acute appendicitis. 30 Male dominance in the study population in our study is comparable to other studies. 31 Mean age of our patients was 20.15 years with a standard deviation of ±7.13 years, this is also comparable with international literature. 32 According to one study 33 sensitivity, specificity, and overall diagnostic accuracy of Tzanakis scoring were 91.48%, 66.66%, and 90% respectively which is like our study but the specificity of our study is higher than this study. Another study 34 reported sensitivity, specificity, and positive and negative predictive values of the Tzanakis scoring system as 86.9%, 75.0%, 97.5%, and 33.3% respectively which is quite similar to our study. In the current study, we have calculated the sensitivity, specificity, and positive and negative predictive values as 88.83%, 88.60%, 98.19%, and 59.41% respectively. While the overall diagnostic accuracy of Tzanakis score was 88.81%. Therefore, our results prove that the Tzanakis scoring system is better than the Alvarado scoring system in the diagnostic accuracy of acute appendicitis. Moreover, the optimum cut-off value for the Tzanakis scoring system is 8.5 which gives higher sensitivity and specificity as 82.3% and 92.5%. Therefore, after using the combination of both scoring systems, a negative appendicectomy rate that is reportedly high (15 to 40%), can be minimized in the future.

Conclusion
The sensitivity of the Tzanakis score was high when compared to the Alvarado score. And specificity was high in the Alvarado score when compared to the Tzanakis score. Moreover, the overall diagnostic accuracy of the Tzanakis score was high when compared to the Alvarado score. So Tzanakis score can be utilized to predict appendix and in the future, we can avoid negative appendectomies.