Blood inflammatory markers, such as WBCs and CRP, cannot be relied upon to make a specific diagnosis. However, these inflammatory markers have contributory values and can aid clinical judgements. Furthermore, when applied to cases with acute right lower quadrant pain, as determined by clinical examination, these inflammatory markers can aid diagnosis. In this setting, elevated levels of inflammatory markers have been reported to increase the probability of acute appendicitis by some investigators [5
], whereas others have concluded that patients with right lower quadrant pain with a normal WBC count and CRP level are unlikely to have acute appendicitis [5
To the best of our knowledge, this is the first study to evaluate relationships between blood inflammatory markers and CT findings in a single patient population. In terms of the CT findings examined, only the presence of acute appendicitis and appendiceal wall changes were found to be significantly related with an elevated WBC count. This finding suggests that an increased WBC count is related to mural inflammation of the appendix, which is a feature of early appendicitis [1
]. By contrast, elevated CRP levels were found to be related to periappendiceal phlegmon and abscess formation, which are features of advanced disease.
Some have reported that WBC count is correlated with the severity of appendicitis [9
]. However, in the present study only a poor correlation (r
= 0.222) was found between WBC count and disease severity, as determined by CT findings. In addition, we found no significant differences between Grades II, III and IV in terms of WBC count. Furthermore, if we did not consider the standard deviation, mean WBC count in Grade III (13 170 µl–1
) was slightly higher than in Grade IV (12 850 µl–1
CRP is synthesised by hepatocytes during the acute response phase to a variety of infectious or inflammatory disease processes [9
]. The reported predictive values of CRP in appendicitis vary widely: reported sensitivities range from 40% to 99% and specificities from 27% to 90% [17
]. Amalesh et al [11
] reported that the accuracy of CRP for diagnosing acute appendicitis is low and added that CRP levels are not useful when deciding on surgery. However, Ortega-Deballon et al [5
] recently concluded that CRP level is the most useful laboratory parameter in terms of diagnosing acute appendicitis and that CRP levels are strongly correlated with inflammation severity. In the present study, we also found a high correlation (r
= 0.669) between CRP level and disease severity based on CT findings. Furthermore, although no significant differences were found between the CRP levels of patients with Grades I, II and III, CRP values were found to be proportional to grade.
In the present study, WBC count was found to better differentiate normal and inflamed appendices than CRP level, whereas CRP level was found to be better at detecting perforated appendicitis. Accordingly, the present study shows that an elevated WBC count better detects early appendiceal inflammation, whereas an elevated CRP level better detects protracted inflammation such as that encountered 2 or 3 days after symptom onset [18
]. Furthermore, the results of the present study, in which disease severities were mainly determined using CT findings, concur with those of previous studies that were based on surgical–pathological results [7
It has been reported that although WBC count and CRP level are helpful in terms of diagnosing appendicitis, they are inferior to imaging studies such as ultrasonography and CT in terms of confirming the presence of acute appendicitis [12
]. Accordingly, it was concluded that these inflammatory markers could not be usefully incorporated into an algorithm designed to restrict or recommend further imaging studies. However, when the appendix is not visualised by imaging studies or when imaging results are inconclusive, inflammatory markers could provide contributory diagnostic information. Therefore, we suggest that additional studies in patients who have equivocal imaging results are needed to determine the potential roles of inflammatory markers.
Several limitations of the present study should be considered. Firstly, the patient selection procedure excluded cases other than those of acute appendicitis. This was done because the inclusion of patients with other inflammatory focuses might have influenced relationships between CT-based severity and inflammatory markers. Secondly, the criteria used to determine CT severity scores were relatively subjective and, furthermore, the presence of appendicolith was not included; however, we suggested that appendicolith per se
does not influence inflammatory marker levels. In addition, less than 10% of the normal population had an appendicolith [20
]. Accordingly, we did not include appendicolith as a CT criterion for scoring purposes. Thirdly, we did not evaluate the correlation between CT findings and surgical–pathological findings, other than when reviewers disagreed on CT grade. Finally, our study population contained a relatively high number of patients with a perforated appendix, which would have contributed to the strong correlation found between CT-determined appendicitis severity and CRP level.
In summary, this study shows that CT-determined acute appendicitis severity is better correlated with CRP level than with WBC count. Our findings suggest that an elevated CRP level supports a diagnosis of perforated appendicitis, whereas an elevated WBC count could help differentiate normal and inflamed appendices. Accordingly, the findings of the present study suggest that blood inflammatory markers might be useful tools in acute appendicitis patients with an equivocal diagnosis or disease stage after CT.