Validity of predictive factors of acute complicated appendicitis
Imaoka et al. World Journal of Emergency Surgery
Validity of predictive factors of acute complicated appendicitis
Yuki Imaoka 0 1
Toshiyuki Itamoto 1
Yuji Takakura 1
Takahisa Suzuki 1
Satoshi Ikeda 1
Takashi Urushihara 1
0 Department of Gastroenterological and Transplant Surgery, Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University , 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551 , Japan
1 Department of Gastroenterological Surgery, Hiroshima Prefectural Hospital , 5-54, Ujinakanda, Minami-ku, Hiroshima 734-00041 , Japan
Background: Our previous retrospective study revealed the three preoperative predictors of complicated appendicitis (perforated or gangrenous appendicitis), which are body temperature ≥37.4 °C, C-reactive protein ≥4. 7 mg/dl, and fluid collection surrounding the appendix on computed tomography. We reported here an additional prospective study to verify our ability to predict complicated appendicitis using the three preoperative predictors and thus facilitate better informed decisions regarding emergency surgery during night or holiday shifts. Methods: We prospectively evaluated 116 adult patients who underwent surgery for acute appendicitis from January 2013 to October 2014. Ninety patients with one or more predictive factors of complicated appendicitis underwent immediate surgery regardless of the time of patient's presentation. Twenty-six patients had no predictive factors and thus were suspected to have uncomplicated appendicitis. Of the 26 patients, 14 who presented to our hospital during office hours underwent immediate surgery. The other 12 patients who presented to our hospital at night or on a holiday underwent short, in-hospital delayed surgery during office hours. Results: All patients with no predictive factors had uncomplicated appendicitis, whereas 37 %, 81 %, and 100 % of patients with one, two, or all three factors, respectively, were diagnosed with complicated appendicitis. The emergency operation rate decreased from 83 % before to 58 % after adopting this scoring system, but no significant differences in postoperative complication rates and hospitalization periods were observed. Conclusions: The above-mentioned preoperative factors predictive of complicated appendicitis preoperatively are useful for emergency surgical decisions and reduce the burdens on surgeons and medical staff.
Acute appendicitis; Predictive factor; Emergency surgery
Acute appendicitis is the most well-known acute
abdominal disease. However, not all diagnosed cases of acute
appendicitis require emergency surgery. Non-operative
management is recommended for uncomplicated
appendicitis , but preoperative distinction between
uncomplicated and complicated disease is challenging. In
addition, cases of complicated appendicitis, which
include perforated appendicitis and gangrenous
appendicitis, may progress to acute peritonitis, a condition that
necessitates emergency surgery regardless of the time of
development. This emergent nature presents additional
complications, as our hospital is staffed by young
surgical residents (3–5 years after graduation) at night and
over holidays, who examine patients and make decisions
regarding the indications for emergency surgeries (e.g.,
appendectomy). In contrast, the short-term risk of
perforation in cases of uncomplicated appendicitis, such as
catarrhal and cellulitis appendicitis is low, and these
cases can be treated conservatively with antibiotics until
sufficient on-duty medical staffs are available to perform
surgery. In addition, some of these cases can continue
receiving conservative treatment with antibiotics [2–4].
To address the challenge presented by the emergent
nature of some appendicitis cases, we performed a
retrospective study in which we considered three factors, a
body temperature ≥37.4 °C, C-reactive protein (CRP) level
≥4.7 mg/dl, and fluid collection surrounding the appendix
on computed tomography (CT), as potential preoperative
factors predictive of complicated appendicitis . Herein,
we report an additional prospective study to verify our
ability to predict complicated appendicitis using these
factors and thus facilitate better informed decisions regarding
emergency surgery during night or holiday shifts.
Our strategies of the diagnostic strategies of and for acute
appendicitis are shown in Fig. 1. Clinical suspicion of
acute appendicitis is made based on the routine use of
Alvarado  and appendicitis inflammatory response
(AIR) scores . In the absence of contraindication to CT
use such as pregnancy, CT scans are performed for
patients with an Alvarado score ≥ of 5 or more and/or
AIR score ≥ of 2 or more, if patients had no
contraindication of use of CT scan such as pregnancy. A diagnosis of
acute appendicitis is given if the patient has when positive
CT findings on all of the following CT findings: a short
appendix diameter greater than >6 mm, a thickened wall
of the appendix, and absence of gas in the appendicular
lumen. Decisions to surgery was performed when the
patient was positive for at least one of the following findings:
the existence of peritoneal irritation, a short appendix
diameter ≥10 mm, stone in the appendix root, and ascites
around the appendix or Douglas fossa. Patients without
these factors received non-operative treatment.
We prospectively evaluated 116 patients who
underwent surgery for acute appendicitis from January 2013
to October 2014 in this study. Patients who were treated
successfully with antibiotics were excluded. Out of the
116 patients, 90 patients who had one or more factors
predictive of complicated appendicitis underwent the
immediate surgery regardless of the time of the patients’
visited to our hospital. Twenty-six patients had no
predictive factors and thus, whose appendicitis were
suspected to have be uncomplicated appendicitis. Out of
the 26 patients, 14 patients who presented to our
hospital during office hours underwent the immediate
surgery. The other 12 patients who presented to our
hospital at night or on a holiday underwent delayed
surgery during office hours (Fig. 2).
Histopathologically, catarrhal appendicitis was defined
as the apparent enlargement of lymphoid follicles in the
appendix mucosa, and cellulitis appendicitis was defined
as neutrophil infiltration into all layers. Gangrenous
appendicitis was defined as neutrophil infiltration and
muscle layer necrosis, and perforated appendicitis was
defined as necrosis and perforation in all layers.
Complicated appendicitis was defined as a pathologically proven
gangrenous or perforated appendix. Our strategies for
patients with acute appendicitis indicated for surgery
included immediate operation for patients with
suspicion of complicated appendicitis and short, in-hospital
delay for patients with suspicion of uncomplicated
JMP statistical software (JMP® 11; SAS Institute Inc.,
Cary, NC, USA) was used for the statistical analysis. A
p-value ≤0.05 was considered statistically significant.
Pearson’s chi-square test was used to determine the
significance of differences between dichotomous groups.
Fisher’s exact test was used when a table included a cell
with an expected frequency of <5.
The prospective study included 65 male (56 %) and 51
female patients (44 %). The general patient
characteristics are shown in Table 1. The mean patient age was
44.5 years, with a range of 14–90 years. Overall, 52
(45 %) of the 116 patients had uncomplicated
appendicitis: 2 had pathologically proven catarrhal appendicitis
and 50 had pathologically proven cellulitis appendicitis.
The remaining 64 patients (55 %) had complicated
appendicitis. All patients without any of the three
predictive factors (body temperature ≥37.4 °C, CRP level
≥4.7 mg/dl, and fluid surrounding the appendix on CT)
had uncomplicated appendicitis. In contrast, 37 %, 81 %,
and 100 % of the patients with one, two, or all three
factors, respectively, were proved pathologically to have
complicated appendicitis (Table 2).
During the prospective study conducted after adopting
this scoring system, 35 (58 %) of the 60 patients
admitted to the hospital at night or over a holiday underwent
immediate surgery. This represented a decrease of 25
percentage points from the immediate surgery rate of
83 % during the retrospective study period of January
aThe time when the patients presented to our hospital
2009 to December 2012 (172 cases). However, there
were no significant differences in the postoperative
complication rate and hospitalization period between the
prospective and retrospective studies (Tables 3 and 4).
The Alvarado and AIR scores are standardized
diagnostic approaches in evaluating patients with suspected
acute appendicitis, using only clinical signs and
symptoms and laboratory values. Di Saverio et al. suggested
that the combination of scores might significantly reduce
the risk of overpredicting acute appendicitis and reach a
diagnostic performance as highly reliable as a CT scan,
thus avoiding the routine use of CT . Moreover, they
emphasized that both scores were the only independent
predictive factors of non-operative management failure
with antibiotics for uncomplicated appendicitis .
The treatment of patients with complicated
intraabdominal infection involves both timely source control
and antimicrobial therapy . Clinical trials have
demonstrated the successful treatment of acute appendicitis
26 (15 %)
with antibiotics [4, 10–12]. Notably, not all cases of
appendicitis can be treated surgically, especially cases
involving catarrhal appendicitis , and unnecessary
surgeries should be avoided in light of the risk
complications such as ileus (1.2 % of cases) and abdominal hernia
(0.68 % of cases) . However, cases of complicated
appendicitis, such as perforated appendicitis and
gangrenous appendicitis, can potentially progress to
acute peritonitis, which necessitates emergency surgery.
Cases of complicated appendicitis with localized
abscesses, however, present a lower risk of progression
to acute peritonitis, allowing surgery to be delayed until
normal office hours, and recent studies of this protocol,
or interval appendectomy, have confirmed the safety of
this approach [3, 15].
The surgical indication criteria for acute appendicitis
in our department are shown in Fig. 1. Some of the
patients with uncomplicated appendicitis and all of the
patients with complicated appendicitis had surgical
indication according to our criteria. Although cases of
complicated appendicitis should be treated immediately, it
remains a question whether cases of uncomplicated
appendicitis indicated for surgical treatment should be
treated immediately even at night or on a holiday.
Results of intentional prevention from immediate surgery at night or on a
holiday compared with those of retrospective study when without
aThe time when the patients presented to our hospital
Although several previous reports have discussed factors
associated with the diagnosis of acute appendicitis, the
ability of preoperative factors in predicting the presence of
complicated appendicitis is not easy to verify [6, 16–18].
However, Atema et al.  reported that the scoring system
accurately predicted the complicated appendicitis using a
maximum possible score of 22 points based on clinical and
CT features and a model was created that included age,
body temperature, duration of symptoms, white blood
cell count, C-reactive protein level, and presence of
extraluminal free air, periappendiceal fluid, and
appendicolith. Of the 284 patients, 150 had a score of 6
points or less, of whom eight (5.3 %) had complicated
appendicitis, giving a negative predictive value (NPV)
of 94.7 %. Herein, we report another simple scoring
system predicting the complicated appendicitis.
To better identify preoperative predictive factors of
complicated appendicitis, we conducted a retrospective and
a prospective study to determine the validity of three
potential factors (body temperature ≥37.4 °C, CRP ≥4.7 mg/dl,
and fluid collection surrounding the appendix on CT) .
We performed a receiver operating characteristic (ROC)
analysis to identify the most sensitive cut-off level and
used multivariate logistic regression analysis to investigate
these three predictive values for clinical events in the
retrospective study . In the prospective study, we were
able to exclude all cases of uncomplicated appendicitis
using these predictive factors. Similarly, we could exclude
all cases of complicated appendicitis by selecting cases
with no predictive factors, giving an NPV of 100 %. In
these latter cases, indicated procedures could be
postponed to avoid surgeries at night or over holidays.
Moreover, a short, in-hospital delay for uncomplicated
appendicitis indicated for surgery has proved to be a safe
procedure. However, the discrimination of cases with only
one or two predictive factors remains controversial, and
further prospective study is needed to support decisions
regarding emergency surgery in such cases.
After adopting our scoring system, we observed an
increase in the frequency of complicated appendicitis,
and we expected that the number of patients treated
successfully with antibiotics also increased.
Nonoperative management would be an alternative for
uncomplicated appendicitis if cases of complicated
appendicitis can be excluded prior to surgery.
However, we also recognized some bias in this study, as we
excluded patients who were treated successfully with
antibiotics from the trial, because we have no way to know
their actual pathology. We observed a statistically
significant reduction in the frequency of immediate surgery
among cases admitted at night or on holidays from 83 %
to 58 % after this scoring system was adopted, indicating
an effective reduction in the burden placed on surgeons
and medical staff. Recently, the strategy of short,
inhospital delay for uncomplicated appendicitis indicated
for surgery has been recommended in the World Society
of Emergency Surgery Jerusalem guidelines for diagnosis
and treatment of acute appendicitis .
In conclusion, the three factors, body temperature
≥37.4 °C, C-reactive protein ≥4.7 mg/dl, and fluid
collection surrounding the appendix on CT, are useful in
predicting cases of complicated appendicitis
preoperatively and can thus facilitate decisions regarding
emergency surgery. The scoring system can avoid
emergency surgery at night or on a holiday and lead to
AIR: Appendicitis inflammatory response; CRP: C-reactive protein;
CT: Computed tomography; NPV: Negative predictive value; ROC: Receiver
This research received no specific grant from any funding agency,
commercial, or not-for-profit sectors.
Availability of data and materials
The data and materials are not available because consent for such an action
was not taken from the participants.
Y.I. and T.I. performed the research/study, analyzed the data, and wrote the
manuscript. Y.T., T.S., S.I., and T.U. performed the research/study and analyzed
the data. T.I. designed the study and interpreted the results. All authors read
and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
Informed consent was obtained from all patients or their caregivers.
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