APPLE study (APPendicitis and Laparoscopic Evaluation) study;
Multicenter prospective validation of the Laparoscopic APPendicitis (LAPP) score

During the last decade, a laparoscopic approach for a suspicion of appendicitis
has become more common in surgical practice. In case the appendix looks normal
the guideline of the Dutch Society of Surgeons advices not to remove it. The
morbidity of a negative appendectomy is approximately 6% and it also leads to
additional costs. However, until recently no criteria on how to assess the
appendix during a laparoscopy has been published. In a recently performed pilot
study we defined the Laparoscopic APPendectomy (LAPP) score. The LAPP score is
an easy applicable score that can be used during a diagnostic laparoscopy to
evaluate the appendix on the presence or absence of 5 laparoscopic criteria on
appendicitis. In our prospective cohort, use of the LAPP score would have led
to a positive predictive value of 99% and a negative predictive value of 100%.
The goal of the current study is to validate the LAPP score in a prospective
multicenter validation study. Our hypothesis is that the application of the
LAPP score leads to a reduction of 50% of negative appendectomies compared with
a retrospective cohort in the same centers. We have chosen to compare the
normal appendectomy rate of this prospective multicenter validation study with
a retrospective control group. The control group consists of 843 patients
operated in 5 centers in 2008 and 2009 with a normal appendectomy rate of 9%.

An alternative approach as a study design would be to initiate a randomized
(non-blinded) control trial, in such a case the surgeon will be asked to use
the LAPP score in half of the included patients and not to use it in the next
patient. We feel that it is not feasible for a surgeon to use the LAPP score in
one patient and not to use it in the next patient. In addition, after
publication of the results of the LAPP study surgeons might already start to
use the LAPP score or at least will evaluate the appendix differently than
before.

The main aim of this study is to validate the LAPP score. We hypothesize that
the use of this score will lead to a 50% reduction of the total number of
negative appendectomies, compared to the retrospective cohort of each
participating center.

Prospective cohort design, multicenter prospective validation study in 760
patients suspected for appendicitis with an indication for diagnostic
laparoscopy. We expect to fulfill the inclusion within one and half year.
This cohort will be compared with a multicenter historical cohort. Each center
will be its own control group.

Intra-operative use of the LAPP score.
The LAPP score consists of five questions regarding signs of appendicitis. Each
question could be answered with 'yes' of 'no'. If all five questions are
answered with no, the appendix is considered sana and it is safe not to remove
the appendix. If one or more questions are answered with yes, it is advised to
perform an appendectomy.

The five questions are:
1. Is there a perforation and/or necrosis?
2. Is the mesentery of the appendix thickened?
3. Is the appendix thickened?
4. Are the vessels on the serosa of the appendix injected?
5. Is there an adhesion around the appendix?

As it is a non-randomized study patients might already benefit from this study.
The percentage of normal appendectomies is approximately 10-20% nowadays. The
objective of the introduction of the LAPP score is to half this percentage. As
the morbidity of a normal appendectomy is approximately 6%, patients might
already benefit from the LAPP score. In our prospective cohort of 134 patients,
use of the LAPP score would have led to no missed appendicitis and a normal
appendectomy rate of 1% (N=1).
The lower incidence of normal appendectomies should not lead to an increase in
missed appendicitis during the diagnostic laparoscopy. We feel that the missed
appendicitis rate should be very low (< 1%).