Review for 10.1186/1471-230X-9-93 (2009)

Reviewer's report
Title:A proposal for a new clinical classification of chronic pancreatitis
Version: 1Date:11 June 2009
Reviewer: Christoph F Dietrich
Reviewer's report:
The article is written about the need of a new classification system for patients
with chronic pancreatitis. The authors assume that up today there is no clinical
reliable classification system available.
The proposed new classification system is divided in 3 groups A-B-C.
Basically group A means patients without complications of chronic pancreatitis
and without noticeable exocrine and endocrine malfunction.
Group B is the group with complications of chronic pancreatitis and Group C are
the patients with noticeable endocrine and exocrine malfunction independent of
the occurrence of complications. The main difference of the already existing
Manchester classification to the new proposed classification of Heidelberg seems
to be that the complications of chronic pancreatitis are moved from stage 3 to
stage 2 (end stage to moderate stage or C to B). Unfortunately the Heidelberg
group did not comment the switch and did not point out the advantages of the
proposed changes in the article.
Proposing a new classification system is always a difficult matter. The question
should be answered, if the new system can provide more information about the
outcome of patients then other (older) systems. To evaluate this, already
published classification systems should be considered and the difference
between the new system and already published systems should be announced
and pointed out. In the article of Büchler et al there is a lack of already existing
successful applied classification systems. Whereas the Cambridge Classification
and the Zürich classification is mentioned but not discussed, there is a lack of
even more recent attempts of classification systems like the Mannheim
classification, the article of Klöppel, or the new Manchester classification
(Schneider A, The Mannheim Classification..., J Gastroenterol, 2007, 42(2)
101-119; Klöppel G, Toward a new classification..., J Gastroenterol, 2007, 42
Suppl 17, 55-57; Bagul A, Evaluation of the Manchester classification, JOP,
2006, 10, 7(4), 390-396).
The authors should compare their system with the already existing systems and
point out the differences, advantages and disadvantages. This is especially of
interest because the Heidelberg group (Friess - mentioned in the article) was
asked for their opinion by the Manchester-group and confirmed the
Manchester-Classification 2006.
A new classification system should be mirroring the natural course of a disease.
To evaluate this, the system should work even with untreated patients. Whereas
the Manchester group proved their system with a retrospective study of patients
over a period of 10 years, the Heidelberg group made a retrospective study of
patients only over a period of 3 years.
The disadvantage of the Heidelberg study is, that only patients with an operative
treatment are involved and that after 3 years only 10 percent of the initial
enclosed patients are still enclosed. The presented data are not sufficient
evaluating a new classification system.
In the Heidelberg classification multiple clinical and diagnostic parameters for
evaluating the patients are involved. Unfortunately the necessary parameters are
not clearly defined, e.g., diabetes mellitus is supposed to be a sign of a class C
patient. However, there is a considerable amount of patients with chronic
pancreatitis suffering from type I or II diabetes mellitus and not a secondary
diabetes mellitus according to the pancreatic disease. Those patients have to be
excluded or the type of diabetes has to be defined more clearly. Furthermore
there is confusion about the appropriate diagnostic method to diagnose chronic
pancreatitis.
Endosonography, the method with the highest resolution, has introduced the
term "minimal change" chronic pancreatitis (Catalano MF, EUS based criteria,
Gastrointest Endosc. 2009, Feb 23). Unfortunately EUS cannot predict the
outcome of patients with minimal change chronic pancreatitis and therefore those
patients have to be classified differently.
According to the article, there is a list of diagnostic criteria of chronic pancreatitis,
whereas the used diagnostic method is not specified (ERCP, MRI, CT and/or
EUS). Those criteria are mixed up for different methods and it is not mentioned
how many criteria are needed to establish the diagnosis chronic pancreatitis.
Because of the fact that endosonographic findings are comparable with ERCP
findings (Stevens T, Comparison of EUS and ERCP, Dig Dis Sci, 2008, 53(4),
1146-1151) in a new classification the involvement of ERCP as a diagnostic
method should be re-considered. There is a considerable risk in using ERCP in
stage A patients which should be pointed out.
The authors are pointing out that the new classification is relying on similarities to
the CHILD Pugh score for liver cirrhosis because the basic pathological findings
in both organs are the same. This does not explain, why the complication state of
chronic pancreatitis was moved from stage C to stage B because the occurrence
of complications in liver cirrhosis leading to a classification in the higher stage
(e.g., ascites, encephalopathy).
There is also a problem with the term classification of the disease. Uomo pointed
out that all existing classifications are in fact staging systems.
The classification should involve general parameters of the patient (already
existing tumor, nutrition state and so on) to allow prognostic statements [Uomo
G, How far are we from the most accurate classification system for chronic
pancreatitis? JOP, 2002, 3(3), 62-65]. The fact, that with the help of an operative
intervention (possible endoscopic intervention) the patient can be reclassified
from stage B to stage A (82 from 191 patients after 3
month) does not help to describe the development of the disease in an individual
person.
In conclusion: The aim of the new classification and especially the advantages of
the new classification in comparison to the Manchester classification should be
proved and described in the article before considering the
Heidelberg-classification. This involves retrospective long term investigations of
surgical and non surgical patients with chronic pancreatitis and also the
comparison of different classification systems within the same patient group. The
clinical and diagnostic criteria should be specified to allow comparable patient
groups.