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Università Cattolica del Sacro Cuore Facoltà di
Medicina e Chirurgia Corso di Chirurgia Generale
VI anno (I canale)
EVIDENCE BASED SURGERY
Prof. Marco Castagneto Dipartimento di Scienze
Chirurgiche
Anno Accademico 2006/2007
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EVIDENCE BASED SURGERY

• While evidence based surgery may be viewed as
  deriving in general from the professionalizing of
  surgery in the 19 century, the origins of
  contemporary evidence-based surgery have been
  influenced by several major developements since
  Warld War I
• The public health movement
• Military medicine and key lernings from Warld War
  II
• Clinical and health services research in practice
  variations
• Toby A. Gordon Origins of Evidence-based Surgery

EVIDENCE BASED SURGERY
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EVIDENCE BASED SURGERY
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EVIDENCE BASED SURGERY
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EVIDENCE BASED MEDICINE
The conscientious and judicious use of the best
current evidence from clinical care research in
the management of individual patients Sackett et
al.
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CARATTERISTICHE DELLEVIDENCE BASED MEDICINE

• definire la migliore evidenza (best evidence)
• diffondere e rendere accessibile levidenza
• discutere in maniera critica levidenza
• applicare levidenza ai singoli pazienti

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LIVELLI di EVIDENZA

• Consentono di applicare le regole dellevidenza e
  le leggi della logica ai dati clinici, al fine di
  stimarne
• Validità
• Affidabilità
• Credibilità
• Utilità

necessarie conoscenze di statistica, analisi
economica, analisi decisionale e clinical
knowledge
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LA GRADAZIONE DELLE RACCOMANDAZIONI
GRADO 1 A Rapporto rischio / beneficio
Guyatt chest 2004 126 179s-187s
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LA GRADAZIONE DELLE RACCOMANDAZIONI

• Il numero accanto al grado indica la
• forza delle raccomandazioni
• Grado 1 certezza degli esperti che i benefici
  possano (o non possano) prevalere su rischi e
  costi ? RACCOMANDIAMO
• Grado 2 certezza minore dellimpatto dellentità
  relativa di rischi, costi e benefici ? SUGGERIAMO

Guyatt chest 2004 126 179s-187s
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LA GRADAZIONE DELLE RACCOMANDAZIONI

• La lettera accanto al numero indica la
• qualità metodologica
• dellevidenza che determina la raccomandazione
• Grado ..A trial clinici randomizzati con
  risultati consistenti in assenza di bias
• Grado ..B trial clinici randomizzati con
  risultati inconsistenti o metodologicamente
  deboli
• Grado ..C studi osservazionali o estrapolazioni
  da studi randomizzati di dati applicati a gruppi
  di pazienti simili che non abbiano partecipato al
  trial

Guyatt chest 2004 126 179s-187s
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LA GRADAZIONE DELLE RACCOMANDAZIONI
Guyatt chest 2004 126 179s-187s
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EVIDENCE BASED SURGERY
A surgeon should be able to distinguish between
clinical and statistical significance.
Statitiscal significance involves calculating a p
value clinical significance relies on the number
needed to treat, which not only tells us wheter a
treatment works but how well it works
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EVIDENCE BASED SURGERY una sorta di checklist

• Quale è lo scopo dello studio?
• Il numero di pazienti arruolati è sufficiente?
• I parametri di misurazione sono validi ed
  affidabili?
• Il risultato è clinicamente rilevante?
• La significatività statistica è espressa in modo
  corretto?
• Qual è il rapporto con i dati già presenti in
  letteratura?
• Come si colloca lo studio nella pratica
  quotidiana?
• Il gruppo di studio e quello di controllo sono
  ben randomizzati?
• Linterpretazione dei risultati è priva di bias?

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EVIDENCE BASED SURGERY
Validation of evidence implies that each
clinician is sufficiently methodologically and
statistically knowledgeable and competent, and
that he can correctely and adequately assess the
methods used in the literature to achieve the
results under scrutiny
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DUE ESEMPI DI DISCREPANZA (I)
Chemotherapy after surgery compared with surgery
alone for adenocarcinoma of the stomach Macdonald
JS et al N. Eng. J. Med. 2001
Interpretation/conclusions Postoperative
chemioradiotherapy should be considered for all
patients at high risk for recurrence of
adenocarcinoma of the stomach who have undergone
curative resection
Methods/Results Most patients (54) had
undergone a D0 dissection which means that a
complete dissection of the N1 nodes was not
performed -We were unable to detect any
differences in the effects of treatment according
to the extent of surgical procedure
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VALUTAZIONE DELLEVIDENZA
Chemotherapy after surgery compared with surgery
alone for adenocarcinoma of the stomach Macdonald
JS et al N. Eng. J. Med. 2001
Poiché la maggior parte dei pazienti è stata
sottoposta a resezione D0, lo stato linfonodale
attuale di tali pazienti non è noto. Pertanto la
conclusione, che si riferisce ai pazienti ad alto
rischio, non è basata sui dati poiché lo stato
linfonodale, il miglior fattore prognostico
predittivo di alto rischio, non è stato
identificato per tutti i pazienti!
NO EVIDENCE!!!
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DUE ESEMPI DI DISCREPANZA (II)
Medical Research Council Oesophageal Cancer
Working Party. Surgical resection with or without
preoperative chemotherapy in oesophageal cancer
a randomised controlled trial. Lancet 2002
Interpretation/conclusions Two cycles of
preoperative cisplatin and fluorouracil improve
survival without additional serious adverse
events in the treatment of patients with
resectable esophageal cancer
Methods/Results Overall survival was better in
the group which received preoperative
chemotherapy than in the immediately surgically
resected patients (p 0.004). We saw no evidence
that effect of chemotherapy varied in accordance
with histology
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VALUTAZIONE DELLEVIDENZA II esempio
Medical Research Council Oesophageal Cancer
Working Party. Surgical resection with or without
preoperative chemotherapy in oesophageal cancer
a randomised controlled trial. Lancet 2002
NO EVIDENCE!!!
Gli autori non commentano il fatto che le curve
di sopravvivenza (Kaplan-Meier) non mostrano
differenza nel caso del carcinoma squamocellulare
(p 0.1), a differenza di quanto accade per
ladenocarcinoma (p 0.002). Si tratta di due
istotipi differenti, ed è comprensibile che
rispondano in maniera differente alla
chemioterapia. Pertanto le conclusioni dello
studio sono applicabili esclusivamente
alladenocarcinoma dellesofago!
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EVIDENCE BASED SURGERY come insegnarla?
Teaching EBS should be a major part of our
academic life and the time spent with our
students. Teaching EBS is fulfilling the role of
teaching an objective, conscientious, realiable
method of practicing our art of medicine and
making it as scientific as possible. This is not
possible without wide and full access to the
medical literature or without the knowledge of
methodology...
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EVIDENCE BASED SURGERY limiti
When applied to surgical practice, it appears
clearly that the concept of Evidence-based
medicine involves some limitations, related to
the low quantity and quality of randomized
controlled trial and meta-analyses in surgery,
the difficulties when critically appraising the
literature and applying the results of evidence
to individual patients
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EVIDENCE BASED SURGERY limiti
Surgeons are faced with an increasing operative
volume, clinical visits, hospitalization care,
growing administrative formalities it is well
known that surgeons are not willing to endorse
all evidences because of their own personalities
(self-confidence, lack of patience, important and
quick clinical decisions, decisive action during
operations)
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EVIDENCE BASED quanto viene applicata?
How good is the quality of health care in the
United States? Schuster M et al - 1998
Success, failure in the implementation of
evidence-based guidelines for clinical
practice. Grol R - Med. Care 2001
Oltre il 40 dei pazienti NON riceve trattamenti
evidence-based!
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EVIDENCE BASED come porre rimedio?

• Definire aspetti fondamentali curve di
  apprendimento, standardizzazione delle procedure,
  etc
• Incoraggiare lo sviluppo di trial multicentrici
• Invogliare i pazienti a partecipare ai trial
  randomizzati
• Incrementare lo studio dellepidemiologia clinica
• Incoraggiare lo sviluppo di meta-analisi
• Introdurre lo studio dellEvidence-based
  nellambito dei corsi universitari

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EVIDENCE BASED come porre rimedio?
Evidence-based surgery a passing fad? Black N
World J. Surg 199923789-793
If we recognize the limits of Evidence-based
Surgery using a purist Evidence-based Medicine
approach and we try to overcome these limits,
there is a chance that EBS will prove to be more
than a passing fad
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EVIDENCE BASED SURGERY