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Class 2

Advisor: Alberto Freitas

Introdução à Medicina II

1. Introduction1. Background2. Justification3. Aims

2. Participants and Methods1. Study participants2. Study design3. Data collection methods4. Variable descriptions5. Statistical analysis

3. Results

4. Conclusion and Discussion

5. References

Abdominal Aortic Aneurysm (AAA)

› Permanent focal dilatation of the abdominal artery below the kidneys (infrarenal) to at least1,5 times its normal diameter1

› Normal values (above 50 years-old)2

Men: 1,99 cm Women: 1,66 cm

1 Upchurch (2006) Am Fam Physician, 73(7): 1198-204

2 Lederle (1997) J Vasc Surg, 26(4): 595-601

3 Johnston (1991) J Vasc Surg, 13(3): 452-8

Normal aorta Aorta with large abdominal aneurysm

Convention: an infrarenal aorta of 3 cm in diameter or larger is considered aneurysmal3

Abdominal aortic aneurysm affects 1% of individuals over the age of 55 and increases in incidence by 2% to 4% per decade thereafter1

Main risk factors:

› Gender: Men are 3 times more likely to develop this type of aneurysm

than women2

Men are 10 times more likely to have an aneurysm of this type of 4 cm or larger3

› Age Incidence rapidly increases after age 55 in men / 70 in women4

1 Berman (2008) J Vasc Surg, 47(2): 287-295

2 Egorova (2008) J Vasc Surg, 48(5): 1092-100

3 Katz (1997) J Vasc Surg, 25(3): 561-8

4 Lederle (1999) JAMA, 281(1): 77-82

Two major types of surgical interventions:

› Open Repair (OR)1

› Endovascular Aneurysm Repair (EVAR) 2

OR EVAR

- Invasive

- Higher recovery time

- Normally does not require subsequent surgeries

- Less invasive

- Lower recovery time

- Normally requires subsequent surgeries (either immediately or for later graft replacement)

Performed in patients with high risk of post-operative complications

1 Prinssen (2004) N Engl J Med, 351(16): 1607-18

2 Greenhalgh (2004) Lancet, 364(9437): 843-8

Abdominal aortic aneurysm is one of the 10 major causes of death in men over 65 years of age in western countries.1

It is important to learn how surgical interventions used and fatality vary in different regions knowing which regions have better outcome for either EVAR or OR

will allow us to conclude where the patient has best chances of survival

Comparing Portugal’s mortality rates with those of other countries will allow us to conclude whether it is better or worse to be submitted to this type of surgical intervention in Portugal

Portugal may serve as an example of either what to do or what not to do in regard to the surgical intervention chosen for treating an abdominal aortic aneurysm

1 Katz (1997) J Vasc Surg, 25(3): 561-8

To analyse the baseline characteristics for patients undergoing endovascular or open abdominal aortic aneurysm repair in Portuguese mainland state hospitals during the studied period

To compare the choice of surgical approach (EVAR or OR) among the different regions;

To determine the most frequent type of abdominal aortic aneurysm (ruptured or non-ruptured) submitted to surgical intervention in Portuguese mainland state hospitals of each region;

To calculate and compare the in-hospital mortality associated: with ruptured / non-ruptured aneurysms with the different surgical approaches (OR and EVAR) with the different regions



3. Results


5. References

All Portuguese mainland state hospitals inpatients episodes

› Diagnosed with ruptured/non-ruptured abdominal aortic aneurysm

› Submitted to either OR or EVAR for these conditions

Database:

› records from all Portuguese mainland state hospitals› period 2000-2009*

* incomplete data (from Jan-Sep)

1. Characterization of the population by: Gender Age

2. Yearly ratio ruptured/non-ruptured surgeries

3. Yearly ratio OR/EVAR

4. In-hospital mortality

Patient hospital episode administrative database using the DRG classification system

Diseases and Injuries Codes

441.3 Ruptured aneurysm of the abdominal aorta

441.5 Aortic aneurysm unspecified site ruptured

441.4 Aneurysm of the abdominal aorta, without mention of rupture

441.9 Aortic aneurysm of unspecified site without mention of rupture

Procedures Codes

39.51 Clipping of aneurysm

39.52 Other repair of aneurysm

39.25 Aorta iliac femoral bypass

38.44 Resection of vessel with replacement, abdominal aorta

39.71 Endovascular implantation of graft in abdominal aorta

39.79 Other endovascular repair (of aneurysm) of other vessels

ICD-9-CM codes used for patient selection

Ruptured aneurysm

Non-ruptured aneurysm

Open repair (OR)

Endovascular repair (EVAR)

Gender (raw data)

Age (raw data)

Type of Aneurysm (recoded variable)

• ruptured vs. non-ruptured

Type of surgical intervention (recoded variable)

• OR vs. EVAR

Mortality (raw data)

Location of mainland state hospital (recoded variable)

• Division in 5 regions (Norte, Centro, Lisboa, Alentejo and Algarve) according to the NUTS II classification



3. Results


5. References

2474 repairs

200 excluded (date of surgery unregistered)

n = 2274

Norte

Centro

Lisboa

Alentejo

Algarve

n = 656

n = 349

n = 1249

n = 19

n = 1

28,85%15,35%54,92%

0,84%

0,04%

Norte (n=656) Centro (n=349) Lisboa (n=1249) Alentejo

(n=19)

Algarve

(n=1)*p**

Characteristics OR

(n=574)

EVAR

(n=82)

OR

(n=335)

EVAR

(n=14)

OR

(n=1112)

EVAR

(n=137)

OR

(n=19)

EVAR

(n=0)

OR

(n=1)

EVAR

(n=0)

Age, mean (SD),

y

71 ± 9 73 ± 7 71 ± 9 69 ± 9 71 ± 9 74 ± 8 73 ± 10 - 65 - 0.005

Male gender, %

(No.)

93.0

(534/574

)

95.1

(78/82)

92.2

(309/335

)

100

(14/14)

92.4

(1028/111

2)

86.1

(118/137

)

89.5

(17/19)

-

(-/-)

100.0

(1/1)

-

(-/-) 0.120

* Lack of cases impaired statistical analysis.**Calculated using the Kruskal-Wallis test for age and the Chi square test for male gender.

Baseline characteristics for patients undergoing endovascular or open abdominal aortic aneurysm repair in Portuguese mainland state hospitals during the studied period

There are significant differences between the age of patients

Patients submitted to EVAR in Lisboa are older than those submitted to OR in Norte, Centro and Lisboa (determined using Mann-Whitney U paired test and Holm-Bonferroni adjustment)

There are no significant differences between the gender of patients

Yearly distribution of total Abdominal aortic aneurysm repairs according to surgical intervention

OR was the preferred method from 2000-2009

EVAR is increasing since 2005

Yearly distribution of total Abdominal aortic aneurysm repairs according to surgical intervention

Yearly percentage of endovascular aneurysm repair in total abdominal aortic aneurysm surgical interventions in Portuguese mainland state hospitals

Yearly distribution of total abdominal aortic aneurysm (AAA) surgical interventions according to aneurysm type

The ratio Non-ruptured/Ruptured AAA is approximately 3/1

Yearly percentage of non-ruptured aneurysm repairs in total abdominal aortic aneurysms surgical interventions in Portuguese mainland state hospitals

AAA /Surgery

types

Norte

(n=656) p*

Centro

(n=349) p*

Lisboa

(n=1249) p**

Alentejo

(n=19)*

**

Algarve

(n=1)***

Total

(n=2274

)

p**

Non-

ruptured

OR

6.2%

(27/438)

0.102

7.0%

(16/228)

0.564

7.9%

(64/815)

0.836

18.8%

(3/16)

-

(-/-)

7.3%

(110/149

7)0.26

5

EVAR1.3%

(1/76)

9.1%

(1/11)

7.3%

(9/123)

-

(-/-)

-

(-/-)

5.2%

(11/210)

Ruptured

OR

45.6%

(62/136)

0.100

54.2%

(58/107)

1.000

50.8%

(151/297

) 0.645

66.7%

(2/3)

100%

(1/1)

50.4%

(274/544

)0.16

3

EVAR83.3%

(5/6)

66.7%

(2/3)

57.1%

(8/14)

-

(-/-)

-

(-/-)

65.2%

(15/23)*Calculated using the Fisher’s exact test.**Calculated using the Chi square test.***Lack of cases impaired statistical analysis.

Regional distribution of in-hospital mortality according to type of abdominal aortic aneurysm and repair procedure

No significant differences on mortality were found between OR and EVAR

Tendency for EVAR to present better outcome in non-ruptured AAAs

Tendency for OR to present better outcome in ruptured AAAs



3. Results


5. References

Gender/Age

Men were the most affected gender undergoing surgery (9 to 1) AAAs 3 times more frequent in men AAAs larger in men

Patients undergoing EVAR in Lisboa are significantly older than those undergoing OR in Norte, Centro and Lisboa triage process where high-risk, older patients are selected

for EVAR

Open Repair vs. Endovascular Aneurysm Repair

Increase in total number of surgeries

OR as the preferred surgical intervention

Increase in the use of EVAR

Open Repair vs. Endovascular Aneurysm Repair

EVAR may present better outcome in non-ruptured aneurysms (not confirmed by statistical analysis)

EVAR in ruptured aneurysm seemingly increases in-hospital mortality only performed as last resort, on patients where survival

odds are already low

Ruptured aneurysm vs. non-ruptured aneurysm

Most surgical interventions performed on non ruptured aneurysm most patients with ruptured aneurysm don’t reach

hospital alive

Elective surgery presents low in-hospital mortality

Treating an aneurysm prior to its rupture is the main factor for achieving lower mortality rates

Prior published in-hospital and 30-day mortalities following treatment of ruptured and non-ruptured abdominal aortic aneurysms

In-hospital mortality rates

Higher than those of other Western countries

Exception: Norte

Limitations

Low number of patients undergoing EVAR could explain high p values obtained,

impairing statistical confirmation of the EVAR better outcome, especially in

Norte

The cause of death of patients with ruptured abdominal aortic aneurysm is

often attributed to other pathologies – numbers may be underestimated

Surgeons’ personal testimonies refer the use of EVAR since the beginning of

the decade – directly contradicts the data

› Flawed insertion of the ICD-9-CM codes on database

› Lack of specific training for using the software

› Complex procedures to registry data



3. Results


5. References

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ana catarina rodrigues, carolina rodrigues, catarina cruz, diogo costa, isabel vazquez, joana...

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