Surveillance Versus Surgical Repair Flashcards
UKSAT
United Kingdom Small Aneurysm Trial
Aims of UKSAT:
- Compare long term survival and treatment costs of early surgical repair versus surveillance of small aneurysms
- Contrast survival of patients with small aneurysms against the general population
Methods of UKSAT:
A randomised controlled trial spanning 1993-95
Had follow up for 10 years (gives a good level of evidence)
1090 patient = a large trial
2 groups:
1 = screening
2= early surgical repair
Used limited evidence from trials in the 1940’s that showed aneurysms >6 were of risk and <6 safer to determine cut off points:
1. 4.0-4.9 = 6 month surveillance
2. 5.0-5.5 = 3 month surveillance
*If aneurysms exceeded 5.5cm or >1cm growth per year then surgery was offered in both groups
UKSAT Outcomes:
Early surgical repair <5.5cm conveyed NO BENEFIT in comparison to surveillance
No significant long-term survival benefit of early surgical repair compared to surveillance
Even with successful repair, mortality in surgical patients was higher than the general population (probably because the risk factors causing AAA are risk factors for other serious morbidities too)
3/4 of the surveillance group ended up having repair but costs remained higher in the early surgery group (because 1/4 of surveillance patients died from other causes before surgical repair of aneurysm so there were fewer patients to operate on = lower cost)
EVARs in UKSAT:
EVARs were introduced during the follow up of UKSAT as a less invasive alternative to open surgical repair; so were offered to UKSAT patients with aneurysm >5.5cm
Showed that in comparison to open EVAR conveyed a lower 30-day mortality but that there was no difference in all-cause mortality at 4 years. These findings sparked further, larger trials
Other key trials for evaluating surveillance versus repair:
- CAESAR
2. PIVOTAL
CAESAR Trial:
750 patients comparing surveillance and EVAR for <5.5cm aneurysms
Found that mortality, rupture and major morbidity were the same in both groups
PIVOTAL Trial:
1000 patients comparing surveillance and EVAR for <5.5cm aneurysms
Found mortality, rupture and major morbidity were similar in both groups
Trial for Risks and Protective Measures of AAA:
ADAM Trial (Aneurysm Detection and Mangement)
ADAM Trial:
Positive Associations: Increasing age, male sex, smoking, family history, atherosclerosis
Negative Associations: Female sex, diabetes, black ethnicity
What size AAA should be considered for Surgical Intervention?
<5.5cm showed no difference between surveillance and early surgical repair so this is the cut off-above this has not been trialled so is not safe to use.
There is discrepancy though as 13% of aneurysms <5.5cm still ruptured in the UKSAT trial so perhaps the cut off should be lower.
What about patients of better health or who are ‘fitter’?
Hypothesised that ‘fitter’ patients would cope better with early surgical repair so UKSAT performed a sub-analysis using a customised probability index to establish fitness
UKSAT Fitness Sub-analysis:
All-cause mortality and AAA-mortality increased as fitness decreased
BUT there was no difference between surgical and surveillance groups in those deemed good or moderately fit. So performing early surgical repair in fitter patients made no difference.
*Surprisingly, all-cause mortality was improved in the surgery arm of the low fitness group
Conclusion of UKSAT Fitness Sub-analysis:
Surgical repair should be limited to >5.5cm regardless of fitness.
Problems with UKSAT Evidence:
- 13% of AAAs <5.5cm still rupture so a surgical repair cut off of 5.5cm is not 100% safe
- Cut-off is arbitrary as it is based on limited evidence (1940’s >6 or <6)
- Doesn’t properly evaluate EVAR
- Issues with measurement of AAA-UKSAT used Ultrasound whereas ADAM used CT; 0.5cm difference could push patients above or below certain cut offs which can affect outcomes
- Other factors such as thrombi and shape of aneurysm can affect rupture risk and these were not assessed
