Systematic review
Patient volume and quality in vascular surgery: a systematic review
Systematic review
|Updated
We conducted a systematic review of studies exploring the relationship between patient volume and quality in vascular surgery.
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Key message
Vascular surgery are procedures related to diseases of the blood vessels, i.e. the arteries and veins of the circulatory system of the body. Typically, this includes surgery of the aorta, carotid arteries, and vessels of the lower extremities. The quality of these procedures is thought to be dependent on patient volume, based on the assumption that complicated procedures are best performed by those who do it often, and that “practice makes perfect”.
We conducted a systematic review of studies exploring the relationship between patient volume and quality in vascular surgery. We included 89 observational studies. We found that:
- higher volume had a possible impact on quality when evaluated on both surgeon and hospital level.
- higher volume had a possible impact on quality for both open and endovascular surgery.
- higher patient volume possibly reduces mortality for patients with abdominal aortic aneurysms, thoracic abdominal aortic aneurysms, carotid artery stenosis, peripheral vascular disease and renal artery disease.
- higher patient volume also possibly reduces complications in patients with abdominal aortic aneurysms, carotid artery disease and peripheral vascular disease, and length of stay (hospital days) in patients with abdominal aortic aneurysms and carotid artery disease.
- there is a need for more studies evaluating the volume-quality relationship for patients with acute admissions, and for studies assessing outcomes such as length of stay and cost.
Summary
Background
Vascular surgery includes procedures related to diseases of the blood vessels, i.e. the arteries and veins of the circulatory system of the body. Typically, this includes surgery of the aorta, carotid arteries, and vessels of the lower extremities. The quality of these procedures is thought to be dependent on patient volume, based on the assumption that complicated procedures are best performed by those who do it often, and that “practice makes perfect”. We conducted a systematic review of studies exploring the relationship between patient volume and quality in vascular surgery.
Method
We performed systematic searches of relevant databases. We searched for systematic reviews, as well as randomized and observational studies comparing institutions or surgeons with high volume of vascular surgery with lower patient volume. We summarized the results descriptively and assessed the certainty of the overall evidence using GRADE for each outcome.
Results
We included 89 observational studies that evaluated the relationship between patient volume and vascular surgery on quality indicators. The studies included patients from USA, Canada, UK, Finland, Germany, Australia, Norway, Japan and France. The smallest study included 155 patients and the largest 491 779 patients. Thresholds for volume varied between studies and procedures, for example, median low volume for elective open surgery for abdominal aortic aneurysms was <9 procedures, and > 35 for high volume. Overall, we judged the evidence to be of moderate to very low certainty. For this summary we describe outcomes judged to be of moderate to low certainty.
Abdominal aortic aneurysms
- For all surgery, there is:
- possibly lower 30-day mortality in high volume hospitals and for high volume surgeons.
- possibly less in-hospital mortality and fewer complications in high volume hospitals.
- For open surgery, there is:
- possibly lower 30-day mortality in high volume hospitals, and possibly also for acute admissions.
- possibly less in-hospital mortality in high volume hospitals.
- probably less in-hospital mortality for high volume surgeons, and possibly also for acute admissions.
- possibly less complications in high volume hospitals.
- possibly fewer days in hospital in high volume hospitals (elective patients).
- For endovascular surgery, there is:
- possibly lower 30-day mortality in high volume hospitals.
- possibly less in-hospital mortality in high volume hospitals (elective patients).
- possibly less complications in high volume hospitals (elective patients).
Thoracic and abdominal aortic aneurysms
- For open surgery, there is:
- possibly lower 30-day mortality in high volume hospitals.
- probably less in-hospital mortality in high volume hospitals.
- possibly less in-hospital mortality for high volume surgeons (elective patients).
- For endovascular procedures, there is:
- possibly lower 30-day mortality in high volume hospitals, and lower risk of in-hospital mortality and complications for high-volume surgeons.
Carotid artery disease
- For open surgery, there is:
- possibly lower 30-day mortality in high volume hospitals and for high volume surgeons.
- possibly less in-hospital mortality in high volume hospitals and for high volume surgeons.
- possibly less complications for high volume surgeons (including patients with severe carotid artery disease).
- possibly fewer hospital days for high volume surgeons (including patients with severe carotid artery disease).
- For endovascular surgery, there is:
- possibly lower 30-day mortality and fewer complications in high volume hospitals and for high volume surgeons (elective patients). For surgeon volume, this also includes patients with severe carotid artery disease.
- possibly less in-hospital mortality and complications combined for high volume surgeons (elective patients).
- possibly fewer hospital days for high volume surgeons.
Peripheral artery disease (aorto-iliac arteries and lower extremities)
- For all surgery, there is:
- possibly less in-hospital mortality and complications combined for high volume surgeons.
- For open surgery, there is:
- possibly lower 30-day mortality and less in-hospital mortality in high volume hospitals.
- possibly fewer complications in high volume hospitals and for high volume surgeons (elective patients).
- For endovascular surgery, there is:
- possibly less in-hospital mortality in high volume hospitals.
Renal artery disease
- For open surgery, there is:
- possibly less in-hospital mortality in high volume hospitals.
Discussion
We considered the evidence to be of moderate to very low certainty. In particular, there was insufficient evidence about the relationship between volume and quality for acute admissions, and for quality measures such as length of stay and costs. This is mainly due to few studies evaluating certain outcomes (precision), and that effect-estimates and measures of variance for several outcomes were not reported in the studies. There is also uncertainty as to some of the outcomes due to variability in results across studies. We judged two outcomes to be of moderate certainty, and which showed evidence of a strong association between volume and in-hospital mortality. Both outcomes were measured for patients undergoing open elective surgery. The first evaluated surgeon volume for abominal aortic aneurysms and the second hospital volume for patients with thoracic and abdominal aortic aneurysms.
In addition to patient volume, patient related or system factors can also affect patient outcomes as well as resource use. Most of the included studies adjusted for such confounding patient factors, but in many studies, the baseline patient characteristics per volume group (high-volume vs. low-volume) were not reported. However, it is important to emphasize that in spite of these weaknesses, the studies included a large number of patients and with consistent conclusions across countries and health systems. Although many of the studies were from contexts with much larger populations, the median volume thresholds were comparable to those in smaller populations such as Norway.
Conclusion
Overall, we found that higher volume had a possible impact on quality when evaluated on both surgeon and hospital level. The available evidence also suggest that volume has an impact on quality for both open and endovascular surgery.
Higher patient volume possibly reduces mortality for patients with abdominal aortic aneurysms, thoracic and abdominal aortic aneurysms, carotid artery stenosis, peripheral vascular disease and renal artery disease. We also found that higher patient volume possibly reduces complications in patients with abdominal aortic aneurysms, carotid artery disease and peripheral vascular disease, and length of stay (hospital days) in patients with abdominal aortic aneurysms and carotid artery disease. More studies are needed evaluating the volume-quality relationship for patients with acute admissions, and for outcomes such as length of stay and cost.
The association was stronger and more certain for in-hospital mortality for patients with abdominal aortic aneurysms (hospital volume) and thoracic- and abdominal aortic aneurisms (surgeon volume) undergoing open elective surgery.
There are many other factors at the local level, including chance, which may explain quality of care associated with surgical procedures. This means that the results from this review cannot be generalized to the individual hospital or surgeon. Instead, this systematic review is intended as a general decision support for informing decisions about the organization of health services.
