***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: We included 10 trials involving 1967 patients undergoing 2157 operations. The quality of trials was generally poor. Follow up varied from hospital discharge to five years. Carotid patch angioplasty was associated with a reduction in the risk of ipsilateral stroke during the perioperative period (odds ratio (OR) 0.31, 95% confidence interval (CI) 0.15 to 0.63, P = 0.001) and long-term follow up (OR 0.32, 95%CI 0.16 to 0.63, P = 0.001). It was also associated with a reduced risk of perioperative arterial occlusion (OR 0.18, 95% CI 0.08 to 0.41, P < 0.0001), and decreased restenosis during long-term follow up in eight trials (OR 0.24, 95% CI 0.17 to 0.34, P < 0.00001). These results are more certain than those of the previous review since the number of operations and events have increased. However, the sample sizes are still relatively small, data were not available from all trials, and there was significant loss to follow up. Very few arterial complications, including haemorrhage, infection, cranial nerve palsies and pseudo-aneurysm formation were recorded with either patch or primary closure. No significant correlation was found between use of patch angioplasty and the risk of either perioperative or long-term all-cause death rates. Limited evidence suggests that carotid patch angioplasty may reduce the risk of perioperative arterial occlusion and restenosis. It would appear to reduce the risk of ipsilateral stroke and there is a non significant trend towards a reduction in perioperative any stroke rate and all-cause case fatality.
Output:

Evidence from this review of 10 trials involving 1967 patients undergoing 2157 operations now suggests a benefit from using routine patch angioplasty during carotid endarterectomy. About 20% of strokes result from narrowing of the carotid artery (the main artery supplying blood to the brain). Carotid endarterectomy is an operation that involves opening the carotid artery to remove this narrowing and, therefore, reduce the risk of stroke. However, there is a 2% to 10% risk of the operation itself causing a stroke. Some surgeons advocate the incorporation of a patch made out of either synthetic material or the patient's own vein, into the arterial closure. This may help to reduce the risk of the artery being narrowed during suture placement and may, therefore, reduce the risk of recurrent blockage and consequent stroke or death or both. However, use of a patch may increase surgical difficulty and operation length. Furthermore, thin-walled vein patches may rupture with potentially fatal consequences and synthetic materials are vulnerable to infection.