***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Background : Data from r and omised studies are lacking on the value of interventional procedures in the management of atheromatous renal artery stenosis . This r and omised prospect i ve trial compared the effects on blood pressure ( BP ) and renal function of percutaneous transluminal angioplasty vs medical therapy in hypertensive patients with both unilateral and bilateral disease . Methods : A total of 135 eligible patients were identified , of whom 55 ( 44 % ) were r and omised . Eligible patients had sustained hypertension , with a minimum diastolic BP of 95 mm Hg on at least two anti-hypertensive drugs . Renal artery stenosis was defined by renal angiography as at least 50 % stenosis in the affected vessel . All patients were observed during an initial 4-week run-in period on a fixed drug regimen and subsequent changes measured from this 4-week baseline . Results : Blood pressure fell during the run-in period in all groups . In patients with bilateral renal artery stenosis r and omised to angioplasty , a statistically significant ( P < 0.05 ) fall in bp was observed at latest follow-up ( range 3–54 months ) . the mean fall in bp at latest follow- up in the angioplasty group , corrected for the medical group response , was 26/10 mm hg . in patients with unilateral renal artery stenosis , no statistically significant or clinical ly important differences in outcome were observed between the two groups . no significant differences or trends in serum creatinine were observed between or within any group during follow-up . major outcome events ( death , myocardial infa rct ion , heart failure , stroke , dialysis ) were similar in the angioplasty and medical groups during follow-up . in the 40/135 patients undergoing angioplasty , serious or potentially serious complications attributable to the procedure were observed in 11 patients , bleeding at the arterial site ( 8 patients ) being the most frequent . Conclusions : In hypertensive patients with atheromatous renal artery stenosis , percutaneous renal angioplasty results in a modest improvement in systolic BP compared with medical therapy alone . This benefit was confined to patients with bilateral disease . No patient was ‘ cured ’ , renal function did not improve , and intervention was accompanied by a significant complication rate The quality of life in patients with hypertension is considered to be impaired mainly by side effects of antihypertensive drug therapy . Since balloon angioplasty for renal artery stenosis has a medication-sparing effect , it may lead to an improvement in quality of life . The objective of the study is to compare the effect of antihypertensive drug therapy and balloon angioplasty on quality of life in patients with hypertension and renal artery stenosis . We compared the quality of life in 56 patients r and omised to balloon angioplasty to that in 50 patients r and omised to antihypertensive drug therapy  after 3 and 12 months of follow-up . Quality of life was measured using a question naire on physical symptoms associated with hypertension and antihypertensive drugs , and two generic health question naires ( MOS Survey and EuroQol instrument ) . After follow-up , the patients who underwent angioplasty used less antihypertensive drugs than the patients who were treated with antihypertensive drugs only ( mean±s.d . , 1.9±0.9 vs 2.5±1.0 drugs after 3 months , P=0.002 ) . They reported similar physical complaints , however , and a similar quality of life . The results after 12 months of follow-up were the same . In conclusion , for patients with hypertension and renal artery stenosis , the decrease in antihypertensive medication after intervention is too small to lead to a detectable improvement in quality of life BACKGROUND Atherosclerotic renal artery stenosis ( ARAS ) is associated with progressive loss of renal function and is one of the most important causes of renal failure in the elderly . Current treatment includes restoration of the renal arterial lumen by endovascular stent placement . However , this treatment only affects damage caused by ARAS due to the stenosis and ensuing post-stenotic ischemia . ARAS patients have severe general vascular disease . Atherosclerosis and hypertension can also damage the kidney parenchyma causing renal failure . Medical treatment focuses on the latter . Lipid-lowering drugs ( statins ) could reduce renal failure progression and could reduce the overall high cardiovascular risk . The additional effect on preserving renal function of stent placement as compared to medical therapy alone is unknown . Therefore , the STAR- study aims to compare the effects of renal artery stent placement together with medication vs. medication alone on renal function in ARAS patients . METHOD Patients with an ARAS of > or = 50 % and renal failure ( creatinine ( Cr ) clearance < 80 mL/min/1.73 m2 ) are r and omly assigned to stent placement with medication or to medication alone . Medication consists of statins , anti-hypertensive drugs and antiplatelet therapy . Patients are followed for 2 yrs with extended follow-up to 5 yrs . The primary outcome of this study is a reduction in Cr clearance > 20 % compared to baseline . This trial will include 140 patients INTRODUCTION AND OBJECTIVES Patients with either renovascular hypertension ( RVH ) and /or renal insufficiency ( RI ) due to renal artery ostial occlusive disease ( RAOOD ) can successfully undergo an open surgical reconstruction procedure ( OSRP ) , but since the publication of Blum et al(1 ) percutaneous balloon stent angioplasty ( PTRA + stent ) leaving a small part of the stent within the aorta has become very popular . However , balloon dilatation and stenting does not remove the atherosclerotic plaque , which is often heavily calcified but leads to disruption of the plaque causing myointimal hyperplasia and recurrent stenosis . Therefore , a comparison of the two treatment modalities concerning complications and durability in a prospect i ve r and omized design was felt to bring more insight to the discussion . METHODS From 1998 to 2004 , we performed  OSRP in 330 patients with RVH and /or RI for various locations of RAOOD . During this time period , 50 patients ( female 18 , male 32 , mean age 64.4 years ) with RAOOD of at least 70 % stenosis ( DSA and duplex criteria ) in one or both renal arteries , who did not require other aorto/mesenteric/iliac reconstructive procedures agreed and were r and omized to either OSRP ( n = 25 patients , 49 arteries ) or PTRA + stent ( n = 25 patients , 28 arteries ) . Two patients crossed over to surgical treatment . Patients were followed on a regular basis for 4 years and longer . Endpoints were re-occurrence of RAOOD and impairment of either kidney function or RVH . RESULTS We approached 77 arteries . There was no early mortality in either group , but directly procedure-related morbidity was 13 % in the interventional group and 4 % in the surgical group . Four-year follow-up mortality was 18 % in the interventional group and 25 % in the surgical group . Both groups showed significant improvement of RVH ( P < .001 in each group ) as well as improvement or stabilization in patients with insufficient renal function . Freedom from recurrent RAOOD ( > 70 % ) was achieved in 90.1 % of the surgical group and 79.9 % of the interventional group . CONCLUSION Both treatment modalities showed good early results concerning RVH , kidney function , and renal perfusion . Despite a higher number of bilateral renal artery reconstructions in patients undergoing OSRP , which was probably due to the preferred technique of transaortic endarterectomy eliminating the plaque originating in the aorta and usually extending into both renal arteries , mortality was not higher and procedure-related morbidity was even lower compared to PTRA + stent . These findings and also longer durability of OSRP imply that surgical reconstruction remains the gold st and ard for patients with RAOOD before PTRA + stent may be considered Data for the effects on blood pressure of renal artery balloon angioplasty are mostly from uncontrolled studies . The aim of this study was to document the efficacy and safety of angioplasty for lowering blood pressure in patients with atherosclerotic renal artery stenosis . Patients were r and omly assigned antihypertensive drug treatment ( control group , n = 26 ) or angioplasty ( n = 23 ) . Twenty-four-hour ambulatory blood pressure , the primary end point , was measured at baseline and at termination . Termination took place 6 months after r and omization or earlier in patients who developed refractory hypertension . In those allocated angioplasty , antihypertensive treatment was discontinued after the procedure but was subsequently resumed if hypertension persisted . Secondary end points were the treatment score and the incidence of complications . Two patients in the control group and 6 in the angioplasty group suffered procedural complications ( relative risk , 3.4 ; 95 % confidence interval , 0.8 to 15.1 ) . Early termination was required for refractory hypertension in 7 patients in the control group . Antihypertensive treatment was resumed in 17 patients in the angioplasty group . Mean ambulatory blood pressure at termination did not differ between control ( 141+/-15/84+/-11 mm Hg ) and angioplasty ( 140+/-15/81+/-9 mm Hg ) groups . Angioplasty reduced by 60 % the probability of having a treatment score of 2 or more at termination ( relative risk , 0.4 ; 95 % confidence interval , 0.2 to 0.7 ) . There was 1 case of dissection with segmental renal infa rct ion and 3 of restenosis in the angioplasty group . No patient suffered renal artery thrombosis . In unilateral atherosclerotic renal artery stenosis , angioplasty is a drug-sparing procedure that involves some morbidity . Previous uncontrolled and unblinded assessment s of angioplasty overestimated its potential for lowering blood pressure BACKGROUND Many studies suggest a major prevalence of atherosclerotic renovascular disease ( ARVD ) , caused by mono or bilateral renal artery stenosis ( RAS ) . Unfortunately , there is no definite therapy to cure this disease to date ; therefore , ARVD is burdened by important clinical complications with high social and economic costs . The last few years have seen important advancements in both medical therapy and in interventional radiology ( for example , percutaneous transluminal renal artery stenting ( PTRS ) ) . All of them could affect , in some way , the natural history of ARVD , but to date the optimal strategy has not been established . METHODS The protocol of a prospect i ve , multicenter , r and omized trial " Nephropathy Ischemic Therapy ( NITER ) " is presented . It enrolls patients with stable renal failure ( glomerular filtration rate ( GFR ) > or=30 ml/min ) and hypertension , and hemodynamically significant atherosclerotic ostial RAS ( > or=70 % ) diagnosed by duplex Doppler ( DD ) ultrasonography and confirmed by magnetic resonance angiography ( MRA ) . This study aims to evaluate whether medical therapy plus interventional PTRS is superior to medical therapy alone according to the following combined primary endpoint : death or dialysis initiation or reduction by > 20 % in estimated GFR after 0.5 , 1 , and 2 yrs of follow-up and an extended follow-up until the 4th year . Medical therapy means drugs to control hypertension , improve dyslipidemia and optimize platelet anti-aggregant therapy .  The sample size is estimated in 50 patients per group to achieve a statistical significance of 0.05 in case of a reduction by 50 % in the combined endpoints This prospect i ve multicenter study included 1,205 patients , who were referred for difficult-to-treat hypertension or analysis of possible secondary hypertension . After a st and ardized selection protocol based on sharply defined drug-resistant hypertension or renal function impairment during angiotensin-converting enzyme inhibition , patients underwent renal scintigraphy and a captopril-renin challenge test . A set of clinical characteristics was also recorded . Sensitivity and specificity of renal scintigraphy  for diagnosing renal artery stenosis were 0.72 and 0.90 and of the captopril-renin test 0.77 to 0.91 and 0.69 to 0.75 depending on the criterion used . The clinical characteristics were used to construct a clinical prediction rule for renal artery stenosis , which had a sensitivity of 0.68 and a specificity of 0.87 at a cut-off level of 30 % predicted probability . However , with the prediction rule a sensitivity of 0.90 could be reached by performing arteriography only in patients with a predicted probability of stenosis of > or = 10 % , result ing in a considerable reduction of the number of arteriograms to be made . A diagnostic strategy is advocated starting with drug-resistant hypertension and continuing to renal arteriography only in patients with increased probability of stenosis . Patients with atherosclerotic renal artery stenosis were then r and omized to balloon angioplasty ( n = 56 ) versus antihypertensive medication ( n = 50 ) . Three months after r and omization 22 patients from the medication group underwent balloon angioplasty in second instance . In an intention-to-treat analysis , no difference in blood pressure was found between the groups after 3 months 
    Output:
    
The available data are insufficient to conclude that revascularisation in the form of balloon angioplasty , with or without stenting , is superior to medical therapy for the treatment of atherosclerotic renal artery stenosis in patients with hypertension .
However , balloon angioplasty results in a small improvement in diastolic blood pressure and a small reduction in antihypertensive drug requirements .
Balloon angioplasty appears safe and results in similar numbers of cardiovascular and renal adverse events to medical therapy