***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Because leukotrienes have potent local effects on cutaneous vasculature , leukotriene antagonists might be effective in the treatment of chronic urticaria . OBJECTIVE A double-blinded , placebo-controlled trial comparing cetirizine 10 mg daily in combination with zafirlukast 20 mg twice a day versus cetirizine 10 mg daily and placebo was conducted to determine whether subjects with chronic urticaria benefit from add-on therapy with a leukotriene-modifying agent . METHODS Patients 12 years or older with a history of chronic urticaria ( more than 6 weeks in duration ) required diary documentation of 6 or more hives on at least 2 days/week and a suboptimal response to H(1)-antagonist therapy for enrollment . At baseline , all subjects were skin tested to autologous serum to assess for the potential presence of FcepsilonRI or IgE autoantibodies . Subjects meeting the initial entry criteria were treated with cetirizine 10 mg a day and placebo twice daily for 1 week . Those patients with persistent hives were r and omized to receive cetirizine 10 mg daily and zafirlukast 20 mg twice a day or cetirizine 10 mg daily and placebo . At each successive weekly visit , physician and patient treatment effectiveness score ( TES ) and visual analog scale ( VAS ) ratings were recorded . Statistical analysis used generalizing estimating equations to compare the effect of combination therapy versus monotherapy on TES and VAS ratings . Results were adjusted for baseline rating , recruiting center , and autologous serum skin test ( ASST ) . A separate analysis evaluated patients with positive ASST results receiving combination therapy versus monotherapy . RESULTS Combination therapy with zafirlukast demonstrated a modest but significantly greater improvement compared with cetirizine monotherapy in physician and patient recorded VAS ratings at visit 4 and across treatment visits 4 through 6 ( P < .05 unless stated otherwise ) . Subjects with ASST positive results receiving combination therapy as compared with subjects with negative ASST results exhibited a significant improvement in patient recorded VAS ratings across visits 4 through 6 . Subgroup analysis of subjects with ASST positive results receiving combination therapy versus monotherapy showed improvement in physician recorded TES at visit 5 , physician recorded VAS at visits 4 and 5 and across visits 4 through 6 , as well as for patient recorded VAS at visit 5 . There were no significant results for patients with ASST negative results . CONCLUSION The results of this study indicate that only patients with autoimmune ( ASST positive ) chronic urticaria refractory to H(1)-antagonist monotherapy might benefit from the addition of the leukotriene D(4)-receptor antagonist zafirlukast to their treatment regimen . These results also suggest that routine screening of patients with chronic urticaria with the ASST might be useful in formulating therapeutic algorithms in the management of chronic urticaria BACKGROUND Antihistamines ( AH ) alleviate pruritus and decrease the incidence of hives in patients with chronic idiopathic urticaria ( CU ) . However , some patients do not respond completely to this therapy . We hypothesized that some of them might benefit from the addition of leukotriene receptor antagonists ( LA ) . METHODS We screened patients diagnosed and treated for CU and selected those that had symptoms despite antihistamine treatment . In a double-blind crossover study , patients took the leukotriene antagonist montelukast ( 10 mg per day ) or placebo .  Efficacy was assessed by a symptom score . RESULTS In a group of 22 patients , the symptom score was not significantly different between periods using montelukast ( 48.8 ; 0 - 214 ) or placebo ( 68.5 ; 0 - 230 ) . However in the subgroup of five patients with the most severe urticaria , defined as patients with symptom scores in the upper quartile at inclusion in the study , montelukast ( 41 ; 11 214 ) was superior to placebo ( 95.5 ; 48 230 ; p < 0.05 ) , but only when using an in-house symptom score question naire and not when using a vali date d urticaria activity score question naire . CONCLUSIONS We showed that in patients with antihistamine-resistant CU the addition of montelukast significantly diminished symptoms in only a small minority of patients . However , response to add-on montelukast was seen in the subgroup of patients with particularly severe disease . To confirm this observation , a study with a larger group of patients is warranted Background Chronic urticaria ( CU ) is a common skin condition . It is frequently a disabling disease due to the persistency of clinical symptoms , the unpredictable course and negative influence on the quality of life Background : Chronic idiopathic urticaria ( CIU ) is often difficult to treat . Although histamine-releasing activity is detectable for up to 50 % of CIU patients , antihistamine therapy provides only a limited response . Objective : This study aim ed to assess the clinical efficacy of combined leukotriene receptor antagonist ( LRA ) and H1 antihistamine , H1 and H2 antihistamine , and two H1 antihistamines as a synergistic therapeutic regimen for treating CIU compared with a matched placebo modality . Methods : A total of 120 newly diagnosed adult patients were evaluated . Patients were single blinded and r and omly assigned to one of four medication groups that received the following regimens for 4 weeks : Group A , combination of sedating H1 antihistamine and non-sedating H1 antihistamine ; Group B , combination of H1 antihistamine and H2 antihistamine ; Group C , combination of H1 antihistamine and LRA ; and Group D , matched placebo medication . The primary measure of treatment efficacy was the daily urticaria activity score ( UAS ) of ‘ wheal and itch ’ . A positive therapeutic response was defined as a reduction to < 25 % of baseline weekly UAS , while a relapse was a return to > 75 % of baseline weekly UAS . Results : In all , 107 patients completed the trial medication . At the end of 4 weeks , the UAS score as a response to treatment was 23.3 % for Group A , 63.3 % for Group B , 53.3 % for Group C , and no real change for the placebo treatment group . Conclusions : The combination of LRA and H1 receptor antagonist is promising for CIU treatment and is reasonably well tolerated by patients . The combination of H1- and H2-receptor antagonists provided the greatest treatment efficacy by the measures used in this small study BACKGROUND H 1 -receptor antagonists are considered to be particularly effective in reducing pruritus , and they are therefore recommended as first-line treatment in patients with chronic idiopathic urticaria ( CIU ) . Recently , antileukotriene receptors have been used in patients with CIU , either administered as monotherapy or combined with H 1 -receptor antagonists . OBJECTIVE We compared the clinical efficacy of 5 mg of desloratadine administered once daily either as monotherapy or combined with a leukotriene antagonist , 10 mg of montelukast daily , and 10 mg of montelukast administered daily as monotherapy for the treatment of patients affected by CIU with placebo . METHODS One hundred sixty patients aged 18 to 69 years ( mean + /- SD , 43.9 + /- 13.4 years ) with a history of moderate CIU were selected . A r and omized , double-blind , double-dummy , placebo-controlled , parallel-group study design was used . Patients were treated with 5 mg of desloratadine once daily ( n = 40 ) , 10 mg of montelukast once daily ( n = 40 ) , 5 mg of desloratadine ( n = 40 ) in the morning plus montelukast in the evening , or matched placebo ( n = 40 ) . Assessment of treatment efficacy was based on scores of daily cutaneous symptoms evaluated reflectively and instantaneously . RESULTS Only the group treated with desloratadine as monotherapy or as combined therapy concluded the whole study . Twenty-seven of the 40 patients in the montelukast group and 35 of the 40 patients in the placebo group discontinued the treatment . As reflective evaluation , all groups showed significant differences compared with the placebo group in terms of total symptom score , number of hives , and size of largest hive . In addition to the pruritus , only the groups treated with desloratadine as monotherapy or combined therapy showed significant differences compared with those receiving placebo , whereas there were no differences between the montelukast and placebo groups . Finally , no differences were found between the desloratadine group and the desloratadine plus montelukast group . The instantaneous evaluation demonstrated similar results regarding the desloratadine group and the desloratadine plus montelukast group versus the placebo group , whereas there were no significant differences between the group treated with montelukast alone and the placebo group for pruritus and size of largest hive . No differences were found between the group treated with desloratadine alone and the desloratadine plus montelukast group . CONCLUSIONS The results of this comparative study demonstrate that desloratadine is highly effective for the treatment of patients affected by CIU . In addition , the regular combined therapy of desloratadine plus montelukast does not seem to offer a substantial advantage with respect to desloratadine as monotherapy in patients affected by moderate CIU BACKGROUND Chronic idiopathic urticaria ( CIU ) might be refractory to st and ard therapies . For the patients with severe unremitting CIU who have failed to benefit from conventional therapy with antihistamines , other effective and safe therapeutic modalities are required . OBJECTIVE A r and omized , single-blind , placebo-controlled crossover study was conducted to evaluate the efficacy and safety of the new selective leukotriene antagonist montelukast sodium in the treatment of refractory CIU . METHODS Thirty patients with refractory CIU were enrolled in the trial . After informed consent was obtained , patients were r and omly assigned to 2 groups . The patients in group A received 10 mg/d montelukast and a nonsedating H(1 ) antihistamine ( cetirizine ) when needed for 6 weeks . After a 2-week washout period , they received placebo for 6 weeks and the same H(1 ) antihistamine as needed . Group B received the treatment vice versa . Improvement was monitored by using the self-estimated urticaria activity score , which is the sum of the wheal number score and the itch severity score , and the antihistamine counts used in each study period . RESULTS More significant decreases occurred in urticaria activity scores with montelukast therapy compared with those with placebo therapy ( P < .001 ) . H(1 ) antihistamine use was also significantly less frequent during the montelukast period ( P < .001 ) . There were no significant side effects with montelukast therapy . CONCLUSION The present study results suggest that montelukast might be an effective and safe therapeutic agent in the treatment of refractory CIU Background Leukotriene receptor antagonists have shown some efficacy in the treatment of asthma . Injection of LTC4 , LTD4 and LTE4 into the skin leads to a weal‐ and ‐flare reaction , suggesting an involvement of leukotrienes in the pathogenesis of urticaria . Indeed , various reports have indicated a beneficial effect for leukotriene receptor antagonists in patients with chronic urticaria Background The cause and pathogenesis of chronic urticaria are still poorly understood . IgE‐independent reactions , are common in adult patients with chronic urticaria , who have daily spontaneous occurrence of weals .  H1‐receptor antagonists ( antihistamines ) are the major class of therapeutic agents used in the management of urticaria and angioedema . Nevertheless , chronic urticaria is often difficult to treat and may not be controlled by antihistamines alone . It has been postulated that mediators other than histamine , such as kinins , prostagl and in and leukotrienes , may be responsible for some of the symptoms in urticaria which are not controlled by antihistamines . In this study , which was r and omized double‐blind , placebo‐controlled , we compare the clinical efficacy and safety of montelukast ( MT ) 10 mg given once a day and cetirizine ( CET ) 10 mg given once a day with placebo ( PLA ) , in the treatment of patients with chronic urticaria who have positive challenge to acetylsalicylic acid ( ASA ) and /or food additives 
    Output:
    
Most trials indicated that LTRA are not superior to placebo or antihistamine therapy , while combination therapy of LTRA and antihistamines appear to be more efficacious compared to antihistamine alone .
The side effect profile and tolerability of this group of drugs is acceptable .
The use of LTRA as monotherapy can not be recommended .
LTRA are effective add-on therapy to anti-histamines , and their use in patients responding poorly to antihistamines is justifiable .