***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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    ***EXAMPLES*** 
    Input: BACKGROUND Therapy with antibiotics influences recovery only in selected cases of COPD exacerbations . We evaluated the efficacy and safety of procalcitonin guidance compared to st and ard therapy with antibiotic prescriptions in patients experiencing exacerbations of COPD . METHODS A total of 208 consecutive patients requiring hospitalization for COPD exacerbation were r and omized at the index exacerbation to procalcitonin-guided or st and ard antibiotic therapy . Patients receiving procalcitonin-guided therapy were treated with antibiotics according to serum procalcitonin levels ; st and ard-therapy patients received antibiotics according to the attending physician . The primary outcome was the antibiotic exposure at the index exacerbation and the subsequent antibiotic requirement for COPD exacerbation within 6 months . Secondary outcomes were clinical recovery , symptom scores , length of hospitalization , ICU stay , death , lung function , exacerbation rate , and time to next exacerbation . RESULTS At the index exacerbation , procalcitonin guidance reduced antibiotic prescription ( 40 % vs 72 % , respectively ; p < 0.0001 ) and antibiotic exposure ( relative risk [ RR ] , 0.56 ; 95 % confidence interval [ CI ] , 0.43 to 0.73 ; p < 0.0001 ) compared to st and ard therapy . Moreover , procalcitonin guidance at the index exacerbation allowed a significant sustained reduction in total antibiotic exposure for up to 6 months ( RR , 0.76 ; 95 % CI , 0.64 to 0.92 ; p = 0.004 ) . Clinical outcome and improvement in FEV(1 ) at 14 days and 6 months did not differ between groups . Within 6 months , the exacerbation rate ( 0.62 vs 0.64 , respectively ) , the rehospitalization rate ( 0.21 vs 0.24 , respectively ) , and mean ( + /- SD ) time to the next exacerbation ( 70.0 + /- 46.1 vs 70.4 + /- 51.9 days , respectively ; p = 0.523 ) were similar in both groups . CONCLUSIONS Procalcitonin guidance for exacerbations of COPD offers a sustained advantage over st and ard therapy in reducing antibiotic use for up to 6 months with a number-needed-to-treat of 3 BACKGROUND Reduced duration of antibiotic treatment might contain the emergence of multidrug-resistant bacteria in intensive care units . We aim ed to establish the effectiveness of an algorithm based on the biomarker procalcitonin to reduce antibiotic exposure in this setting . METHODS In this multicentre , prospect i ve , parallel-group , open-label trial , we used an independent , computer-generated r and omisation sequence to r and omly assign patients in a 1:1 ratio to procalcitonin ( n=311 patients ) or control ( n=319 ) groups ; investigators were masked to assignment before , but not after , r and omisation . For the procalcitonin group , antibiotics were started or stopped based on predefined cut-off ranges of procalcitonin concentrations ; the control group received antibiotics according to present guidelines . Drug selection and the final decision to start or stop antibiotics were at the discretion of the physician . Patients were expected to stay in the intensive care unit for more than 3 days , had suspected bacterial infections , and were aged 18 years or older . Primary endpoints were mortality at days 28 and 60 ( non-inferiority analysis ) , and number of days without antibiotics by day 28 ( superiority analysis ) . Analyses were by intention to treat . The margin of non-inferiority was 10 % . This trial is registered with Clinical Trials.gov , number NCT00472667 . FINDINGS Nine patients were excluded from the study ; 307 patients in the procalcitonin group and 314 in the control group were included in analyses .  Mortality of patients in the procalcitonin group seemed to be non-inferior to those in the control group at day 28 ( 21.2 % [ 65/307 ] vs 20.4 % [ 64/314 ] ; absolute difference 0.8 % , 90 % CI -4.6 to 6.2 ) and day 60 ( 30.0 % [ 92/307 ] vs 26.1 % [ 82/314 ] ; 3.8 % , -2.1 to 9.7 ) . Patients in the procalcitonin group had significantly more days without antibiotics than did those in the control group ( 14.3 days [ SD 9.1 ] vs 11.6 days [ SD 8.2 ] ; absolute difference 2.7 days , 95 % CI 1.4 to 4.1 , p<0.0001 ) . INTERPRETATION A procalcitonin-guided strategy to treat suspected bacterial infections in non-surgical patients in intensive care units could reduce antibiotic exposure and selective pressure with no apparent adverse outcomes . FUNDING Assistance Publique-Hôpitaux de Paris , France , and Brahms , Germany CONTEXT In previous smaller trials , a procalcitonin ( PCT ) algorithm reduced antibiotic use in patients with lower respiratory tract infections ( LRTIs ) . OBJECTIVE To examine whether a PCT algorithm can reduce antibiotic exposure without increasing the risk for serious adverse outcomes . DESIGN , SETTING , AND PATIENTS A multicenter , noninferiority , r and omized controlled trial in emergency departments of 6 tertiary care hospitals in Switzerl and with an open intervention of 1359 patients with mostly severe LRTIs r and omized between October 2006 and March 2008 . INTERVENTION Patients were r and omized to administration of antibiotics based on a PCT algorithm with predefined cutoff ranges for initiating or stopping antibiotics ( PCT group ) or according to st and ard guidelines ( control group ) . Serum PCT  was measured locally in each hospital and instructions were Web-based . MAIN OUTCOME MEASURES Noninferiority of the composite adverse outcomes of death , intensive care unit admission , disease-specific complications , or recurrent infection requiring antibiotic treatment within 30 days , with a predefined noninferiority boundary of 7.5 % ; and antibiotic exposure and adverse effects from antibiotics . RESULTS The rate of overall adverse outcomes was similar in the PCT and control groups ( 15.4 % [ n = 103 ] vs 18.9 % [ n = 130 ] ; difference , -3.5 % ; 95 % CI , -7.6 % to 0.4 % ) . The mean duration of antibiotics exposure in the PCT vs control groups was lower in all patients ( 5.7 vs 8.7 days ; relative change , -34.8 % ; 95 % CI , -40.3 % to -28.7 % ) and in the subgroups of patients with community-acquired pneumonia ( n = 925 , 7.2 vs 10.7 days ; -32.4 % ; 95 % CI , -37.6 % to -26.9 % ) , exacerbation of chronic obstructive pulmonary disease ( n = 228 , 2.5 vs 5.1 days ; -50.4 % ; 95 % CI , -64.0 % to -34.0 % ) , and acute bronchitis ( n = 151 , 1.0 vs 2.8 days ; -65.0 % ; 95 % CI , -84.7 % to -37.5 % ) . Antibiotic-associated adverse effects were less frequent in the PCT group ( 19.8 % [ n = 133 ] vs 28.1 % [ n = 193 ] ; difference , -8.2 % ; 95 % CI , -12.7 % to -3.7 % ) . CONCLUSION In patients with LRTIs , a strategy of PCT guidance compared with st and ard guidelines result ed in similar rates of adverse outcomes , as well as lower rates of antibiotic exposure and antibiotic-associated adverse effects . TRIAL REGISTRATION is rct n.org Identifier : IS RCT N95122877 RATIONALE In patients with community-acquired pneumonia , guidelines recommend antibiotic treatment for 7 to 21 d. Procalcitonin is elevated in bacterial infections , and its dynamics have prognostic implication s. OBJECTIVE To assess procalcitonin guidance for the initiation and duration of antibiotic therapy in community-acquired pneumonia . METHODS In a r and omized intervention trial , 302 consecutive patients with suspected community-acquired pneumonia were included . Data were assessed at baseline , after 4 , 6 , and 8 d , and after 6 wk . The control group ( n = 151 ) received antibiotics according to usual practice . In the procalcitonin group ( n = 151 ) , antibiotic treatment was based on serum procalcitonin concentrations as follows : strongly discouraged , less than 0.1 microg/L ; discouraged , less than 0.25 microg/L ; encouraged , greater than 0.25 microg/L ; strongly encouraged , greater than 0.5 microg/L. The primary endpoint was antibiotic use ; secondary endpoints were measures of clinical , laboratory , and radiographic outcome . RESULTS At baseline , both groups were similar regarding clinical , laboratory , and microbiology characteristics , and Pneumonia Severity Index .  Procalcitonin guidance reduced total antibiotic exposure ( relative risk , 0.52 ; 95 % confidence interval , 0.48 - 0.55 ; p < 0.001 ) , antibiotic prescriptions on admission ( 85 vs. 99 % ; p < 0.001 ) , and antibiotic treatment duration ( median , 5 vs. 12 d ; p < 0.001 ) compared with patients treated according to guidelines . After adjustment for Pneumonia Severity Index , the hazard ratio of antibiotic discontinuation was higher in the procalcitonin group than in the control group ( 3.2 ; 95 % confidence interval , 2.5 to 4.2 ) . Outcome was similar in both groups , with an overall success rate of 83 % . CONCLUSIONS Procalcitonin guidance substantially reduces antibiotic use in community-acquired pneumonia . These findings may have important clinical and public health implication Recent studies have suggested that procalcitonin ( PCT ) is a safe marker for the discrimination between bacterial and viral infection , and that PCT-guided treatment may lead to substantial reductions in antibiotic use . The present objective was to evaluate the effect of a single PCT measurement on  antibiotic use in suspected lower respiratory tract infections ( LRTIs ) in a Danish hospital setting . In a r and omized , controlled intervention study , 223 adult patients admitted to the hospital because of suspicion of LRTI were included with 210 patients available for analysis . Patients were r and omized to either PCT-guided treatment or st and ard treatment . Antibiotic treatment duration in the PCT group was based on the serum PCT value at admission . The cut-off point for recommending antibiotic treatment was PCT > or = 0.25 microg/L. Physicians could overrule treatment guidelines . The mean duration of hospital stay was 5.9 days in the PCT group vs. 6.7 days in the control group ( p 0.22 ) . The mean duration of antibiotic treatment during hospitalization in the PCT group was 5.1 days on average , as compared to 6.8 days in the control group ( p 0.007 ) . In a subgroup analysis of chronic obstructive pulmonary disease patients , the mean length of stay was reduced from 7.1 days in the control group to 4.8 days in the PCT group ( p 0.009 ) . It was concluded that the determination of a single PCT value at admission in patients with suspected LRTIs can lead to a reduction in the duration of antibiotic treatment by 25 % without compromising outcome . No effect on the length of hospital stay was found BACKGROUND Acute respiratory tract infections are the most common reason for antibiotic therapy in primary care despite their mainly viral etiology . A laboratory test measuring procalcitonin levels in blood specimens was suggested as a tool to reduce unnecessary prescribing of antibiotics . We consider whether antibiotic therapy guided by procalcitonin reduces the use of antibiotics without increasing the restrictions experienced by patients by more than 1 day . METHODS Fifty-three primary care physicians recruited 458 patients , each patient with an acute respiratory tract infection and , in the physician 's opinion , in need of antibiotics .  Patients were central ly r and omized to either a procalcitonin-guided approach to antibiotic therapy or to a st and ard approach . For patients r and omized to procalcitonin-guided therapy , the use of antibiotics was more or less strongly discouraged ( procalcitonin level , < or = 0.1 or < or = 0.25 microg/L , respectively ) or recommended ( procalcitonin level , > 0.25 microg/L ) . Follow-up data were collected at 7 days by treating physicians and at 14 and 28 days by blinded 
    Output:
    
Procalcitonin guidance reduces antibiotic initiation and use among adults with LRTIs with no apparent adverse impact on length of hospital stay or mortality