***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 —Pulmonary hypertension is a clinical ly useful predictor of death in patients with heart failure . Whether pulmonary hypertension has the same prognostic value among specific underlying causes of cardiomyopathy is unknown . Using a diverse cohort of cardiomyopathy patients , we tested the hypotheses that ( 1 ) elevated mean pulmonary arterial pressure is the most important hemodynamic predictor of death and ( 2 ) the prognostic value of mean pulmonary pressure varies among different cardiomyopathies . Methods and Results — Patients ( n=1134 ) with new cardiomyopathy were prospect ively assigned a specific diagnosis on the basis of clinical evaluation and endomyocardial biopsy .  All patients underwent right heart catheterization at baseline and were followed for an average of 4.4 years . In multivariate Cox models that allowed for nonlinear relations between hemodynamics and death , mean systemic pressure ( mSP ) and mean pulmonary arterial pressure ( mPA ) emerged as the most important hemodynamic predictors of death . Moreover , there was a statistically significant positive interaction between mPA and the diagnosis of myocarditis . For each 5–mm Hg increase in baseline mSP , mortality rates decreased with relative hazard ( RH ) of 0.89 ( 0.86 to 0.92 ) . For a 5–mm Hg increase in baseline mPA , mortality rates increased in patients who did not carry the diagnosis of myocarditis with RH 1.23 ( 1.17 to 1.29 ) ; among patients with myocarditis , mortality rates increased substantially with RH of 1.85 ( 1.50 to 2.29;P < 0.001 for interaction ) . Conclusions —Baseline mPA is particularly important for stratifying risk in myocarditis . These findings suggest that secondary pulmonary hypertension may have different biological features in myocarditis and that patients with pulmonary hypertension and myocarditis should be targeted for aggressive medical therapy Prognosis studies are investigations of future events or the evaluation of associations between risk factors and health outcomes in population s of patients ( 1 ) . The results of such studies improve our underst and ing of the clinical course of a disease and assist clinicians in making informed decisions about how best to manage patients . Prognostic research also informs the design of intervention studies by helping define subgroups of patients who may benefit from a new treatment and by providing necessary information about the natural history of a disorder ( 2 ) . There has recently been a rapid increase in the use of systematic review methods to synthesize the evidence on research questions related to prognosis . It is essential that investigators conducting systematic review s thoroughly appraise the method ologic quality of included studies to be confident that a study 's design , conduct , analysis , and interpretation have adequately reduced the opportunity for bias ( 3 , 4 ) . Caution is warranted , however , because inclusion of method ologically weak studies can threaten the internal validity of a systematic review ( 4 ) . This follows abundant empirical evidence that inadequate attention to biases can cause invalid results and inferences ( 5 - 9 ) . However , there is limited consensus on how to appraise the quality of prognosis studies ( 1 ) . A useful framework to assess bias in such studies follows the basic principles of epidemiologic research ( 10 , 11 ) . We focus on 6 areas of potential bias : study participation , study attrition , prognostic factor measurement , confounding measurement and account , outcome measurement , and analysis . The main objectives of our review of review s are to describe methods used to assess the quality of prognosis studies and to describe how well current practice s assess potential biases . Our secondary objective is to develop recommendations to guide future quality appraisal , both within single studies of prognostic factors and within systematic review s of the evidence . We hope this work facilitates future discussion and research on biases in prognosis studies and systematic review s. Methods Literature Search and Study Selection We identified systematic review s of prognosis studies by search ing MEDLINE ( 1966 to October 2005 ) using the search strategy recommended by McKibbon and colleagues ( 12 ) . This strategy combines broad search terms for systematic review s ( systematic review .mp ; meta- analysis .mp ) and a sensitive search strategy for prognosis studies ( cohort , incidence , mortality , follow-up studies , prognos * , predict * , or course ) . We also search ed the reference lists of included review s and method ologic papers to identify other relevant publications . We restricted our search to English- language publications . One review er conducted the search and selected the studies . Systematic review s , defined as review s of published studies with a comprehensive search and systematic selection , were included if they assessed the method ologic quality of the included studies by using 1 or more explicit criteria . We excluded studies if they were meta-analyses of independent patient data only , if their primary goal was to investigate the effectiveness of an intervention or specific diagnostic or screening tests , or if they included studies that were not done on humans . Data Extraction and Synthesis Individual items included in the quality assessment of the systematic review s were recorded as they were reported in the publication ( that is , the information that would be available to readers and future review ers ) . We review ed journal Web sites and contacted the authors of the systematic review s for additional information when authors made such an offer in their original papers . When review s assessed different study design s by using different sets of quality items , we extracted only those items used to assess cohort studies . We constructed a comprehensive list of distinct items that the review s used to assess the quality of their included studies . The full text of each review was screened . All items used by the review authors to assess the quality of studies were extracted into a computerized spreadsheet by 1 review er . Two experienced review ers , a clinical epidemiologist and an epidemiologist , independently synthesized the quality items extracted from the prognosis review s to determine how well the systematic review s assessed potential biases . We did this in 3 steps : 1 ) identified distinct concepts or domains addressed by the quality items ; 2 ) grouped each extracted quality item into the appropriate domain or domains ; and 3 ) identified the domains necessary to assess potential biases in prognosis studies . We then used this information to assess how well the review s ' quality assessment included items from the domains necessary to assess potential biases . After completing each of the first 3 steps , the review ers met to attempt to reach a consensus . The consensus process involved each review er presenting his or her observations and results , followed by discussion and debate . A third review er was available in cases of persistent disagreement or uncertainty . In the first step , all domains addressed by the quality items were identified . The first review er iteratively and progressively defined the domains as items were extracted from the included review s. The second review er defined domains from a r and om list of all extracted quality items . Limited guidance was provided to the review ers so that their assessment s and definitions of domains would be independent . The review ers agreed on a final set of domains that adequately and completely defined all of the extracted items . In the second step , review ers independently grouped each extracted item into the appropriate domains . Review ers considered each extracted item by asking , What is each particular quality item addressing ? or What are the review 's authors getting at with the particular quality assessment item ? . Items were grouped into the domain or domains that best represented the concepts being addressed . For example , the extracted items at least 80 % of the group originally identified was located for follow-up and follow-up was sufficiently complete or does n't jeopardize validity were each independently classified by both review ers as assessing the domain completeness of follow-up adequate , whereas the extracted item quantification and description of all subjects lost to follow-up was classified as assessing the domain completeness of follow-up described . In the third step , we identified the domains necessary to assess potential biases . Each review er considered the ability of the identified domains to adequately address , at least in part , 1 of the following 6 potential biases : 1 ) study participation , 2 ) study attrition , 3 ) prognostic factor measurement , 4 ) confounding measurement and account , 5 ) outcome measurement , and 6 ) analysis . Domains were considered to adequately address part of the framework if information garnered from that domain would inform the assessment of potential bias . For example , both review ers judged that the identified domain study population represents source population or population of interest assessed potential bias in a prognosis study , whereas the domain research question definition did not , although the latter is an important consideration in assessing the inclusion of studies in a systematic review . Finally , on the basis of our previous ratings , we looked at whether each review included items from the domains necessary to assess the 6 potential biases . We calculated the frequency of systematic review s by assessing each potential bias and the number of review s that adequately assessed bias overall . From this systematic synthesis , we developed recommendations for improving quality appraisal in future systematic review s of prognosis studies . We used Microsoft Access and Excel 2002 ( Microsoft Corp. , Redmond , Washington ) for data management and SAS for Windows , version 9.1 ( SAS Institute , Inc. , Cary , North Carolina ) for descriptive statistics . Role of the Funding Sources The funding sources , the Canadian Institutes of Health Research , the Canadian Chiropractic Research Foundation , the Ontario Chiropractic Association , and the Ontario Ministry of Health and Long Term Care , did not have a role in the collection , analysis , or interpretation of the data or in the decision to su bmi t the manuscript for publication . Results We identified 1384 potentially relevant articles . Figure 1 shows a flow chart of studies that were included and excluded . Figure 2 shows the number of review s identified by year of publication . We excluded 131 systematic review s of prognosis studies that did not seem to include any quality assessment of the included studies ; this represented 44 % of prognosis review s. We included 163 review s of prognosis studies in our analysis ( 13 - 175 ) . The most common topics were cancer ( 15 % ) , musculoskeletal disorders and rheumatology ( 13 % ) , cardiovascular ( 10 % ) , neurology ( 10 % ) , and obstetrics ( 10 % ) . Other review s included a wide range of health and health care topics . Sixty-three percent of the review s investigated the association between a specific prognostic factor and a particular outcome ; the remainder investigated multiple prognostic factors or models . The number of primary studies included in each systematic review ranged from 3 to 167 ( median , 18 [ interquartile range , 12 to 31 ] ) . A complete description of the included review s is available from the authors on request . Figure 1 . Flow diagram of inclusion and exclusion criteria of systematic review s. Figure 2 . Number of systematic review s of prognosis studies identified over time . Quality Items One hundred fifty-three review s provided adequate detail to allow extraction of quality items . Eight hundred eighty-two distinct quality items were extracted from the review s. Most review s developed their own set of quality items , with only a few applying criteria from previous review s. Most quality items BACKGROUND Acute heart failure ( AHF ) in sub-Saharan Africa has not been well characterized . Therefore , we sought to describe the characteristics , treatment , and outcomes of patients admitted with AHF in sub-Saharan Africa . METHODS The Sub-Saharan  Africa Survey of Heart Failure ( THESUS-HF ) was a prospect i ve , multicenter , observational survey of patients with AHF admitted to 12 university hospitals in 9 countries . Among patients presenting with AHF , we determined the causes , treatment , and outcomes during 6 months of follow-up . RESULTS From July 1 , 2007 , to June 30 , 2010 , we enrolled 1006 patients presenting with AHF . Mean ( SD ) age was 52.3 ( 18.3 ) years , 511 ( 50.8 % ) were women , and the predominant race was black African ( 984 of 999 [ 98.5 % ] ) .  Mean ( SD ) left ventricular ejection fraction was 39.5 % ( 16.5 % ) . Heart failure was most commonly due to hypertension ( n = 453 [ 45.4 % ] ) and rheumatic heart disease ( n = 143 [ 14.3 % ] ) . Ischemic heart disease ( n = 77 [ 7.7 % ] ) was not a common cause of AHF . Concurrent renal dysfunction ( estimated glomerular filtration rate , < 30 mL/min/173 m(2 ) ) , diabetes mellitus , anemia ( hemoglobin level , < 10 g/dL ) , and atrial fibrillation were found in 73 ( 7.7 % ) , 114 ( 11.4 % ) , 147 ( 15.2 % ) , and 184 cases ( 18.3 % ) , respectively ; 65 of 500 patients undergoing testing ( 13.0 % ) were seropositive for the human immunodeficiency virus . The median hospital stay was 7 days ( interquartile range , 5 - 10 ) , with an in-hospital mortality of 4.2 % . Estimated 180-day mortality was 17.8 % ( 95 % CI , 15.4%-20.6 % ) . Most patients were treated with renin-angiotensin system blockers but not β-blockers at discharge . Hydralazine hydrochloride and nitrates were rarely used . CONCLUSIONS In African patients , AHF has a predominantly nonischemic cause , most commonly hypertension . The condition occurs in middle-aged adults , equally in men and women , and is associated with high mortality . The outcome is similar to that observed in non-African AHF registries , suggesting that AHF has a dire prognosis globally , regardless of the cause BACKGROUND Prognostic implication s of echocardiographic assessment of pulmonary hypertension ( PH ) in non-selected patients hospitalized for acute heart failure ( AHF ) are not clearly defined . The aim of this study was to evaluate the association between echocardiography-derived PH in AHF and 1-year all-cause mortality . METHODS We prospect ively included 1210 consecutive patients admitted for AHF . Patients with significant 
    Output:
    
PH was consistently associated with increased mortality risk in all forms of LHD , except for aortic valve disease where findings were inconsistent .
CONCLUSIONS PH is almost invariably associated with increased mortality risk in patients with LHD .