You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
Cardiovascular responses to treadmill and cycle ergometer exercise in children and adults.
Abstract 1:
This study was conducted to determine whether submaximal cardiovascular responses at a given rate of work are different in children and adults , and , if different , what mechanisms are involved and whether the differences are exercise-modality dependent . A total of 24 children , 7 to 9 yr old , and 24 adults , 18 to 26 yr old ( 12 males and 12 females in each group ) , participated in both submaximal and maximal exercise tests on both the treadmill and cycle ergometer . With the use of regression analysis , it was determined that cardiac output ( Q ) was significantly lower ( P < /= 0.05 ) at a given O2 consumption level ( VO2 , l/min ) in boys vs. men and in girls vs. women on both the treadmill and cycle ergometer . The lower Q in the children was compensated for by a significantly higher ( P < /= 0.05 ) arterial-mixed venous O2 difference to achieve the same or similar VO2 . Furthermore , heart rate and total peripheral resistance were higher and stroke volume was lower in the children vs. in the adult groups on both exercise modalities . Stroke volume at a given rate of work was closely related to left ventricular mass , with correlation coefficients ranging from r = 0.89 - 0.92 and r = 0.88 - 0.93 in the males and females , respectively . It was concluded that submaximal cardiovascular responses are different in children and adults and that these differences are related to smaller hearts and a smaller absolute amount of muscle doing a given rate of work in the children . The differences were not exercise-modality dependent


Title 2:
[Arterial prehypertension and elevated pulse pressure in adolescents: prevalence and associated factors].
Abstract 2:
OBJECTIVE To estimate the prevalence of prehypertension and elevated pulse pressure in adolescents and assess the association between those two conditions and sex , age , sexual development , obesity and physical activity . METHODS  Anthropometrical data and blood pressure were measured in and a question naire was applied to 456 adolescents ( aged 12 to 17 years ) recruited from public and private schools , in the Fonseca district , in the city of Niterói , state of Rio de Janeiro , Brazil , from 2003 to 2004 . RESULTS Thirty nine ( 8.6 % ) presented prehypertension ( PH ) and 13.4 % , elevated pulse pressure ( PP ) . At bivariate analysis , PH was significantly associated with sex , age and obesity , with more prevalent in boys aged between 15 and 17 years , and in the obese . Elevated PP was associated with gender only , as it was more prevalent in boys . Sexual maturation did not show an association with PH or elevated PP . Similar correlations were found at logistic regression . PH prevalence odds ratio was 7.7 for sex , 4.3 for age and 4.6 for obesity . Elevated PP prevalence odds ratio was 10.8 for sex . The correlation between PP and physical activity was positive and significant . The elevation of PP was attributable to systolic blood pressure . CONCLUSION PH and the elevated PP were shown to be present in adolescents from a population with a low prevalence of hypertension , mostly in boys . Further prospect i ve studies are necessary to assess the persistence and the impact of those conditions


Title 3:
C-reactive protein as a predictor of improvement and readmission in heart failure.
Abstract 3:
OBJECTIVES Only recently , new risk factors to explain atherosclerotic disease have been identified . One of the most important clinical manifestations of atherosclerosis is heart failure . Our study was aim ed at investigating  C-reactive protein ( CRP ) , a marker of systemic inflammation , in the context of heart failure , and to determine its usefulness in predicting the need for readmission in patients with heart failure and their degree of improvement . DESIGN We studied patients admitted to our hospital due to heart failure , independent of the cause .  CRP levels  were measured with a sensitive st and ard assay on a Nephelometer analyser .  Patients were classified on admission and discharge following New York Heart Association ( NYHA ) functional criteria ; left ejection fraction was also determined by transthoracic echocardiography . Patients presenting clear sources of infection or inflammatory disease were excluded . Our control group consisted of patients admitted for syncope .  Each patient was followed up through a computer system controlling admissions to and discharge from the hospital , for a period of 18 months after initial admission . End points considered were NYHA functional class on discharge , readmission and death . RESULTS We studied prospect ively 76 patients with a mean age of 73.5+/-11 [ 95 % confidence interval ( CI ) 71.2 - 75.8 ] ; 44 were male ( 58 % ) and 32 female ( 42 % ) . The mean CRP level in patients with heart failure was 3.94+/-5.87 ( 95 % CI , 1.26 - 7.60 ) , while in 15 patients with syncope it was 0.84+/-1.95 ( 95 % CI , 0.96 - 2.94 ) ( P=0.0007 ) . The principal causes of heart failure included dilated cardiomyopathy due to coronary arterial disease ( 30 % ) , valvular disease ( 28 % ) and heart failure secondary to hypertension ( 25 % ) . The mean left ejection fraction adequately measured in 72 ( 95 % ) patients was 50.41+/-9.88 ( 95 % CI , 41.20 - 59.65 ) . We observed a trend of higher CRP levels in relation to ejection fractions below 35 % : 7.50+/-9.88 vs. 3.75+/-4.57 , ( P=0.09 ) . Our results showed that on discharge CRP levels increased in relation to NYHA class : I : 0.74+/-0.69 ; II : 3.78+/-3.76 ; III : 7.4+/-8.65 ; IV : 12.2+/-15.27 ( P<0.05 ) . On follow-up of each patient for 18 months , 32 ( 43 % ) were readmitted due to deterioration of their heart condition . For patients who were readmitted , those presenting CRP levels > 0.9 mg/dl were identified as c and i date s for earlier hospitalisation than those with levels below 0.9 mg/dl ( P=0.02 ) RR=1.43 . In logistic-regression analysis the only group of tested variables predicting readmission were levels of CRP , NYHA class and plasmatic K on discharge and left ventricle ejection fraction . Analysis of covariates yields CRP levels as being an independent predictor of readmission . CONCLUSIONS An inflammatory response is present in deteriorating heart failure . We observed higher CRP levels in patients with higher NYHA functional class , perhaps signalling a poor therapeutic response . Higher CRP levels were also related to higher rates of readmission and mortality and it could be an independent marker of improvement and readmission in heart failure


Title 4:
[Blood pressure in school children and adolescents - The Belo Horizonte study]
Abstract 4:
OBJECTIVE : To investigate epidemiological aspects of blood pressure ( BP ) levels , and the prevalence of arterial hypertension  in a representative sample of the whole elementary and high school population of the city of Belo Horizonte ( state of Minas Gerais , southeastern Brazil ) . To describe the blood pressure levels found and the prevalence of BP levels above the 90th and 95th percentiles in the first and second measurements . To evaluate prevalence using four different normality references separately to assess the impact of choice of reference . To study the frequency at which the studentś blood pressure has been evaluated . METHODS : In an observational cross-sectional epidemiological study , we studied a sample of 1005 students , aged 6 to 18 year , r and omized from an universe of 486,166 students from the 521 public and private elementary and high schools in the city . Each student was evaluated by means of a personal interview , anthropometric measurements , and two blood pressure measurements in a single visit and at a 10-minute interval . RESULTS : The systolic and diastolic blood pressure levels , by age and gender , were slightly lower than those described by the Task Force Report ( 1987 ) and by Rosner et al. ( 1993 ) . The prevalence of BP levels ( systolic or diastolic ) over the 95th percentile were , according to the reference used : 8.7 % - Task Force Report ( 1987 ) ; 5.5 % - Rosner et al. ( 1993 ) ; 6.5 % - Up date on the Task Force Report ( 1996 ) ; and 9.8 % - the 95th percentile from our own study . In the second measurement these prevalence rates dropped to 4.9 % ; 2.4 % ; 3.5 % and 5.8 % , respectively . CONCLUSIONS : We present a detailed description ( mean values and st and ard deviations , and the 90th , 95th and 99th percentiles by age and gender ) of the BP levels found in both measurements . Mean values and upper percentiles found in this study are very close to those found in the American references , which vali date s the current use of these references in Brazil . The prevalence of 9.0 % of BP levels above the 90th percentile in two measurements made at r and om hints at the number of children who should be monitored for hypertension , and reinforces the importance of routine evaluation of blood pressure at every pediatric examination


Title 5:
Comparison between the growth of Brazilian children and adolescents and the reference growth charts: data from a Brazilian project.
Abstract 5:
OBJECTIVE To compare the growth of Brazilian children and adolescents with reference growth charts . METHODS School-based cross-sectional study involving 41,654 students ( 23,328 boys and 18,326 girls ) aged 7 to 17 years .  Physical growth variables ( body weight , height ) and body mass index ( BMI )  were measured . Height , 50th percentile , and BMI , 85th percentile , were compared with the World Health Organization ( WHO ) reference values , and weight , 50th percentile , was compared with the Centers for Disease Control and Prevention ( CDC ) growth charts . RESULTS Mean height and body weight of Brazilian schoolchildren were generally higher than the WHO and CDC reference values for both genders at most ages . BMI values of Brazilian schoolchildren were significantly lower than the WHO obesity values at all ages . CONCLUSION The growth in body weight , height , and BMI of children and adolescents in the urban area of Brazil is increasingly similar to those reported in developed countries . Further prospect i ve studies should be conducted in Brazil comparing their results with the international growth charts to enable more accurate inferences


Title 6:
Atherosclerosis risk factors in children and adolescents with or without family history of premature coronary artery disease.
Abstract 6:
BACKGROUND Although coronary artery disease ( CAD ) becomes symptomatic much later in life , the early identification and modification of risk factors may reduce its later incidence . MATERIAL / METHODS 100 subjects 2 - 18 years old , evenly divided by sex , were r and omly selected from among children of patients suffering from premature myocardial infa rct ion ( < 55 years ) ; the controls were 100 age- and sex-matched subjects without a similar family history . In the Pediatric Preventive Cardiology Clinic at the Isfahan Cardiovascular Research Center , the subjects completed a special question naire consisting of anthropometric data , blood pressure , skinfold thickness , rate of physical activity , and active or passive cigarette smoking . Fasting venous blood was analyzed for serum lipids , lipoproteins fibrinogen , and apolipoproteins A1 and B100 . The data were analyzed with SPSS V6/win using the independent t-test , Kruskal-Wallis , chi-squared , and st and ard linear multiple regression tests . RESULTS The data showed higher prevalence of some major and new risk factors in the experimental group than in the controls . The mean total cholesterol , LDL-C , TG , fibrinogen and Apo B100 were significantly higher in the experimental group , while the mean values of HDL-C and Apo A1 were significantly lower . The differences in terms of Body Mass Index , percentage body fat , rate of regular physical activity , and active and passive smoking were not significant between groups . CONCLUSIONS Major and new CAD risk factors should be identified and modified as early as possible in children with high family risk by screening and health education at an early age


Title 7:
The effects of nonpharmacologic interventions on blood pressure of persons with high normal levels. Results of the Trials of Hypertension Prevention, Phase I.
Abstract 7:
OBJECTIVE To test the short-term feasibility and efficacy of seven nonpharmacologic interventions in persons with high normal diastolic blood pressure . DESIGN R and omized control multicenter trials . SETTING Volunteers recruited from the community , treated and followed up at special clinics . PARTICIPANTS Of 16,821 screenees , 2182 men and women , aged 30 through 54 years , with diastolic blood pressure from 80 through 89 mm Hg were selected . Of these , 50 did not return for follow-up blood pressure measurements . INTERVENTIONS Three life-style change groups ( weight reduction , sodium reduction , and stress management ) were each compared with unmasked nonintervention controls over 18 months . Four nutritional supplement groups ( calcium , magnesium , potassium , and fish oil ) were each compared singly , in double-blind fashion , with placebo controls over 6 months . MAIN OUTCOME MEASURES Primary : change in diastolic blood pressure from baseline to final follow-up , measured by blinded observers . Secondary : changes in systolic blood pressure and intervention compliance measures . RESULTS Weight reduction intervention produced weight loss of 3.9 kg ( P less than .01 ) , diastolic blood pressure change of -2.3 mm Hg ( P less than .01 ) , and systolic blood pressure change of -2.9 mm Hg ( P less than .01 ) . Sodium reduction interventions lowered urinary sodium excretion by 44 mmol/24 h ( P less than .01 ) , diastolic blood pressure by 0.9 mm Hg ( P less than .05 ) , and systolic blood pressure by 1.7 mm Hg ( P less than .01 ) . Despite good compliance , neither stress management nor nutritional supplements reduced diastolic blood pressure or systolic blood pressure significantly ( P greater than .05 ) . CONCLUSIONS Weight reduction is the most effective of the strategies tested for reducing blood pressure in normotensive persons . Sodium reduction is also effective . The long-term effects of weight reduction and sodium reduction , alone and in combination , require further evaluation
The death rate from cardiovascular disease is lowest in children with lower cholesterol levels and in individuals who exercise regularly .
In addition , there is a high prevalence of sedentariness in children and adolescents .
The identification of risk factors in asymptomatic children could contribute to a decrease in cardiovascular disease , preventing such diseases as hypertension , obesity , and dyslipidemia from becoming the epidemics of this century