***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 —Tai Chi Chuan ( TTC ) exercise has beneficial effects on the components of physical condition and can produce a substantial reduction in the risk of multiple falls . Previous studies have shown that short term TCC exercise did not improve the scores in the single leg stance test with eyes closed and the sit and reach test . There has apparently been no research into the effects of TCC on total body rotation flexibility and heart rate responses at rest and after a three minute step test . Methods —In this cross sectional study , 28 male TCC practitioners with an average age of 67.5 years old and 13.2 years of TCC exercise experience were recruited to form the TCC group . Another 30 sedentary men aged 66.2 were selected to serve as the control group . Measurements included resting heart rate , left and right single leg stance with eyes closed , modified sit and reach test , total body rotation test ( left and right ) , and a three minute step test . Results —Compared with the sedentary group , the TCC group had significantly better scores in resting heart rate , three minute step test heart rate , modified sit and reach , total body rotation test on both right and left side ( p<0.01 ) , and both right and left leg st and ing with eyes closed ( p<0.05 ) . According to the American Fitness St and ards , the TCC group attained the 90th percentile rank for sit and reach and total body rotation test , right and left . Conclusion —Long term regular TCC exercise has favourable effects on the promotion of balance control , flexibility , and cardiovascular fitness in older adults Tai Chi , a moving meditation , is examined for its efficacy in post-stressor recovery . Forty-eight male and 48 female Tai Chi practitioners were r and omly assigned to four treatment groups : Tai Chi , brisk walking , mediation and neutral reading . Mental arithmetic and other difficult tests were chosen as mental challenges , and a stressful film was used to produce emotional disturbance . Tai Chi and the other treatments were applied after these stressors . After all treatments , the salivary cortisol level dropped significantly , and the mood states were also improved . In general the stress-reduction effect of Tai Chi characterized moderate physical exercise . Heart rate , blood pressure , and urinary catecholamine changes for Tai Chi were found to be similar to those for walking at a speed of 6 km/hr . Although Tai Chi appeared to be superior to neutral reading in the reduction of state anxiety and the enhancement of vigour , this effect could be partially accounted for by the subjects ' high expectations about gains from Tai Chi . Approaches controlling for expectancy level are recommended for further assessment Health status measures are conceptually relevant to the assessment of clinical outcome in the rheumatic diseases , but their ability to detect meaningful changes in health has not been clearly demonstrated . This report describes the performance of a self-administered health status question naire in a r and omized , double-blind , 21-week comparison of placebo , oral gold , and injectable gold in rheumatoid arthritis patients . Outcome was assessed by st and ard clinical measures , including joint count , grip strength , and laboratory tests , and by the Arthritis Impact Measurement Scales , a reliable and valid health status measure that assesses physical disability , psychological status , and pain . Data from the clinical and health status measures produced highly similar conclusions : injectable and oral gold are more effective than placebo for rheumatoid arthritis , and injections are slightly more effective than oral gold . The health status measure was thus quite sensitive to clinical ly meaningful drug-induced improvements . These findings provide justification for the further application of health status measures to clinical trials of chronic disease OBJECTIVES To determine the effectiveness of tai chi on self-rated sleep quality and daytime sleepiness in older adults reporting moderate sleep complaints . DESIGN R and omized , controlled trial with allocation to tai chi or exercise control . SETTING General community . PARTICIPANTS One hundred eighteen women and men aged 60 to 92 . INTERVENTION Participants were r and omized into tai chi or low-impact exercise and participated in a 60-minute session , three times per week , for 24 consecutive weeks . MEASUREMENTS Primary outcome measures were the seven subscales of the Pittsburgh Sleep Quality Index ( PSQI ) , PSQI global score , and Epworth Sleepiness Scale ( ESS ) . Secondary outcome measures were physical performance ( single leg st and , timed chair rise , 50-foot speed walk ) and 12-item short form ( SF-12 ) physical and mental summary scores . RESULTS Tai chi participants reported significant improvements in five of the PSQI subscale scores ( sleep quality , sleep-onset latency , sleep duration , sleep efficiency , sleep disturbances ) ( P<.01 ) , PSQI global score ( P=.001 ) , and ESS scores ( P=.002 ) in comparison with the low-impact exercise participants . Tai chi participants reported sleep-onset latency of about 18 minutes less per night ( 95 % confidence interval (CI)=-28.64 to -7.12 ) and sleep duration of about 48 minutes more per night ( 95 % CI=14.71 - 82.41 ) than low-impact exercise participants . Tai chi participants also showed better scores in secondary outcome measures than low-impact exercise participants . Both groups reported improvements in SF-12 mental summary scores . CONCLUSION Older adults with moderate sleep complaints can improve self-rated sleep quality through a 6-month , low- to moderate-intensity tai chi program . Tai chi appears to be effective as a nonpharmacological approach to sleep enhancement for sleep-disturbed elderly individuals This paper describes some of the statistical considerations in the intent-to-treat design and analysis of clinical trials . The pivotal property of a clinical trial is the assignment of treatments to patients at r and om . R and omization alone , however , is not sufficient to provide an unbiased comparison of therapies . An additional requirement is that the set of patients contributing to an analysis provides an unbiased assessment of treatment effects , or that any missing data are ignorable . A sufficient condition to provide an unbiased comparison is to obtain complete data on all r and omized subjects . This can be achieved by an intent-to-treat design wherein all patients are followed until death or the end of the trial , or until the outcome event is reached in a time-to-event trial , irrespective of whether the patient is still receiving or complying with the assigned treatment . The properties of this strategy are contrasted with those of an efficacy subset analysis in which patients and observable patient data are excluded from the analysis on the basis of information obtained postr and omization . I describe the potential bias that can be introduced by such postr and omization exclusions and the pursuant effects on type I error probabilities . Especially in a large study , the inflation in type I error probability can be severe , 0.50 or higher , even when the null hypothesis is true . St and ard statistical methods for the analysis of censored or incomplete observations all require the assumption of missing at r and om to some degree , and none of these methods adjust for the potential bias introduced by post hoc subset selection . Nor is such adjustment possible unless one posits a model that relates the missing observations to other observed information for each subject-models that are inherently untestable . Further , the subset selection bias is confounded with the subset-specific treatment effect , and the two components are not identifiable without additional untestable assumptions . Methods for sensitivity analysis to assess the impact of bias in the efficacy subset analysis are described . It is generally believed that the efficacy subset analysis has greater power than the intent-to-treat analysis . However , even when the efficacy subset analysis is assumed to be unbiased , or have a true type I error probability equal to the desired level alpha , situations are described where the intent-to-treat analysis in fact has greater power than the efficacy subset analysis . The intent-to-treat design , wherein all possible patients continue to be followed , is especially powerful when an effective treatment arrests progression of disease during its administration . Thus , a patient benefits long after the patient becomes noncompliant or the treatment is terminated . In such cases , a l and mark analysis using the observations from the last patient evaluation is likely to prove more powerful than life-table or longitudinal analyses . Examples are described CONTEXT A prior national survey documented the high prevalence and costs of  alternative medicine use in the United States in 1990 . OBJECTIVE To document trends in alternative medicine use in the United States between 1990 and 1997 . DESIGN Nationally representative r and om household telephone surveys using comparable key questions were conducted in 1991 and 1997 measuring utilization in 1990 and 1997 , respectively . PARTICIPANTS A total of 1539 adults in 1991 and 2055 in 1997 . MAIN OUTCOMES MEASURES Prevalence , estimated costs , and disclosure of alternative therapies to physicians . RESULTS Use of at least 1 of 16 alternative therapies during the previous year increased from 33.8 % in 1990 to 42.1 % in 1997 ( P < or = .001 ) . The therapies increasing the most included herbal medicine , massage , megavitamins , self-help groups , folk remedies , energy healing , and homeopathy . The probability of users visiting an alternative medicine practitioner increased from 36.3 % to 46.3 % ( P = .002 ) . In both surveys alternative therapies were used most frequently for chronic conditions , including back problems , anxiety , depression , and headaches . There was no significant change in disclosure rates between the 2 survey years ; 39.8 % of alternative therapies were disclosed to physicians in 1990 vs 38.5 % in 1997 . The percentage of users paying entirely out-of-pocket for services provided by alternative medicine practitioners did not change significantly between 1990 ( 64.0 % ) and 1997 ( 58.3 % ) ( P=.36 ) . Extrapolations to the US population suggest a 47.3 % increase in total visits to alternative medicine practitioners , from 427 million in 1990 to 629 million in 1997 , thereby exceeding total visits to all US primary care physicians . An estimated 15 million adults in 1997 took prescription medications concurrently with herbal remedies and /or high-dose vitamins ( 18.4 % of all prescription users ) . Estimated expenditures for alternative medicine professional services increased 45.2 % between 1990 and 1997 and were conservatively estimated at $ 21.2 billion in 1997 , with at least $ 12.2 billion paid out-of-pocket . This exceeds the 1997 out-of-pocket expenditures for all US hospitalizations . Total 1997 out-of-pocket expenditures relating to alternative therapies were conservatively estimated at $ 27.0 billion , which is comparable with the projected 1997 out-of-pocket expenditures for all US physician services . CONCLUSIONS  Alternative medicine use and expenditures increased substantially between 1990 and 1997 , attributable primarily to an increase in the proportion of the population seeking alternative therapies , rather than increased visits per patient OBJECTIVES To determine the effectiveness of a 16-week community-based tai chi program in reducing falls and improving balance in people aged 60 and older . DESIGN R and omized , controlled trial with waiting list control group . SETTING Community in Sydney , Australia . PARTICIPANTS Seven hundred two relatively healthy community-dwelling people aged 60 and older ( mean age 69 ) . INTERVENTION Sixteen-week program of community-based tai chi classes of 1 hour duration per week . MEASUREMENTS Falls during 16 and 24 weeks of follow-up were assessed using a calendar method . Balance was measured at baseline and 16-week follow-up using six balance tests . RESULTS Falls were less frequent in the tai chi group than in the control group . Using Cox regression and time to first fall , the hazard ratio after 16 weeks was 0.72 ( 95 % confidence interval (CI)=0.51 - 1.01 , P=.06 ) , and after 24 weeks it was 0.67 ( 95 % CI=0.49 - 0.93 , P=.02 ) . There was no difference in the percentage of participants who had one or more falls . There were statistically significant differences in changes in balance favoring the tai chi group on five of six balance tests . CONCLUSION Participation in once per week tai chi classes for 16 weeks can prevent falls in relatively healthy community-dwelling older people AIM This paper reports a study to examine change in psychosocial status following a 12-week Tai Chi exercise intervention among ethnic Chinese people with cardiovascular disease risk factors living in the United States of America . BACKGROUND Regular participation in physical activity is associated with protection against cardioavascular disease , and improvements in physical and psychological health . Increasing amounts of scientific evidence suggests that mind-body exercise , such as Tai Chi , are related to improvements in mental health , emotional well-being , and stress reduction . No prior study has examined the effect of a Tai Chi exercise intervention on psychosocial status among people with cardiovascular disease risk factors . METHODS This was a quasi-experimental study . Participants attended a 60-minute Tai Chi exercise class three times per week for 12 weeks . Data were collected at baseline , 6 and 12 weeks following the intervention . Psychosocial status was assessed using Chinese versions of Cohen 's Perceived Stress Scale , Profile of Mood States , Multidimensional Scale of Perceived Social Support , and Tai Chi exercise self-efficacy . RESULTS A total of 39 participants , on average 66-year-old ( + /-8.3 ) , married ( 85 % ) , Cantonese-speaking ( 97 % ) , immigrants participated . The majority were women ( 69 % ) , with < or = 12 years education ( 87 % ) . Statistically significant improvements in all measures of psychosocial status were found ( P < or = 0.05 ) following the intervention . Improvement in mood state 
    Output:
    
It is still premature to make any conclusive remarks on the effect of Tai Chi on psychosocial well-being