Patient utilities in fibromyalgia and the association with other outcome measures. Patient utilities in chronic musculoskeletal pain: how useful is the standard gamble method? Measuring preferences for schizophrenia outcomes with the time tradeoff method How do the EQ-5D, SF-6D and the well-being rating scale compare in patients with ankylosing spondylitis? Methodological Issues of Patient Utility Measurement Experience From Two Clinical Trials Do medical house officers value the health of veterans differently from the health of non-veterans? Proportional Heuristics in Time Tradeoff and Conjoint Measurement A view from the bridge: agreement between the SF-6D utility algorithm and the Health Utilities Index. Stroke Recovery Profile and the Modified Rankin Assessment SF-36 scores vary by method of administration: implications for study design. Assessing utility values in rheumatoid arthritis: a comparison between time trade-off and the EuroQol. Validity of the Assessment of Quality of Life (AQoL) utility instrument in patients with operable and inoperable lung cancer. Quality of life in epilepsy: comparison of four preference measures Comparing Three Versions of the Time Tradeoff Comparative responsiveness of generic versus disease-specific and weighted versus unweighted health status measures in carpal tunnel syndrome. Estimation of patient preference-based utility weights from the functional assessment of cancer therapy - general. Sequential boundaries approach in clinical trials with unequal allocation ratios
OBJECTIVE To compare in patients with fibromyalgia ( FM ) utilities derived by rating scale and st and ard gamble methods ; to gain insight into construct validity by relating utility values to other outcome measures ; to assess the sensitivity to change of utilities . METHODS A total of 73 patients with FM were r and omized into one of 3 groups : low impact fitness training , biofeedback , or controls . At baseline and after 6 mo the Maastricht Utility Measurement Question naire was applied . By means of both the rating scale and st and ard gamble method patients were asked to value their own health status . Construct validity of patient utility measurements was evaluated by Spearman correlation and multiple regression of baseline values with pain , stiffness , patient 's global assessment , Sickness Impact Profile ( SIP ) , modified Health Assessment Question naire and Arthritis Impact Measurement Scale ( AIMS ) . Sensitivity to change was assessed against changes in these outcomes . RESULTS Rating scale utilities correlated significantly ( p < 0.05 ) with patient 's global assessment ( rs = 0.53 ) , pain ( rs = -0.47 ) , SIP ( rs = -0.43 ) , and with 9 of 11 dimensions of the AIMS ( rs ranging from 0.23 to 0.62 ) . St and ard gamble utilities correlated significantly with mobility , pain , and arthritis impact of the AIMS scale ( rs from 0.22 to 0.36 ) and with pain by visual analog scale ( rs = -0.24 ) and patient 's global assessment ( rs = 0.32 ) . Multiple regression analysis showed that patient 's global assessment explained 41 % ( rating scale ) and 10 % ( st and ard gamble ) of total variance in baseline utilities . Also , 16 % of the variance in change in rating scale utility values was explained by changes in patient 's global assessment . In contrast , variance of changes in st and ard gamble utility values was not explained significantly by changes in other disease outcomes . CONCLUSION Rating scale utilities correlated more strongly with disease outcome measures than st and ard gamble utilities . Also , construct validity for the rating scale was better than for the st and ard gamble . In FM , utility measurement is sensitive to the method chosen to elicit patient priorities The main goal of current pain management approaches is to increase the patients ' quality of life by improving pain coping skills and by reducing the levels of disability in daily life , often despite persistent pain . Direct measurement of quality of life is of crucial importance in economic evaluation research , in which not only is the estimation of financial costs and benefits included , but so is the evaluation of costs and benefits in terms of changes in health states . The purpose of this study is to compare the psychometric qualities of two instruments for assessing patients ' utilities , the  rating scale ( RS )  and the st and ard gamble ( SG ) . Such instruments are design ed for their application in economic evaluation research , but have seldomly been used in chronic pain trials . Both methods provide a single measure between 0 and 1 . The relationship between these utility measures and descriptive and domain-specific quality of life measures was examined in 133 fibromyalgia patients and 148 patients with chronic non-specific low back pain .  Mean utility score at baseline was 0.43 with the RS and 0.78 for the SG . The correlation between both methods was found to be poor ( r = 0.21 ) . Both measures appeared to be fairly stable in a 2-week test-retest period ( intra class correlation coefficient ( ICC ) = 0.74 and 0.77 ) . Scores on the description of patient 's own health on six domains , global assessment of change and domain specific measures correlated moderately with the RS scores and low with the SG . Multiple regression analyses demonstrated that 32 % of the variance in RS values and only 13 % of the variance in SG utilities could be explained by domain-specific measures . These results suggest an acceptable construct validity for the RS but insufficient construct validity for the SG . Valuations of ones own health appear only partially to be related to the assessment of the pain-specific measures and measures of distress . It can be concluded that the RS and domain-specific measures assess partly different , but nevertheless complementary aspects of health-related quality of life . It is therefore recommended to include in economic evaluation studies both domain-specific measures and valuation measures . Finally , in chronic musculoskeletal pain patients , RS scores were found to be more responsive in detecting significant changes in preferences than SG scores . For use in patients with chronic musculoskeletal pain , the RS is preferred to the SG for establishing accurate decisions about the impact of new interventions on their health outcomes Measuring preferences for schizophrenia outcomes facilitates meaningful integration of multiple outcome measures and multiple perspectives on treatment outcomes . The Time Tradeoff ( TTO ) technique , specifically developed for measuring health state preferences , is used widely in health research , but some evidence suggests that the TTO may work less well with schizophrenia than with other health conditions . This study tested the hypotheses that tailoring the time frame of the st and ard TTO to the course of schizophrenia and simplifying its presentation fromat would improve its feasibility and efficiency .  Forty clinicians provided  TTO ratings using 1 of 4 combinations of time frame and presentation format . Numeric ratings and quantitative and qualitative measures of feasibility showed that while participants preferred the simpler format , none of the alterations improved feasibility . Participants ' ratings were prone to logical inconsistencies and participants found all 4 versions of the TTO confusing and poorly suited to the context of schizophrenia treatment Purpose : To compare aspects of validity of EuroQol—5 Dimensions ( EQ-5D ) and Short-Form—6 Dimensions ( SF-6D ) , two indirect utility instruments , and the well-being rating scale ( RS ) in ankylosing spondylitis ( AS ) . Methods : EQ-5D , SF-6D and RS were available for 254 patients fulfilling modified New York criteria . 134 patients were part of an observational cohort and 120 were part of a r and omised controlled trial ( RCT ) . Aspects of validity assessed were truth ( agreement and correlation with external health measures ) and discrimination ( differentiation between health states , repeatability and detection of treatment effect ) . Results : Median ( range ) values were 0.69 ( −0.08–1.00 ) for the EQ-5D , 0.65 ( 0.35–0.95 ) for the SF-6D and 0.65 ( 0.14–1.00 ) for the RS . Agreement ( intraclass correlation coefficient ) was moderate ( 0.46–0.55 ) . Instruments correlated equally with disease activity , functioning and quality of life . The SF-6D showed smaller average differences in utility between patients with better and worse disease compared with the EQ-5D and the RS . The smallest detectable difference ( SDD ) ( in the control group of RCT ) was 0.36 , 0.17 and 0.33 for EQ-5D , SF-6D and RS , respectively . The ability to detect treatment effect ( in the intervention trial ) showed st and ardised effect sizes that were moderate for EQ-5D and SF-6D ( 0.63 and 0.64 ) and low for the RS ( 0.23 ) . Conclusion : In patients with AS , EQ-5D , SF-6D and the RS correlate equally well with external measures of health , but have different psychometric properties . The SDD is most favourable for the SF-6D , but it discriminates less well between patients with different disease severities . The RS has a poorer ability to detect treatment effects . It is difficult to recommend one of the instruments This article explores various method ological issues of  patient utility  measurement in two r and omized controlled clinical trials involving 85 patients with fibromyalgia and 144 with ankylosing spondylitis . In both trials one baseline and two follow-up measurements of the patients ' preferences for their own health state and several hypothetical states were performed using the rating scale and the st and ard gamble methods .It was confirmed that st and ard gamble scores are consistently higher than rating scale scores for both the experienced and the hypothetical states . The 3-month test-retest reliability for hypothetical states measured by intraclass correlation coefficients ranged from 0.24 to 0.33 for the rating scale and from 0.43 to 0.70 for the st and ard gamble . Although the reproducibility is not high , the group mean scores are fairly stable over time . Mean st and ard gamble scores tend to differ depending on the way the measurements are undertaken . Utilities elicited with chained gambles were significantly higher than utilities elicited with basic reference gambles . At the individual level some inconsistent responses occurred . However , more than 70 % of these fell within the bounds of the measurement error , which ranged from 0.11 to 0.13 on the st and ard gamble ( 0–1 scale ) and from 8 to 10 on the rating scale ( 0–100 scale ) . The large number of negative utilities for the severe hypothetical state , which was used as an anchor point in the chained gambles , and the magnitude of these negative utilities ( down to −19 ) calls for intensified research efforts to h and le these responses in utility calculations Background Little information is available regarding medical residents ' perceptions of patients ' health-related quality of life . Patients cared for by residents have been shown to receive differing patterns of care at Veterans Affairs facilities than at community or university setting s. We therefore examined : 1 ) how resident physicians value the health of patients ; 2 ) whether values differ if the patient is described as a veteran ; and 3 ) whether residency-associated variables impact values . Methods All medicine residents in a teaching hospital were asked to watch a digital video of an actor depicting a 72-year-old patient with mild-moderate congestive heart failure . Residents were r and omized to 2 groups : in one group , the patient was described as a veteran of the Korean War , and in the other , he was referred to only as a male . The respondents assessed the patient 's health state using 4 measures : rating scale ( RS ) , time tradeoff ( TTO ) , st and ard gamble ( SG ) , and willingness to pay ( WTP ) . We also ascertained residents ' demographics , risk attitudes , residency program type , post-graduate year level , current rotation , experience in a Veterans Affairs hospital , and how many days it had been since they were last on call . We performed univariate and multivariable analyses using the RS , TTO , SG and WTP as dependent variables . Results Eighty-one residents ( 89.0 % of eligible ) participated , with 36 ( 44.4 % ) viewing the video of the veteran and 45 ( 55.6 % ) viewing the video of the non-veteran . Their mean ( SD ) age was 28.7 ( 3.1 ) years ; 51.3 % were female ; and 67.5 % were white . There were no differences in residents ' characteristics or in RS , TTO , SG and WTP scores between the veteran and non-veteran groups . The mean RS score was 0.60 ( 0.14 ) ; the mean TTO score was 0.80 ( 0.20 ) ; the mean SG score was 0.91 ( 0.10 ) ; and the median ( 25th , 75th percentile ) WTP was $ 10,000 ( $ 7600 , $ 20,000 ) per year . In multivariable analyses , being a resident in the categorical program was associated with assigning higher RS scores , but no residency-associated variables were associated with the TTO , SG or WTP scores . Conclusion Physicians in training appear not to be biased either in favor of or against military veterans when judging the value of a patient 's health The time-tradeoff ( TTO ) test is widely used to measure quality of life for different health states . Subjects are asked to equate the value of living a given period in an inferior health state to the value of living a shorter period in good health . Applications of TTOs have been criticized based on the fact that the value of future life duration is taken as the future life duration itself . The authors show that for a health state in which a subject does not want to live longer than a specified amount of time , subjects ' responses do not comply with the assumption that the value of the period in inferior health is equated to the value of the shorter period in good health Actually , preference reversals with respect to such a health state point to the use of a proportional heuristic in the TTO test . Comparisons of the TTO test in these subjects with category scaling and difference measurements also favor a proportional inter pretation of the TTO test . In tests based on conjoint measurement , these subjects also appear to use a proportional heuristic . Consequences of the use of the TTO test and conjoint measurement m quality -of-life models are discussed Key words : utility assessment , QALY , conjoint measurement ; preference reversals ; compatibility effect . ( Med Decis Making 1996;16:36 - 44 BACKGROUND The SF-6D is a new health state classification and utility scoring system based on 6 dimensions ( ' 6D ' ) of the Short Form 36 , and permits a " bridging " transformation between SF-36 responses and utilities . The Health Utilities Index , mark 3 ( HUI3 ) is a valid and reliable multi-attribute health utility scale that is widely used . We assessed within-subject agreement between SF-6D utilities and those from HUI3 . METHODS Patients at increased risk of sudden cardiac death and participating in a r and omized trial of implantable defibrillator therapy completed both instruments at baseline . Score distributions were inspected by scatterplot and histogram and mean score differences compared by paired t-test . Pearson correlation was computed between instrument scores and also between dimension scores within instruments . Between-instrument agreement was by intra-class correlation coefficient ( ICC ) . RESULTS SF-6D and HUI3 forms were available from 246 patients .  Mean scores for HUI3 and SF-6D were 0.61 ( 95 % CI 0.60 - 0.63 ) and 0.58 ( 95 % CI 0.54 - 0.62 ) respectively ; a difference of 0.03 ( p<0.03 ) . Score intervals for HUI3 and SF-6D were ( -0.21 to 1.0 ) and ( 0.30 - 0.95 ) . Correlation between the instrument scores was 0.58 ( 95 % CI 0.48 - 0.68 ) and agreement by ICC was 0.42 ( 95 % CI 0.31 - 0.52 ) . Correlations between dimensions of SF-6D were higher than for HUI3 . CONCLUSIONS Our study casts doubt on the whether utilities and QALYs estimated via SF-6D are comparable with those from HUI3 . Utility differences may be due to differences in underlying concepts of health being measured , or different measurement approaches , or both . No gold st and ard exists for utility measurement and the SF-6D is a valuable addition that permits SF-36 data to be transformed into utilities to estimate QALYs . The challenge is developing a better underst and ing as to why these classification-based utility instruments differ so markedly in their distributions and point estimates of derived utilities Background and Purpose : The purpose of this study was to examine the relationship between the Modified Rankin Scale ( MRS ) and poststroke recovery in neurological deficits , activities of daily living ( ADL ) , higher level of physical and social functioning and the patients ’ preference for health state . Methods : Four hundred and fifty-nine participants in the Kansas City Stroke Study were prospect ively assessed for measures of  MRS , NIH Stroke Scale ( NIHSS ) , Barthel ADL , SF-36 physical functioning , SF-36 social functioning , and Time Trade-Off ( TTO ) . ANOVA and Bonferroni multiple comparisons were used to examine any differences in 3-month scores of NIHSS , Barthel ADL , SF-36 physical functioning , SF-36 social functioning and TTO between levels of the MRS . In addition , SF-36 physical functioning , SF-36 social functioning and TTO were characterized in patients who demonstrated improvement in global MRS outcome and also achieved a  Barthel Index ( BI ) ≧95 at 3 months after stroke . Results : Two hundred and eighty patients ( 62 % ) shifted at least one grade in MRS from baseline to 3 months after stroke . Only 67 or 194 patients were considered to have a favorable outcome using MRS 0/1 or MRS 0/1/2 , respectively , as criteria . Mean 3-month NIHSS and Barthel ADL scores were not significantly different between Rankin 0/1 and 2 , but they were significantly different among Rankin 3 , 4 and 5 ( all p < 0.05 ) . Mean 3-month scores of physical functioning and SF-36 social functioning were significantly different among Rankin 0/1 , 2 , 3 and 4 ( all pairwise p < 0.05 ) . Proportions of patients who achieved NIHSS ≤1 or BI ≧95 decreased as MRS grade s worsened . In patients who showed improvement in MRS global outcome and also achieved BI ≧95 , mean scores on TTO were similar . Conclusions : Definition of favorable outcomes should include transition in the Modified Rankin score rather than MRS dichotomized as 0/1 or 0/1/2 because patients with transition in MRS scores have improvement in ADL , increased higher level of functioning and higher utility for health state BACKGROUND Previous research suggests that people respond differently to health status measures when data are collected by interview or self completion of a question naire . The objective of this study was to determine whether SF-36 health status scores differ systematic ally by method of administration . METHOD A r and omized cross-over study was carried out on 210 new attenders at general medicine , endocrinology , gastroenterology and urological out-patient departments . The outcome was the difference in SF-36 profiles comparing clinic based interviews with self completion at home by the same subjects . RESULTS For seven of the eight variables of the SF-36 scores were lower in the  self assessment  , the differences being statistically significant in four of the eight comparisons . The largest differences were in role limitations due to emotional problems ( difference 14.74 , 95 per cent confidence interval ( CI ) 7.76 - 21.7 ) and social function ( difference 7.21 , 95 per cent CI 3.19 - 11.23 ) . CONCLUSIONS Clinic based interviews systematic ally exaggerate health status compared with self assessment .  The difference is sufficiently large to underestimate the effectiveness of health service interventions when a clinic based pre-intervention and postal self completed follow-up design is used , unless adjustment is made for this systematic bias OBJECTIVE To compare the utility values and quality -adjusted life years ( QALYs ) obtained by the Time Trade-Off instrument ( TTO ) and the EuroQol-5D ( EQ-5D ) in patients with rheumatoid arthritis ( RA ) ; to analyze the association between utility values and Disease Activity Score 28 ( DAS28 ) and Health Assessment Question naire ( HAQ ) . METHODS We conducted a longitudinal , prospect i ve , 1-year study of RA patients selected r and omly from 10 rheumatology clinics .  TTO and EQ-5D were administered at 4 scheduled visits . RESULTS The study sample comprised 300 RA patients ( 82 % women , mean age 59 years , mean disease duration 10.3 years ) . A total of 260 patients completed both the TTO and the EQ-5D at baseline , and the mean + /- SD TTO scores were significantly higher than the EQ-5D scores ( 0.81 + /- 0.22 versus 0.53 + /- 0.35 , P < 0.0001 ) . The intraclass correlation coefficient ( ICC ) for the utility methods was 0.19 . Data about changes in both TTO and EQ-5D scores during the study year were available in 163 patients . These changes tended to be larger in the TTO scores than the EQ-5D scores ( mean + /- SD 0.05 + /- 0.25 versus -0.005 + /- 0.35 , P = 0.054 ) . The ICC for the mean changes in the utility scores was 0.24 . Patients obtained a mean + /- SD of 0.04 + /- 0.20 QALYs based on TTO scores and 0.004 + /- 0.27 based on EQ-5D scores ( P = 0.12 ) . At baseline , the EQ-5D scores were highly correlated with the HAQ ( r = -0.74 ) and moderately correlated with the DAS28 ( r = -0.47 ) , whereas the TTO correlated poorly with both the HAQ and DAS28 . Correlation between the mean change in the EQ-5D and in the HAQ was moderate ( r = -0.55 ) . CONCLUSION TTO and EQ-5D do not yield the same utility values . The results suggest that the EQ-5D is more representative of RA status than the TTO , a valuable conclusion when addressing economic evaluations in RA There have been few longitudinal studies of quality of life in patients with all stages of lung cancer , particularly those that have included measures of utility . The purpose of this study was to examine the psychometric properties of the Assessment of Quality of Life instrument ( AQoL )  in patients with lung cancer . The AQoL is a health-related quality of life question naire and provides a descriptive system for a multi-attribute utility instrument ( MAU ) , so that scores can be used in cost-utility evaluations . In the present study the reliability ( internal consistency ) of the AQoL was examined and the concurrent validity was assessed using the Medical Outcomes 36-item Short Form Health Survey ( SF-36 ) as the comparator instrument . The sensitivity to different health states of the AQoL and the responsiveness to change over time was also examined . A prospect i ve , non-experimental cohort study was undertaken . Ninety-two participants with all stages of lung cancer were recruited from a tertiary multi-disciplinary lung cancer clinic . Ninety participants had non-small cell lung cancer ( NSCLC ) and two had limited stage small cell lung cancer . The  AQOL and SF-36 surveys  were administered concurrently at baseline . In patients with NSCLC the surveys were then repeated 3 and 6 months later . Correlations between the baseline AQoL summary scales and SF-36 summary scales support the divergent and convergent validity of the AQoL.  Reliability was also found to be sufficient ( Cronbach 's Alpha=0.76 ) . In addition , in patients with inoperable NSCLC , baseline AQoL scores were found to be predictive of survival at 6 months in Cox proportional hazards multivariate analysis . However , the physical components summary score of the SF-36 was more sensitive to differences in health states between patients with different stages of NSCLC at 6 months of follow-up and more responsive to change over time in both operable and inoperable patients with NSCLC than the AQoL. The findings support the construct validity and reliability of the  AQoL  in this population . However , there remains some uncertainty about whether the AQoL has sufficient sensitivity to different health states in this population . Further studies using other MAU instruments may determine whether alternative instruments are more sensitive to different health states in individuals with lung cancer Several specific and general measures are available for the assessment of overall health related quality of life in epilepsy . Few of the commonly used measures provide utility weights for use in cost-utility analyses . This study compares four methods for measuring utility weights : time trade-off ( TTO ) , st and ard gamble ( SG ) , 15D , end the EuroQol visual analog scale .  All patients aged 18 - 67 years with a diagnosis of epilepsy , who had been admitted to or attended the outpatient clinic at a large county hospital 1987 - 1994 , received a comprehensive question naire . From 397 respondents , 82 patients were r and omly selected . Most of the 57 patients completing the study generally had well-controlled epilepsy , but were still on anti-epileptic medication . Mean age was 44 years . Fourty-one percent were male and 59 % female . The result ing utility weights differed considerably between the measures , both with regard to central tendency and dispersion . Median utility scores : EuroQol visual analog scale 0.75 , 15D 0.90 , TTO 0.98 , SG 0.99 . There was a good association between the EuroQol rating scale and the 15D , and a moderate association between SG and TTO . These preference instruments measure different aspects of health-related quality of life and thus yield different results . Caution should be taken when interpreting cost-utility studies , as results will depend on the choice of utility instrument This paper reports a comparative study of three formulations of the time-tradeoff ( TTO ) method of health valuation . One asks people to consider giving up time each day in exchange for better health . The second asks people to consider giving up time during a 12-month interval . The third is the more conventional TTO in which people are asked to contemplate a reduction in life expectancy . Question naires were sent to 4,087 adults selected at r and om from the population of Scotl and . Each respondent provided a de scription of his or her health , and was asked to value an improvement in that health , using all three formulations of the TTO . The daily TTO appeared to be an improvement on the conventional formulation , correlating more strongly with health , eliciting re sponses that appeared to be more precise , and obtaining information about the value of health from a far greater number of respondents . The performance of the annual TTO appeared to be only slightly inferior to that of the daily TTO . Key words : time tradeoff ; quality of life ; health valuation . ( Med Decis Making 1996;16:335 - 347 OBJECTIVES The authors evaluated the relative responsiveness to change of generic versus disease-specific and unweighted versus weighted health status measures in carpal tunnel syndrome ( CTS ) . METHODS Data were obtained from 196 subjects followed in a prospect i ve community-based cohort study in Maine who underwent carpal tunnel release ( The Maine Carpal Tunnel Syndrome Study ) . Patients were evaluated before and 6 months after surgery . The disease-specific , unweighted severity score was derived from the vali date d Carpal Tunnel Syndrome Assessment Question naire . Patients were asked to rate the importance of each symptom included in the severity score . Each severity question was weighted by its importance , creating a disease-specific weighted score . Generic instruments were the SF-36 , SF-12 , and a  Quality of Life Rating Scale .  Sensitivity to change was calculated with the st and ardized response mean ( SRM , mean change/st and ard deviation of change ) as well as the effect size ( ES , mean change/st and ard deviation of baseline values ) . The ability of the instruments to distinguish clinical ly important differences was assessed by correlating the changes in scores with global ratings on satisfaction and perceived improvement as external criteria . RESULTS The disease-specific weighted score ( SRM : 1.56 , ES : 1.99 ) was more responsive than the unweighted score ( SRM : 1.36 , ES : 1.57 ) . The Quality of Life Rating Scale , SF-36 , and SF-12 subscales were less sensitive to change , with st and ardized response means and effect sizes that ranged from -0.23 to 0.88 . The ability to distinguish clinical ly important differences was higher for the two disease-specific scales . The coefficients of correlation with the external criteria ranged from 0.50 to 0.56 for the unweighted score and 0.56 to 0.62 for the weighted score and were significantly stronger than the correlations between external measures and the most responsive subscale of the SF-36 ( Bodily Pain subscale , r = 0.36 ) . The SF-12 health survey performed as well as the SF-36 in term of responsiveness and ability to distinguish clinical ly important change . CONCLUSIONS Disease-specific measures were superior to generic measures in capturing clinical change after carpal tunnel release , and a weighted score was slightly more responsive than the unweighted score . The SF-12 showed comparable psychometric properties compared with the longer 36-item Short-Form Survey OBJECTIVE The goal of this study was to estimate an algorithm to convert responses to the Functional Assessment of Cancer Therapy - General ( FACT-G ) to time trade-off ( TTO ) utilities based on utilities for current health elicited from cancer patients . METHODS Data for 1433 cancer patients were r and omly separated into construction and validation sample s. Four FACT-G questions were selected for inclusion based on correlation with Eastern Clinical Oncology Group - Performance Status ( ECOG-PS ) scores and TTO utilities . Item response theory was used to collapse response categories . Ordinary least squares regression with the constant constrained to one was used to estimate the algorithm . RESULTS The algorithm estimated mean utility for the full validation sample within three points of observed mean utility ( 0.805 vs. 0.832 , P < 0.01 ) . Mean utilities were well predicted ( mean absolute difference < 0.03 , P > 0.05 ) for most subgroups defined by ECOG-PS and Short Form-36 physical functioning scores , and responses to the FACT-G overall quality of life item . Nevertheless , the algorithm systematic ally overpredicted utilities for poorer health states . CONCLUSIONS A FACT-G-based algorithm of cancer patient utilities was developed that estimates group mean utility scores with accuracy comparable to other indirect preference-based measures of health-related quality of life . Patient-based preferences for health outcomes of cancer treatment may be useful in multiple situations , such as managing re sources within cancer centers and in underst and ing health states preferences among cancer experienced patients before and after treatment Background In clinical trials , both unequal r and omization design and sequential analyses have ethical and economic advantages . In the single-stage- design ( SSD ) , however , if the sample size is not adjusted based on unequal r and omization , the power of the trial will decrease , whereas with sequential analysis the power will always remain constant . Our aim was to compare sequential boundaries approach with the SSD when the allocation ratio ( R ) was not equal . Methods We evaluated the influence of R , the ratio of the patients in experimental group to the st and ard group , on the statistical properties of two-sided tests , including the two-sided single triangular test ( TT ) , double triangular test ( DTT ) and SSD by multiple simulations . The average sample size numbers ( ASNs ) and power ( 1-β ) were evaluated for all tests . Results Our simulation study showed that choosing R = 2 instead of R = 1 increases the sample size of SSD  by 12 % and the ASN of the TT and DTT by the same proportion . Moreover , when R = 2 , compared to the adjusted SSD , using the TT or DTT allows to retrieve the well known reductions of ASN observed when R = 1 , compared to SSD . In addition , when R = 2 , compared to SSD , using the TT and DTT allows to obtain smaller reductions of ASN than when R = 1 , but maintains the power of the test to its planned value . Conclusion This study indicates that when the allocation ratio is not equal among the treatment groups , sequential analysis could indeed serve as a compromise between ethicists , economists and statisticians
The results of this study do not support the common view that RS values are lower than TTO values , may suggest that TTO biases largely cancel , and support the validity of formulas for correcting SG bias
Background .
A common assertion is that rating scale ( RS ) values are lower than both st and ard gamble ( SG ) and time tradeoff ( TTO ) values .
However , differences among these methods may be due to method specific bias .
Although SG and TTOs suffer systematic bias , RS responses are known to depend on the range and frequency of other health states being evaluated .
Over many diverse studies this effect is predicted to diminish .
Thus , a systematic review and data synthesis of RS-TTO and RS-SG difference scores may better reveal persistent dissimilarities .
The purpose of this study was to establish through systematic review and meta- analysis the net effect of biases that endure over many studies of utilities .