Quality of life six months after myocardial infarction treated with thrombolytic therapy. AUS-TASK Group. Australian arm of International tPA/SK Mortality Trial

Decision analysis and reinforcement learning in surgical decision-making

BACKGROUND

Surgical patients incur preventable harm from cognitive and judgment errors made under time constraints and uncertainty regarding patients' diagnoses and predicted response to treatment. Decision analysis and techniques of reinforcement learning theoretically can mitigate these challenges but are poorly understood and rarely used clinically. This review seeks to promote an understanding of decision analysis and reinforcement learning by describing their use in the context of surgical decision-making.

METHODS

Cochrane, EMBASE, and PubMed databases were searched from their inception to June 2019. Included were 41 articles about cognitive and diagnostic errors, decision-making, decision analysis, and machine-learning. The articles were assimilated into relevant categories according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines.

RESULTS

Requirements for time-consuming manual data entry and crude representations of individual patients and clinical context compromise many traditional decision-support tools. Decision analysis methods for calculating probability thresholds can inform population-based recommendations that jointly consider risks, benefits, costs, and patient values but lack precision for individual patient-centered decisions. Reinforcement learning, a machine-learning method that mimics human learning, can use a large set of patient-specific input data to identify actions yielding the greatest probability of achieving a goal. This methodology follows a sequence of events with uncertain conditions, offering potential advantages for personalized, patient-centered decision-making. Clinical application would require secure integration of multiple data sources and attention to ethical considerations regarding liability for errors and individual patient preferences.

CONCLUSION

Traditional decision-support tools are ill-equipped to accommodate time constraints and uncertainty regarding diagnoses and the predicted response to treatment, both of which often impair surgical decision-making. Decision analysis and reinforcement learning have the potential to play complementary roles in delivering high-value surgical care through sound judgment and optimal decision-making.

Acute and chronic impact of cardiovascular events on health state utilities

BACKGROUND

Cost-utility models are frequently used to compare treatments intended to prevent or delay the onset of cardiovascular events. Most published utilities represent post-event health states without incorporating the disutility of the event or reporting the time between the event and utility assessment. Therefore, this study estimated health state utilities representing cardiovascular conditions while distinguishing between acute impact including the cardiovascular event and the chronic post-event impact.

METHODS

Health states were drafted and refined based on literature review, clinician interviews, and a pilot study. Three cardiovascular conditions were described: stroke, acute coronary syndrome (ACS), and heart failure. One-year acute health states represented the event and its immediate impact, and post-event health states represented chronic impact. UK general population respondents valued the health states in time trade-off tasks with time horizons of one year for acute states and ten years for chronic states.

RESULTS

A total of 200 participants completed interviews (55% female; mean age = 46.6 y). Among acute health states, stroke had the lowest utility (0.33), followed by heart failure (0.60) and ACS (0.67). Utility scores for chronic health states followed the same pattern: stroke (0.52), heart failure (0.57), and ACS (0.82). For stroke and ACS, acute utilities were significantly lower than chronic post-event utilities (difference = 0.20 and 0.15, respectively; both p < 0.0001).

CONCLUSIONS

Results add to previously published utilities for cardiovascular events by distinguishing between chronic post-event health states and acute health states that include the event and its immediate impact. Findings suggest that acute versus chronic impact should be considered when selecting scores for use in cost-utility models. Thus, the current utilities provide a unique option that may be used to represent the acute and chronic impact of cardiovascular conditions in economic models comparing treatments that may delay or prevent the onset of cardiovascular events.

A systematic literature review of cardiovascular event utilities

Cardiovascular disease (CVD) results in half of the non-communicable disease-related deaths worldwide. Rising treatment costs have increased the need for cost-utility models designed to compare the value of new and existing therapies. Cost-utility models require utilities, values representing the strength of preferences for various health states. This systematic literature review aimed to identify and evaluate utilities reported for stroke, myocardial infarction (MI) and angina. In total, 83 unique studies were identified that reported utilities for these events. Approximately two-thirds reported utility values for stroke, and most used the EuroQoL five dimension to derive utilities. Utility values were lower in patients who experienced cardiovascular (CV) events than in patients who did not. The utility estimates for each condition varied greatly, likely due to differences in assessment methodologies and patient populations. This variability must be considered when choosing values for cost-utility models. Comparisons among reported utilities are further complicated by inconsistent CV event definitions.

Quality-adjusted life year weights among elderly patients with heart failure

BACKGROUND

When assessing health-related quality of life (HRQoL) in elderly patients with heart failure (HF), the process of obtaining quality-adjusted life year (QALY) weights is generally complicated and time-consuming.

AIM

To evaluate whether information regarding HRQoL and QALY weights can be derived directly from the established and widely used New York Heart Association (NYHA) functional classification system.

METHODS

NYHA functional status was assessed independently both by the individual patients and by the examining cardiologist in 323 elderly patients with symptoms of HF recruited from primary care. HRQoL was evaluated using the SF-36 questionnaire and a time trade-off (TTO) scenario. The TTO technique generates direct QALY weights.

RESULTS

Both the TTO technique and SF-36 values demonstrated a statistically significant correlation with NYHA functional status. The TTO values also correlated with all SF-36 dimensions. Increasing impairment was associated with statistically significant drops in both SF-36 values and TTO-based QALY weights. For patients in NYHA classes I-IV the QALY weights were 0.77, 0.68, 0.61, and 0.50, respectively. Thus in elderly patients, symptoms of HF have a major impact on perceived quality of life.

CONCLUSION

The results of the present study show that QALY weights, an important instrument in the health economic evaluation of treatment strategies, can be derived directly from NYHA classification in elderly HF patients.

Psychological and social impacts of automated external defibrillators (AEDs) in the home

BACKGROUND

The majority of cardiac arrests occur in the home. The placement of AEDs in the homes of at-risk patients may save lives through early defibrillation. However, the impact of having an AED in the home on psychological outcomes and quality-of-life is unknown.

OBJECTIVE

The purpose of this research was to determine whether training in the use of and possessing an automated external defibrillator (AED) has an effect on a patient at risk's quality of life.

METHODS

We investigated the psychological consequences of AED training and possession of such a device for patients who recently experienced an acute ischemic event. One hundred fifty eight patients and their family members were assigned at random to receive cardiopulmonary resuscitation (CPR) training (N=66) or AED/CPR training and possession of the device after training (N=92). We measured quality of life using the Short-Form (SF-36) survey and a 9-item survey we developed specifically for this study to measure differences in social activities and worries about being left alone. Participants answered these questions at enrollment, 2 weeks, 3 months, and 3 months after enrollment.

RESULTS

Patients in the AED group reported lower (worse) scores on most SF-36 subscales at all periods, particularly in those subscales relating to social functioning. The differences were most often small and probably not clinically meaningful. The social activities/worry scales also favored the CPR group at all periods, but with no significant differences.

CONCLUSIONS

Physicians counselling patients about AEDs should be aware of the potential effects the device may have on a patient's social functioning.

Economic evaluation of a randomised trial of early return to normal activities versus cardiac rehabilitation after acute myocardial infarction

BACKGROUND

Although there have been a number of economic evaluations of cardiac rehabilitation after acute myocardial infarction (AMI), none has considered only low-risk patients or control groups with no rehabilitation at all.

METHODS

An economic evaluation was included in a randomised controlled trial of patients following uncomplicated AMI. Eligible patients were randomised to return to normal activities after 6 weeks of standard rehabilitation (REHAB, n = 70) or to early return to normal activities 2 weeks after AMI with no formal rehabilitation (ERNA, n = 72). Outcomes were assessed weekly for 6 weeks, then 3, 6 and 12 months post-AMI. Outcomes included four quality of life (QOL) measures (physical abilities, distress, usual/social activities, self-care) and four measures of return to normal activities (paid and unpaid return to any work and to pre-AMI level of work). Statistical analysis included repeated-measures regression (QOL outcomes) and survival analysis (work outcomes).

RESULTS

There were no statistically significant differences between the two groups in any of the outcomes measured or in the use of other health services. The net cost that could be saved by the health service by targeting rehabilitation to high-risk patients was approximately $300 (Australian, 1999) per low-risk patient.

CONCLUSIONS

Early return to normal activities without formal rehabilitation is cost-effective for low-risk patients.

Quality of life after acute myocardial infarction: a comparison of diabetic versus non-diabetic acute myocardial infarction patients in Quebec acute care hospitals

BACKGROUND

Previous studies have evaluated the individual effects of acute myocardial infarction (AMI) and diabetes mellitus on health-related quality of life outcomes (QOL). Due to the rising incidence of these comorbid conditions, it is important to examine the synergistic impact of diabetes mellitus and AMI on QOL.

METHODS

In this study, we assessed using several previously validated questionnaires the QOL and functional status of 96 diabetic patients and 491 non-diabetic patients admitted to Quebec hospital sites with AMI between 1997 and 1998. We also conducted multivariate analyses to ascertain whether diabetes mellitus was an independent determinant of SF-36 physical functioning (PCS) and mental health (MCS) component score QOL outcomes after AMI.

RESULTS

Both patient groups had similar baseline clinical characteristics, but diabetic patients had slightly higher rates of cardiac risk factors compared to non-diabetics. Overall, QOL measures were similar between both patient groups at baseline, but diabetic patients reported poorer functional status than non-diabetic patients. Over the study period, there were significant differences between the QOL and functional status of diabetic and non-diabetic populations. By one year, diabetic patients reported poorer QOL outcomes than non-diabetic patients. However, diabetic patients showed greater improvements in their functional status, but were less likely to return to work compared to non-diabetic patients. In contrast with these findings, our multivariate analyses showed that diabetes mellitus was not an independent determinant of QOL and functional status.

CONCLUSION

Our study findings suggest that diabetes mellitus is not an independent determinant of QOL after AMI.

Reassessment of the cost-effectiveness of hormone replacement therapy in Sweden: Results based on the Women's Health Initiative randomized controlled trial

Objectives:The purpose of the study is to reassess the cost-effectiveness of hormone replacement therapy (HRT) based on new medical evidence found in the Women's Health Initiative (WHI). Within a model framework using an individual state transition model, the cost-effectiveness of 50- to 60-year-old women with menopausal symptoms is assessed based on a societal perspective in Sweden.

Methods:The model has a 50-year time horizon divided into a cycle length of 1 year. The model consists of the following disease states: coronary heart disease, stroke, venous thromboembolic events, breast cancer, colorectal cancer, hip fracture, vertebral fracture, and wrist fracture. An intervention is modeled by its impact on the disease risks during and after the cessation of therapy. The model calculates costs and quality-adjusted life years (QALYs) with and without intervention. The resulting cost per QALY gained is compared with the value of a QALY gained, which is set to SEK 600,000. The model requires data on clinical effects, risks, mortality rates, quality of life weights, and costs valid for Sweden.

Results:The cost-effectiveness ratios are estimated at approximately SEK 10,000, which is below the threshold value of cost-effectiveness. On the condition that HRT increases the quality of life weight more than 0.013 units, the therapy is cost-effective.

Conclusions:In conclusion, given the new evidence in WHI, there is still a high probability that HRT is a cost-effective strategy for women with menopausal symptoms.

Cost-effectiveness of fluvastatin following successful first percutaneous coronary intervention

BACKGROUND

In the LIPS (Lescol Intervention Prevention Study), fluvastatin 80 mg/day reduced the risk of major adverse cardiac events (MACE) by 22% versus placebo (p = 0.01) following successful first percutaneous coronary intervention (PCI) in patients with stable or unstable angina or silent ischemia. The cost-effectiveness of such therapy is unknown.

OBJECTIVE

To evaluate the cost-effectiveness of fluvastatin following successful first PCI from a US healthcare system perspective.

METHODS

We used a Markov model to estimate expected outcomes and costs of 2 alternative treatment strategies following successful first PCI in patients with stable or unstable angina or silent ischemia: (1) diet/lifestyle counseling plus immediate fluvastatin 80 mg/day; and (2) diet/lifestyle counseling only, with initiation of fluvastatin 80 mg/day following occurrence of future nonfatal MACE. The model was estimated with data from LIPS and other published sources. Cost-effectiveness was calculated as the ratio of the difference in expected medical-care costs to the expected difference in life-years (LYs) and quality-adjusted life-years (QALYs) alternatively.

RESULTS

Treatment with fluvastatin following successful first PCI was found to increase life expectancy by 0.78 years (QALYs 0.68). Cost-effectiveness of fluvastatin following successful first PCI is 13 505 dollars per LY (15 454 dollar per QALY) saved. Ratios are lower for patients with diabetes (9396 dollar per LY; 10 718 dollar per QALY) and those with multivessel disease (9662 dollar per LY; 11 076 dollar per QALY). Findings were robust with respect to changes in key model parameters and assumptions.

CONCLUSIONS

Fluvastatin therapy following PCI is cost-effective compared with other generally accepted medical interventions.

Association of time elapsed since the last coronary event with health services utilization

BACKGROUND

Patients with chronic illness use health services more often but little is known about the use that coronary heart disease patients make of primary care.

OBJECTIVE

To determine whether the time elapsed and the perceived quality of life following a major acute coronary event are associated with utilization rate of primary care services.

DESIGN

Cross-sectional, multicentre study.

SETTING

Twenty-three primary care health centres in Catalonia (Spain).

PARTICIPANTS

Patients aged 30-80 years who had suffered a major coronary event in the previous 6 years.

MAIN OUTCOME MEASURES

The number of consultations with the general practitioner during the year before the beginning of the study was noted and patients who consulted nine or more times were considered frequent attenders. The time elapsed since the last major coronary event was categorized using the median (2 years) as a cut-off value. The SF-12 quality of life questionnaire was administered.

RESULTS

A total of 1022 patients with coronary heart disease were included. The median number of consultations with a general practitioner within the previous year was 5 (range 0 - 36). Patients with a shorter time elapsed since the last coronary event were seen more often by their general practitioner. The probability of being frequent attender was 24% Iower among patients with less recent coronary events (adjusted odds ratio: 0.76, 95% confidence interval: 0.69 - 0.85, p < 0.001). Quality of life scores were similar in frequent and non-frequent attenders. No relationship between comorbidity and frequent attendance was found.

CONCLUSIONS

The shorter time elapsed since the last coronary event was an important factor related with frequent attendance in coronary heart disease patients regardless of cardiovascular comorbidity, and perceived quality of life.

A Bayesian approach to evaluating net clinical benefit allowed for parameter uncertainty

BACKGROUND AND OBJECTIVE

Although randomized controlled trials (RCTs) are conducted to establish whether novel interventions work on average in the patient population, there is a growing desire to move to a more individualized approach to evaluation. The potential benefits and harms of a treatment policy may differ between individuals. If these benefits and harms are not evaluated distinctly, and in a quantitative framework, transparency can be lost in the decision-making process.

METHODS

Glasziou and Irwig have outlined the concept of net clinical treatment benefit for identifying the patients for whom the potential benefits of treatment outweigh the possible side effects. This study revisits the decision whether to use warfarin to treat atrial fibrillation. In this analysis, RCT and various sorts of observational data are synthesized.

RESULTS

This reanalysis brings into question the conclusions of the original analysis on who would benefit from warfarin; however, caution is advised, due to limitations in the quality of life data available.

CONCLUSION

A fully realized Bayesian implementation of the model is presented. This provides a framework for including uncertainty related to the estimation of all model parameters, and permits both direct probability statements and credible intervals for specific patient groups to be expressed.

Health-related quality of life in patients 7 months after a myocardial infarction: factors affecting the Short Form-12

We assessed patients' health-related quality of life after myocardial infarction and identified related variables. Clinical data were obtained retrospectively from medical records of consecutive patients admitted to a Midwestern university-affiliated medical center with diagnosis of myocardial infarction from July 1999-July 2000. Telephone interviews 7 months after discharge were made to administer the Short Form-12 (SF-12) and obtain patient, disease, drug, and intervention data. Complete information was obtained from 200 patients (mean age 63.4 +/- 13.1 yrs, 68% men). The mean Physical Component Summary (PCS)-12 score was 40.6 +/- 12.0, and the mean Mental Component Summary (MCS)-12 score was 52.1 +/- 10.0. Based on univariate analyses, low PCS-12 scores were associated with women; non-Q-wave infarctions; greater number of illnesses; history of myocardial infarction, chronic heart failure (CHF), transient ischemic attack (TIA), renal disease, peripheral vascular disease, or percutaneous coronary intervention (PCI); rehospitalization during the interim period; and unscheduled PCI since index myocardial infarction. Low MCS-12 scores were associated with age below 65 years, low overall self-reported drug therapy compliance, low self-reported compliance with angiotensin-converting enzyme inhibitor and lipid-lowering therapy, no history of coronary artery bypass graft, and no stress test since index myocardial infarction. A multivariate regression model for PCS-12 kept the following variables: greater number of illnesses, history of CHF or TIA, and rehospitalization since index myocardial infarction. The MCS-12 model contained age below 65 years, low overall compliance, and low compliance with lipid-lowering therapy. Further work is necessary to determine noncardiovascular predictors of quality of life and whether interventions for these patients will result in improved quality of life.

Economics of drug treatment: for which patients is it costeffective to lower cholesterol?

Today's society places a great emphasis on value for money, so medical interventions must not only be shown to be effective but also be proved to be costeffective. Drug treatment is no exception. In health economics, costeffectiveness is calculated differently depending on the indication and the perspective. For cholesterol-lowering drugs (as an example) there is a difference between primary and secondary intervention. In primary prevention, the cut off value for absolute risk when treatment is costeffective varies with age and sex, but in secondary prevention, although treatment is costeffective for all groups of patients, costeffectiveness varies with age, sex, cholesterol concentration, and other risk factors. There are three complementary approaches to economic assessment of secondary prevention-analysis of the whole population, subgroup analysis, and modelling.

The utility of health states after stroke: a systematic review of the literature

BACKGROUND

To perform decision analyses that include stroke as one of the possible health states, the utilities of stroke states must be determined. We reviewed the literature to obtain estimates of the utility of stroke and explored the impact of the study population and the elicitation method.

SUMMARY OF REVIEW

We searched various databases for articles reporting empirical assessment of utilities. Mean utilities of major stroke (Rankin Scale 4 to 5) and minor stroke (Rankin Scale 2 to 3) were calculated, stratified by study population and elicitation method. Additionally, the modified Rankin Scale was mapped onto the EuroQol classification system. Utilities were obtained from 23 articles. Patients at risk for stroke assigned utilities of 0.26 and 0.55 to major and minor stroke, respectively. Stroke survivors assigned higher utilities to both major (0.41) and minor stroke (0.72). The EuroQol completed by stroke survivors revealed a utility of 0.32 and 0.71 for major and minor stroke, respectively. Utilities elicited by the Standard Gamble were generally higher, while those obtained by the Visual Analogue Scale were lower than the Time Trade Off values. Remaining variation between utilities may be caused by differences in definitions of the health states. The mapped EuroQol indicated a utility of 0.64 for minor stroke and a value just below zero for major stroke.

CONCLUSIONS

For minor stroke, a utility between 0.50 and 0.70 seems to be reasonable for both decision analyses and cost-effectiveness studies. The utility of major stroke may range between 0 and 0.30 and may possibly be negative.

Risks and benefits of glycoprotein IIb/IIIa antagonists in acute coronary syndrome

BACKGROUND

Recommendations for the use of glycoprotein (GP) IIb/IIIa antagonists should consider not only their effectiveness but also their links with other clinical findings (both favorable and adverse), the risk/benefit ratio in different subgroups of patients, and the existence of other therapeutic alternatives; additionally, the estimates underlying the recommendation should be explicit.

OBJECTIVE

To establish explicit evidence-based recommendations regarding the use of GP IIb/IIIa antagonists in medically treated patients with acute coronary syndrome without ST-segmentelevation.

DATA SOURCES

MEDLINE-based search (1980 to November 1999) of randomized controlled trials for effectiveness data and nonsystematic review of published data regarding utilities of relevant status and clinical events.

STUDY SELECTION

We included clinical trials in which the patients were randomly assigned either to an experimental group treated with intravenous GP IIb/IIIa antagonists or to a control group. We excluded studies in which the intention to perform a percutaneous procedure was a criterion for inclusion.

DATA EXTRACTION

The effectiveness of the treatment was defined as the incidence of death or a nonfatal infarct at 30 days. The risks of the treatment were estimated using the incidence of moderate to severe hemorrhage.

DATA SYNTHESIS

Meta-analysis of randomized controlled trials in patients with acute coronary syndrome and calculation of the threshold number needed to treat (t-NNT).

RESULTS

Compared with conventional treatment, GP IIb/IIIa antagonists reduce the risk of death or nonfatal infarct at 30 days by approximately 11.7% (number needed to treat [NNT] = 65 for the basal risk of patients included in the studies; 95% CI 40 to 203). However, the use of GP IIb/IIIa antagonists increases the risk of moderate to severe hemorrhage by 32%. In an analysis biased in favor of the use of GP IIb/IIIa antagonists, these risks imply a t-NNT of approximately 150, which overlaps with the confidence interval of the basal NNT. The limits of a 95% confidence interval of the NNT are only lower than the t-NNT in patients with a high risk of death/infarct (at least 5%) and low risk of hemorrhage (less than the weighted basal risk in the trials analyzed).

CONCLUSIONS

At present, there is no conclusive evidence that the expected benefits outweigh the nsks in the average patient included in the available trials. The benefit is probably greater than the risks in patients with a high risk of death/infarct and low risk of hemorrhage. In patients with a low risk of death/infarct and/or high risk of hemorrhage, the risks seem to outweigh the benefits and so, in the latter case, such therapy should not be used.

When should an effective treatment be used? Derivation of the threshold number needed to treat and the minimum event rate for treatment

Clinicians and patients must decide when treatment effects are large enough to more than offset the adverse effects and costs of therapy. Calculation of the number of patients one needs to treat (NNT) in order to prevent one patient from having the target event is one tool to help with this decision. Clinicians should treat patients when the NNT is lower than a threshold NNT at which point the therapeutic risk equals the therapeutic benefit. We aimed: (1) to identify the determinants of the threshold NNT, and (2) to derive equations for the explicit estimation of the threshold NNT and of the minimum expected rate of target event, without treatment, above which treatment is justified. We conceived the threshold number needed to treat to prevent one target event as the point at which the benefits of treating that number of patients equal the negative consequences of treating that same number of patients. After identifying the various elements comprising the treatment impact, we equated the benefits and negative consequences and solved the equation for threshold NNT. We then derived the minimum expected rate of target event which would justify treatment. We derived an equation that relates the threshold NNT to the treatment-attributable adverse event rates (AER) and the relative values (RV) of the adverse events compared to that of the target event prevented. Specifically, the threshold NNT, denoted NNT(T) is given by NNT(T) = 1/(AER(1).RV(1) +...+ AER(n).RV(n)). We also derived a more complex equation which addresses the costs incurred by treatment and costs avoided by preventing target events. Solving the equation that includes costs requires specifying both the value of preventing a target event and the values of adverse treatment effects in economic units. The threshold NNT and the relative risk reduction (RRR) for the target event determine the minimum target event rate above which treatment is justified. This minimum event rate for treatment is 1/(NNT(T).RRR). The values that clinicians and patients use determine the threshold NNT and therefore also the minimum target event rate, without treatment, above which treatment is justified. Quantification of the determinants of the threshold NNT and of the minimum event rate to justify treatment can assist clinicians and patients in the explicit use of underlying values when making treatment decisions.

Health related quality of life after conservative or invasive treatment of inducible postinfarction ischaemia. DANAMI study group

OBJECTIVE

To assess health related quality of life in patients with inducible postinfarction ischaemia.

DESIGN

A questionnaire based follow up study on patients randomised to conservative or invasive treatment because of postinfarction ischaemia.

SETTING

Seven county hospitals in eastern Denmark and the Heart Centre, National University Hospital, Copenhagen, Denmark.

PATIENTS

113 patients with inducible postinfarction ischaemia: 51 were randomised to conservative treatment and 62 to invasive treatment. Average follow up time was three years (19-57 months).

MAIN OUTCOME MEASURES

SF-36, Rose angina and dyspnoea questionnaire, drug use, lifestyle, and cognitive function.

RESULTS

Invasively treated patients scored better on the SF-36 scales of physical functioning (p = 0.03) and on role-physical (p = 0.04) and physical component scales (p = 0.05) and took significantly less anti-ischaemic drug treatment. Angina occurred in 18% of the invasively treated patients and 31% of the conservatively treated patients (p = 0.09). However, more invasively treated patients suffered from concentration difficulties (18% v 4%; p = 0.04).

CONCLUSIONS

Patients who were treated invasively had better health related quality of life scores in the physical variables compared with conservatively treated patients. However, a larger proportion of invasively treated patients had concentration difficulties.

Relationship of infarct artery patency and left ventricular ejection fraction to health-related quality of life after myocardial infarction: the GUSTO-I Angiographic Study experience

BACKGROUND

Post-myocardial infarction global ejection fraction and infarct-related artery patency might be expected to be associated with health-related quality-of-life (HRQOL) outcomes, but this association has not been previously shown. The GUSTO-I Angiographic Study cohort 2-year follow-up afforded an examination of such potential relationships.

METHODS AND RESULTS

A total of 1848 patients (87.7% response rate) who were enrolled in the GUSTO-I Angiographic Study were contacted for a telephone interview regarding their current HRQOL (physical function, psychological well-being, perceived health status, and social function) 2 years after MI. In multivariable models, left ventricular ejection fraction (EF) was significantly related to physical (P:=0.021) and social (P:=0.014) function, psychological well-being (P:=0.042), and perceived health status (P:=0.024). Infarct-related artery patency was not directly related to any HRQOL outcome. A decreasing EF was predictive of poorer outcomes in each HRQOL dimension. Men consistently had better outcomes in all HRQOL dimension with the exception of perceived health status. Increasing age was predictive of poorer outcomes in all dimensions of HRQOL except for psychological well-being where the inverse occurred; younger patients experienced greater depression, anxiety and worry than their older counterparts. The presence of comorbidities increased the likelihood of worse outcomes in all dimensions.

CONCLUSIONS

This is the first study to demonstrate a significant relationship between EF and long-term HRQOL outcomes. This advantage in left ventricular function preservation should be added to the mortality advantage when considering the impact of treatment strategies for myocardial infarction.

The health and activities limitation index in patients with acute myocardial infarction

Utility assessment is required to estimate quality-adjusted life years, but is often avoided due to the cumbersome nature of elicitation techniques. The Health Activities and Limitations Index (HALex) offers a method of utility assessment using existing values from the National Health Interview Survey (NHIS) and a utility algorithm to derive preferences. The authors assessed the construct validity of the HALex by comparing derived values with directly assessed HALex utilities in patients post acute myocardial infarction (AMI). OLS regression was used to model the relationship between utilities and patient demographics, comorbidities, and treatment. The mean and median utility for patients (n = 160) was.57 (SD = 22) and.55 respectively, and was not statistically different from the mean [.57 (SD =.30)] and median (.58) for similar NHIS respondents (n = 46). Patients with a comorbidity index of three or less had mean utilities.13 higher than the mean utility for patients with an index of four or more. No relationship was found between patients' age, race, and income and their utilities. The HALex scoring algorithm is a promising means to obtain utilities, and provides a methodology to easily estimate utilities for patients, but is not without limitations.

Rethinking fundamental assumptions: SUPPORT's implications for future reform. Study to Understand Prognoses and Preferences and Risks of Treatment

BACKGROUND

The intervention in SUPPORT, the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments, was ineffective in changing communication, decision-making, and treatment patterns despite evidence that counseling and information were delivered as planned. The previous paper in this volume shows that modest alterations in the intervention design probably did not explain the lack of substantial effects.

OBJECTIVE

To explore the possibility that improved individual, patient-level decision-making is not the most effective strategy for improving end-of-life care and that improving routine practices may be more effective.

DESIGN

This paper reflects our efforts to synthesize findings from SUPPORT and other sources in order to explore our conceptual models, their consistency with the data, and their leverage for change.

RESULTS

Many of the assumptions underlying the model of improved decision-making are problematic. Furthermore, the results of SUPPORT suggest that implementing an effective intervention based on a normative model of shared decision-making can be quite difficult. Practice patterns and social expectations may be strong influences in shaping patients' courses of care. Innovations in system function, such as quality improvement or changing the financing incentives, may offer more powerful avenues for reform.

CONCLUSIONS

SUPPORT's intervention may have failed to have an impact because strong psychological and social forces underlie present practices. System-level innovation and quality improvement in routine care may offer more powerful opportunities for improvement.

Establishing health state valuations for disease specific states: an example from heart disease

This study considers the feasibility of defining a QALY from disease-specific data using the New York Heart Association (NYHA) classification of heart failure. The study derives health state values for the four different NYHA classifications of disease progression using the time trade-off (TTO) instrument associated with the five dimensional (EQ-5D) health state valuation method. Consistent mappings between the disease classification and the chosen QALY instrument are found. With this being the case, the assumption of constant proportionality, which is necessary to define the QALY as an acceptable measure of health related preferences, is considered. It is found that constant proportionality does not hold across the more severe health states, thus questioning the use of QALYs as representing cardinal preference structures.

Quality of life related to fear of falling and hip fracture in older women: a time trade off study

OBJECTIVE

To estimate the utility (preference for health) associated with hip fracture and fear of falling among older women.

DESIGN

Quality of life survey with the time trade off technique. The technique derives an estimate of preference for health states by finding the point at which respondents show no preference between a longer but lower quality of life and a shorter time in full health.

SETTING

A randomised trial of external hip protectors for older women at risk of hip fracture.

PARTICIPANTS

194 women aged >/= 75 years enrolled in the randomised controlled trial or who were eligible for the trial but refused completed a quality of life interview face to face.

OUTCOME MEASURES

Respondents were asked to rate their own health by using the Euroqol instrument and then rate three health states (fear of falling, a "good" hip fracture, and a "bad" hip fracture) by using time trade off technique.

RESULTS

On an interval scale between 0 (death) and 1 (full health), a "bad" hip fracture (which results in admission to a nursing home) was valued at 0.05; a "good" hip fracture (maintaining independent living in the community) 0.31, and fear of falling 0.67. Of women surveyed, 80% would rather be dead (utility=0) than experience the loss of independence and quality of life that results from a bad hip fracture and subsequent admission to a nursing home. The differences in mean utility weights between the trial groups and the refusers were not significant. A test-retest study on 36 women found that the results were reliable with correlation coefficients within classes ranging from 0.61 to 0.88.

CONCLUSIONS

Among older women who have exceeded average life expectancy, quality of life is profoundly threatened by falls and hip fractures. Older women place a very high marginal value on their health. Any loss of ability to live independently in the community has a considerable detrimental effect on their quality of life.

Valuing health-related quality of life. A review of health state valuation techniques

Given the growing need to value health-related quality of life, a review of the literature relating to health state valuation techniques was undertaken to appraise the current theoretical and empirical evidence available to inform on the techniques, to identify consensus, identify disagreement and identify important areas for future research. A systematic search of the literature was conducted, covering standard gamble (SG), time trade-off (TTO), visual analogue scale (VAS), magnitude estimation (ME) and person trade-off (PTO) techniques. The basic concepts of practicality, reliability, theoretical validity and empirical validity formed the criteria for reviewing the performance of valuation techniques. In terms of practicality and reliability, we found little evidence relating to ME and PTO. SG, TTO and VAS have been shown to be practical on a range of populations. There is little difference between the reliability of SG, TTO and VAS, and present evidence does not offer a basis to differentiate between them. When considering the theoretical basis of techniques, we conclude that choice-based methods (i.e. SG, TTO and PTO) are best placed to reflect the strength of preference for health, with the choice between these techniques depending on the study characteristics and the perspective employed. Empirical evidence relating to the theoretical perspective of the techniques has shown that there are problems with all techniques in terms of descriptive validity.

A cardiovascular extension of the Health Measurement Questionnaire

OBJECTIVE

To investigate the psychometric properties of a cardiovascular extension of an existing utility-based quality of life questionnaire (Health Measurement Questionnaire). The new instrument has been named the Utility Based Quality of life--Heart questionnaire, or UBQ-H.

DESIGN

Explored the test-retest reliability, construct validity, and responsiveness of the UBQ-H.

PATIENTS

A sample of 322 patients attending cardiac outpatient clinics were recruited from two large metropolitan teaching hospitals. A second sample of 1112 patients taking part in the LIPID trial was also used to investigate the validity and responsiveness of the UBQ-H.

RESULTS

Ninety per cent of all UBQ-H questionnaires were returned, and item completion rates were high (median of less than 1% missing or N/A answers). Cronbach's alpha measure of internal consistency for the scales ranged between 0.79-0.91, and each item was also most strongly correlated with its hypothesised domain than alternative domains. The intra-class test-retest reliability of the UBQ-H scales ranged from 0.65 to 0.81 for patients with stable health. Results supported the construct validity of the UBQ-H. The UBQ-H was significantly correlated with other information on quality of life (for example, General Health Questionnaire) as anticipated. The instrument was able to distinguish between contrasted groups of patients (for example, with versus without symptoms of dyspnoea, prior myocardial infarction versus none, etc), and was responsive to changes in health associated with adverse events requiring hospitalisation.

CONCLUSIONS

The modifications made to the Health Measurement Questionnaire has resulted in an assessment designed for cardiovascular patients that has proved to be both reliable and valid.

Quality of life four years after acute myocardial infarction: short form 36 scores compared with a normal population

OBJECTIVES

To assess the impact of myocardial infarction on quality of life in four year survivors compared to data from "community norms", and to determine factors associated with a poor quality of life.

DESIGN

Cohort study based on the Nottingham heart attack register.

SETTING

Two district general hospitals serving a defined urban/rural population.

SUBJECTS

All patients admitted with acute myocardial infarction during 1992 and alive at a median of four years.

MAIN OUTCOME MEASURES

Short form 36 (SF 36) domain and overall scores.

RESULTS

Of 900 patients with an acute myocardial infarction in 1992, there were 476 patients alive and capable of responding to a questionnaire in 1997. The response rate was 424 (89. 1%). Compared to age and sex adjusted normative data, patients aged under 65 years exhibited impairment in all eight domains, the largest differences being in physical functioning (mean difference 20 points), role physical (mean difference 23 points), and general health (mean difference 19 points). In patients over 65 years mean domain scores were similar to community norms. Multiple regression analysis revealed that impaired quality of life was closely associated with inability to return to work through ill health, a need for coronary revascularisation, the use of anxiolytics, hypnotics or inhalers, the need for two or more angina drugs, a frequency of chest pain one or more times per week, and a Rose dyspnoea score of >/= 2.

CONCLUSIONS

The SF 36 provides valuable additional information for the practising clinician. Compared to community norms the greatest impact on quality of life is seen in patients of working age. Impaired quality of life was reported by patients unfit for work, those with angina and dyspnoea, patients with coexistent lung disease, and those with anxiety and sleep disturbances. Improving quality of life after myocardial infarction remains a challenge for physicians.

Quality of life and later adverse health outcomes in patients with suspected heart attack

We tested the hypothesis that low quality of life (QOL) after discharge from hospital with ischaemic heart disease (IHD) is associated with higher rates of later adverse outcomes (death and subsequent hospital admission for acute myocardial infarction or congestive cardiac failure). Three hundred and seventy-five patients previously enrolled in an intervention study which assessed QOL six months after hospitalisation were followed up for an additional 18 months. The rates of adverse outcomes increased as QOL decreased (high QOL 9%; moderate 18%; low 28%). After adjustment for known prognostic factors, the risk of an adverse outcome was still higher in 'low' and 'moderate' compared to 'high' QOL subjects (low QOL adjusted OR = 2.6, 95% CI = 1.2-5.8; moderate 1.9, 0.8-4.2). In conclusion, QOL after discharge from hospital appears to be an independent predictor of later morbidity and mortality.

Prostate cancer patients' utilities for health states: how it looks depends on where you stand

Two versions of the time-tradeoff (TTO) method were compared. In the personal TTO version, 31 prostate cancer patients decided whether they personally would give up some longevity to have perfect health rather than a longer life in a state of poor health associated with prostate cancer. In the impersonal version, 28 patients compared two hypothetical friends, one of whom has perfect health but will live less time than the other who is in poor health, and decided which person they would rather be. All patients evaluated three hypothetical health states. The two TTO methods were assessed by examining 1) how well they distinguished three health states of varying degrees of dysfunction and 2) patients' willingness to trade time for quality of life. Patients using the impersonal TTO version were more likely than those using the personal version to order the three health states appropriately (68% vs 16%, p < 0.0001) and were more willing to trade off length of life for quality of life (p < 0.05).

Quality adjusted survival analysis with repeated quality of life measures

One way of examining trade-offs between quantity and quality of life (QOL) is to combine them into a single measure such as quality-adjusted life year (QALY). If censoring occurs, then estimation presents some difficulties. One approach, known as Q-TWiST, is to define a series of health states, use a 'partitioned' survival analysis to calculate the average time in each state, and then weight each state according to its quality of life to calculate QALYs. Such health-state models, however, are unhelpful when the transitions between health states are unclear or if they do not adequately reflect variations in quality of life. We therefore examine an alternative analysis to be used when repeated measures of quality of life are available from individual patients in a clinical trial. The method proceeds by separating quality of life and survival, that is, dQALY/dt = S(t)Q(t), where S(t) is the survival curve, estimated from the standard Kaplan-Meier method, and Q(t) is the quality of life function, derived from individual repeated measures of quality of life. We derive single health-state (QALY) and multiple health-state (Q-TWiST) models and illustrate the approach by comparing different durations of adjuvant chemotherapy for breast cancer.

Design of a cost-effectiveness study within a randomized trial: the LIPID Trial for Secondary Prevention of IHD. Long-term Intervention with Pravastatin in Ischemic Heart disease

The Long-term Intervention with Pravastatin in Ischemic Heart Disease (LIPID) trial is a double-blind, randomized, placebo-controlled trial evaluating the long-term effect of pravastatin on coronary mortality in patients with a previous myocardial infarction or unstable angina-ischemic heart disease (IHD). It is planned to run for at least five years with 9014 patients from 85 centers in Australia and New Zealand. The trial will monitor cause-specific mortality and major clinical events associated with each treatment. Running in parallel with the main study is a prospective economic analysis, the objectives of which are (1) to estimate the effectiveness of pravastatin compared with placebo in terms of survival, quality of life (QOL), and quality-adjusted life-years (QALY); (2) to estimate the resource usage associated with pravastatin compared with placebo-in particular, to study whether it alters resource usage through prevention of disease progression; and (3) to use this information for a cost-utility analysis with cost per quality-adjusted life-year as the unit of analysis. A novel aspect of the design is the use of a preliminary cost-effectiveness analysis, based on "best-guess" values, and a sensitivity analysis over plausible ranges to guide the choice of subsample size. Some data, such a mortality, days spent in hospital, major clinical events, and drug use, are being collected within the main LIPID trial. However, additional subsamples for the cost-effectiveness study will include information on quality of life, time off work, and resources used, such as time in hospital, procedures, and medications taken. The methods and sample sizes for these substudies have been a crucial issue in validity and feasibility.

Incorporating future costs in medical cost-effectiveness analysis: implications for the cost-effectiveness of the treatment of hypertension

It has been shown that the difference between consumption and production during life years gained should be included as a cost in cost-effectiveness analysis. In this study the authors estimate the impact of including these future costs on the cost-effectiveness of the treatment of hypertension in Sweden. The cost per quality-adjusted life year (QALY) gained changes little among young men and women due to the addition of future costs, but increases by about $14,000 for middle-aged men and women and about $27,000 for older men and women. When future costs are not included, the cost per QALY gained is generally lowest among older men and women, but when future costs are included, the cost per QALY gained is generally lowest among middle-aged men and women. The authors conclude that the total resource consequences of changes in mortality should be routinely considered in cost-effectiveness analyses.

The cost-effectiveness of a cardiovascular risk reduction program in general practice

An economic evaluation was conducted alongside a randomised controlled trial of two lifestyle interventions and a routine care (control) group to assess the cost-effectiveness of a general practice-based lifestyle change program for patients with risk factors for cardiovascular disease. Routine care was the base case comparator because it represents 'current therapy' for cardiovascular disease (CVD). A 'no care' control group was not considered a clinically acceptable alternative to lifestyle interventions. The interventions consisted of an education guide and video for GPs to assess individual patient risk factors and plan a program for risk factor behavior change. Each patient received a risk factor assessment, education materials, a series of videos to watch on lifestyle behaviors and some patients received a self-help booklet. Eighty-two general practitioners were randomised from 75 general practices in Sydney's Western Metropolitan Region to (i) routine care (n = 25), (ii) video group (n = 29) or (iii) video + self help group (n = 28). GPs enrolled patients into the trial who met selection criteria for being at risk of CVD. There were 255 patients in the routine care (control) group, 270 in the video (intervention) group and 232 in the video + self help (intervention) group enrolled in the trial. Outcome measures included patient risk factor status: blood pressure, body mass index, cholesterol and smoking status at entry to trial and after 1 year. Changes in risk factors were used to estimate quality adjusted life years (QALYs) gained. One hundred and thirty patients in the routine care group, 199 in the video group and 155 in the video + self help group remained in the trial at the 12-month review and had complete data. The cost per QALY for males ranged from $AUD152,000 to 204,000. Further analysis suggests that a program targeted at 'high risk' males would cost approximately $30,000 per QALY. The lifestyle interventions had no significant effect on cardiovascular risk factors when compared to routine patient care. There remains insufficient evidence that lifestyle programs conducted in general practices are effective. Resources for general practice-based lifestyle programs may be better spent on high risk patients who are contemplating changes in risk factor behaviours.

An evidence based approach to individualising treatment

To which groups of patients can the results of clinical trials be applied? This question is often inappropriately answered by reference to the trial entry criteria. Instead, the benefit and harm (adverse events, discomfort of treatment, etc) of treatment could be assessed separately for individual patients. Patients at greatest risk of a disease will have the greatest net benefit as benefit to patients usually increases with risk while harm remains comparatively fixed. To assess net benefit, the relative risks should come from (a meta-analysis of) randomised trials; the risk in individual patients should come from multivariate risk equations derived from cohort studies. However, before making firm conclusions, the assumptions of fixed adverse effects and constant reduction in relative risk need to be checked.

A cost-effectiveness model of thrombolytic therapy for acute myocardial infarction

OBJECTIVE

To assess the short- and long-term costs and clinical and quality of life outcomes with the use of streptokinase (SK) vs tissue plasminogen activator (tPA) for acute myocardial infarction (MI).

DESIGN

A decision analysis model.

PATIENTS

Patients with acute MI who were candidates for thrombolytic therapy and who presented within six hours of symptom onset.

MEASUREMENTS

30-day and one-year mortality, impacts of disabling and nondisabling stroke, reinfarction, hemorrhage, hypotension, anaphylaxis, and long-term medical costs.

RESULTS

Using 30-day mortality data from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) trial, the baseline analysis yielded an incremental cost-effectiveness for tPA of $30,300 per additional quality-adjusted life year (QALY) gained, compared with SK. Using one-year mortality data from the GUSTO trial, the analysis yielded an incremental cost-effectiveness for tPA of $27,400 per additional QALY, compared with SK. The incremental cost-effectiveness of tPA over SK was sensitive to the difference in mortality seen with the two agents, exceeding $100,000 per QALY, for a relative survival advantage of approximately one-third that seen in the GUSTO trial. The incremental cost per QALY of tPA remained under $60,000 if the survival benefit was half that seen in the GUSTO trial. The cost-effectiveness of tPA declined with a shorter projected life expectancy following MI and for inferior (vs anterior) wall infarction. The analysis was modestly sensitive to the costs of the thrombolytic agents.

CONCLUSIONS

In spite of its higher cost relative to SK, tPA is a cost-effective therapy for MI under a wide range of assumptions regarding clinical outcomes and costs.