Medical Decision Making current issue

Budget Impact Analysis and Its Rational Basis

Hilden, J. — 2008-07-25

Quality Performance Measurement Using the Text of Electronic Medical Records

Pakhomov, S., Bjornsen, S., Hanson, P., Smith, S. — 2008-07-25

Background. Annual foot examinations (FE) constitute a critical component of care for diabetes. Documented evidence of FE is central to quality-of-care reporting; however, manual abstraction of electronic medical records (EMR) is slow, expensive, and subject to error. The objective of this study was to test the hypothesis that text mining of the EMR results in ascertaining FE evidence with accuracy comparable to manual abstraction. Methods. The text of inpatient and outpatient clinical reports was searched with natural-language (NL) queries for evidence of neurological, vascular, and structural components of FE. A manual medical records audit was used for validation. The reference standard consisted of 3 independent sets used for development (n=200 ), validation (n=118), and reliability (n=80). Results. The reliability of manual auditing was 91% (95% confidence interval [CI]= 85—97) and was determined by comparing the results of an additional audit to the original audit using the records in the reliability set. The accuracy of the NL query requiring 1 of 3 FE components was 89% (95% CI=83—95). The accuracy of the query requiring any 2 of 3 components was 88% (95% CI=82—94). The accuracy of the query requiring all 3 components was 75% (95% CI= 68— 83). Conclusions. The free text of the EMR is a viable source of information necessary for quality of health care reporting on the evidence of FE for patients with diabetes. The low-cost methodology is scalable to monitoring large numbers of patients and can be used to streamline quality-of-care reporting.

Development and Validation of a Risk Scoring Tool to Predict Respiratory Syncytial Virus Hospitalization in Premature Infants Born at 33 through 35 Completed Weeks of Gestation

2008-07-25

Objective. The purpose of the study was to develop and validate a clinical instrument predicting the risk of respiratory syncytial virus (RSV)-associated hospitalization (RSV-H) in premature infants born at 33 through 35 completed weeks of gestation (33—35GA). Design. An RSV risk scoring tool (RSV-RS) was developed by entering risk factors for RSV-H, determined in a Canadian prospective study, into a multiple logistic regression model. The scoring tool was then validated externally with data from a Spanish case-control study (FLIP). The Canadian cohort comprised 1758 RSV-positive infants born 33—35GA, of whom 66 (3.7%) had confirmed RSV-H. The FLIP data set comprised 186 (33.4%) RSV-H cases and 371 (66.7%) controls. Method. The primary outcome measure was RSV-H. The RSV-RS score was the sum of the weighted probabilities for each included risk factor multiplied by 100 and ranged from 0 to 100. Receiver operator characteristic curve analyses determined cutoff points to predict subjects at low, moderate, or high RSV-H risk. Results. The RSV-RS included 7 risk factors and cutoff scores of 0—48, 49—64, and 65— 100 for low-, moderate-, and high-risk subjects, respectively. For the Canadian cohort, RSV-RS sensitivity in predicting RSV-H cases was 68.2%, with 71.9% specificity. With the FLIP data set, the RSV-RS had lower accuracy (61.3% sensitivity; 65.8% specificity) but showed significant positive association with increased risk for RSV-H. Conclusion. The RSV-RS accurately identified 33—35GA infants at increased risk for RSV-H in a Canadian cohort. External validation with Spanish case-control study data further confirmed that the scoring tool is appropriate for the estimation of RSV-H risk.

Calculation of Prevalence with Markov Models: Budget Impact Analysis of Thrombolysis for Stroke

Mar, J., Sainz-Ezkerra, M., Miranda-Serrano, E. — 2008-07-25

Objectives . The objective is to develop a method for calculating the prevalence of stroke based on Markov models and to apply it to the assessment of the budget impact analysis of thrombolytic treatment. Methods. A Markov model was used to reproduce the natural history of stroke. The first step was to run the model to build the sojourn matrix from the initial population vector. The second step was to ascertain the number of individuals in the origin of each annual cohort. Finally, prevalence figures were obtained, validated, and used to calculate the impact of treatment with thrombolysis in 10% of patients with stroke in the Basque Country as if thrombolysis had begun in 2000 and would continue to 2015. Results. Stroke prevalence rates per 100,000 for the entire population are 898 for men and 686 for women, with a combined rate of 774 for men and women. Rates for stroke-related disability are 358 per 100,000 for men, 275 for women, and 309 for men and women combined. If 10% of the stroke patients would have received thrombolytic treatment from 2000 to 2015, the number of disabled in 2015 would be reduced by 328, and the net savings for the Basque society (2,100,000 inhabitants) would be 1.7 million. Conclusions. The budget impact analysis of thrombolysis for stroke starting in 2000 shows a positive impact on the health budget because it saves costs after 2006 and produces a net benefit in health from the beginning of treatment.

Estimating EuroQol EQ-5D Scores from Population Healthy Days Data

Jia, H., Lubetkin, E. I. — 2008-07-25

Background. Preference-based assessments of population health, which may be used for cost-utility analyses, are lacking for most states and communities. With adequate population data, preference-based values can be estimated from non-preference-based health-related quality of life (HRQOL) data. This study estimates scores on the EuroQol EQ-5D, a preference-based measure, from the Healthy Days Measures. Methods. No data set from the US population asks both the Healthy Days and EQ-5D questions for the same respondents. Therefore, estimates for EQ-5D scores were obtained indirectly by matching cumulative distributions of the 2 measures. These distributions were estimated from the 2000— 2002 Behavioral Risk Factor Surveillance System (BRFSS) and the Medical Expenditure Panel Survey (MEPS). The validity of estimates was examined by comparing the mean estimated and observed scores across particular population subgroups. A simulation study was conducted to compare the performance of the proposed method to the regression method. Results. The overall mean observed EQ-5D index was 0.871 and the mean estimated EQ-5D index was 0.872. In the majority of examined subgroups, the mean scores demonstrated a good match according to sociodemographic variables and health-related conditions and, with the exception of the most impaired health states, the differences tended to be less than 0.04. Conclusions. This study provided preliminary estimates of EQ-5D scores from the Healthy Days Measures and demonstrated acceptable validity of the estimates. Because the Healthy Days Measures have been included in many state and local surveys, preliminary cost-utility analyses and determination of burden of disease might be able to be conducted at the national, state, and community levels as well as over time. Key words: health-related quality of life; EQ-5D; Healthy Days Measures; cost-effective analysis. (Med Decis Mak ing 2008;28:491—499)

Feasibility and Reliability of the Annual Profile Method for Deriving QALYs for Short-Term Health Conditions

Janssen, M. F., Birnie, E., Bonsel, G. — 2008-07-25

Introduction . When health varies over time, the standard quality-adjusted life year model operates under the assumptions of time utility independence within each health state and additive independence between health states. These assumptions can be relaxed by an integral assessment of disease severity over time. The authors present the annual profile method (APM), which values health profiles on a 1-year base, and test the APM for feasibility, consistency, and test-retest reliability. Methods. A population panel, general practitioners, medical advisers, and a panel of the Dutch Consumers Association valued vignettes for 46 disease stages using the visual analog scale (VAS) and time tradeoff (TTO) methods. Vignettes contained disease-specific information, a generic description (EQ-6D5L), a description of the disease course over time, and a visual representation of the disease. Feasibility was tested by missing and inconsistent responses. Consistency between and within panels was tested with a generalizability study, analysis of variance, and standard correlation coefficients. Test-retest reliability was tested with a generalizability study and intra-class correlation coefficients. Results. Missing and inconsistent responses were < 2.6%. The valuations were consistent across panels, with generalizability coefficients of 0.78 (VAS) and 0.64 (TTO). Within the main population panel, internal consistency was satisfactory and the influence of background characteristics negligible. Test-retest reliability was high, with generalizability coefficients of 0.90 (VAS) and 0.72 (TTO). Conclusion. Feasibility and reliability of the APM for realistic health profiles are good to excellent. The APM is a promising step to bridge the gap between the quality-adjusted life year methodology and clinical reality.

End-of-Life Medical Treatment Choices: Do Survival Chances and Out-of-Pocket Costs Matter?

Chao, L.-W., Pagan, J. A., Soldo, B. J. — 2008-07-25

Background . Out-of-pocket medical expenditures incurred prior to the death of a spouse could deplete savings and impoverish the surviving spouse. Little is known about the public's opinion as to whether spouses should forego such end-of-life (EOL) medical care to prevent asset depletion. Objectives . To analyze how elderly and near elderly adults assess hypothetical EOL medical treatment choices under different survival probabilities and out-of-pocket treatment costs. Methods. Survey data on a total of 1143 adults, with 589 from the Asset and Health Dynamics Among the Oldest Old (AHEAD) and 554 from the Health and Retirement Study (HRS), were used to study EOL cancer treatment recommendations for a hypothetical anonymous married woman in her 80s. Results. Respondents were more likely to recommend treatment when it was financed by Medicare than by the patient's own savings and when it had 60% rather than 20% survival probability. Black and male respondents were more likely to recommend treatment regardless of survival probability or payment source. Treatment uptake was related to the order of presentation of treatment options, consistent with starting point bias and framing effects. Conclusions. Elderly and near elderly adults would recommend that the hypothetical married woman should forego costly EOL treatment when the costs of the treatment would deplete savings. When treatment costs are covered by Medicare, respondents would make the recommendation to opt for care even if the probability of survival is low, which is consistent with moral hazard. The sequence of presentation of treatment options seems to affect patient treatment choice.

Patient and Surrogate Disagreement in End-of-Life Decisions: Can Surrogates Accurately Predict Patients' Preferences?

Marks, M. A. Z., Arkes, H. R. — 2008-07-25

Background . When a patient is too incapacitated to make important end-of-life decisions, doctors may ask a preappointed surrogate to predict the patient's preferences and make decisions on the patient's behalf. The current study investigates whether surrogates project their own views onto what they predict the patients' preferences are. Methods. Using data from seriously ill patients and their surrogates, the authors created a ``projection'' variable that addresses the following question: When surrogates are asked to predict a patient's end-of-life preferences, do they mistakenly replace this prediction with what they would want the patient to do? The authors examined the 144 patient-surrogate pairs in which surrogates inaccurately predicted patients' CPR (cardiopulmonary resuscitation) v. DNR (do not resuscitate) decisions and the 294 pairs in which surrogates inaccurately predicted patients' extend life v. relieve pain preferences. Among these patient-surrogate pairs, the authors determined the extent to which surrogates' wishes for the patient matched their incorrect predictions of what the patient wanted. Results. Of the patient-surrogate pairs who disagreed on CPR v. DNR and extend life v. relieve pain preferences, 62.5% and 88.4% of surrogates demonstrated projection for CPR v. DNR decisions and extend life v. relieve pain preferences, respectively. Age-related and demographic variables did not predict cases in which projection did and did not occur. Conclusion. When surrogates inaccurately predict the CPR v. DNR and extend life v. relieve pain preferences of seriously ill, hospitalized loved ones, surrogates' prediction errors often represent surrogates' own wishes for the patient.

Do Decision Biases Predict Bad Decisions? Omission Bias, Naturalness Bias, and Influenza Vaccination

DiBonaventura, M. d., Chapman, G. B. — 2008-07-25

Purpose. Numerous studies using hypothetical vignettes have demonstrated decision biases or deviations from utility theory. Do people who commit biases in questionnaire studies make worse real-world decisions than do less biased people? Methods. Two hundred seventy university faculty and staff participated in a questionnaire study in which they reported whether they accepted a free influenza vaccine offered at their work place. Influenza vaccine acceptance was the measure of real-world decision making. Participants responded to 3 hypothetical scenarios. Two scenarios measured the omission bias and described a vaccine (scenario 1) and a medication (scenario 2) that prevented a negative health outcome but that itself could cause the negative health outcome. The omission bias is a preference for not vaccinating or medicating even when the vaccine/medication lowers the total risk of the negative outcome. A 3rd scenario measured the naturalness bias by presenting a choice between 2 chemically identical medications, one extracted from a natural herb and the other synthesized in a laboratory. Preference for the natural medication indicated the naturalness bias. Results. The results indicated that a substantial proportion of participants exhibited these biases and that participants who exhibited these biases were less likely to accept the flu vaccine. Conclusions. To the extent that declining a free flu vaccine is a worse real-world decision, people who demonstrate the naturalness and omission biases in hypothetical scenarios make worse real-world decisions. Key words: omission bias; naturalness bias; influenza; vaccination. (Med Decis Making 2008;28:532—539)

When Is Diagnostic Testing Inappropriate or Irrational? Acceptable Regret Approach

Hozo, I., Djulbegovic, B. — 2008-07-25

The authors provide a new model within the framework of theories of bounded rationality for the observed physicians' behavior that their ordering of diagnostic tests may not be rational. Contrary to the prevailing thinking, the authors find that physicians do not act irrationally or inappropriately when they order diagnostic tests in usual clinical practice. When acceptable regret (i.e., regret that a decision maker finds tolerable upon making a wrong decision) is taken into account, the authors show that physicians tend to order diagnostic tests at a higher level of pretest probability of disease than predicted by expected utility theory. They also show why physicians tend to overtest when regret about erroneous decisions is extremely small. Finally, they explain variations in the practice of medicine. They demonstrate that in the same clinical situation, different decision makers might have different acceptable regret thresholds for withholding treatment, for ordering a diagnostic test, or for administering treatment. This in turn means that for some decision makers, the most rational strategy is to do nothing, whereas for others, it may be to order a diagnostic test, and still for others, choosing treatment may be the most rational course of action.

Wide Social Participation in Prioritizing Patients on Waiting Lists for Joint Replacement: A Conjoint Analysis

2008-07-25

Objective. The aim was to develop a priority scoring system for patients on waiting lists for joint replacement based on a wide social participation, and to analyze the differences among participants. Methods. Conjoint analysis. Focus groups in combination with a nominal technique were employed to identify the priority criteria (N=36). A rank-ordered logit model was then applied for scoring estimations. Participants (N=860) represented: consultants, allied-health professionals, patients and their relatives, and the general population of Catalonia. Results. Clinical and social criteria were selected, and their relative importance (over 100 points) was: pain (33), difficulty in doing activities of daily living (21), disease severity (18), limitations on ability to work (10), having someone to look after the patient (9), being a caregiver (6), and recovery probability (4). Estimated criteria coefficients had the expected positive sign and all were statistically significant (P < 0.001). There were differences between groups; pain was rated higher by patients/relatives, and difficulty in doing activities was rated lower by patients/relatives and the general public. Most interaction terms for these criteria and groups were significant (P < 0.001). Consultants and allied-health professionals had the most similar prioritization pattern (r=0.97). Conclusion. Both clinical and social criteria are considered for prioritization of joint replacement surgery from a wide social perspective. The preference among professional and social groups varies and this might impact the result of patient prioritization. A wide social participation for obtaining adequate prioritizing systems for patients on waiting lists is desirable.

The Effect of Graphical and Numerical Presentation of Hypothetical Prenatal Diagnosis Results on Risk Perception

Siegrist, M., Orlow, P., Keller, C. — 2008-07-25

Objective. To evaluate various formats for the communication of prenatal test results. Design. In study 1 (N=400), female students completed a questionnaire assessing risk perception, affect, and perceived usefulness of prenatal test results. A randomized, 2 (risk level; low, high) x 4 (format; ratio with numerator 1, ratio with denominator 1000, Paling Perspective Scale, pictograms) design was used. Study 2 (N=200) employed a 2 (risk level; low, high) x 2 (format; Paling Perspective Scale, risk comparisons in numerical format) design. Results. In study 1, the Paling Perspective Scale resulted in a higher level of perceived risk across different risk levels compared with the other formats. Furthermore, participants in the low-risk group perceived the test results as less risky compared with participants in the high-risk group (P < 0.001) when the Paling Perspective Scale was used. No significant differences between low and high risks were observed for the other 3 formats. In study 2, the Paling Perspective Scale evoked higher levels of perceived risks relative to the numerical presentation of risk comparisons. For both formats, we found that participants confronted with a high risk perceived test results as more risky compared with participants confronted with a low risk. Conclusion. The Paling Perspective Scale resulted in a higher level of perceived risk compared with the other formats. This effect must be taken into account when choosing a graphical or numerical format for risk communication.

Expectations of Benefit in Early-Phase Clinical Trials: Implications for Assessing the Adequacy of Informed Consent

2008-07-25

Background. Participants in early-phase clinical trials have reported high expectations of benefit from their participation. There is concern that participants misunderstand the trials to which they have consented, which is based on assumptions about what patients mean when responding to questions about likelihood of benefit. Methods. Participants were 27 women and 18 men in early-phase oncology trials at 2 academic medical centers in the United States. To determine whether expectations of benefit differ depending on how patients are queried, the authors randomly assigned participants to 1 of 3 interviews corresponding to 3 questions about likelihood of benefit: frequency type, belief type, and vague. In semistructured interviews, participants were queried about how they understood and answered the question. Participants then answered and discussed 1 of the other questions. Results. Expectations of benefit in response to the belief-type question were significantly greater than expectations in response to the frequency-type and vague questions (P=0:02). The most common justifications involved positive attitude (n=27 [60%]) and references to physical health (n=23 [51%]). References to positive attitude were most common among participants with higher (> 70%) expectations (n = 11 [85%]) and least common among those with lower ( < 50%) expectations (n = 3 [27%]). Conclusions. The wording of questions about likelihood of benefit shapes the expectations that patients express. Patients who express high expectations may not do so to communicate understanding but rather to register optimism. Ongoing research will clarify the meaning of high expectations and examine methods for assessing understanding.

Systematic Review: Health-State Utilities in Liver Disease: A Systematic Review

McLernon, D. J., Dillon, J., Donnan, P. T. — 2008-07-25

Objectives. Health-state utilities are essential for cost-utility analysis. Few estimates exist for liver disease in the literature. The authors' aim was to conduct a systematic review of health-state utilities in liver disease, to look at the variation of study designs used, and to pool utilities for some liver disease states. Methods. A search of MED-LINE, EMBASE, and CINAHL from 1966 to September 2006 was conducted including key words related to liver disease and utility measuring tools. Articles were included if health-state utility tools or expert opinion were used. Variance-weighted mean utility estimates were pooled using metaregression adjusting for disease state and utility assessment method. Results. Thirty studies measured utilities of liver diseases/disease states. Half of these estimated utilities for hepatitis viruses: hepatitis A (n = 1), hepatitis B (n = 4), and hepatitis C (n = 10). Others included liver transplant (n= 6) and chronic liver disease (n= 5) populations. Twelve utility methods were used throughout. The EQ-5D (n = 10) was most popular method, followed by visual analogue scale (n = 9), time tradeoff (n = 6), and standard gamble (n = 4). Respondents were patients (n= 16), an expert panel (n = 10), non—liver diseases adults ( n=2), patient and expert (n = 1), and patient and healthy adult (n = 1). Type of perspective included community (n=21), patient (n=4), and both (n = 5). The pooled mean estimates in hepatitis C with moderate disease, compensated cirrhosis, decompensated cirrhosis, and post—liver transplant using the EQ-5D were 0.75, 0.75, 0.67, and 0.71, respectively. The change in these utilities using different methods were -0.07 (visual analogue scale), -0.01 (health utilities index version 3), +0.04 (standard gamble), + 0.08 (health utilities index version 2), + 0.12 (time tradeoff), and + 0.15 (standard gamble—transformed visual analogue scale). Conclusions. The authors have created a valuable liver disease— based utility resource from which researchers and policy makers can easily view all available utility estimates from the literature. They have also estimated health-state utilities for major states of hepatitis C.

Modeling the Incubation Period of Inhalational Anthrax

Wilkening, D. A. — 2008-07-25

Ever since the pioneering work of Philip Sartwell, the incubation period distribution for infectious diseases is most often modeled using a lognormal distribution. Theoretical models based on underlying disease mechanisms in the host are less well developed. This article modifies a theoretical model originally developed by Brookmeyer and others for the inhalational anthrax incubation period distribution in humans by using a more accurate distribution to represent the in vivo bacterial growth phase and by extending the model to represent the time from exposure to death, thereby allowing the model to be fit to nonhuman primate time-to-death data. The resulting incubation period distribution and the dose dependence of the median incubation period are in good agreement with human data from the 1979 accidental atmospheric anthrax release in Sverdlovsk, Russia, and limited nonhuman primate data. The median incubation period for the Sverdlovsk victims is 9.05 (95% confidence interval = 8.0-10.3) days, shorter than previous estimates, and it is predicted to drop to less than 2.5 days at doses above 10⁶ spores. The incubation period distribution is important because the left tail determines the time at which clinical diagnosis or syndromic surveillance systems might first detect an anthrax outbreak based on early symptomatic cases, the entire distribution determines the efficacy of medical intervention—which is determined by the speed of the prophylaxis campaign relative to the incubation period—and the right tail of the distribution influences the recommended duration for antibiotic treatment.

Willingness to Pay for a Cure in Patients with Chronic Gout

Khanna, D., Ahmed, M., Yontz, D., Ginsburg, S. S., Tsevat, J. — 2008-07-25

Introduction. Gout is a chronic painful inflammatory arthritis. The authors interviewed patients with chronic stable gout to assess their hypothetical willingness to pay (WTP) to be cured of their gout. Patients and Methods. Patients with gout were asked how much money they would be willing to pay every month out of pocket or as a co-pay to cure their gout. To assess determinants of WTP amounts, the authors performed stepwise multivariable linear regression analysis, controlling for demographics, health status, and relative concern about gout. Results. Of the 78 patients, 70 (90%) were male, 54 (69%) were Caucasian, 21 (27%) were African American, and 32 (41%) had annual incomes < $25,000. The median WTP amount was $25 ($0, $75) per month, and the mean (s) was $52 ($74) per month (range, $0-$350); 23 (30%) patients were unwilling to pay any amount. Patients who rated their gout as their top health concern were willing to pay a median of $63 ($25, $100) per month. In multivariable analysis, gout as the top health concern, greater frequency of gouty attacks over the past 1 y, and younger age were significantly associated with WTP amounts (R² =0:19 ). Conclusion. Many patients with chronic gout would be willing to pay money every month in perpetuity to be cured of their gout. Younger patients, patients whose main health concern is gout, and patients with frequent attacks are willing to pay the most.

Errata

2008-07-25