Quality-adjusted Years Research Articles

Donor specific transfusions or cyclosporine for related-donor kidney transplantation?

DST and cyclosporine are two immunosuppressive strategies to improve first year graft survival in high MLC, one-haplotype matched, living-related donor kidney transplantation. However, each has disadvantages: The conventional strategy of DST may sensitize the recipient to donor antigens, precluding transplantation from that donor, and cyclosporine may increase graft failure due to nephrotoxicity. We used decision analysis to compare these two strategies. We assumed that the risk of sensitization by DST is 12%, that graft failure in the first year is equal in both strategies, but that the annual probability of graft failure in later years is 2.6% with DST and from 2.7% to 3.6% with cyclosporine. Patients sensitized by DST and patients with graft failure undergo dialysis while awaiting cadaveric donor transplantation using cyclosporine. Outcomes were assessed as quality-adjusted years of survival. The analysis was deliberately biased to favor DST, the conventional strategy. Quality-adjusted life expectancy for a 40-year-old patient in both strategies is from 17.7 to 19.1 years. The difference between the DST and cyclosporine strategies ranges from -0.7 to +0.6 years. Given current data on sensitization by DST, long-term cyclosporine nephrotoxicity, and deliberate biases favoring the DST strategy, we conclude that there is no substantive advantage of the DST strategy. Cyclosporine is equally efficacious for recipients of high MLC, one-haplotype matched kidney transplants, and may be preferred for transplants from more distant relatives and unrelated living donors.

Cost-effectiveness of antibiotic prophylaxis for dental procedures in patients with artificial joints.

We performed a cost-effectiveness analysis to evaluate whether patients with artificial joints should take penicillin, erythromycin, or no antibiotics before dental procedures. We modeled the risk of anaphylaxis from penicillin, the risks and consequences of an artificial joint infection, and the actual variable costs of hospitalization and antibiotics. Penicillin prophylaxis is slightly less expensive than erythromycin prophylaxis but is both more expensive and less effective than no prophylaxis. Erythromycin prophylaxis, the most effective, is the most expensive strategy. The marginal cost effectiveness of erythromycin prophylaxis compared to no prophylaxis is $12,900 per quality-adjusted year of life saved. Sensitivity analysis demonstrates that the risk of developing a joint infection is the key parameter in the analysis. Based on our estimated risk of developing a joint infection, the cost-effectiveness of antibiotic prophylaxis with erythromycin compares favorably with other medical interventions. Thus, until a definitive study to quantify the risk is conducted, patients with artificial joints should take prophylactic erythromycin when they undergo dental procedures.

Application of Quality of Life and Weli-Being Measurement as Input into Cost-Effectiveness Analyses

For the most part, cost-effectiveness analysis has attempted to incorporate the effects of medical treatments on patients’quality of life by adjusting years of survival with an index of the quality of fife in the surviving years. The construction of such a quality-adjusted year index is typically based on implicitly value-laden assumptions regarding tradeoffs of hypothetical situations, ie, survival periods with or without a disabling condition. The construction of the index relies on judgments and other procedures that have been shown to generate figures that are widely discrepant from those suggested by empirical studies. Indeed, only empirical studies based on individuals’ direct assessments of their quality of life, and those which focus on the persons subjected to the treatments at issue, can provide the necessary valid input to cost-effectiveness analysis. It is therefore suggested that cost-effectiveness analysis should rely on quality-oflife data generated by empiricalstudies of persons subjected to the treatments; and it should report separately the cost of treatment per year of life and per quality of life expressed in effect size units. The latter effect size units in quality of life should be specified separately for global measures of physical, mental, and social functioning and well being, as well as for specific measures of the presenting symptoms and disabilities that are produced in these areas of life by the disease. The degree of relationship among these various aspects of quality of life can provide yet another itnportant indication of the overall effect of the treatment. The advantages of focusing on quality-of-life data in terms of effect size units stem from: (a) the greater convergence in the conceptualization of quality of life than in the use of specific measures, and (b) the availability of meta-analytic technigues for synthesizing effect size units from different studies and comparing them across different treatments.

Postmenopausal estrogens in prevention of osteoporosis. Benefit virtually without risk if cardiovascular effects are considered

Postmenopausal estrogens can delay or prevent osteoporosis and decrease the frequency of fractures, but they also increase the risk of endometrial cancer. A decision analytic model was developed using a Markov process with 18 different states to estimate quality-adjusted life expectancy with and without estrogen therapy. The model considered fractures of the hip, wrist, pelvis, humerus and spine with potential outcomes of short-term morbidity, long-term disability, nursing home placement, and death. Quality adjustments were based on expert opinions. In sensitivity analyses, various risks of endometrial cancer and hysterectomy due to estrogens were examined. The effect of estrogen therapy on cardiac mortality also was considered. For a cohort of 50-year-old white women who would take estrogens for 15 years, the analysis showed a benefit of 0.47 years but 0.67 quality-adjusted years. For every five-fold increase in the relative risk of endometrial cancer, the benefit decreases by 0.07 quality years. The benefit would increase by 0.17 quality years for each 10 percent decrease in the fracture rate and 0.32 for each 10 percent decrease in cardiovascular mortality rate. Thus, estrogen therapy provides a significant gain in quality-adjusted life expectancy. In considering the efficacy of any drug, all the benefits of the drug as well as all its risks must be included. If the beneficial effect of estrogens on cardiovascular mortality is confirmed, it will overshadow all other effects. Any recommendation about postmenopausal estrogens with respect to osteoporosis that excludes their cardiovascular effects markedly underestimates the potential gains from therapy.

Glaucoma screening. A cost-effectiveness analysis

We designed an intricate model of the process of glaucoma screening, diagnosis, and treatment in order to evaluate the medical care costs of such efforts in relation to the benefits in terms of quality-adjusted years of vision saved, utilizing the economic principles of cost-effectiveness analysis. Although a relatively limited data base and numerous assumptions concerning the accuracy of diagnostic tests, the natural history of ocular hypertension and glaucoma, and the effectiveness of available treatment modalities, limit our ability to draw definitive conclusions concerning the cost-effectiveness of various glaucoma screening options, our analysis indicates that glaucoma screening is probably cost-effective when targeted at certain subgroups of the population. Our analysis suggests that changes in several aspects of existing screening policies may be appropriate if cost-effectiveness is to be used as one of the criteria for the efficient allocation of resources to and within screening programs. Specifically, combinations of screening tests and screening targeted at high risk populations such as blacks, diabetics, and relatives of glaucoma patients are probably more cost-effective than screening of the general population with a single test. In younger populations, the importance of detecting ocular hypertension argues for the use of tonometry. Ophthalmoscopy may be more cost-effective in older age groups in whom the higher prevalence of glaucoma outweighs the need for identifying ocular hypertensives. In the very elderly, automated perimetry becomes cost-effective since the detection of established field loss will have greater yield. In addition, it is evident that diversion of resources away from actual screening efforts and towards efforts aimed at improving follow-up and compliance would be an additional cost-effective strategy.

Coronary artery bypass graft surgery: clinical decision making and cost-effectiveness analysis.

Decision-analytic techniques were used to evaluate the choice between an aortocoronary bypass operation and medical management in a set of hypothetical patients with coronary artery disease. The decision framework incorporates variables believed to have an important bearing on the choice of treatment. Probability estimates were obtained from two cardiologists and one cardiac surgeon. Patient preferences for the trade-off between years of survival and the quality of life as reflected by the severity of angina pectoris were made explicit by assigning utility values to alternative health outcomes. The results are expressed in terms of quality-adjusted years of life expectancy. Decision analysis favored operation for 13 of the 14 hypothetical patients, including patients with one- and two-vessel disease. The one patient for whom medical treatment was preferred had mild angina pectoris, severe left ventricular dysfunction, and a poor prognosis regardless of therapeutic modality. The results are sensitive to changes in the probability of long-term survival, but not to changes in operative mortality rates. In five patients, the physicians' clinical judgments favored medical treatment, whereas their decision-analysis-derived estimates of survival favored operation. Possible explanations for these discrepancies are discussed. A simplified cost-effectiveness analysis for patients in whom surgery was the optimal treatment indicated costs ranging from $1,500 to $250,000 per year of life gained and from $1,500 to $32,000 per quality-adjusted year of life gained.