Diagnostic testing following fecal occult blood screening in the elderly.

BACKGROUND: Screening with a fecal occult blood test (FOBT) has been shown to reduce colorectal cancer mortality in controlled trials. Recently, Medicare approved payment for FOBT screening. We evaluated the pattern of diagnostic testing following the initial FOBT in elderly Medicare beneficiaries. Such follow-up testing would in the long run influence both the cost and the benefit of widespread use of FOBT. METHODS: Using Medicare's National Claims History System, we identified 24 246 Americans 65 years old or older who received FOBT at physician visits between January 1 and April 30, 1995. Prior to FOBT, these people had no evidence of any conditions for which FOBT might be used diagnostically. We examined relevant diagnostic testing in this cohort during the subsequent 8 months and determined what proportion of those received an evaluation recommended by the American College of Physicians. RESULTS: For every 1000 Medicare beneficiaries who received FOBT, 93 (95% confidence interval = 89-96 per 1000) had positive findings and relevant testing in the subsequent 8 months. Of these, 34% had the recommended evaluation of either colonoscopy or flexible sigmoidoscopy with an air-contrast barium enema. Another 34% received a partial colonic evaluation with either flexible sigmoidoscopy or a barium enema. The remaining 32% received other gastrointestinal (GI) testing without evaluation of the colonic lumen: computed tomography or magnetic resonance imaging of the abdomen (15%), upper GI series (10%), carcinoembryonic antigen (7%), and upper endoscopy (2%). Restricting the analysis to testing performed within 2 months of the initial FOBT yielded similar results. CONCLUSION: Following FOBT, many Medicare beneficiaries get further diagnostic testing, but only a small proportion receives the recommended evaluation. With this pattern of practice, population screening is likely to be more costly and less effective than estimated from controlled trials.

Diagnostic testing following screening mammography in the elderly.

BACKGROUND: To provide some sense of the general frequency and timing of diagnostic testing following screening mammography in the United States, we investigated the experience of women screened in the Medicare population. METHODS: By use of Medicare's National Claims History System, we identified a cohort (n=23172) of women 65 years old or older screened during the period from January 1, 1995, through April 30, 1995, and tracked each woman over the subsequent 8 months for the performance of additional breast imaging and biopsy procedures. Using two claims-based definitions for newly detected breast cancer, we also estimated the positive predictive value of screening mammography. RESULTS: For every 1000 women aged 65-69 years who underwent screening, 85 (95% confidence interval [CI]=79-91) had follow-up testing in the subsequent 8 months; 76 (95% CI=71-82) had additional breast imaging, and 23 (95% CI=20-26) had biopsy procedures. Corresponding numbers for women aged 70 years or more were similar. Some women underwent repeated examinations; 13% of those receiving diagnostic mammograms had more than one; 11% of those undergoing biopsy procedures had more than one. About half of the women who underwent a biopsy had the procedure more than 3 weeks after the imaging test upon which the decision to perform a biopsy was presumably made. The estimated positive predictive value of an abnormal screening mammogram (defined as a mammogram that engendered additional testing) was 0.08 (95% CI=0.06-0.10) for women aged 65-69 years and 0.14 (95% CI=0.12-0.16) for women aged 70 years or more. CONCLUSION: Additional testing is a frequent consequence of screening mammography and may require a considerable period of time to come to closure. The need for additional testing, however, is weakly predictive of cancer.

Marrow transplantation, cost effectiveness analysis and setting limits.

Marrow transplantation is currently second only to kidney in major organ transplants performed in the United States. Like other forms of transplantation, marrow transplantation is expensive. Unlike other forms of transplantation, however, marrow transplantation is not particularly constrained by a limited supply of donor organs. High costs combined with the potential for substantial growth make difficult resource choices inevitable.

Trends in diagnostic testing following a national guideline for evaluation of dyspepsia.

BACKGROUND: The extent to which national guidelines affect actual clinical practice is largely unknown. OBJECTIVE: To gauge the impact of a national guideline about dyspepsia on subsequent clinical practice. DESIGN: We compared trends in the rates of the two principal diagnostic tests used to evaluate dyspepsia: upper gastrointestinal tract series (UGI) and endoscopy. METHODS: We used the Health Care Financing Administration's (Baltimore, Md) 100% National Medicare part B file to determine annual counts for the two procedures in each of 10 years (1984 through 1993). To calculate procedure rates, we divided the number of procedures in each year by the total population enrolled in Medicare part B in that year. RESULTS: In 1984, before publication of the guideline, the UGI rate was more than triple the rate of endoscopy (UGI rate, 59 per 1000 beneficiaries; endoscopy rate, 17 per 1000). Subsequent to publication of the guideline in 1985, UGI use slowly decreased while endoscopy utilization slowly increased. The rate of change for both procedures was steady over the 10-year period. Endoscopy rates finally exceeded UGI in 1993 (endoscopy, 37 per 1000; UGI, 36 per 1000). CONCLUSIONS: Despite a prominent national guideline, UGI utilization remains high and is slowly decreasing. Because utilization data before 1984 are incomplete, we cannot isolate the precise impact of the guideline. However, the slow decline in UGI utilization suggests that, at best, the guideline had limited impact on clinical practice. If this response is representative of other guidelines, alternative approaches to change clinical practice will need to be found.

Advance directives and the cost of terminal hospitalization.

BACKGROUND: It has been assumed that patients using advance directives would direct terminal care away from the intensive care unit and choose shorter, less costly, less technological terminal hospital stays. METHODS: This retrospective cohort study examined 336 consecutive patients who died in a university tertiary care medical center: 242 without advance directives, 66 with a previously completed advance directive, 13 admitted for the express purpose of terminal care, and 15 who signed an advance directive during their terminal hospitalization. Total charges (hospital and physician) were calculated for all patients and were adjusted using both physician and hospital diagnosis-related group weights. Patient participation in end-of-life decisions was determined by chart review. RESULTS: The group without advance directives had dramatically higher mean total ($49,900 vs $31,200) terminal hospitalization charges than the group with previously completed advance directives, producing a charge ratio of 1.6. After diagnosis-related group adjustment, the charge ratio was 1.35 (95% confidence interval, 1.07 to 1.72) for physician charge, 1.36 (95% confidence interval, 1.06 to 1.74) for hospital charge, and 1.35 (95% confidence interval, 1.08 to 1.73) for total charge. Multiple regression analysis controlling for age, sex, and cancer diagnosis confirmed these findings. Patients with advance directives were significantly more likely to limit treatment and to participate in end-of-life decisions. CONCLUSION: Patients without advance directives have significantly higher terminal hospitalization charges than those with advance directives. Our investigation suggests that the preferences of patients with advance directives are to limit care and these preferences influence the cost of terminal hospitalization.

Women's understanding of the mammography screening debate.

BACKGROUND: The fractious public debate over mammography screening recommendations for women aged 40 to 49 years has received extensive attention in medical journals and in the press. OBJECTIVE: To learn how women interpret the mammography screening debate. METHODS: We mailed a survey to a random sample of American women 18 years and older, oversampling women of screening age (40-70 years). Sixty-six percent of women completed the survey (n = 503). MAIN OUTCOME MEASURES: The main outcome measures were women's reactions to the debate, their suggestion for the starting age for mammography screening, and their understanding of the source of the debate. RESULTS: Almost all women (95%) said that they had paid some attention to the recent discussion about mammography screening. Only 24% said the discussion had improved their understanding of mammography, while 50% reported being upset by the public disagreement among screening experts. Women's beliefs about mammography differed from those articulated by experts in the debate. Eighty-three percent believed that mammography had proven benefit for women aged 40 to 49 years, and 38% believed that benefit was proven for women younger than 40 years. Most women suggested that mammography screening should begin before age 40 years, while only 5% suggested a first mammogram should be performed at 50 years or older. In response to an open-ended question about why mammography has been controversial, 15% cited concerns about the potential harms of radiation and another 12% cited questions about efficacy. Nearly half (49%), however, identified costs as the major source of debate (eg, "Health maintenance organizations [HMOs] don't want to pay for mammography"). CONCLUSIONS: Most women paid attention to the recent debate about routine mammography screening for women aged 40 to 49 years, but many believed the debate was about money rather than the question of benefit. Policy makers issuing recommendations about implementation of large-scale mammography screening services need to consider how to effectively disseminate their message.

Risk communication in clinical practice: putting cancer in context.

CONTEXT: Clinicians are increasingly urged-even mandated-to help patients make informed medical decisions by paying more attention to risk counseling. For many, the role of risk counseling is new and unfamiliar. This effort is made more difficult given the practical constraints created by 15-minute visits and competing demands (e.g., patient's chief complaint and institutional needs). OBJECTIVE: We detail a three-part approach for improving risk communication, acknowledging the role of clinicians, patients, and other communicators (i.e., media or public health agencies). PROPOSED APPROACH: Office-based tools to help clinicians do more. We suggest two ways to help make up-to-date estimates of disease risk and treatment benefit easily available during office visits. We propose the development of a comprehensive population database about disease risk and treatment benefit to be created and maintained by the federal government. Educating patients. We propose "Understanding Numbers in Health" a tutorial that reviews basic concepts of probability and their application to medical studies to help people become better critical readers of health information. Guidance for communicators. Finally, we propose a writer's guide to risk communication: a set of principles to help health communicators present data to the public clearly and objectively. CONCLUSION: In addition to tools to help clinicians better communicate risk information, serious efforts to improve risk communication must go beyond the clinic. Efforts that help the public to better interpret health risk information and guide communicators to better present such information are a place to start.

Test performance in systemic sclerosis: anti-centromere and anti-Scl-70 antibodies.

PURPOSE: To determine the sensitivity and specificity of anti-centromere (ACA) and anti-Scl-70 antibodies in systemic sclerosis (SSc). METHODS: Four-hundred ninety-seven English language articles published from 1966 to 1994 were identified by structured MEDLINE search. Articles in which either ACA or anti-Scl-70 antibodies were measured in both SSc patients and a non-SSc control group were reviewed and rated using a previously published diagnostic testing scale. Reported sensitivity and specificity from each study was converted into a 2 x 2 table, and combined across studies to calculate summary rates for each antibody. Author's clinical classification criteria for SSc served as the gold standard for disease diagnosis. RESULTS: In 30 articles that fulfilled inclusion criteria, ACA were found in 441 of 1,379 SSc patients (sensitivity 32%, range 17% to 56%). This increased to 57% (332 of 585) in patients with the limited cutaneous, or CREST, subset of SSc (IcSSc). Anti-Scl-70 antibodies were found in 366 of 1,074 SSc patients (sensitivity 34%, range 3% to 75%), and this increased slightly to 40% in patients with the diffuse cutaneous form of SSc (dcSSc). Both antibodies were measured in 670 patients, and either test was positive in 58% (range 29% to 86%), but in only 3 patients were both antibodies present. The specificity of each antibody was high, but varied by control group. ACA were present in 5% and anti-Scl-70 antibodies were present in 2% of patients with other connective tissue diseases, but fewer than 1% of disease free controls had either antibody present. CONCLUSIONS: As individual diagnostic tests in SSc, both ACA and anti-Scl-70 antibodies are highly specific. Each performs somewhat better as discriminators of clinical subsets for patients in whom a diagnosis of SSc has already been established. Clinicians can rely on a positive test result as being specific in the detection of disease, but 40% of SSc patients are likely to have neither antibody present, and a negative result does not exclude the diagnosis. Measurement of these antibodies should be considered secondary to the clinical features when making a diagnosis of SSc.

The cost of institutional care in Alzheimer's disease: nursing home and hospital use in a prospective cohort.

OBJECTIVE: To assess the nursing home and hospital use of patients with Alzheimer's Type Dementia. DESIGN: A prospective cohort study of 126 patients entered into an Alzheimer's disease registry after diagnosis at a university hospital clinic between 1980 and 1982. Only four patients were in nursing homes at enrollment. MEASUREMENTS AND MAIN RESULTS: Data regarding nursing home use came from the registry and the individual nursing homes themselves. Hospital-use data were obtained using Medicare claims files. Follow-up was obtained on 123 patients (98%). Eighty-five (69%) had died by July 1, 1989. Three-quarters of the cohort (92) eventually resided in nursing homes. The median nursing home length of stay was 2.75 years (mean 2.95, 95% CI = 2.5, 3.4), over 10 times the national median length of stay for all diagnoses. Based on prevailing rates in the region, nursing home charges for the cohort were estimated to be between $4.3 and $6.4 million ($35,000-$52,000 per patient). During the 5-year period 1983-1988, 69 patients filed Part A (hospital) claims to Medicare for 76 admissions and 616 inpatient days. Part A Medicare reimbursement for the cohort totaled $460,000 over 5 years ($3,700 per patient), an expenditure comparable to what a random Medicare cohort might incur. CONCLUSIONS: The combination of a high rate of nursing home entry and lengthy stays makes long-term care the largest determinant of the cost of care in Alzheimer's disease. While Alzheimer's Type Dementia undoubtedly has profound indirect costs, this study demonstrates that the direct institutional costs alone are considerable.

Rationing surgery: rules or constraints?

BACKGROUND: As U.S. health care expenditures climb, the need to set limits on surgery is becoming more generally accepted. If limits are necessary, how should they be established and by whom? This article considers two fundamental approaches, rules and constraints. RESULTS: With rules, payers or policymakers ration care by prioritizing and then restricting specific procedures. Although they have the advantage of explicitness, rules based on treatment prioritization are limited by patient heterogeneity and the lack of outcomes data necessary to rank many procedures. Rules are unambiguous and free the surgeon from the obligation to set limits, but they do not accommodate clinical judgment or patient preferences. With constraints, limits are set on surgical resources (e.g., the number and distribution of surgeons), but individual surgeons determine which procedures are provided to which patients. Although constraints are more feasible than rules, it is difficult to establish an "adequate" supply of surgical resources and to ensure that limits set by the individual surgeon are based on treatment efficacy. While preserving clinical autonomy, constraints require the surgeon to assume the responsibility of rationing care. CONCLUSIONS: Surgeons should consider carefully the approach to rationing that best serves their professional interests, their patients, and society.

Effect of respiratory alkalosis on skeletal muscle metabolism in the dog.

These experiments were conducted to determine whether changes in skeletal muscle metabolism contribute to the previously reported increase in whole-body O2 uptake (VO2) during respiratory alkalosis. The hind-limb and gastrocnemius-plantaris preparations in anesthetized and paralyzed dogs were used. VO2 of the hindlimb and gastrocnemius muscle was calculated from measurements of venous blood flow and arterial and venous O2 concentrations (Van Slyke analysis). Whole-body VO2 was measured by the open-circuit method. Minute ventilation (hence blood gases and pH) was controlled by a mechanical respirator. Whole-body, hind-limb, and gastrocnemius muscle VO2 increased 14, 19, and 20%, respectively, during alkalosis (P less than 0.05). In all experiments, arterial lactate concentration increased significantly (P less than 0.05) during alkalosis. A positive venoarterial lactate difference across muscle during alkalosis indicated that skeletal muscle is a source of the elevated blood lactate. We concluded that VO2 of resting skeletal muscle is increased during states of respiratory alkalosis and that this increase can account for much of the increase in whole-body VO2.

Fee-for-data: a strategy to open the HMO black box.

This paper outlines a simple proposal to maintain utilization data in the face of managed care growth. Health maintenance organizations (HMOs) would be required to submit claims (encounter-level data) and in return would be paid a percentage of what Medicare would pay fee-for-service providers. The capitation payment rate would be lowered to maintain budget-neutrality. This proposal would enable the collection of key data that might not otherwise be captured in a Medicare program dominated by HMOs and other forms of managed care. The data are necessary to drive Medicare policies and to gauge the impact of changes to the program. The program would be well advised to make the small additional investment to make the data system complete. The key issue in implementing such a proposal will be HMOs' ability to generate those data at reasonable cost.

Probabilities for singleton and multiple pregnancies after in vitro fertilization.

OBJECTIVE: To help physicians provide risk estimates for specific pregnancy outcomes. DESIGN: Computation of exact binomial probabilities for singleton and multiple pregnancies as a function of two inputs: the number of embryos transferred and the implantation rate. Inputs were varied over the range of values reported in the literature. MAIN OUTCOME MEASURE(S): Probabilities for a singleton pregnancy (none), a multiple pregnancy (Pmult), and no pregnancy (Pnone) after one IVF cycle. RESULT(S): Given a 30% implantation rate and three embryos transferred, Pone=.44, Pmult=.22, and Pnone=.34. Although further increasing the number of embryos transferred increases the chance of pregnancy, it also raises the probability of a multiple pregnancy and lowers the chance of a singleton pregnancy. Although varying the implantation rate changes the specific probability estimates, the same trade-off persists. CONCLUSION(S): Those who consider an IVF "success" to be a singleton pregnancy should be attentive to the number of embryos transferred. Infertility therapy may be one area in medicine where more is not necessarily better.

A reader's guide to surgical decision analysis.

BACKGROUND: Studies using decision analysis appear increasingly often in the surgical literature. Because readers and reviewers may be unfamiliar with decision analysis, we review the technique and provide guidance on its interpretation. STUDY DESIGN: Review article. RESULTS: Decision analysis is a systematic approach to structuring a decision, collecting relevant information about the probability and relative value of outcomes, and making quantitative recommendations. Decision analysis includes the following basic components: (1) the decision model, (2) the probabilities of clinical outcomes in the model, (3) the utilities of clinical outcomes, and (4) the analysis and interpretation. To critically interpret the results of a decision analysis, readers must consider the validity of each component. The model should include all relevant clinical strategies and all important clinical outcomes. Probability estimates, whether derived from published studies or based on "clinical consensus," should be in general agreement with the reader's clinical experience. Utilities (values assigned to outcomes) are often expressed in terms of quality-adjusted life expectancy. Methods used to estimate life expectancy and to adjust for quality of life must be scrutinized carefully. Within the analysis, readers should consider the effect of varying uncertain variables in the model (sensitivity analysis) and, thus, the stability of the results. Finally, readers must assess whether the magnitude of expected benefit from the favored clinical strategy is clinically important. CONCLUSIONS: As decision analysis becomes more frequently used to influence clinical policy in surgery, surgeons must learn to examine the technique more critically.

Could distance be a proxy for severity-of-illness? A comparison of hospital costs in distant and local patients.

OBJECTIVE: We test the hypothesis that hospital costs, after adjusting for DRG mix, are higher in distant patients than in local patients. DATA SOURCES AND STUDY SETTING: Data were obtained from the Washington State Commission Hospital Abstract Reporting System (CHARS) and included all patients discharged from 15 metropolitan hospitals in the state of Washington during fiscal year 1987 (N = 181,072). STUDY DESIGN: Distant patients were initially defined as those patients residing outside a 15-mile radius of the hospital from which they were discharged; all other patients were considered local. Distance was determined using the patient's residence zip code. Hospital charge, calculated for all patients regardless of payer, served as a proxy for cost and was adjusted using the DRG weight. PRINCIPAL FINDINGS: Average charge (adjusted for DRG weight) was higher for distant patients in all but two hospitals. Overall adjusted charge for distant patients was 15 percent higher (p < .001). This finding persisted when different distances were used to dichotomize distant and local patients. When the 20 most common DRGs were examined individually, little charge difference was found in surgical DRGs that require tertiary center services (tertiary DRGs) and in those DRGs with both moderate and predictable resource use (routine DRGs); the charge difference seemed most prominent in those DRGs with a wide array of possible resource use (heterogeneous DRGs). CONCLUSIONS: Results suggest that patients traveling long distances use more resources and incur higher hospital charges than local patients. This is not accounted for in prospective payment. We postulate that distance might serve in part as a proxy for severity-of-illness.

Teaching evidence-based medicine: caveats and challenges.

Evidence-based medicine (EBM) is an important new paradigm of the medical profession. While the quantitative approach of EBM has its place, clinical medicine must take into account many subtleties that EBM fails to consider. In this article, the authors describe three caveats to this quantitative approach: (1) the detection of "maybe disease" (physiologic, anatomic, or histologic abnormalities that may not ever be overtly expressed in the patient's lifetime) inflates apparent diagnostic test performance; (2) probability revision is valuable primarily as an exercise to gain qualitative insights; and (3) patients are likely to be interested more than just central tendencies in making treatment decisions. They then consider some challenging questions facing clinician-educators: how do they prepare students for situations where there is an absence of rigorous evidence? Should they teach students that the burden of proof lies in demonstrating efficacy or in demonstrating ineffectiveness? And what should they tell students about when to seek evidence to aid diagnostic and treatment decisions?

Discounting in cost-effectiveness analysis of healthcare programmes.

Discounting is a technique commonly used in cost-effectiveness analysis to 'make fair' comparisons of programmes whose costs and outcomes occur at different times. It is not a correction for inflation. While there is general agreement among health economists regarding the need to discount, there is less consensus on the procedure for discounting costs or benefits. We describe the method of constant-rate discounting, which uses the same rate to discount costs and benefits, and examine its impact on the cost effectiveness of selected health interventions. This methodology has significant limitations, however. Constant-rate discounting may not accurately represent the values of a society. Furthermore, discounting does not reflect the longitudinal time preferences of individuals (or groups). The philosophical rationale for constant-rate discounting is the concept of longitudinal equity, i.e. that society should make allocation decisions in such a way that present and future cohorts are treated equally, regardless of when they come into existence. In general, discounting affects the cost effectiveness of preventive interventions more than acute interventions, and it affects programmes with immediate cost more that those with ongoing cost. The reader of such analyses should be aware of these effects, and should use caution in comparing the cost effectiveness of interventions with vastly different timing of cost and benefit.

Hyperoxia and human performance: a brief review.

The intent of this review was to examine the effects of hyperoxic gas mixtures on human performance. The evidence seems clear that performance is enhanced when O2-enriched gases are inhaled during exercise; however, the physiological mechanisms responsible for the improvement remain obscure. Increased pressure has a detrimental effect on performance, so that studies using hyperbaric oxygenation are ambiguous if the intent is to understand the effects of increased PO2. The large increases in maximal O2 uptake with hyperoxia reported in the literature may be erroneous because of problems encountered with the Douglas bag technique when gases with elevated O2 fractions are used. These apparent increases cannot be easily reconciled with published values for cardiac output and blood gas concentrations during exercise with hyperoxia. The effects of elevated PO2 are apparently widespread and, to a degree, independent; these include effects on pulmonary ventilation, on vascular smooth muscle, and on cellular metabolism. The available data do not lend strong support to the hypothesis that improvement in O2 delivery is responsible for the enhanced performance with hyperoxia. There are effects of hyperoxia on the pulmonary responses to exercise and on the acid-base responses. There is evidence that one or both of these mechanisms could play an important role in the changes in performance with hyperoxia.

Effects of varying concentrations of N2/O2 and He/O2 on exercise tolerance in man.

Hyperoxic gas mixtures improve exercise tolerance in humans. It is not clear whether this improvement is due to 1) a decreased anaerobiosis in the working cell, 2) a decreased cost of breathing resulting from the relative hypoventilation in hyperoxia, 3) the reduction of a possible metabolic depressant-N2, or a combination of these. This study made use of He/O2 breathing mixtures to gather data relative to #2 and #3, primarily. Ten subjects ran to exhaustion on a treadmill breathing one of four mixtures-20 O2/80 N2, 20 O2/80 He, 80 O2/20 N2, 80 O2/20 He. Running time to exhaustion, minute ventilation, respiratory frequency, tidal volume, and heart rate were measured. Performance increased significantly on hyperoxic mixtures (P < .001) and He/O2 mixtures (P < .001). Although the peak ventilatory volumes were higher on He/O2 mixtures, the ventilatory mass moved was significantly less (P < .001) on those mixtures conceivably resulting in a decreased cost of breathing. These data did not reject any of the hypotheses but offered the greatest support for hypothesis #2.

A pictographic essay on blood and tissue oxygen transport.

This review describes the transport of oxygen from ambient air to mitochondria in the cells. Using simple equations and diagrams, the presentation illustrates the variables which determine the magnitude of each of the three major steps in the partial pressure of O2 along the passage, from: (i) ambient air to alveolar gas; (ii) arterial blood to venous blood; and (iii) capillary blood to tissue. The emphasis is on steps (ii) and (iii), and how they are modified from the normoxic case by ischemia, anemia, hypoxia, and increased VO2. The basic context of step (iii) is the Krogh model. This model, despite its limitations, is proposed as conceptually useful in analyzing whole-body or tissue O2 transport.