Benjamin A. Barnes

Professional uncertainty and the problem of supplier-induced demand

This paper discusses the puzzling problem of large differences in per capita use of certain common surgical procedures among neighboring populations, which by all available measures are quite similar in need for and access to services. The evidence reviewed here supports the hypothesis that variations occur to a large extent because of differences among physicians in their evaluation of patients (diagnosis) or in their belief in the value of the procedures for meeting patient needs (therapy). This hypothesis, which we call the professional uncertainty hypothesis, is germane to current controversies concerning the nature and extent of supplier influence on the demand for medical services. It is also important because of its implications for health regulatory policy. Our plan is to (1) review the relevance of the hypotheses for the supplier-induced demand controversy; (2) review the epidemiologic evidence on the nature and causes of variation; (3) examine patterns of use of common surgical procedures to illustrate the importance of supplier influence on utilization; and (4) consider some of the implications of the professional uncertainty hypotheses for public policy.

Identification of Adverse Events Occurring during Hospitalization: A Cross-Sectional Study of Litigation, Quality Assurance, and Medical Records at Two Teaching Hospitals

STUDY OBJECTIVES To estimate the efficacy of a medical record review for identifying adverse events and negligent case suffered by hospitalized patients. DESIGN Cross-sectional study comparing an objective medical record review with information available from hospital quality assurance records as well as risk management and litigation records. SETTING Two metropolitan teaching hospitals in the northeastern United States. MEASUREMENTS AND MAIN RESULTS Using the litigation and risk management records as a criterion standard, we found that the medical record review had a sensitivity of 80% (93 of 116; 95% CI, 73% to 88%) for discovering adverse events and a sensitivity of 76% (51 of 67; 95% CI, 66% to 86%) for discovering negligent care. We estimated that record review of a random sample of hospitalizations across a geographic region would have even higher sensitivity (adverse-event sensitivity, 84%; negligence sensitivity, 80%). Moreover, we found that the adverse events we failed to discover led to less costly malpractice claims. A significant number of adverse events (20 of 172) among hospitalizations never gave rise to litigation or risk management investigation. Six of the twenty were due to negligent care. Quality assurance efforts at the level of the clinical departments in one hospital led to review of only 12 out of 82 risk management records. CONCLUSIONS The overwhelming majority of adverse events and episodes of negligent care are discoverable with the methods we used to evaluate medical records. Quality assurance efforts using similar record review methods should be further evaluated.

Mechanism of Pulmonary Conversion of Anglotensin II to Angiotensin II in the Dog

The mechanism of conversion of angiotensin I to angiotensin II was studied in vivo in the pulmonary circulation of the intact anesthetized dog and in vitro in plasma by using L-Leu-anglotensin I, D-Leu-angiotensin I, and des-Leu-angiotensin I which had been synthesized by the solid-phase technique. None of the peptides were active in the rabbit aortic strip preparation; D-Leu-angiotensin I and des-Leu-angiotensin I gave less than 5% of the pressor response of L-Leu-angiotensin I in the pentolinium-treated rat. D-Leu-angiotensin I and des-Leu-angiotensin I were not converted to angiotensin II when incubated with diluted human or dog plasma or partially purified converting enzyme from dog plasma. In a single pulmonary circulation time, following injection of a 20-nmole bolus of L-Leu-angiotensin I into the dog right ventricle, 56% of the material recovered had been converted to angiotensin II, as measured by radioimmunoassay. Conversion was accompanied by a rise in mean blood pressure of 30 mm Hg. After injection of equimolar amounts of D-Leu-angiotensin I and des-Leu-angiotensin I, no generation of angiotensin II and no pressor response occurred. These observations indicate that pulmonary conversion in vivo and plasma conversion in vitro occur via a dipepridylcarboxypeptidase and that a D-amino acid at the C-terminus prevents conversion.

Therapeutic Bilateral Renal Infarction in End-Stage Renal Disease

Bilateral nephrectomy, which has been performed in patients with end-stage renal disease for a variety of reasons, has a substantial morbidity and an appreciable mortality.1 2 3 We recently used th...

The determination of exchangeable magnesium in alcoholic patients

Abstract Mg 28 was administered to 13 alcoholic patients admitted to the Massachusetts General Hospital with symptoms of tremulousness following alcohol withdrawal. These patients were also given an intravenous magnesium tolerance test. Data were compared with values obtained from a group of 6 healthy chronic alcoholic subjects studied during sobriety. Exchangeable magnesium levels and urine loss of injected magnesium following intravenous magnesium loading were significantly lower in the tremulous group. Alcoholic individuals with withdrawal symptoms have a magnesium deficit which may be caused by poor dietary intake plus a variety of intercurrent illness. However, the data do not support a direct causal relationship between low serum magnesium levels and the onset of alcohol withdrawal symptoms.

MAGNESIUM CONSERVATION: A STUDY OF SURGICAL PATIENTS

Magnesium conservation in the surgical patient is a major consideration in an important but restricted number of diseases. The purpose of this paper is to consider magnesium conservation and its implications as illuminated by selected surgical experience, Other presentations will delineate clinical magnesium abnormalities in medical disease. The surgical patient presents unusual opportunities for the study of magnesium conservation by virute of malabsorption syndromes following extirpative gastrointestinal surgery and by virute of the acute state of hypoparathyroidism following excision of hyperactive parathyroid tissue. These conditions will be emphasized in this report, since other surgical disorders associated with magnesium deficits, such as acute pancreatitis (Wills, 1966) or postoperative renal transplant status, have limited descriptive and metabolic data available.

THE ROLE OF VASCULAR INJURY IN PULMONARY ALLOGRAFT REJECTION

The morphologic features of pulmonary allograft rejection are described. The graft recipients were either unmodified or treated with Imuran (Azathiaprine), an immunosuppressive agent. The morphological features of graft rejection in the two groups differ, but vascular alterations are a significant feature of both patterns. In unmodified recipients, the earliest changes are the appearance of perivenous mononuclear infiltrates at about 5 days; these progress to involve the vein wall leading to the local disruption of the endothelial and muscular layers. Periarterial mononuclcar infiltrates also appear at about this time, but these initially spare the vessel wall. However, at about 10 days there is progressive mononuclear infiltration of the artery wall as well, primarily subintimal, with concomitant reduction and even obliteration of the arterial lumen. This generalized vasculitis, without vascular necrosis, appears to result in generalized hemorrhagic necrosis of the allograft on an ischemic basis. In the attenuated allograft rejection following immunosuppressive therapy, “chronic” arterial and, to a lesser extent, venous lesions are observed. These show varying degrees of subendothelial inflammation, hyperplasia, and fibrosis. Similar vascular lesions are not found in autografts. The features which distinguish these unique vascular lesions from other forms of allergic vasculitis and the vascular changes found in other types of allografts are described.

The Search For An Hl-a- And Abo-compatible Cadaver Organ For Transplantation: Probabilistic Asssessment of the Outlook

The degree to which discriminating criteria are asserted in the selection of cadaveric donor organs for transplantation depends on the probabilities of finding, within a tolerable waiting period, donors of different degrees of histocompatibility with the recipient. A means of assessing these probabilities is described, considering the HL-A and ABO factors. The theoretical development, together with available data on the frequencies of the various alleles, permits the construction of a simple table and nomogram for practical assessment of the probabilities. The necessary input information includes the estimate of the total number of potential donors that will become available within, the projected waiting period, together with the HL-A and ABO types of the recipient.

Irradiation of the Blood: Method for Reducing Lymphocytes in Blood and Spleen

Insertion of a beta-emitting source into the right atrium of the heart permits intensive irradiation of the circulating blood, with subsequent depletion of lymphocytes in the peripheral blood and lymphoid organs.

Recurrent idiopathic membranous glomerulonephritis.

This study reports the clinical and pathological findings in a patient with recurrent membranous glomerulonephritis following transplantation of an HLA-identical kidney. Such a recurrence has been previously reported only once, although membranous glomerulonephritis is a common cause of nephrotic syndrome in adults. This case confirms that membranous glomerulonephritis may occasionally recur following renal transplantation and demonstrates that immunofluorescence and electron microscopic studies may be necessary to distinguish recurrent membranous glomerulonephritis from the membranous changes frequently seen with chronic rejection. In light of the apparent low incidence of recurrent membranous glomerulonephritis, renal transplantation remains an excellent therapeutic option in this disease.