Using Catchment Population to Estimate Sporadic Creutzfeldt-Jakob Disease Incidence.

INTRODUCTION: Catchment populations have several uses. A method using catchment population to estimate the incidence of sporadic Creutzfeldt-Jakob disease (sCJD) is described. MATERIALS AND METHODS: A cohort of nine consecutive patients diagnosed with sCJD, symptom onset spanning 26 months, were observed at a rural tertiary university medical center that has approximately 40,000 hospital discharges annually. An effective catchment population was determined using surrounding county utilization frequency that captured all nine sCJD patients and accounted for over 87% of discharges. RESULTS: The effective sCJD hospital catchment population was 1.266 million, implying an annual sCJD incidence rate of 3.39 per million (95% CIs, 1.55-6.43), assuming a Poisson distribution for sCJD occurrence. CONCLUSIONS: This annual incidence rate suggests that many sCJD patients are unrecognized and unreported. An advantage of this catchment population method is independence from death certificate accuracy, important in rare diseases that are both rapidly and invariably fatal. The relative absence of significant healthcare systems competition in this rural population enhances the reliability of this finding. The most likely explanation for the high sCJD incidence rate suggested by this study is enhanced clinical suspicion and improved diagnostic accuracy.

Intravenous thrombolysis of large vessel occlusions is associated with higher hospital costs than small vessel strokes: a rationale for developing stroke severity-based financial models.

BACKGROUND: Owing to their severity, large vessel occlusion (LVO) strokes may be associated with higher costs that are not reflected in current coding systems. This study aimed to determine whether intravenous thrombolysis costs are related to the presence or absence of LVO. METHODS: Patients who had undergone intravenous thrombolysis over a 9-year period were divided into LVO and no LVO (nLVO) groups based on admission CT angiography. The primary outcome was hospital cost per admission. Secondary outcomes included admission duration, 90-day clinical outcome, and discharge destination. RESULTS: 119 patients (53%) had LVO and 104 (47%) had nLVO. Total mean±SD cost per LVO patient was $18,815±14,262 compared with $15,174±11,769 per nLVO patient (p=0.04). Hospital payments per admission were $17,338±13,947 and $15,594±16,437 for LVO and nLVO patients, respectively (p=0.4). A good outcome was seen in 33 LVO patients (27.7%) and in 69 nLVO patients (66.4%) (OR 0.2, 95% CI 0.1 to 0.3, p<0.0001). Hospital mortality occurred in 31 LVO patients (26.1%) and in 7 nLVO patients (6.7%) (OR 0.2, 95% CI 0.08 to 0.5, p<0.0001). 31 LVO patients (32.6%) were discharged to home versus 64 nLVO patients (61.5%) (OR 4.5, 95% CI 2.6 to 8, p<0.0001). Admission duration was 7.5±6.9 days in LVO patients versus 4.9±4.2 days in nLVO patients (p=0.0009). Multivariate regression analysis after controlling for comorbidities showed the presence of LVO to be an independent predictor of higher total hospital costs. CONCLUSIONS: The presence or absence of LVO is associated with significant differences in hospital costs, outcomes, admission duration, and home discharge. These differences can be important when developing systems of care models for acute ischemic stroke.

Discordant thymectomy in identical twins concordant for myasthenia gravis.

BACKGROUND: Thymectomy is standard therapy fornonthymomatousmyasthenia gravis despite the absence of randomized clinical trials (1). Myasthenia gravis is uncommonly reported in monozygous twins; disease concordance occurs in approximately one third of such identical twin pairs; and treatment for myasthenia gravis, when described,is usually concordant in identical twin pairs (2). OBJECTIVE: To report an 11-year clinical course of a pair of identical twins concordant for generalized acetylcholine receptor antibody­positive nonthymomatous myasthenia gravis in whom only 1 was treated with extended transsternal thymectomy. CASE REPORT: Twin A was a 19-year-old white woman who presented with an 8-week history of intermittent leg weakness, causing her to fall during activities, such as climbing stairs. On examination,she had moderately severe fatigable proximal muscle weakness and ptosis. Her weakness improved with intravenous edrophonium administration.Initial binding acetylcholine receptor antibody titer was 1.22 nmol/L (normal value, 0.03 nmol/L). Repetitive 2-Hz nerve(median, ulnar, and facial) stimulation studies demonstrated up to a 16% decremental response. Chest computed tomography showed residual thymic tissue without thymoma. An extended transsternal thymectomy was performed 11 weeks after the onset of symptoms.

Infant homicide and accidental death in the United States, 1940-2005: ethics and epidemiological classification.

Potential ethical issues can arise during the process of epidemiological classification. For example, unnatural infant deaths are classified as accidental deaths or homicides. Societal sensitivity to the physical abuse and neglect of children has increased over recent decades. This enhanced sensitivity could impact reported infant homicide rates. Infant homicide and accident mortality rates in boys and girls in the USA from 1940 to 2005 were analysed. In 1940, infant accident mortality rates were over 20 times greater than infant homicide rates in both boys and girls. After about 1980, when the ratio of infant accident mortality rates to infant homicide rates decreased to less than five, and the sum of infant accident and homicide rates became relatively constant, further decreases in infant accident mortality rates were associated with increases in reported infant homicide rates. These findings suggest that the dramatic decline of accidental infant mortality and recent increased societal sensitivity to child abuse may be related to the increased infant homicide rates observed in the USA since 1980 rather than an actual increase in societal violence directed against infants. Ethical consequences of epidemiological classification, involving the principles of beneficence, non-maleficence and justice, are suggested by observed patterns in infant accidental deaths and homicides in the USA from 1940 to 2005.

The role of CT perfusion imaging in acute stroke diagnosis: a large single-center experience.

The objective of this study was to determine the utility of computed tomography perfusion (CTP) scans in diagnosing acute ischemic stroke (AIS). CTP abnormalities in two contiguous supratentorial levels were correlated with diffusion weighted image (DWI) abnormalities on magnetic resonance imaging (the standard for stroke diagnosis) performed within 1 week in 422 suspected acute ischemic strokes. Of 157 AIS confirmed by DWI, 78 showed CTP abnormalities (sensitivity 49.7%). All of these examinations were performed with a mean of 35 min from the initial emergency department neurological examination. Excluding small non-vascular territory strokes left 77 AIS with a total volume of infarcted tissue of more than 5 cc by DWI. Of these, 71 showed CTP abnormalities (sensitivity 92.2%). Of the 265 patients without AIS, none showed CTP abnormalities (specificity 100%). CTP is a rapid, readily available and effective method of diagnosing AIS in clinical practice, particularly the major intracranial vessel strokes that result in a more devastating outcome.

Impact of institution of a stroke program upon referral bias at a rural academic medical center.

CONTEXT: Referral bias reflecting the preferential hospital transfer of patients with intracerebral hemorrhage (ICH) has been demonstrated as the major contributing factor for an observed high nonrisk-adjusted in-hospital crude acute stroke mortality rate at a rural academic medical center. PURPOSE: This study was done to assess the impact of a clinical acute stroke program upon referral bias in August 2000. METHODS: A chart review of acute stroke (DRG 14) discharges during 2001 from a rural academic medical center was compared with the same data from 1999. RESULTS: The odds ratio of ICH in hospital-transfer patients compared with nonhospital-transfer patients decreased from 11.7 in 1999 to 3.2 in 2001 (P < .035). CONCLUSIONS: This study demonstrated the rapid magnitude and significance that clinical programs can have upon referral bias. Changes in referral bias may be more rapid at rural academic medical centers because of the relative lack of health care delivery competition.

Epilepsy's role in the historical differentiation of religion, magic, and science.

A distinction between religion, magic, and science has not always been recognized. Ancient Greek physicians, in their writings about epilepsy, were likely among the first to record the historically important differentiation between religion, magic, and science.

The contributions of Lavoisier, Carnot, and Mayer to understanding heat illness.

Although heat illness has been described throughout recorded history, an understanding of its pathophysiology was only achieved in the 20th century. Lavoisier, Carnot, and Mayer described fundamental concepts about thermodynamics in the late 18th and early 19th centuries that were crucial to the eventual understanding of heat illness. Lavoisier recognized that the human body was a heat engine. Carnot recognized that useful heat engines must dissipate heat. Mayer recognized that humans possess the capacity to regulate body heat. The fundamental contributions of Lavoisier, Carnot, and Mayer to the understanding of heat illness have gone largely unacknowledged.

Critical illness myopathy associated with hyperthyroidism.

A 51-year-old woman was admitted to the intensive care unit for exacerbation of chronic obstructive pulmonary disease. She received antibiotics, neuromuscular blocking agents, and steroids. After 8 days in the intensive care unit, she was noted to be severely weak, her serum creatine kinase had risen to 1,692 U/L (normal, 20-220 U/L), and a muscle biopsy was consistent with critical illness myopathy. As a result of evaluating for resting tachycardia, the patient was found to be hyperthyroid. Her weakness rapidly improved within 1 month after treatment of her hyperthyroidism with iodine-131 and methimazole. The metabolic alterations associated with hyperthyroidism may enhance the risk of developing critical illness myopathy after the administration of antibiotics, neuromuscular blocking agents, and steroids in the intensive care unit.

"Guessing it right," John A. Simpson, and myasthenia gravis: the role of analogy in science.

In 1960, John A. Simpson hypothesized that myasthenia gravis "is an 'auto-immune' response of muscle in which an antibody to end-plate protein may be formed." Simpson's speculation was subsequently shown to be correct. A review of Simpson's hypothesis from a historical perspective illustrates the role of analogy in science.