The Canadian C-spine rule for radiography in alert and stable trauma patients

CONTEXT

High levels of variation and inefficiency exist in current clinical practice regarding use of cervical spine (C-spine) radiography in alert and stable trauma patients.

OBJECTIVE

To derive a clinical decision rule that is highly sensitive for detecting acute C-spine injury and will allow emergency department (ED) physicians to be more selective in use of radiography in alert and stable trauma patients.

DESIGN

Prospective cohort study conducted from October 1996 to April 1999, in which physicians evaluated patients for 20 standardized clinical findings prior to radiography. In some cases, a second physician performed independent interobserver assessments.

SETTING

Ten EDs in large Canadian community and university hospitals.

PATIENTS

Convenience sample of 8924 adults (mean age, 37 years) who presented to the ED with blunt trauma to the head/neck, stable vital signs, and a Glasgow Coma Scale score of 15.

MAIN OUTCOME MEASURE

Clinically important C-spine injury, evaluated by plain radiography, computed tomography, and a structured follow-up telephone interview. The clinical decision rule was derived using the kappa coefficient, logistic regression analysis, and chi(2) recursive partitioning techniques.

RESULTS

Among the study sample, 151 (1.7%) had important C-spine injury. The resultant model and final Canadian C-Spine Rule comprises 3 main questions: (1) is there any high-risk factor present that mandates radiography (ie, age >/=65 years, dangerous mechanism, or paresthesias in extremities)? (2) is there any low-risk factor present that allows safe assessment of range of motion (ie, simple rear-end motor vehicle collision, sitting position in ED, ambulatory at any time since injury, delayed onset of neck pain, or absence of midline C-spine tenderness)? and (3) is the patient able to actively rotate neck 45 degrees to the left and right? By cross-validation, this rule had 100% sensitivity (95% confidence interval [CI], 98%-100%) and 42.5% specificity (95% CI, 40%-44%) for identifying 151 clinically important C-spine injuries. The potential radiography ordering rate would be 58.2%.

CONCLUSION

We have derived the Canadian C-Spine Rule, a highly sensitive decision rule for use of C-spine radiography in alert and stable trauma patients. If prospectively validated in other cohorts, this rule has the potential to significantly reduce practice variation and inefficiency in ED use of C-spine radiography.

Neuroprotective effect of mild hypothermia in patients undergoing coronary artery surgery with cardiopulmonary bypass: a randomized trial

BACKGROUND

Neuropsychological deficits occur in 30% to 80% of patients undergoing heart surgery and are due in part to ischemic cerebral injury during cardiopulmonary bypass. We tested whether mild hypothermia, the most efficacious neuroprotective strategy found in laboratory studies, improved cognitive outcome in patients undergoing coronary artery surgery.

METHODS AND RESULTS

Patients 60 years or older scheduled for coronary artery surgery were enrolled. During cardiopulmonary bypass, patients were initially cooled to 32 degrees C then randomly assigned to rewarming to 37 degrees C (control) or 34 degrees C (hypothermic), with no further intraoperative warming. Testing was scheduled preoperatively and 1 week and 3 months postoperatively. Eleven tests were combined into 3 cognitive domains: memory, attention, and psychomotor speed and dexterity. A patient was classified as having a cognitive deficit if a decrease of >/=0.50 SD was realized in 1 or more domains. The incidence of cognitive deficits 1 week after surgery, which was the primary outcome, was 62% () in the control group and 48% () in the hypothermic group (relative risk 0.77, P=0.048). In the hypothermic group, the magnitude of deterioration in attention and in speed and dexterity was reduced by 55.6% (P=0.038) and 41.3% (P=0.042), respectively. At 3 months, the hypothermic group still performed better on one test of speed and dexterity (grooved pegboard). There was no difference in morbidity or mortality.

CONCLUSIONS

Our findings support a neuroprotective effect of mild hypothermia in patients undergoing coronary artery surgery and should encourage physicians and perfusionists to pay careful attention to brain temperature during cardiopulmonary bypass.

Effects of exercise on glycemic control and body mass in type 2 diabetes mellitus: a meta-analysis of controlled clinical trials

CONTEXT

Exercise is widely perceived to be beneficial for glycemic control and weight loss in patients with type 2 diabetes. However, clinical trials on the effects of exercise in patients with type 2 diabetes have had small sample sizes and conflicting results.

OBJECTIVE

To systematically review and quantify the effect of exercise on glycosylated hemoglobin (HbA(1c)) and body mass in patients with type 2 diabetes.

DATA SOURCES

Database searches of MEDLINE, EMBASE, Sport Discuss, Health Star, Dissertation Abstracts, and the Cochrane Controlled Trials Register for the period up to and including December 2000. Additional data sources included bibliographies of textbooks and articles identified by the database searches.

STUDY SELECTION

We selected studies that evaluated the effects of exercise interventions (duration >/=8 weeks) in adults with type 2 diabetes. Fourteen (11 randomized and 3 nonrandomized) controlled trials were included. Studies that included drug cointerventions were excluded.

DATA EXTRACTION

Two reviewers independently extracted baseline and postintervention means and SDs for the intervention and control groups. The characteristics of the exercise interventions and the methodological quality of the trials were also extracted.

DATA SYNTHESIS

Twelve aerobic training studies (mean [SD], 3.4 [0.9] times/week for 18 [15] weeks) and 2 resistance training studies (mean [SD], 10 [0.7] exercises, 2.5 [0.7] sets, 13 [0.7] repetitions, 2.5 [0.4] times/week for 15 [10] weeks) were included in the analyses. The weighted mean postintervention HbA(1c) was lower in the exercise groups compared with the control groups (7.65% vs 8.31%; weighted mean difference, -0.66%; P<.001). The difference in postintervention body mass between exercise groups and control groups was not significant (83.02 kg vs 82.48 kg; weighted mean difference, 0.54; P =.76).

CONCLUSION

Exercise training reduces HbA(1c) by an amount that should decrease the risk of diabetic complications, but no significantly greater change in body mass was found when exercise groups were compared with control groups.

Canadian CT head rule study for patients with minor head injury: methodology for phase II (validation and economic analysis)

Prospective validation on a new set of patients is an essential test of a new decision rule. However, many clinical decision rules are not prospectively assessed to determine their accuracy, reliability, clinical sensibility, or potential impact on practice. This validation process is important because many statistically derived rules or guidelines do not perform well when tested in a new population. The methodologic standards for a validation study are similar to those described in the article on phase I for derivation studies in the August 2001 issue of Annals of Emergency Medicine. The goal of phase II is to prospectively assess the accuracy, reliability, and acceptability of the decision rule in a new set of patients with minor head injury. This will determine the clinical utility of the rule and is essential if such a rule is to be widely adopted into clinical practice.

Physicians' accuracy and interrator reliability for the diagnosis of unstable meniscal tears in patients having osteoarthritis of the knee

OBJECTIVE

To determine clinicians' accuracy and reliability for the clinical diagnosis of unstable meniscus tears in patients with symptomatic osteoarthritis of the knee.

DESIGN

A prospective cohort study.

SETTING

A single tertiary care centre.

PATIENTS

One hundred and fifty-two patients with symptomatic osteoarthritis of the knee refractory to conservative medical treatment were selected for prospective evaluation of arthroscopic debridement.

INTERVENTION

Arthroscopic debridement of the knee, including meniscal tear and chondral flap resection, without abrasion arthroplasty.

OUTCOME MEASURES

A standardized assessment protocol was administered to each patient by 2 independent observers. Arthroscopic determination of unstable meniscal tears was recorded by 1 observer who reviewed a video recording and was blinded to preoperative data. Those variables that had the highest interobserver agreement and the strongest association with meniscal tear by univariate methods were entered into logistic regression to model the best prediction of resectable tears.

RESULTS

There were 92 meniscal tears (77 medial, 15 lateral). Interobserver agreement between clinical fellows and treating surgeons was poor to fair (kappa < 0.4) for all clinical variables except radiographic measures, which were good. Fellows and surgeons predicted unstable meniscal tear preoperatively with equivalent accuracy of 60%. Logistic regression modelling revealed that a history of swelling and a ballottable effusion were negative predictors. A positive McMurray test was the only positive predictor of unstable meniscal tear. "Mechanical" symptoms were not reliable predictors in this prospective study. The model was 69% accurate for all patients and 76% for those with advanced medial compartment osteoarthritis defined by a joint space height of 2 mm or less.

CONCLUSIONS

This study underscored the difficulty in using clinical variables to predict unstable medial meniscal tears in patients with pre-existing osteoarthritis of the knee. The lack of interobserver agreement must be overcome to ensure that the findings can be generalized to other physician observers.

The Canadian CT Head Rule Study for patients with minor head injury: rationale, objectives, and methodology for phase I (derivation)

Head injuries are among the most common types of trauma seen in North American emergency departments, with an estimated 1 million cases seen annually. "Minor" head injury (sometimes known as "mild") is defined by a history of loss of consciousness, amnesia, or disorientation in a patient who is conscious and talking, that is, with a Glasgow Coma Scale score of 13 to 15. Although most patients with minor head injury can be discharged without sequelae after a period of observation, in a small proportion, their neurologic condition deteriorates and requires neurosurgical intervention for intracranial hematoma. The objective of the Canadian CT Head Rule Study is to develop an accurate and reliable decision rule for the use of computed tomography (CT) in patients with minor head injury. Such a decision rule would allow physicians to be more selective in their use of CT without compromising care of patients with minor head injury. This paper describes in detail the rationale, objectives, and methodology for Phase I of the study in which the decision rule was derived. [Stiell IG, Lesiuk H, Wells GA, McKnight RD, Brison R, Clement C, Eisenhauer MA, Greenberg GH, MacPhail I, Reardon M, Worthington J, Verbeek R, Rowe B, Cass D, Dreyer J, Holroyd B, Morrison L, Schull M, Laupacis A, for the Canadian CT Head and C-Spine Study Group. The Canadian CT Head Rule Study for patients with minor head injury: rationale, objectives, and methodology for phase I (derivation). Ann Emerg Med. August 2001;38:160-169.]

Vasopressin versus epinephrine for inhospital cardiac arrest: a randomised controlled trial

BACKGROUND

Survival rates for cardiac arrest patients, both in and out of hospital, are poor. Results of a previous study suggest better outcomes for patients treated with vasopressin than for those given epinephrine, in the out-of-hospital setting. Our aim was to compare the effectiveness and safety of these drugs for the treatment of in-patient cardiac arrest.

METHODS

We did a triple-blind randomised trial in the emergency departments, critical care units, and wards of three Canadian teaching hospitals. We assigned adults who had cardiac arrest and required drug therapy to receive one dose of vasopressin 40 U or epinephrine 1 mg intravenously, as the initial vasopressor. Patients who failed to respond to the study intervention were given epinephrine as a rescue medication. The primary outcomes were survival to hospital discharge, survival to 1 h, and neurological function. Preplanned subgroup assessments included patients with myocardial ischaemia or infarction, initial cardiac rhythm, and age.

FINDINGS

We assigned 104 patients to vasopressin and 96 to epinephrine. For patients receiving vasopressin or epinephrine survival did not differ for hospital discharge (12 [12%] vs 13 [14%], respectively; p50.67; 95% CI for absolute increase in survival 211.8% to 7.8%) or for 1 h survival (40 [39%] vs 34 [35%]; p50.66; 210.9% to 17.0%); survivors had closely similar median mini-mental state examination scores (36 [range 19-38] vs 35 [20-40]; p50.75) and median cerebral performance category scores (1 vs 1).

INTERPRETATION

We failed to detect any survival advantage for vasopressin over epinephrine. We cannot recommend the routine use of vasopressin for inhospital cardiac arrest patients, and disagree with American Heart Association guidelines, which recommend vasopressin as alternative therapy for cardiac arrest.

Tolterodine versus oxybutynin in the treatment of urge urinary incontinence: a meta-analysis

OBJECTIVE

To compare tolterodine with oxybutynin in treatment of urge incontinence.

STUDY DESIGN

A systematic review, following Cochrane methods, was performed to retrieve results of randomized trials that compared tolterodine with oxybutynin in adults with urge incontinence. Composite point estimates of efficacy (episodes of incontinence per 24-hour period, frequency, and voided volume) and safety (dry mouth, withdrawal, and dose modification) were calculated.

RESULTS

Four studies were included. Both drugs similarly decreased the number of micturitions in a 24-hour period. Oxybutynin was marginally superior to tolterodine in decreasing the number of incontinent episodes in a 24-hour period (weighted mean difference, 0.41; 95% confidence interval [CI], 0.04 to 0.77) and increasing the mean voided volume per micturition (8.24 mL; 95% CI, 14.19 to 3.38). Fewer patients had dry mouth (relative risk, 0.54; 95% CI, 0.48 to 0.61) and withdrew from the study because of side effects (relative risk, 0.63; 95% CI, 0.46 to 0.88) with tolterodine.

CONCLUSIONS

Oxybutynin and tolterodine share a clinically similar efficacy profile (although oxybutynin is statistically superior), but tolterodine is better tolerated and leads to fewer withdrawals as a result of adverse events.

CPR-only survivors of out-of-hospital cardiac arrest: implications for out-of-hospital care and cardiac arrest research methodology

STUDY OBJECTIVE

There is little evidence that cardiopulmonary resuscitation (CPR) alone may lead to the resuscitation of cardiac arrest victims with other than respiratory causes (eg, pediatric arrest, drowning, drug overdose). The objective of this study was to identify out-of-hospital cardiac arrest survivors resuscitated without defibrillation or advanced cardiac life support.

METHODS

This observational cohort included all adult survivors of out-of-hospital cardiac arrest of a cardiac cause from phases I and II of the Ontario Prehospital Advanced Life Support Study. During the study period, the system provided a basic life support/defibrillation level of care but no advanced life support. CPR-only patients were patients determined to be without vital signs by EMS personnel who regained a palpable pulse in the field with precordial thump or CPR only and then were admitted alive to the hospital. Six members of a 7-member expert review panel had to rate the patient as either probably or definitely having an out-of-hospital cardiac arrest, and a rhythm strip consistent with a cardiac arrest rhythm had to be present to be considered a patient. Criteria considered were witness status, citizen or first responder CPR, CPR duration, arrest rhythm and rate, and performance of precordial thump.

RESULTS

From January 1, 1991, to June 30, 1997, 9,667 patients with out-of-hospital cardiac arrest were treated. The overall survival rate to hospital discharge was 4.6%. There were 97 apparent CPR-only patients admitted to the hospital. Application of the inclusion criteria yielded 24 CPR-only patients who had true out-of-hospital cardiac arrest and 73 patients judged not to have cardiac arrest. Of the 24 true CPR-only patients admitted to the hospital, 15 patients were discharged alive, 10 patients were witnessed by bystanders, and 7 patients were witnessed by EMS personnel. The initial arrest rhythm was pulseless electrical activity in 9 patients, asystole in 12 patients, and ventricular tachycardia in 3 patients. One patient with ventricular tachycardia converted to sinus tachycardia with a single precordial thump.

CONCLUSION

CPR-only survivors of true out-of-hospital cardiac arrest do exist; some victims of out-of-hospital cardiac arrest of primary cardiac cause can survive after provision of out-of-hospital basic life support care only. However, many patients found to be pulseless by means of out-of-hospital evaluation likely did not have a true cardiac arrest. This has implications for the survival rates of most, if not all, previous cardiac arrest reports. Survival rates from cardiac arrest may actually be lower if one excludes survivors who never had a true arrest. The absence of vital signs by out-of-hospital assessment alone is not adequate to include patients in research reports or quality evaluations for cardiac arrest.

The Canadian CT Head Rule for patients with minor head injury

BACKGROUND

There is much controversy about the use of computed tomography (CT) for patients with minor head injury. We aimed to develop a highly sensitive clinical decision rule for use of CT in patients with minor head injuries.

METHODS

We carried out this prospective cohort study in the emergency departments of ten large Canadian hospitals and included consecutive adults who presented with a Glasgow Coma Scale (GCS) score of 13-15 after head injury. We did standardised clinical assessments before the CT scan. The main outcome measures were need for neurological intervention and clinically important brain injury on CT.

FINDINGS

The 3121 patients had the following characteristics: mean age 38.7 years); GCS scores of 13 (3.5%), 14 (16.7%), 15 (79.8%); 8% had clinically important brain injury; and 1% required neurological intervention. We derived a CT head rule which consists of five high-risk factors (failure to reach GCS of 15 within 2 h, suspected open skull fracture, any sign of basal skull fracture, vomiting >2 episodes, or age >65 years) and two additional medium-risk factors (amnesia before impact >30 min and dangerous mechanism of injury). The high-risk factors were 100% sensitive (95% CI 92-100%) for predicting need for neurological intervention, and would require only 32% of patients to undergo CT. The medium-risk factors were 98.4% sensitive (95% CI 96-99%) and 49.6% specific for predicting clinically important brain injury, and would require only 54% of patients to undergo CT.

INTERPRETATION

We have developed the Canadian CT Head Rule, a highly sensitive decision rule for use of CT. This rule has the potential to significantly standardise and improve the emergency management of patients with minor head injury.

Inconsistent detection of PrP in extraneural tissues of cats with feline spongiform encephalopathy

Feline spongiform encephalopathy (FSE), a transmissible spongiform encephalopathy or prion disease of cats, first reported in Great Britain in 1990, is believed to result from the consumption of food contaminated by the agent of bovine spongiform encephalopathy (BSE). The accumulation of PrP in non-neural tissues of cats diagnosed as suffering from FSE was investigated by immunohistochemistry. In the majority of the cats no disease-specific PrP was detected in lymphoid tissues. Small amounts of PrP were detected in the spleen of only two of 13 samples examined, in Peyer's patches of one of the two cases for which suitable material was available, but in the myenteric plexus of all four cats in which sections of intestine were examined. In addition PrP immunostaining was found in the kidney of all the cats with FSE whose kidneys were examined.

Cardiac troponin T predicts long-term outcomes in hemodialysis patients

BACKGROUND

Increased plasma troponin T (cTnT), but not troponin I (cTnI), is frequently observed in end-stage renal failure patients. Although generally considered spurious, we previously reported an associated increased mortality at 12 months.

METHODS

We studied long-term outcomes in 244 patients on chronic hemodialysis for up to 34 months, correlating the outcomes to plasma cTnT in routine predialysis samples. In addition, subsequent plasma samples at least 1 year later and within 6 months of data analysis were available in 97 patients and were used to identify patients with increasing plasma cTnT. The endpoints used were death and new or worsening coronary, cerebro-, and peripheral vascular disease and neuropathy.

RESULTS

Transplantation occurred more frequently in patients with low initial cTnT: 31%, 13%, and 3% in the groups with cTnT < 0.010, 0.010-0.099, and > or = 0.100 microg/L, respectively. In the same groups, total deaths occurred in 6%, 43%, and 59% and cardiac deaths in 0%, 14%, and 24% of patients. In patients with follow-up samples, the group with increasing cTnT had a significantly increased death (relative risk, 2.0; P = 0.028). The increase was mainly in cardiac and sudden deaths.

CONCLUSIONS

Higher plasma cTnT predicts long-term all-cause mortality in hemodialysis patients, even at concentrations < 0.100 microg/L, as does an increasing cTnT concentration over time.

Histological observations on the brains of symptomless 7-year-old cattle

The histological changes in the brains of 506 clinically normal 7-year-old cattle, which were part of a cohort study on maternal transmission of bovine spongiform encephalopathy, are described. Vacuolation of the white matter, of unknown aetiology, located particularly in the substantia nigra, was a frequent finding. Vacuolated neurons were commonly observed in the red nucleus (64.3% of the animals) and in the habenular nucleus (50.1%). Spheroids were found in 10.8% of the brains, most frequently in the vestibular nuclei. Cellular inflammatory infiltrates in association with blood vessels occurred in 30% of the animals at various locations in the brain; their aetiology remains uncertain, but they may have reflected subclinical or latent infections. Mineralization of the wall of blood vessels, with proliferation of the intima, was observed frequently in vessels of the internal capsule and was probably associated with ageing. The description of histological findings in the brain of symptomless adult cattle in the present study provides a useful background for diagnostic bovine neuropathology.

Neonatal and fetal methylenetetrahydrofolate reductase genetic polymorphisms: an examination of C677T and A1298C mutations

Methylenetetrahydrofolate reductase (MTHFR) mutations are commonly associated with hyperhomocysteinemia, and, through their defects in homocysteine metabolism, they have been implicated as risk factors for neural tube defects and unexplained, recurrent embryo losses in early pregnancy. Folate sufficiency is thought to play an integral role in the phenotypic expression of MTHFR mutations. Samples of neonatal cord blood (n=119) and fetal tissue (n=161) were analyzed for MTHFR C677T and A1298C mutations to determine whether certain MTHFR genotype combinations were associated with decreased in utero viability. Mutation analysis revealed that all possible MTHFR genotype combinations were represented in the fetal group, demonstrating that 677T and 1298C alleles could occur in both cis and trans configurations. Combined 677CT/1298CC and 677TT/1298CC genotypes, which contain three and four mutant alleles, respectively, were not observed in the neonatal group (P=.0402). This suggests decreased viability among fetuses carrying these mutations and a possible selection disadvantage among fetuses with increased numbers of mutant MTHFR alleles. This is the first report that describes the existence of human MTHFR 677CT/1298CC and 677TT/1298CC genotypes and demonstrates their potential role in compromised fetal viability.

Adverse outcomes and opioid analgesic administration in acute abdominal pain

To the authors' knowledge, no outcome-based, randomized clinical trial of the safety of opioid analgesics in acute abdominal pain exists.

OBJECTIVES

1) To assess the feasibility of a randomized clinical trial of opioid safety by estimating the adverse outcome rate among patients with abdominal pain severe enough to necessitate opioid analgesics. 2) To explore the association of opioid administration with adverse outcomes in acute abdominal pain.

METHODS

The authors conducted a prospective observational study of emergency department (ED) abdominal pain patients, and followed them by telephone at three weeks to determine whether an adverse outcome occurred (defined as obstruction, perforation, ischemia, hemorrhage, peritonitis, sepsis, or death). A logistic regression of factors predicting adverse outcome was performed.

RESULTS

Adverse outcomes occurred in 67 of 860 abdominal pain patients (7.8%, 95% CI = 6.1% to 9.8%), and 252 of 860 (29%) received opioids. The adverse outcome rate was 12.7% (95% CI = 9.0% to 17.0%) among patients who received opioids. Variables predictive of adverse outcome in logistic regression included: ED diagnosis of adverse outcome (OR 12.4), age (OR 1.6 per decade), fever (OR 4.6), received opioids (OR 2.1), pain duration (OR 1.5 per day), and leukocytosis (OR 2.0).

CONCLUSIONS

A clinical trial would need to randomize more than 1,500 patients to establish the equivalent adverse outcome rates of opioids and placebo: the sample size of all existing studies combined is insufficient to make such a conclusion. Although opioids were associated with a higher adverse outcome rate in this logistic regression, the authors believe this may be due to confounding by pain severity. They emphasize that the study's design precludes conclusion of a causal link. No change in clinical practice is warranted. A randomized clinical trial of sufficient size to definitively resolve this issue is needed.

Preclinical diagnosis of scrapie by immunohistochemistry of third eyelid lymphoid tissue

Ovine scrapie is a member of the transmissible spongiform encephalopathies (TSEs), a heterogeneous family of fatal neurologic disorders characterized by deposition of an abnormal isoform (prion protein [PrP] PrP-Sc) of a cellular sialoglycoprotein in neural tissue. PrP-Sc is detectable in some lymphoid tissues of infected sheep months or years before development of clinical disease. Detection of PrP-Sc in these tissues is the basis for live-animal testing. In this study, we characterize the performance of a preclinical diagnostic test for ovine scrapie based on a monoclonal antibody (MAb)-based immunohistochemistry assay of nictitating membrane ("third eyelid")-associated lymphoid tissue. The results of third eyelid immunohistochemistry assay agreed with the scrapie status of the sheep for 41 of 42 clinical suspects with confirmed scrapie and 174 of 175 sheep without scrapie. Third eyelid sampling agreed with the scrapie status for 36 of 41 clinically normal sheep positive for PrP-Sc immunostaining of brain tissue, including 27 sheep with positive biopsy specimens that progressed to clinical disease with confirmed scrapie 3 to 20 months after biopsy. The assay used MAb F89/160.1.5, which binds to residues 142 to 145 of ovine PrP. This antibody can be used in combination with MAb F99/97. 6.1, which binds to residues 220 to 225. One or both MAbs in this cocktail recognize PrP sequences conserved in most mammalian species in which natural TSEs have been reported. Immunohistochemistry assay of routinely formalin-fixed lymphoid tissues with a cocktail of pan-specific MAbs is a practical, readily standardized live-animal and preclinical test for ovine scrapie.

Effect of hemoglobin levels in hemodialysis patients with asymptomatic cardiomyopathy

BACKGROUND

Hemoglobin levels below 10 g/dL lead to left ventricular (LV) hypertrophy, LV dilation, a lower quality of life, higher cardiac morbidity, and a higher mortality rate in end-stage renal disease. The benefits and risks of normalizing hemoglobin levels in hemodialysis patients without symptomatic cardiac disease are unknown.

METHODS

One hundred forty-six hemodialysis patients with either concentric LV hypertrophy or LV dilation were randomly assigned to receive doses of epoetin alpha designed to achieve hemoglobin levels of 10 or 13.5 g/dL. The study duration was 48 weeks. The primary outcomes were the change in LV mass index in those with concentric LV hypertrophy and the change in cavity volume index in those with LV dilation.

RESULTS

In patients with concentric LV hypertrophy, the changes in LV mass index were similar in the normal and low target hemoglobin groups. The changes in cavity volume index were similar in both targets in the LV dilation group. Treatment-received analysis of the concentric LV hypertrophy group showed no correlation between the change in mass index and a correlation between the change in LV volume index and mean hemoglobin level achieved (8 mL/m2 per 1 g/dL hemoglobin decrement, P = 0.009). Mean hemoglobin levels and the changes in LV mass and cavity volume index were not correlated in patients with LV dilation. Normalization of hemoglobin led to improvements in fatigue (P = 0.009), depression (P = 0.02), and relationships (P = 0.004).

CONCLUSIONS

Normalization of hemoglobin does not lead to regression of established concentric LV hypertrophy or LV dilation. It may, however, prevent the development of LV dilation, and it leads to improved quality of life.

Randomized trial of high-flux vs low-flux haemodialysis: effects on homocysteine and lipids

BACKGROUND

Uncontrolled studies have found that high-flux haemodialysis favourably modifies homocysteine and lipid profiles. We sought to confirm these findings by carrying out a randomized prospective comparison of high-flux and low-flux polysulphone in chronic, stable dialysis patients.

METHODS

Forty-eight patients were randomly assigned to either high or low-flux dialysis for 3 months. Serum levels of homocysteine, lipoprotein (a), and lipids were compared between the treatment groups at monthly intervals.

RESULTS

All patient characteristics and laboratory variables were equally distributed between the groups at baseline. Over the study duration, we observed no differences between high- and low-flux treatment groups for the following outcomes: pre-dialysis homocysteine, lipoprotein (a), total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides (all P>0.05). Geometric mean (interquartile range) homocysteine at baseline was 20.0 (16.8-24.5) and 19.5 (15.3-22.0) micromol/l for the high-and low-flux groups respectively (P=0.80), and levels did not change significantly during the study. We did demonstrate a more pronounced intradialytic effect of high-flux dialysis on homocysteine levels, which fell during dialysis by 42%, compared to 32% with low-flux dialysis (P<0. 001).

CONCLUSIONS

In this randomized controlled trial, the effects of high-flux and low-flux haemodialysis on homocysteine and lipid profiles were comparable. The greater intradialytic effect of high-flux dialysis on homocysteine did not translate into a significant difference in pre-dialysis levels after 3 months of study.

Scrapie surveillance in Great Britain: results of an abattoir survey, 1997/98

A randomised sample of 2,809 apparently healthy sheep, 55 per cent of them less than 15 months of age, which were slaughtered for human consumption at abattoirs in Great Britain in 1997/98, was taken to establish the prevalence of scrapie infection. The medulla oblongata of each sheep was examined histopathologically at the level of the obex, and fresh brain tissue was examined for scrapie-associated fibrils (SAF) to establish whether there was evidence of scrapie. In addition, histological sections of the medulla from 500 of the sheep were immunostained with an antiserum to PrP, and the same technique was also applied to any animal found positive or inconclusive by the histological or SAF examinations. Any sheep which was positive by any of these diagnostic methods was also examined by Western immunoblotting, for the detection of the disease-specific protein PrP(Sc). A total of 2,798 sheep (99.6 per cent) were negative by all the methods applied. Ten animals were SAF-positive but negative by all the other methods, and in one animal there was immunohistochemical staining which could not be interpreted unequivocally as disease-specific. A mathematical model was used to estimate the prevalence of scrapie infection in the national slaughtered sheep population which would be consistent with these results. By this model, the absence of unequivocally substantiated cases of scrapie in the sample was consistent with a prevalence of infection in the slaughter population of up to 11 per cent.

Cardiac arrest witnessed by emergency medical services personnel: descriptive epidemiology, prodromal symptoms, and predictors of survival. OPALS study group

STUDY OBJECTIVE

The Utstein guidelines recommend that emergency medical services (EMS)-witnessed cardiac arrests be considered separately from other out-of-hospital cardiac arrest cases. The objective of this study was to assess EMS-witnessed cardiac arrest and to determine predictors of survival in this group.

METHODS

This prospective cohort included all adults with an EMS-witnessed cardiac arrest in the 21 communities of the Ontario Prehospital Advanced Life Support (OPALS) study. Systems provided a basic life support with defibrillation (BLS-D) level of care. Case and survival definitions followed the Utstein style. Descriptive and univariate methods (chi(2) and t test) were used to characterize EMS-witnessed cardiac arrest. Multivariate logistic regression was undertaken to assess predictors of survival to hospital discharge.

RESULTS

From January 1, 1991, to December 31, 1996, there were 9,072 cardiac arrest cases in the study communities. Of these, 610 (6.7%) were EMS-witnessed. The majority had preexisting cardiac or respiratory disease (81.5%) and experienced prodromal symptoms before EMS personnel arrived (91.4%). An initial rhythm of pulseless electrical activity was present in 50.1% of the patients, ventricular fibrillation/ventricular tachycardia in 34.2%, and asystole in 15.7%. Survival to discharge was 12.6%. Multivariate analysis identified the following as independent predictors of survival (odds ratio with 95% confidence intervals [CIs]): nitroglycerin use before EMS arrival: 2.3 (95% CI 1.2 to 4.5), prodromal symptoms of chest pain: 2.5 (95% CI 1.4 to 4.5) or dyspnea: 0.5 (95% CI 0.3 to 1.0), and unconsciousness on EMS arrival: 0.5 (95% CI 0.2 to 0.9). Patients with chest pain were more likely than dyspneic patients to experience ventricular fibrillation/ventricular tachycardia (62% versus 17%, P<.0001), and were 5 times more likely to survive (30.6% versus 6.3%, P<.0001).

CONCLUSION

EMS-witnessed cases are clearly an important subset of out-of-hospital cardiac arrest and are characterized by 2 distinct symptom groups: chest pain and dyspnea. These symptoms are important predictors of survival and may also help determine underlying mechanisms before patient collapse. A later phase of the OPALS study will prospectively evaluate the impact of out-of-hospital advanced life support on the survival of victims of EMS-witnessed cardiac arrest.

The neuropathology of experimental bovine spongiform encephalopathy in the pig

In an experimental study of the transmissibility of BSE to the pig, seven of 10 pigs, infected at 1-2 weeks of age by multiple-route parenteral inoculation with a homogenate of bovine brain from natural BSE cases developed lesions typical of spongiform encephalopathy. The lesions consisted principally of severe neuropil vacuolation affecting most areas of the brain, but mainly the forebrain. In addition, some vacuolar change was identified in the rostral colliculi and hypothalamic areas of normal control pigs. PrP accumulations were detected immunocytochemically in the brains of BSE-infected animals. PrP accumulation was sparse in many areas and its density was not obviously related to the degree of vacuolation. The patterns of PrP immunolabelling in control pigs differed strikingly from those in the infected animals.

An assessment of methods to combine published survival curves

PURPOSE

To assess the accuracies of different techniques for combining published survival curves, for use in disease modeling applications.

METHODS

Five methods were identified: 1) iterative generalized least-squares (IGLS), 2) meta-analysis of failure-time data with adjustment for covariates (MFD), 3) nonlinear regression (NLR), 4) log relative risk (LRR), and 5) weighted LRR (w-LRR). Each method was used to combine the survival curves from eight single-arm Phase II trials of chemotherapy in 918 patients with advanced non-small-cell lung cancer (NSCLC). The resulting summary curves were compared with the curve calculated from the corresponding individual patient data (IPD).

RESULTS

All methods were able to produce accurate summary survival curves statistically similar to the IPD-derived curve. Maximum discrepancies ranged from 1.8% to 4.7%. MFD appeared to be the most accurate when censoring information was complete. Characteristics of the component trials that adversely affected the accuracies of the different techniques were 1) a high proportion of censored observations (MFD); 2) variability in the length of follow-up (IGLS, NLR, LRR, w-LRR); and 3) the heterogeneity of the treatment results (NLR, w-LRR).

CONCLUSIONS

All methods were able to accurately reproduce summary survival curves from the published literature. The best method depends on characteristics of the data and the purpose of the analysis.

Increased mortality in hemodialyzed patients with elevated serum troponin T: a one-year outcome study

OBJECTIVES

To determine the significance of elevated serum troponin T (cTnT) occurring in hemodialysis patients in the absence of clinical evidence of acute coronary ischemia.

DESIGN AND METHODS

Twelve-month follow-up of cohort of 172 hemodialyzed patients with known serum cTnT concentration. The cohort consisted of patients undergoing hemodialysis in a hospital unit over a 5-month period, with one to four measurements of cTnT. The main outcome measure was death. Cause of death was determined by autopsy in six patients.

RESULTS

Of the 31 deaths, 12 were due to acute coronary disease, 14 were noncoronary, and 5 were undefined. Death rates of patients with cTnT <0.1, 0.1-0.2, and >0.2 microg/L were 9.9% (11/111), 32.4% (12/37), and 33.3% (8/24), respectively. The increase in death rate with cTnT > or =0.1 microg/L was significant (p<0.001) for noncoronary deaths, but not for acute coronary deaths. The risk ratios for noncoronary deaths in the subgroups were: nondiabetics 6.6 (95% CI 1.9-23.6), patients with no coronary artery disease 7.3 (1.6-32.4), patients with no peripheral vascular disease 8.9 (2.0-39.7), and hypertensives 9.0 (1.1-76.5). Significant increase in coronary deaths was seen only in patients without hypertension and those aged > or =50 years. The risk ratios for these groups were 9.3 (1.2-74.3) and 3.3 (1.0-10.6), respectively.

CONCLUSIONS

Serum cTnT is a potential prognostic marker of mortality in hemodialyzed patient, with increase in death from coronary and noncoronary causes.