Predicting the risk of pressure ulcers in critically ill patients

BACKGROUND

Critically ill patients are at high risk for pressure ulcers.

OBJECTIVES

To determine the contributions of the Braden subscales in predicting pressure ulcers in critically ill patients and to investigate how often the Braden scale should be completed to assess the risk for pressure ulcers in critically ill patients.

METHOD

The Braden scale was used to assess repeatedly 136 adult patients without pressure ulcers in a medical intensive care unit, a surgical intensive care unit, and a noninvasive respiratory care unit, and the patients' skin was inspected routinely for pressure ulcers.

RESULTS

A total of 36 pressure ulcers, most commonly on the sacrum or coccyx and the heels (15 stage 1, 20 stage 2, 1 stage 3), developed in 17 patients (12%). In 14 (82%) of the 17, the ulcers developed within 72 hours of admission to the intensive care unit. The risk for pressure ulcers increased as the mean sensory perception (P = .01) and the mean total Braden (P = .046) scores decreased. The mean sensory perception scores obtained at 12 and 36 hours after admission also had a significant relationship to the risk for pressure ulcers (P = .03).

CONCLUSIONS

Patients in intensive care units have an increased risk for pressure ulcers. Although waiting until 12 hours after a patient's admission to the intensive care unit to obtain the initial Braden rating may be reasonable (with the second rating obtained 36 hours after admission), additional research is needed before this practice can be recommended.

Review of the development, validation, and application of predictive instruments in interventional cardiology

Within the last few years, risk assessment has become an integral part of clinical practice, particularly for thoracic surgery and interventional procedures. Risk assessment statistical models are being used in medical decision making, quality improvement tools, and as aids to patient counseling. This literature review was conducted to evaluate the types of predictive models and outcomes measures that have been examined, and methods used in development, validation, and application of these models. A Medline search performed to identify articles (limited to human studies) published in English from 1980 to 1999 resulted in 89 articles, of which 71 were evaluable. Populations studied for model development included patients undergoing coronary artery bypass graft (CABG), percutaneous transluminal coronary revascularization (PTCR), cardiac catheterization, or stenting procedures and patients with angina or stroke. The models were equally developed from a single center versus multicenter and from retrospective databases versus prospective studies. In terms of model perspectives, only three of the models measured cost or cost-effectiveness as the outcome; the remainder considered only clinical outcomes. The most commonly reported types of predictive models were developed using logistic regression and Bayesian techniques, followed by neural networks, rule-based artificial intelligence, simultaneous equation system, and multiple linear regression. Factors to consider when developing or evaluating a predictive model include uniformity of definitions of outcomes, uniformity of definitions of variables, completeness of data, number and frequency of variables, timeliness and source of data, development population characteristics, development and testing (validation) cohorts, and calibration and discrimination. Application of these models to an individual patient can spur quality improvement efforts that can lead to dramatic, system-wide improvements in outcomes.

International standards for the assessment of the risk of thermal strain on clothed workers in hot environments

The International Standards Organisation (ISO) has produced an integrated series of international standards for the assessment of human responses to thermal environments. They include standards for the assessment of thermal comfort, heat stress and cold stress and many have been adopted as European and British standards. This paper describes the series of standards and in particular those concerned with the assessment of risk in hot environments. A three tier approach is taken which involves a simple thermal index that can be used for monitoring and control of hot environments (ISO 7243), a rational approach which involves an analysis of the heat exchange between a worker and his or her environment (ISO 7933) and a standard that describes the principles of physiological measurement which can be used in the establishment of personal monitoring systems of workers exposed to hot environments (ISO 9886). The standards are self-contained and can be used independently. In any comprehensive assessment however they would be used in conjunction. The simple index provides a first stage analysis and can confirm whether or not there is likely to be unacceptable thermal strain. Where a more detailed analysis is required then ISO 7933 provides an analytical method that can provide a more extensive assessment and interpretation leading to recommendations for improvement to the working environment. Where a method needs to be confirmed, or conditions are beyond the scope of ISO 7243 and ISO 7933, then ISO 9886 provides guidance on physiological measurement and interpretation. This would be used in extreme environments where individual responses are required to ensure health and safety or, in the case where personal protective equipment (PPE) is worn, which is beyond the scope of ISO 7243 and ISO 7933. The ISO system therefore covers almost all exposures to hot environments. It would be useful however to extend the scope of the standards that provide a simple index or analytical approach. This paper describes the current standards and their scope and forms the basis and background for descriptions of proposed extensions to the scope of the standards described in other papers in this special issue.

Heat stress and protective clothing: an emerging approach from the United States

There is little doubt that heat stress affects many workers adversely and that protective clothing generally adds to the burden. The ACGIH threshold limit value for heat stress is the guiding document for evaluation of heat stress in the United States. Adjustment factors have been used to reflect the change in heat stress imposed by different clothing ensembles. While the first proposed factors started with limited experimental data and professional judgment, heat balance methods in the laboratory have yielded better estimates of adjustment factors and for a wider selection of ensembles. These same experiments have provided the starting point to accounting for nonporous clothing in heat balance evaluation schemes such as required sweat rate. Proposed changes to the ACGIH TLV have been mentioned and a framework for thinking about controls presented.

Can sickness absence be predicted at the pre-placement health assessment?

Pre-placement health assessments may be used not only to assess fitness for work but also to predict sickness absence. A risk assessment based on available evidence is proposed for making such judgements.

The role of performance tests, manikins and test houses in defining clothing characteristics relevant to risk assessment

Clothing is an important determinant of human heat exchange and accordingly a critical factor for heat stress risk assessment. A large number of international standards exist concerning protective properties of clothing. However, few standards deal with ergonomic properties and requirements of clothing, making it difficult to evaluate the function of a clothing ensemble in terms of both protection and physiological strain or discomfort. The paper examines existing test methods and procedures for improvement of the situation. Much of the work are presently at research stages, but should in the near future be available for test houses and consumers.

European system for cardiac operative risk evaluation (EuroSCORE)

OBJECTIVE

To construct a scoring system for the prediction of early mortality in cardiac surgical patients in Europe on the basis of objective risk factors.

METHODS

The EuroSCORE database was divided into developmental and validation subsets. In the former, risk factors deemed to be objective, credible, obtainable and difficult to falsify were weighted on the basis of regression analysis. An additive score of predicted mortality was constructed. Its calibration and discrimination characteristics were assessed in the validation dataset. Thresholds were defined to distinguish low, moderate and high risk groups.

RESULTS

The developmental dataset had 13,302 patients, calibration by Hosmer Lemeshow Chi square was (8) = 8.26 (P < 0.40) and discrimination by area under ROC curve was 0.79. The validation dataset had 1479 patients, calibration Chi square (10) = 7.5, P < 0.68 and the area under the ROC curve was 0.76. The scoring system identified three groups of risk factors with their weights (additive % predicted mortality) in brackets. Patient-related factors were age over 60 (one per 5 years or part thereof), female (1), chronic pulmonary disease (1), extracardiac arteriopathy (2), neurological dysfunction (2), previous cardiac surgery (3), serum creatinine >200 micromol/l (2), active endocarditis (3) and critical preoperative state (3). Cardiac factors were unstable angina on intravenous nitrates (2), reduced left ventricular ejection fraction (30-50%: 1, <30%: 3), recent (<90 days) myocardial infarction (2) and pulmonary systolic pressure >60 mmHg (2). Operation-related factors were emergency (2), other than isolated coronary surgery (2), thoracic aorta surgery (3) and surgery for postinfarct septal rupture (4). The scoring system was then applied to three risk groups. The low risk group (EuroSCORE 1-2) had 4529 patients with 36 deaths (0.8%), 95% confidence limits for observed mortality (0.56-1.10) and for expected mortality (1.27-1.29). The medium risk group (EuroSCORE 3-5) had 5977 patients with 182 deaths (3%), observed mortality (2.62-3.51), predicted (2.90-2.94). The high risk group (EuroSCORE 6 plus) had 4293 patients with 480 deaths (11.2%) observed mortality (10.25-12.16), predicted (10.93-11.54). Overall, there were 698 deaths in 14,799 patients (4.7%), observed mortality (4.37-5.06), predicted (4.72-4.95).

CONCLUSION

EuroSCORE is a simple, objective and up-to-date system for assessing heart surgery, soundly based on one of the largest, most complete and accurate databases in European cardiac surgical history. We recommend its widespread use.

Strategy for evaluation and prevention of risk due to work in thermal environments

A strategy in four successive stages is described and justified for the prevention and control of thermal problems in the workplace. This should allow these problems to be approached and solved progressively in small as well as large companies by relying successively, when necessary, on the complementary competencies of the workers themselves, their technical assistance, the occupational health specialists and the experts. The criteria to fulfil at each stage are described and discussed. Appendix 1 describes in detail the methods to be used at stages 2, "Observation" by the workers and their assistance; at stage 3, "Analysis" with the help of specialists; and outlines the stage 4, "Expertise".

Development of a draft British standard: the assessment of heat strain for workers wearing personal protective equipment

Existing methods for estimating heat stress, enshrined in British/International Standards (the Wet Bulb Globe Temperature (WBGT) index [BS EN 27243] and the Required Sweat Rate equation [BS EN 12515; ISO 7933 modified]), assume that the clothing worn by the individual is water vapour permeable; the WBGT index also assumes that the clothing is relatively light. Because most forms of personal protective equipment (PPE) either have a higher insulative value than that assumed or are water vapour impermeable, the Standards cannot be accurately applied to workers wearing PPE. There was, therefore, a need to develop a British Standard which would allow interpretation of these existing Standards for workers wearing PPE. Relevant information was obtained through reviewing the literature and consulting experts. Two questionnaire surveys of potential users of the Standards were conducted, and physiological data collected both experimentally and in work situations were considered. The information collected was used to develop the draft British Standard. It provides information and data on: The general effect of PPE on heat balance of the body (the ability of the body to maintain its 'core' temperature within an acceptable range). The effect of specific forms of PPE on metabolic heat production rate. The thermal insulation and evaporative resistance of types of PPE. The effect of the closure of the garments to the body on heat transfer. The effect of the PPE on the proportion of the body covered. The effect of an air supply (for example, Breathing Apparatus [BA]) to the wearer. Guidance is given on conducting an analysis of the work situation, taking account of the impact of PPE. Detailed methods of interpreting both BS EN 27243 and BS EN 12515 for workers wearing PPE are given, taking account of the factors listed above. Three worked examples using BS EN 27243 and BS EN 12515 are given in the Annex of the draft Standard.

Do physicians assess lifestyle health risks during general medical examinations? A survey of general practitioners and obstetrician-gynecologists in Quebec

BACKGROUND

In Canada several guidelines have been published for the screening of lifestyle health risks during general medical examinations. The authors sought to examine the extent to which such screening practices have been integrated into medical practice, to measure physicians' perceived level of difficulty in assessing these risks and to document physicians' evaluation of their formal medical training in lifestyle risk assessment.

METHODS

An anonymous mail survey was conducted in 1995 in Quebec with a stratified random sample of 1086 general practitioners (GPs) and with all 241 obstetrician-gynecologists (Ob-Gyns). The authors evaluated the proportion of physicians who reported routine assessment (with 90% or more of their patients) of substance use, family violence and sexual history during general medical examinations of adult and adolescent patients; the proportion of those who find inquiring about these issues difficult; and the proportion of those who evaluated their medical training in lifestyle risk assessment as adequate or excellent.

RESULTS

The overall response rate was 72.6%. Among adult patients, 82.2% of the GPs reported routinely assessing tobacco use, 67.2% alcohol consumption, 34.2% illicit drug use and 3.2% family violence; the corresponding proportions for assessment among adolescent patients were 77.1%, 61.8%, 52.9% and 5.6%. Comparatively fewer Ob-Gyns reported routinely assessing these issues (56.1%, 28.6%, 20.4% and 1.3% respectively among adults and 62.7%, 35.2%, 26.8% and 2.8% respectively among adolescents). In the area of sexual history, condom use was routinely assessed by more Ob-Gyns than GPs (47.0% v. 28.2%); however, the proportion of Ob-Gyns and GPs was equally low for assessing number of partners (24.8% and 23.1%), sexual orientation (18.8% and 16.9%) and STD risk (26.2% and 21.2%). The vast majority of GPs and Ob-Gyns reported finding it difficult to assess family violence (86.5% and 93.0%) and sexual abuse (92.7% and 92.4% respectively). Over 80% of the physicians felt that they had had adequate or excellent medical training in assessing risk behaviours for heart disease and STD risk. The proportion who felt this way about their training in screening for illicit drug use, family violence and sexual abuse ranged between 12.7% and 31.6%.

INTERPRETATION

Although morbidity and mortality associated with smoking, alcohol consumption, illicit drug use, unsafe sexual practices, family violence and sexual abuse have been well documented, routine screening for these risk factors during general medical examinations has yet to be integrated into medical practice.

Risk-informed selection of a highway trajectory in the neighborhood of an oil-refinery

A methodology for characterizing alternative trajectories of a new highway in the neighborhood of an oil-refinery with respect to the risk to public health is presented. The approach is based on a quantitative assessment of the risk that the storage facilities of flammable materials of the refinery pose to the users of the highway. Physical phenomena with a potential for detrimental consequences to public health such as BLEVE (Boiling Liquid Expanding Vapor Explosion), Unconfined Vapor Cloud Explosion, flash fire and pool fire are considered. Methodological and procedural steps for assessing the individual risk around the tank farm of the oil-refinery are presented. Based on the individual risk, group risk for each alternative highway trajectory is determined.

[Prognosis in meningococcal disease: methodology and practice]

78 patients with systemic meningococcal disease admitted to the Intensive Care Unit of the 2nd Moscow Hospital for Infectious Diseases were studied and the composite prognostic score was developed to estimate the risk of lethal outcome. The stepwise variable selection procedure for the multiple logistic regression was applied to 30 potential clinical and laboratory risk factors and markers. Five factors were selected for the score, namely the platelet count (< 150 x 10(6)/ml), the presence of hemorrhages into the eye or mucosal tissue, the interval from the last urination before admission (> 4 h), the respiration rate (> 170% of age-adjusted normal value) and age (< 2 or > 65 years) with regression coefficients 0.3, 0.2, 0.2 and 0.1, respectively. Both for the source clinical group and for the additional test group (64 patients), the scale was able to classify correctly 95% of cases using the data collected at admission. Ten prognostic scores proposed previously by foreign investigators were tested in the same patients and the best four scores were selected (GMSPS, Gedde-Dahl, Niklasson, Kahn); the scores classified correctly 85-90% of cases. This study is an example of methodological approaches to prognostic score construction in medicine.

Assessment of the U.S. Environmental Protection Agency methods for identification of hazards to developing organisms, Part I: The reproduction and fertility testing guidelines

BACKGROUND

Successful reproduction depends on the coordination of many processes, particularly the normal development and subsequent maturation of the sexual organs. The Food Quality Protection Act of 1996 mandates that the U.S. Environmental Protection Agency must protect infants and children from the effects of toxins, including those that affect the reproductive system. Therefore, the Agency finds itself at a critical juncture to make sure that the methods it requires for toxicity testing, the Health Effects Test Guidelines or Series 870 Guidelines, are adequate to determine possible toxicity to children.

METHODS AND RESULTS

We found that two testing protocols included in the core guidelines assess toxicological effects on developing animals. This article aims to provide a detailed analysis of the protocols included in the Reproduction and Fertility Effects Test Guideline. An accompanying article assesses the Developmental Toxicity Testing Guideline. We conducted this analysis on the basis of whether the test would yield the information needed to adequately determine risk to infants and children.

CONCLUSIONS

Our analysis concludes that given the limitations inherent in testing for reproduction and fertility effects during development, it is necessary to include a safety factor during risk assessment of chemicals. This action will fulfill the mandate expressed in the FQPA to protect infants and children from environmental hazards.

Critical analysis of methods for assessment of predicted no-effect concentration

Current risk assessment procedures for chemical substances are based on hazard quotients and require determination of a predicted no-effect concentration (PNEC). These concentrations are usually computed by applying an assessment factor to the lowest available toxicity value. However, other approaches have also been proposed based on statistical distribution of ecotoxicity data. This paper compares the various approaches in terms of precision and robustness. When only a few data are available, an assessment factor approach can be used. However, whenever possible (i.e. for a large set of chronic data), a statistical approach like that developed by T. Aldenberg and W. Slob (1991, Confidence Limits for Hazardous Concentrations Based on Logistically Distributed NOEC Toxicity Data, RIVM Report 71902002) with a 50% confidence level is the most precise and provides a stable value with increasing confidence when the number of tests increases.

Assessment of the U.S. Environmental Protection Agency methods for identification of hazards to developing organisms, Part II: The developmental toxicity testing guideline

BACKGROUND

The effects of toxins on developing animals depend not only on the nature of the chemical but also on the timing of exposure and assessment of outcomes. This complicates the task of regulatory agencies such as the U.S. Environmental Protection Agency (EPA), which must comply with the 1996 Food Quality Protection Act to ensure that their standards and policies protect infants and children from environmental toxins. For this task, the Agency relies heavily on scientific data obtained by manufacturers of industrial chemicals and pesticides following protocols collected under EPA's Health Effects Test Guidelines.

METHODS AND RESULTS

This article reviews the protocols included in the EPA guidelines to assess developmental toxicity, which are required for food-use pesticides under the core testing battery. We reviewed these protocols on the basis of their adequacy for identifying hazards to infants and children. Our analysis found limitations in the protocols that hinder their potential for identifying developmental hazards.

CONCLUSIONS

Methods that the EPA currently depends upon to identify developmental toxicity of chemicals have limitations that impede obtaining complete and reliable data on which to base regulatory decisions that protect children. Other methodological approaches need to be explored as alternatives or supplements to the current protocols. Until more accurate testing protocols become available, it may well be necessary under existing laws to employ safety factors that are more protective of the health of children at all stages of development.

Prediction of metal bioavailability in Dutch field soils for the oligochaete Enchytraeus crypticus

Current risk assessment procedures ignore that variation in soil properties results in substantial differences for uptake and effects in organisms in different soils. In this contribution is presented the results of a study on the soil-related factors that modulate metal uptake and elimination by the oligochaete worm Enchytraeus crypticus. Uptake of Cd, Cu, Pb, and Zn was quantified in 20 Dutch field soils as a function of time. Uptake rate constants and equilibrium concentrations were estimated using compartment modeling. Internal metal concentrations varied less than the corresponding external levels. Zn and especially Cu provided the most extreme examples of this general behavior, which suggests regulation by the organism. Body residues by Cd increased linearly over time in 11 of the 20 soils studied, whereas in the remaining 9 soils equilibration of internal Cd levels was observed. CaCl2 extraction could be used to discriminate the 9 soils in which there is Pb accumulation from the 11 soils in which bioavailable Pb levels were too low to allow for uptake. Multivariate expressions that describe uptake rate constants and bioaccumulation factors as a function of soil characteristics were derived. pH and cation exchange capacity were the most important parameters. The formulae were very similar to those describing partitioning of metals over the solid and liquid phase of the soils, which suggests pore water-mediated uptake. A semi-mechanistic approach yielded further evidence of pore water-related uptake, modulated by competition between H+ and metal ions at the active sites of the membranes.

Review of methods applicable to the assessment of mold exposure to children

This article presents discussion of the assessment of the exposure of children to fungi, substances derived from fungi, and the environmental conditions that may lead to exposure. The principles driving investigations of fungal contamination and subsequent exposure are presented as well as guidelines for conducting these investigations. A comprehensive description of available research sampling and analysis techniques is also presented.

A comparison of three risk assessment scales

Nurses often use pressure sore risk assessment tools without clearly understanding their underlying principles. Comparing different tools can help to determine which are of most value to nurses. Assessment tools can aid decision-making and give objective credibility to practice.

Exposure endpoint selection in acute dietary risk assessment

Current USEPA Office of Pesticide Program approaches to acute dietary risk assessment do not adequately address uncertainty in the distributional analysis of exposure. This is especially true with respect to regulatory decision points (bright lines) located at the far extreme of the cumulative output distribution. Use of the 99.9th centile as a risk assessment endpoint necessitates confidence in food consumption and residue input distributions that cannot be demonstrated with currently available data and analysis approaches. Even for a pesticide with a rich residue database, data limitations are sufficient to skew results to significantly overestimate exposure. This is compounded when extremes in food consumption are used that go beyond the stated error bounds for the database used. Risk management decision making need not consider endpoints at extremes of exposure output distributions in order for mitigation to be protective of sensitive populations. In fact, such decision making is better informed by utilizing more statistically reliable endpoint selection in the risk assessment process. The richest data content in cumulative exposure distributions occurs in regions well removed from output tails, where the pattern of exposure distribution is driven by the effects of residue concentrations. In contrast, the extreme upper tail of the exposure distribution is data poor and is characterized by high uncertainty reflecting extremes in food consumption patterns. At present, risk managers are better served with exposure endpoints removed from the highly uncertain tails of exposure distributions such as the 99.9th centile bright line. The selection of more appropriate risk management decision points should consider the nature of the distribution, the severity of the effect being assessed, and robustness of the data available for assessing acute dietary risk.

Measuring risk in a children's unit: developing a local strategy for health, safety and risk management at Queen's Medical Centre, Nottingham

This article demonstrates the Queen's Medical Centre approach to assessing and addressing risk in terms of Health and Safety within a busy children's unit. This article focuses on compartmentalising a large clinical area on two floors of a busy teaching hospital which become manageable sized subunits; each has a health, safety and risk management link person who attends the regular meetings to discuss key issues. These link people, with experience and training observe clinical areas within the zone, for hazards and potential hazards (risk inspection) and then calculate the hazard on a risk score. This is then risk assessed and all risk prioritised within the Children's Services Directorate Team. The author describes how a proactive approach to health, safety and risk management has brought about significant improvements, enhanced quality of care and improved morale and motivation of the nursing team.

TWODEE: the Health and Safety Laboratory's shallow layer model for heavy gas dispersion. Part 1. Mathematical basis and physical assumptions

The Major Hazard Assessment Unit of the Health and Safety Executive (HSE) provides advice to local planning authorities on land use planning in the vicinity of major hazard sites. For sites with the potential for large scale releases of toxic heavy gases such as chlorine this advice is based on risk levels and is informed by use of the computerised risk assessment tool RISKAT [C. Nussey, M. Pantony, R. Smallwood, HSE's risk assessment tool RISKAT, Major Hazards: Onshore and Offshore, October, 1992]. At present RISKAT uses consequence models for heavy gas dispersion that assume flat terrain. This paper is the first part of a three part paper. Part 1 describes the mathematical basis of TWODEE, the Health and Safety Laboratory's shallow layer model for heavy gas dispersion. The shallow layer approach used by TWODEE is a compromise between the complexity of CFD models and the simpler integral models. Motivated by the low aspect ratio of typical heavy gas clouds, shallow layer models use depth-averaged variables to describe the flow behaviour. This approach is particularly well suited to assess the effect of complex terrain because the downslope buoyancy force is easily included. Entrainment may be incorporated into a shallow layer model by the use of empirical formulae. Part 2 of this paper presents the numerical scheme used to solve the TWODEE mathematical model, and validated against theoretical results. Part 3 compares the results of the TWODEE model with the experimental results taken at Thorney Island [J. McQuaid, B. Roebuck, The dispersion of heavier-than-air gas from a fenced enclosure. Final report to the US Coast Guard on contract with the Health and Safety Executive, Technical Report RPG 1185, Safety Engineering Laboratory, Research and Laboratory Services Division, Broad Lane, Sheffield S3 7HQ, UK, 1985].

Avoidance of lithium intoxication: advice based on knowledge about the renal lithium clearance under various circumstances

To avoid lithium intoxications, clinicians should counteract conditions under which lithium clearance changes. If that is not possible, the lithium dosage should be adjusted to the lithium clearance. Lithium clearance is usually 20-30 per cent of the glomerular filtration rate and varies with it, for example during pregnancy and kidney disease. Lithium clearance may also change independently of the glomerular filtration rate. It decreases for example during dehydration (water deficiency) and low sodium intake, pathological conditions with edema formation, treatment with diuretics, anti-hypertensive drugs, or non-steroid anti-inflammatory drugs. It increases during treatment with some vasodilating drugs. Precautionary measures against lithium intoxication are suggested for each of these situations.

The TWEAK: application in a prenatal setting

OBJECTIVE

The TWEAK is a screening instrument used to identify women who are risk drinkers. Potential limitations of previous studies of the TWEAK in the prenatal setting include indirect administration of the instrument to minority, indigent pregnant women. The purpose of this study is to assess the efficacy of the TWEAK when it is given directly to a sample of pregnant women of different socioeconomic backgrounds.

METHOD

The original TWEAK, with two different tolerance questions, was administered to a sample of 135 pregnant women enrolled in a study of alcohol use during pregnancy at the obstetrics practices of the Brigham and Women's Hospital in Boston, Massachusetts.

RESULTS

The TWEAK, using the first tolerance question (number of drinks before feeling the first effects of alcohol) with the cut point set at more than two drinks, had the best predictive ability for lifetime alcohol diagnoses and risk drinking. The sensitivity of the TWEAK can be increased if the cut point for the first tolerance question is set at two drinks, with some loss of specificity and predictive ability. Medical record assessment was the least sensitive but most specific method of identifying alcohol use by pregnant women.

CONCLUSIONS

The TWEAK has promise as a screening instrument for identifying risk drinking during pregnancy. Future work should include testing in other clinical populations.

Exposure of U.S. workers to environmental tobacco smoke

The concentrations of environmental tobacco smoke (ETS) to which workers are exposed have been measured, using nicotine or other tracers, in diverse workplaces. Policies restricting workplace smoking to a few designated areas have been shown to reduce concentrations of ETS, although the effectiveness of such policies varies among work sites. Policies that ban smoking in the workplace are the most effective and generally lower all nicotine concentrations to less than 1 microg/m3; by contrast, mean concentrations measured in workplaces that allow smoking generally range from 2 to 6 microg/m3 in offices, from 3 to 8 microg/m3 in restaurants, and from 1 to 6 microg/m3 in the workplaces of blue-collar workers. Mean nicotine concentrations from 1 to 3 microg/m3 have been measured in the homes of smokers. Furthermore, workplace concentrations are highly variable, and some concentrations are more than 10 times higher than the average home levels, which have been established to cause lung cancer, heart disease, and other adverse health effects. For the approximately 30% of workers exposed to ETS in the workplace but not in the home, workplace exposure is the principal source of ETS. Among those with home exposures, exposures at work may exceed those resulting from home. We conclude that a significant number of U.S. workers are exposed to hazardous levels of ETS.

To what extent are biomonitoring data available in chemical risk assessment?

1. Chemical risk assessment integrates the identification of hazards and the human exposure levels which can be established from external and/or internal exposure data. 2. The availability of biomonitoring and metabolism animal data, the skin penetration ability, and the existence of atmospheric threshold limit values were examined for twelve substances of the European first list of priority existing substances. This investigation was focused on workplace exposures and on urinary biomarkers of exposure. Appropriate biomonitoring data appeared to be available for two substances: styrene and trichloroethylene. Some biomonitoring research has been conducted on acrylonitrile, buta-1,3-diene, cyclohexane, 1,4-dichlorobenzene, hydrogen fluoride, 2-(2-methoxyethoxy)ethanol, however additional studies could be usefully carried out. No biomonitoring data are available for alkanes, C10-13, chloro; benzene, C10-13-alkyl derivatives; bis(pentabromophenyl)ether; diphenylether, octabromo-derivative. 3. It was concluded that in some cases, biomonitoring data are either lacking or scarce. This is rather surprising since the selection of the substances of the priority list was based on high tonnage, widespread use, extent of human exposure, and toxicological concern. The development of biomonitoring information could be helpful in assessing individual or population chemical exposure whatever the source and route, and would result in both more realistic and more accurate risk assessments.

Workshop summary: assessing exposure to environmental tobacco smoke in the workplace

Environmental tobacco smoke (ETS) is a term now widely used to refer to the mixture of sidestream smoke and exhaled mainstream smoke that pollutes air in locations where tobacco smoking is taking place. A multidisciplinary workshop was convened to address key issues related to ETS exposure in the workplace in order to prepare the groundwork for a risk assessment of the hazard ETS poses to workers. Workshop participants concluded that substantial evidence was now available on worker exposure to ETS using both direct and indirect approaches to exposure assessment and that these data could be used to project distribution of exposures to ETS in the nation's workplaces. This summary of the discussions at the workshop is an overview of the suggested approach to exposure assessment.

Atrial fibrillation after coronary artery bypass surgery: P wave signal averaged ECG, clinical and angiographic variables in risk assessment

BACKGROUND

Atrial fibrillation (AF) is a commonly encountered arrhythmia and occurs in up to 40% of patients after coronary artery bypass surgery (CABG). The preoperative signal averaged ECG (SAECG) P wave may be useful indicator of AF after CABG. We prospectively analyzed the predictive value of SAECG P wave compared to clinical variables.

METHODS

Fifty-three patients with coronary artery disease undergoing first elective CABG were enrolled. All patients had P wave specific SAECG, standard 12 lead ECG, ejection fraction and left atrial posteroanterior diameter from the echocardiogram within the 24 h before surgery. From the SAECG P wave, filtered P wave duration was measured. Lead II P wave duration, left atrial enlargement and left ventricular hypertrophy were determined from standard ECG. Patients were continuously monitored during their postoperative period and serial ECGs were taken.

RESULTS

During an observation period of up to 16 days, 19 (35.8%) patients developed AF 2.8+/-1.3 days after CABG. Patients with AF more often had left atrial enlargement (LAE) on ECG (P = 0.041) and right coronary artery (RCA) lesion (P = 0.0034). The filtered P wave duration on the SAECG was significantly longer in the AF patients than those without AF (129.7+/-13.2 ms versus 113.9+/-9.0 ms, P = 0.001). Logistic regression analysis identified independent predictors, estimated adjusted relative risk (95% confidence interval) of AF: with LAE, the relative risk was 2.72 (1.13-5.82), RCA lesion, the relative risk was 3.06 (1.45-6.45) and SAECG P wave duration >122.3 ms, the relative risk was 4.58 (2.11-9.97). The occurrence of AF was predicted by electrocardiographically determined left atrial enlargement with a sensitivity of 36%, specificity of 88%, positive predictive accuracy of 63%, negative predictive accuracy of 71%. If presence of right coronary artery lesion was evaluated these values were 63%, 79%, 63%, 79% subsequently. P wave duration >122.3 ms had a sensitivity of 68%, specificity of 88%, positive predictive accuracy of 76%, negative predictive accuracy of 83%. If both P wave >122.3 ms and presence of right coronary artery lesion were combined, these values were 47%, 94%, 81%, 76% subsequently.

CONCLUSION

The predictors of AF after CABG were left atrial enlargement on standard 12 lead ECG, RCA lesion and SAECG P wave duration. Among these predictors, SAECG P wave duration was the best predictor of AF after CABG.

Food safety issues associated with products from aquaculture. Report of a Joint FAO/NACA/WHO Study Group

The past decade has seen rapid expansion in aquaculture production. In the fisheries sector, as in animal production, farming is replacing hunting as the primary food production strategy. In future, farmed fish will be an even more important source of protein foods than they are today, and the safety for human consumption of products from aquaculture is of public health significance. This is the report of a Study Group that considered food safety issues associated with farmed finfish and crustaceans. The principal conclusion was that an integrated approach--involving close collaboration between the aquaculture, agriculture, food safety, health and education sectors--is needed to identify and control hazards associated with products from aquaculture. Food safety assurance should be included in fish farm management and form an integral part of the farm-to-table food safety continuum. Where appropriate, measures should be based on Hazard Analysis and Critical Control Point (HACCP) methods; however, difficulties in applying HACCP principles to small-scale farming systems were recognized. Food safety hazards associated with products from aquaculture differ according to region, habitat and environmental conditions, as well as methods of production and management. Lack of awareness of hazards can hinder risk assessment and the application of risk management strategies to aquaculture production, and education is therefore needed. Chemical and biological hazards that should to be taken into account in public health policies concerning products from aquaculture are discussed in this report, which should be of use to policy-makers and public health officials. The report will also assist fish farmers to identify hazards and develop appropriate hazard-control strategies.

[Retrospective estimation methods of pesticide occupational exposure]

The extensively growing use of pesticides in the last decades has led to great improvements in agriculture but also to threats for human health. Studying long term effects to assess individual exposures encounters difficulties in exposure assessment. This article summarizes retrospective methods for assessing occupational exposures to pesticides currently used in epidemiological studies. Questionnaires, environmental and biological monitoring constitute direct assessment of exposure, in an individual approach. But the validity of questionnaires is often poor and the metrology rarely reflects past exposures. Some indirect measures have been used together with job exposure matrices. To establish dose-response relationships is important to quantify the risk, but needs accurate exposure assessment based on quantitative indexes.

Fundamentals of health risk assessment. Use, derivation, validity and limitations of safety indices

We investigated the way results of human health risk assessments are used, and the theory used to describe those methods, sometimes called the "NAS paradigm." Contrary to a key tenet of that theory, current methods have strictly limited utility. The characterizations now considered standard, Safety Indices such as "Acceptable Daily Intake," "Reference Dose," and so on, usefully inform only decisions that require a choice between two policy alternatives (e.g., approve a food additive or not), decided solely on the basis of a finding of safety. Risk is characterized as the quotient of one of these Safety Indices divided by an estimate of exposure: a quotient greater than one implies that the situation may be considered safe. Such decisions are very widespread, both in the U.S. federal government and elsewhere. No current method is universal; different policies lead to different practices, for example, in California's "Proposition 65," where statutory provisions specify some practices. Further, an important kind of human health risk assessment is not recognized by this theory: this kind characterizes risk as likelihood of harm, given estimates of exposure consequent to various decision choices. Likelihood estimates are necessary whenever decision makers have many possible decision choices and must weigh more than two societal values, such as in EPA's implementation of "conventional air pollutants." These estimates can not be derived using current methods; different methods are needed. Our analysis suggests changes needed in both the theory and practice of human health risk assessment, and how what is done is depicted.

Ergonomic exposure assessment: an application of the PATH systematic observation method to retail workers. Postures, Activities, Tools and Handling

This study examined biomechanical stressor variables (physical work exposures) in relation to job title, gender, and back-belt status in 134 retail store workers. The principal concerns were to quantitatively describe physical work exposures and to determine the degrees to which these quantitative variables correlated with job title and with the use of back belts. An additional objective was to assess the inter-rater reliability of the observation method. The systematic observation method employed was based on a modification of the PATH (Postures, Activities, Tools, and Handling) measurement method. Chi-square analysis indicated that the frequencies of bent or twisted postures followed the pattern of unloaders > stockers > department managers. For weight handled per lift, lower, or carry, the pattern was unloaders > department managers > stockers. The mean lifting frequencies per hour were 35.9 for department managers, 48.8 for stockers, and 137.4 for unloaders. Back-belt-wearing percentages were higher for unloaders (63%) compared with stockers (48%) and department managers (25%). Back-belt-wearing workers had higher levels of biomechanical stressor variables, including arm position, twisting, weight handled, and number of lifts per hour. Kappa statistics ranged from 0.5 to 0.63, a level of adequate or good reliability beyond chance. The method employed in this study is applicable in studies that require only fairly crude distinctions among biomechanical stressor variables. Nevertheless, this level of distinction may be sufficient when implementing intervention studies and control strategies for many material-handling-intensive jobs.

The 35% CO2 inhalation procedure: test-retest reliability

The subjective response to a single-breath, 35% carbon dioxide challenge test shows promise as a tool for the study of panic disorder and may comprise a trait marker for that disorder. Little has been done to measure the reliability of test results, however. Subjects took a single breath at 35% CO2 and completed a self-rating of anxiety symptoms immediately thereafter. This procedure was repeated after a mean interval of 29 days. One group, considered at high risk for panic disorder, consisted of well, first-degree relatives of individuals treated for panic disorder. The control group included well subjects at high risk for affective disorder and subjects who had family histories negative for both affective disorder and panic disorder. On both testing occasions, subjects at high risk for panic disorder had symptom scores that were significantly higher than those of control subjects. Group differences in the portions who experienced a panic attack were dependent on the symptom threshold used to define an attack. A lower threshold was optimal with the second testing and a single, positive test result appeared to be more meaningful than a single negative result. The majority of individual symptom ratings were highly correlated across tests. Ratings for "smothering sensations," in particular, correlated highly across tests and consistently discriminated high-risk from control subjects. The sources of test result variability are unclear and warrant more investigation before the tests can be clinically useful. Research efforts should seek optimal thresholds to define positive test results within given data sets.

Estimation of mortality and morbidity risk in vascular surgery using POSSUM and the Portsmouth predictor equation

BACKGROUND

The Physiological and Operative Severity Score for enUmeration of Mortality and morbidity (POSSUM) is a simple scoring system previously validated in general surgical patients which enables estimation of the risk of complications and death after operation. The Portsmouth predictor equation (P-POSSUM) is a modification that may result in more accurate prediction of death than POSSUM. The aim of this study was to test the validity of POSSUM and P-POSSUM in patients undergoing major arterial surgery in a specialist unit.

METHODS

Physiological and operative severity scores in 221 patients undergoing elective and emergency arterial surgery in a pure vascular practice under a single consultant were recorded prospectively. Observed morbidity and mortality rates were compared with the rates predicted by POSSUM and P-POSSUM using a linear method of analysis.

RESULTS

The POSSUM equation overestimated deaths with this analysis but the mortality rate estimated by P-POSSUM was not significantly different from the observed death rate. The risk of morbidity predicted by POSSUM was not significantly different from the observed complication rate.

CONCLUSION

The POSSUM methodology combined with the P-POSSUM adjustment for death allows satisfactory prediction of mortality and morbidity rates in patients undergoing vascular surgery.

HIV risk behaviors, intentions, and perceptions among Namibian youth as assessed by a theory-based questionnaire

Considerable progress has been made in the United States and Europe regarding HIV risk prevention efforts targeting adolescents. However, in Africa less progress has been made to date. This article address three questions: Can risk assessment questionnaires developed in Western countries be modified so as to be appropriate for use in African countries? Are social cognitive models appropriate in African settings? Does covariation among risk behaviors occur among youth residing in African countries? The data was obtained from a cross-sectional survey conducted among 922 youth ages 12 to 18 years living in school-based hostels in Namibia. Data were collected using a theory-based risk assessment questionnaire. One third of the youth were sexually experienced, three quarters of whom had engaged in sexual intercourse in the previous 6 months. Over one third of these youth had had more that one sexual partner in the previous 6 months and over one half had not used a condom at last episode of intercourse. The psychometric properties of the questionnaire and the relationship between perceptions and behaviors provide evidence that theory-based questionnaires developed in Western countries can be modified for use in different cultural settings. The data also provide strong evidence of covariation between risk behaviors among Namibian youth.

Calculating correct Down's syndrome risks

Women having both first trimester nuchal translucency and second trimester serum screening tests are likely to receive two different Down's syndrome risks. Neither will be correct, and we describe how to calculate a valid combined risk. This uses the reported serum-based risk and a likelihood ratio derived from the nuchal translucency report. Tables, figures and examples are provided to aid the calculation of the likelihood ratio from either the nuchal translucency in multiples of the normal median, the nuchal translucency and crown-rump length in millimetres, or the reported prior and nuchal translucency-based risks.

Agreement between self- and clinician-rated suicidal symptoms in a clinical sample of young adults: explaining discrepancies

This study compared self- versus clinician-rated suicide assessment among participants referred for suicidal ideation or behavior, with emphasis on understanding self- versus clinician-rated discrepancies. A total of 328 participants in a suicide-treatment project completed baseline measures of symptoms and personality (including self-report and clinician-rated indexes of suicidal tendency), and portions of the sample completed follow-up assessments at 6, 12, and 18 months. A high rate of discrepancy between self- and clinician ratings of suicidal tendency was noted: the nature of this discrepancy was such that clinicians were likely to see patients as high in suicidal tendency, whereas patients were less likely to see themselves as such. Data on future symptoms indicated that patients' self-ratings contained considerable predictive value. Variables such as history of previous attempts and histrionic personality style may help explain self-versus clinician-rated discrepancies.

Assessing violence risk among discharged psychiatric patients: toward an ecological approach

This paper draws upon data from the Pittsburgh site of the MacArthur Foundation's Risk Assessment Study, a large-scale study of violence risk among persons discharged from psychiatric hospitals, to examine the effect of the neighborhood context on risk of violence. This paper has two purposes: (1) to assess the extent to which the inclusion of neighborhood characteristics enhances violence prediction models-models that traditionally only include individual-level characteristics; and (2) to assess the consistency of individual level risk factors across different neighborhood contexts. Results indicate that neighborhood poverty has an impact over and above the effects of individual characteristics in identifying cases with violence. These findings support efforts to include neighborhood context in the assessment and management of violence risk among discharged psychiatric patients.

Pharmacokinetic data needs to support risk assessments for inhaled and ingested manganese

Manganese (Mn)-deficiency or Mn-excess can lead to adverse biological consequences. Central nervous system tissues, rich in dopaminergic neurons, are the targets whether the Mn gains entrance by inhalation, oral ingestion, or intravenous administration. Risk assessments with Mn need to ensure that brain concentrations in the globus pallidus and striatum stay within the range of normal. This paper first provides a critical review of the biological factors that determine the disposition of Mn in tissues within the body. Secondly, it outlines specific data needs for developing a physiologically based pharmacokinetic (PBPK) model for Mn to assist in conducting risk assessments for inhaled and ingested Mn. Uptake of dietary Mn appears to be controlled by several dose-dependent processes: biliary excretion, intestinal absorption, and intestinal elimination. Mn absorbed in the divalent form from the gut via the portal blood is complexed with plasma proteins that are efficiently removed by the liver. Absorption of Mn via inhalation, intratracheal instillation or intravenous infusions bypasses the control processes in the gastrointestinal tract. After absorption into the blood system by these alternate routes, Mn is apparently oxidized by ceruloplasmin and the trivalent Mn binds to the iron carrying protein, transferrin. Brain uptake of Mn occurs via transferrin receptors located in various brain regions. Transferrin-bound trivalent Mn is not as readily removed by the liver, as are protein complexes with divalent Mn. Thus, Mn delivered by these other dose routes would be available for uptake into tissues for a longer period of time than the orally administered Mn, leading to quantitative differences in tissue uptake for different dose routes. Several important data gaps impede organizing these various physiological factors into a multi-dose route PK model for Mn. They include knowledge of (1) oxidation rates of Mn in blood, (2) uptake rates of protein-bound forms of Mn by the liver, (3) neuronal transfer rates within the CNS, and (4) quantitative analyses of the control processes that regulate uptake of ingested Mn by the intestines and liver. These data gaps are the main obstacles to developing a risk assessment strategy for Mn that considers contributions of both inhalation and ingestion of this essential nutrient in determining brain Mn concentrations.

Estimating noncancer uncertainty factors: are ratios NOAELs informative?

The prominent role of animal bioassay evidence in environmental regulatory decisions compels a careful characterization of extrapolation uncertainties. In noncancer risk assessment, uncertainty factors are incorporated to account for each of several extrapolations required to convert a bioassay outcome into a putative subthreshold dose for humans. Measures of relative toxicity taken between different dosing regimens, different endpoints, or different species serve as a reference for establishing the uncertainty factors. Ratios of no observed adverse effect levels (NOAELs) have been used for this purpose; statistical summaries of such ratios across sets of chemicals are widely used to guide the setting of uncertainty factors. Given the poor statistical properties of NOAELs, the informativeness of these summary statistics is open to question. To evaluate this, we develop an approach to "calibrate" the ability of NOAEL ratios to reveal true properties of a specified distribution for relative toxicity. A priority of this analysis is to account for dependencies of NOAEL ratios on experimental design and other exogenous factors. Our analysis of NOAEL ratio summary statistics finds (1) that such dependencies are complex and produce pronounced systematic errors and (2) that sampling error associated with typical sample sizes (50 chemicals) is nonnegligible. These uncertainties strongly suggest that NOAEL ratio summary statistics cannot be taken at face value; conclusions based on such ratios reported in well over a dozen published papers should be reconsidered.

The Behavioural Status Index: therapeutic assessment of risk, insight, communication and social skills

An overview is given of the Behavioural Status Index (BSI), a developing classification instrument offering practical approaches to assessment and therapy surrounding social 'risk'. The approach hypothesizes that social 'risk' presented by a patient tends to correlate inversely with his/her degree of personal insight and capacity to perform well in key communicative and social skills, though no causal claims are made. Evidence exists to suggest that personal insight and communicative and social skills deserve serious consideration in a therapeutic approach to violent and dangerous behaviours. 'Risky' behaviours, as operationalized in the 'risk' subscale of the BSI, insight into the self and its activities, and communicative and social skills, may provide three critical foci for treatment planning in high security psychiatric care. A hypothetical linked factorial structure is proposed.