Reference Interval Harmonization: Harnessing the Power of Big Data Analytics to Derive Common Reference Intervals across Populations and Testing Platforms

BACKGROUND

Harmonization in laboratory medicine is essential for consistent and accurate clinical decision-making. There is significant and unwarranted variation in reference intervals (RIs) used by laboratories for assays with established analytical traceability. The Canadian Society of Clinical Chemists (CSCC) Working Group on Reference Interval Harmonization (hRI-WG) aims to establish harmonized RIs (hRIs) for laboratory tests and support implementation.

METHODS

Harnessing the power of big data, laboratory results were collected across populations and testing platforms to derive common adult RIs for 16 biochemical markers. A novel comprehensive approach was established, including: (a) analysis of big data from community laboratories across Canada; (b) statistical evaluation of age, sex, and analytical differences; (c) derivation of hRIs using the refineR method; and (d) verification of proposed hRIs across 9 laboratories with different instrumentation using serum and plasma samples collected from healthy Canadian adults.

RESULTS

Harmonized RIs were calculated for all assays using the refineR method, except free thyroxine. Derived hRIs met proposed verification criterion across 9 laboratories and 5 manufacturers for alkaline phosphatase, albumin (bromocresol green), chloride, lactate dehydrogenase, magnesium, phosphate, potassium (serum), and total protein (serum). Further investigation is needed for some analytes due to failure to meet verification criteria in one or more laboratories (albumin [bromocresol purple], calcium, total carbon dioxide, total bilirubin, and sodium) or concern regarding excessively wide hRIs (alanine aminotransferase, creatinine, and thyroid stimulating hormone).

CONCLUSIONS

We report a novel data-driven approach for RI harmonization. Findings support feasibility of RI harmonization for several analytes; however, some presented challenges, highlighting limitations that need to be considered in harmonization and big data analytics.

Establishing quality indicators for point of care glucose testing: recommendations from the Canadian Society for Clinical Chemists Point of Care Testing and Quality Indicators Special Interest Groups

OBJECTIVES

Monitoring quality indicators (QIs) is an important part of laboratory quality assurance (QA). Here, the Canadian Society of Clinical Chemists (CSCC) Point of Care Testing (POCT) and QI Special Interest Groups describe a process for establishing and monitoring QIs for POCT glucose testing.

METHODS

Key, error prone steps in the POCT glucose testing process were collaboratively mapped out, followed by risk assessment for each step. Steps with the highest risk and ability to detect a non-conformance were chosen for follow-up. These were positive patient identification (PPID) and repeat of critically high glucose measurements. Participating sites were asked to submit aggregate data for these indicators from their site(s) for a one-month period. The PPID QI was also included as part of a national QI monitoring program for which fifty-seven sites submitted data.

RESULTS

The percentage of POCT glucose tests performed without valid PPID ranged from 0-87%. Sites without Admission-Discharge-Transfer (ADT) connectivity to POCT meters were among those with the highest percentage of POCT glucose tests performed without valid PPID. The percentage repeated critically high glucose measurements ranged from 0-50%, indicating low compliance with this recommendation. A high rate of discordance was also noted when critically high POCT glucose measurements were repeated, demonstrating the importance of repeat testing prior to insulin administration.

CONCLUSIONS

Here, a process for establishing these QIs is described, with preliminary data for two QIs chosen from this process. The findings demonstrate the importance of QIs for identification and comparative performance monitoring of non-conformances to improve POCT quality.

Canadian Society of Clinical Chemists Harmonized Clinical Laboratory Lipid Reporting Recommendations on the Basis of the 2021 Canadian Cardiovascular Society Lipid Guidelines

There is limited guidance on laboratory reporting and interpretation of lipids and lipoproteins used in cardiovascular risk stratification. This contributes to inconsistencies in lipid reporting across clinical laboratories. Recently, the Canadian Cardiovascular Society (CCS) published the 2021 CCS guidelines for the management of dyslipidemia for the prevention of cardiovascular disease in the adult. A subcommittee of the Working Group on Reference Interval Harmonization of the Canadian Society of Clinical Chemists has developed harmonized lipid reporting recommendations that are aligned with the 2021 CCS guidelines, to improve the standardization of lipid assessment and clinical decision-making. The proposed harmonized lipid reporting recommendations were critically reviewed by a broad range of laboratory and clinical experts across Canada. Feedback from approximately 30 expert reviewers was reviewed by the Working Group on Reference Interval Harmonization lipid subcommittee, and consensus decisions were incorporated into the 2021 harmonized lipid reporting recommendations. In this position statement, we provide 6 recommendations for laboratory reporting of lipid parameters. These recommendations include implementing the new National Institutes of Health equation to replace the Friedewald equation for calculating low-density lipoprotein cholesterol, offering lipoprotein (a), either as an in-house or send-out test, and using assays that report lipoprotein (a) in molar units (nmol/L). We also developed a harmonized lipid reporting format with interpretive comments that includes flagging results based on screening patients using treatment decision thresholds in a primary prevention setting. Overall, harmonized lipid reporting will help bridge the gap between clinical guideline recommendations and clinical laboratory reporting and interpretation, and will improve cardiovascular risk assessment across Canada.

A Snapshot of Lipid-Reporting Practices in Canadian Clinical Laboratories: An Urgent Need for Harmonisation

To effectively implement the Canadian Cardiovascular Society (CCS) guidelines for dyslipidemia management into clinical laboratories, clear recommendations for lipid reporting are essential. In this study, the Canadian Society of Clinical Chemists Working Group on Reference Interval Harmonisation surveyed Canadian laboratories on adult lipid reporting practices to set a foundation for the development and implementation of harmonised lipid reporting across Canada. Key aspects of the survey asked laboratories: what reporting parameters were in place to assess lipid results; what interpretative comments were provided; whether nonfasting lipids were permitted and, if so, what strategy was used to document fasting status; and whether there was interest in implementing a harmonised lipid report. A total of 101 laboratories were represented by 24 respondents, as many responses were submitted by laboratory networks that included more than 1 laboratory. There was at least 1 response from 9 Canadian provinces and representation across 5 testing platforms. Upper and lower limits for lipid parameters and referenced source of limits varied substantially across laboratories, with only 56% of laboratories (9 respondents) referencing the 2016 CCS guidelines. Eighty-six percent of laboratories (19 respondents) report nonfasting lipids, although the method of documenting nonfasting status varied. Overall, 36% of laboratories (8 respondents) reported interest in implementing a harmonised lipid report. Assessment of current lipid-reporting practices supports the need for harmonised lipid reporting across Canada. Development of a harmonised lipid report for the adult population, consistent with up-to-date Canadian guidelines, will improve continuity of lipid test interpretation across Canada and improve clinical decision making.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Fine sediment and particulate organic matter: A review and case study on ridge-to-reef transport, transformations, fates, and impacts on marine ecosystems

Studies documenting the effects of land-derived suspended particulate matter (SPM, i.e., particulate organic matter and mineral sediment) on marine ecosystems are typically disconnected from terrestrial studies that determine their origin, transport and fate. This study reviews sources, transport, transformations, fate and effects of SPM along the 'ridge-to-reef' continuum. We show that some of the SPM can be transported over long distances and transformed into large and easily resuspendible organic-rich sediment flocs. These flocs may lead to prolonged reductions in water clarity, impacting upon coral reef, seagrass and fish communities. Using the Great Barrier Reef (NE Australia) as a case study, we identify the latest research tools to determine thresholds of SPM exposure, allowing for an improved appreciation of marine risk. These tools are used to determine ecologically-relevant end-of-basin load targets and reliable marine water quality guidelines, thereby enabling enhanced prioritisation and management of SPM export from ridge-to-reef.

Early life traits of farm and wild Atlantic salmon Salmo salar and first generation hybrids in the south coast of Newfoundland

This study examined fertilization rates, survival and early life-trait differences of pure farm, wild and first generation (F1) hybrid origin embryos after crossing farm and wild Atlantic salmon Salmo salar. Results show that despite a trend towards higher in vitro fertilization success for wild females, differences in fertilization success in river water are not significantly different among crosses. In a hatchery environment, wild females' progeny (pure wild and hybrids with wild maternal parent) hatched 7-11 days earlier than pure farm crosses and hybrids with farm maternal parents. In addition, pure wild progeny had higher total lengths (L_T ) at hatch than pure farm crosses and hybrids. Directions in trait differences need to be tested in a river environment, but results clearly show the maternal influence on early stages beyond egg-size differences. Differences in L_T were no longer significant at 70 days post hatch (shortly after the onset of exogenous feeding) showing the need to investigate later developmental stages to better assess somatic growth disparities due to genetic differences. Higher mortality rates of the most likely hybrids (farm female × wild male hybrids) at egg and fry stages and their delayed hatch suggest that these F1 hybrids might be less likely to survive the early larval stages than wild stocks.

Mevalonate Biosynthesis Intermediates Are Key Regulators of Innate Immunity in Bovine Endometritis

Metabolic changes can influence inflammatory responses to bacteria. To examine whether localized manipulation of the mevalonate pathway impacts innate immunity, we exploited a unique mucosal disease model, endometritis, where inflammation is a consequence of innate immunity. IL responses to pathogenic bacteria and LPS were modulated in bovine endometrial cell and organ cultures by small molecules that target the mevalonate pathway. Treatment with multiple statins, bisphosphonates, squalene synthase inhibitors, and small interfering RNA showed that inhibition of farnesyl-diphosphate farnesyl transferase (squalene synthase), but not 3-hydroxy-3-methylglutaryl-CoA reductase or farnesyl diphosphate synthase, reduced endometrial organ and cellular inflammatory responses to pathogenic bacteria and LPS. Although manipulation of the mevalonate pathway reduced cellular cholesterol, impacts on inflammation were independent of cholesterol concentration as cholesterol depletion using cyclodextrins did not alter inflammatory responses. Treatment with the isoprenoid mevalonate pathway-intermediates, farnesyl diphosphate and geranylgeranyl diphosphate, also reduced endometrial cellular inflammatory responses to LPS. These data imply that manipulating the mevalonate pathway regulates innate immunity within the endometrium, and that isoprenoids are regulatory molecules in this process, knowledge that could be exploited for novel therapeutic strategies.

Thunderstorm asthma: an overview of the evidence base and implications for public health advice

Thunderstorm asthma is a term used to describe an observed increase in acute bronchospasm cases following the occurrence of thunderstorms in the local vicinity. The roles of accompanying meteorological features and aeroallergens, such as pollen grains and fungal spores, have been studied in an effort to explain why thunderstorm asthma does not accompany all thunderstorms. Despite published evidence being limited and highly variable in quality due to thunderstorm asthma being a rare event, this article reviews this evidence in relation to the role of aeroallergens, meteorological features and the impact of thunderstorm asthma on health services. This review has found that several thunderstorm asthma events have had significant impacts on individuals' health and health services with a range of different aeroallergens identified. This review also makes recommendations for future public health advice relating to thunderstorm asthma on the basis of this identified evidence.

Change in the ileal bacterial population of turkeys fed different diets and after infection with Salmonella as determined with denaturing gradient gel electrophoresis of amplified 16s ribosomal DNA

Changes in ileal bacterial populations of Salmonella-infected turkeys fed different diets were analyzed by using 16S-V3 PCR denaturing gradient gel electrophoresis. Turkeys raised on litter flooring were fed wheat- and corn-based diets with and without enzyme preparations (XY1 and XY2, respectively) from 0 to 126 d. Preparation XY1 contained exclusively endoxylanase, whereas preparation XY2 contained endoxylanase, protease, and alpha-amylase (Danisco, , Wiltshire, UK). The dietary activity levels of XY1 and XY2 were 2,500 and 650 endo-1,4-beta-xylanase units/kg of feed, respectively. Microbial DNA was extracted from the ileal content of 16-wk-old turkeys, and the 16S rDNA gene was amplified by PCR and analyzed by denaturing gradient gel electrophoresis. Diversity indexes, including richness (number of species, S), evenness (relative distribution of species, EH), diversity (using Shannon's index, H'), and Sorenson's pairwise similarities coefficient (measures the species in common between different habitats, Cs) were calculated. Additionally, diversity indexes were associated with Salmonella prevalence determined from fresh fecal droppings collected from each pen. On the basis of contrast analysis, the wheat-based diets resulted in higher microbial diversity indexes than the corn-based diets (S = 10 vs. 12; EH = 0.9 vs. 0.8; H' = 2.2 vs. 1.9, P < 0.05). Likewise, enzyme supplementation stimulated growth of the microbiota and increased the diversity indexes in comparison with unsupplemented treatments (S = 13 vs. 10; EH = 0.9 vs. 0.8; H' = 2.2 vs. 1.9, P < 0.05). Salmonella prevalence was higher (P < 0.05) at 15 wk in turkeys fed the corn-based diet (Salmonella prevalence = 50%) than in turkeys fed the corn-enzyme (Salmonella prevalence = 13%) and wheat-based (Salmonella prevalence = 0%) dietary treatments. Therefore, contrast analysis showed that birds fed the corn control diet had lower microbiota diversity but higher Salmonella prevalence than birds fed the enzyme-supplemented and wheat-based diets. In contrast, birds fed the wheat-based diets had higher diversity but lower Salmonella prevalence than birds fed the corn-based diets. High dietary nonstarch polysaccharides from wheat and dietary exogenous enzyme supplementation promoted microbial community diversity and apparently discouraged Salmonella colonization through competitive exclusion. Nonstarch polysaccharides and dietary exogenous enzyme supplementation may be practical tools to control enteric pathogens and benefit the intestinal health and food safety of the birds.

Insulin infusion via an intraosseous needle in diabetic ketoacidosis

We report the successful management of a five-year-old child with severe diabetic ketoacidosis with dehydration, who received his initial resuscitative fluids and a continuous infusion of insulin via an intraosseous needle. The patient had presented to a remote community hospital and intravenous access could not be gained. The correction of hyperglycaemia and metabolic acidaemia was achieved at a rate comparable to intravenous therapy. No complications were observed. Although intraosseous access is well described in paediatric resuscitation guidelines, it is not mentioned in International Diabetes Society guidelines for the management of diabetic ketoacidosis. Alternatives to intravenous administration of insulin delivery recommended in such guidelines, such as the subcutaneous or intramuscular routes, may be less appropriate than the intraosseous route. This route can also allow resuscitation fluids and other drugs to be reliably administered in children with diabetic ketoacidosis and severe dehydration where intravenous access can not be attained. We suggest that the potential role of intraosseous access, when intravenous access can not be obtained, should be considered when management guidelines for paediatric diabetic ketoacidosis with dehydration are reviewed.

Fast and Slow Skeletal Troponin I in Serum from Patients with Various Skeletal Muscle Disorders: A Pilot Study

Background: Detection of skeletal muscle injury is hampered by a lack of commercially available assays for serum markers specific for skeletal muscle; serum concentrations of skeletal troponin I (sTnI) could meet this need. Moreover, because sTnI exists in 2 isoforms, slow (ssTnI) and fast (fsTnI), corresponding to slow- and fast-twitch muscles, respectively, it could provide insight into differential injury/recovery of specific fiber types. The purpose of this study was to investigate whether the 2 isoforms of sTnI and their modified forms are present in the blood of patients with various skeletal muscle disorders.

Methods: Serial serum samples were obtained from 25 patients with various skeletal muscle injuries. Serum proteins were separated by a modified sodium dodecyl sulfate–polyacrylamide gel electrophoresis protocol followed by Western blotting for sTnI with monoclonal antibodies specific to ssTnI and fsTnI.

Results: We observed (a) intact and, in some cases, degraded sTnI products; (b) evidence of posttranslational modifications in addition to proteolysis; and (c) differential detectability of both skeletal isoforms in the same patient.

Conclusions: It is possible to monitor both sTnI isoforms; this could lead to the development of new diagnostic assays for skeletal muscle damage.

Age-adjustment in experimental animal data and its application to lung cancer in radon-exposed rats

Procedures for age-adjustment of cancer fractions are proposed which do not require fixed age intervals. The full available information on survival times can then be used, which is especially important in small treatment groups. For incidental cancers a non-decreasing prevalence function and for fatal cancers the Kaplan-Meier estimator is used. In the latter case, the estimated competing risk of the control population is standardized, not its true survival. This makes the technique also applicable to treatment groups with high incidence, which otherwise may give adjusted rates above 100%. In the application part these age-adjustment techniques are used here to study lung cancer in radon-exposed Wistar and Sprague-Dawley rats. The data include a classification in fatal and incidental lung cancers. For fatal lung cancer, the lifetime excess absolute risk (LEAR) at 1 WLM averaged over all exposed groups is 0.67x10(-4) for the Wistar rats, while for the Sprague-Dawley rats it is 0.40x10(-4). For the Sprague-Dawley rats, there are several groups exposed later in life. When the averaging is restricted to animals with start of exposure prior to 150 days of age, the weighted average risk among the Sprague-Dawley rats is 0.79x10(-4). Compared to groups with similar exposures as young adults (up to about 150 days), animals exposed later in life have substantially lower lifetime risks. The Wistar rats include groups with roughly equal exposure rates and ages at start of exposure, but with increasing exposure duration. Within these groupings the LEAR at 1 WLM does not decrease with additional exposure at higher age, as would be expected if the risk from exposures at different ages would be additive.

Screening for acute myocardial injury: creatine kinase is comparable to myoglobin

During the last decade, there have been many studies comparing myoglobin and the troponins to creatine kinase MB. Myoglobin was introduced as an early marker, but most studies have not directly compared it to total creatine kinase in any detail. We retrospectively (9/98-5/99) examined 1772 paired samples from 1572 patients drawn in the emergency department to assess the optimum decision limits, sensitivity, specificity, positive predictive values (PPV), and negative predicitve value (NPV) for creatine kinase and myoglobin in predicting acute myocardial injury. Of the admitted patients, 114 had acute myocardial injury, 166 had angina and 89 had non-cardiac chest pain; 1203 patients were discharged. Initially low creatine kinase (<100 IU/l; minimum 19 IU/l) and myoglobin (<100 microg/l; minimum 9.5 microg/l) results were identified in 63.5% and 88.3% of patients, respectively, emphasizing the importance of serial sampling. Receiver operator characteristic analysis demonstrated optimum decision limits at 100 IU/l and 70 microg/l, respectively. These levels were associated with sensitivity/specificity/PPV/NPV of 66/66/13/96 for creatine kinase and 54/85/22/96 for myoglobin. We conclude that both tests are comparable for initial screening of patients with chest pain in the emergency department. Since creatine kinase is faster, cheaper, and more widely available, it is the test of choice for our institution.

Extensive troponin I and T modification detected in serum from patients with acute myocardial infarction

BACKGROUND

Cardiac troponin I and T (cTnI and cTnT) are specific biochemical serum markers for acute myocardial infarction (AMI). However, cTnI diagnostic assays are plagued by difficulties, resulting in >/=20-fold differences in measured values. These discrepancies may result from the release of the numerous cTnI modification products that are present in ischemic myocardium. The resolution of these discrepancies requires an investigation of the exact forms of cTnI present in the bloodstream of patients after myocardial injury.

METHODS AND RESULTS

A western blot-direct serum analysis protocol was developed that allowed us to detect intact cTnI and a spectrum of up to 11 modified products in the serum from patients with AMI. For the first time, we document both a cTnI degradation pattern and the existence of phosphorylated cTnI in serum. The number and extent of these modifications reflect patterns similar to the time profiles of the routine clinical serum markers of total creatine kinase, creatine kinase-MB, and cTnI (determined by ELISA). Data from in vitro experiments, which were undertaken to study the degradation of human recombinant cTnI and cTnT when spiked in serum, indicate that some modification products present in patient serum existed in the myocardium and that recombinant cTnI alteration dramatically reduces the detectability of cTnI by the Immuno1 assay over time (our assay was unaffected).

CONCLUSIONS

This pilot study defines, for the first time, what forms of cTnI and cTnT appear in the bloodstream of AMI patients, and it clarifies the lack of standardization between different cTnI diagnostic assays.

Chest pain with nondiagnostic electrocardiogram in the emergency department: a randomized controlled trial of two cardiac marker regimens

BACKGROUND

Early detection of acute myocardial infarction (AMI) may save lives. In the emergency setting, it is unclear whether the early use of certain cardiac markers (myoglobin and cardiac troponin I [cTnI]) assists in making appropriate decisions whether to admit or discharge patients with chest pain of possible ischemic cause who have nondiagnostic electrocardiograms (ECGs). We performed a study to determine whether the addition of new cardiac markers in the emergency department results in improved clinical decisions.

METHODS

A single-blind randomized controlled trial was conducted between June 1997 and June 1998 in a tertiary care emergency department in Kingston, Ont. Of 296 patients aged 30 years or more who presented to the emergency department with chest pain and nondiagnostic ECGs, 146 were randomly assigned to the intervention group (determination of baseline creatine kinase [CK] level, CK MB fraction and cTnI level, and myoglobin level at baseline and at 2 hours) and 150 to the control group (determination of baseline CK level and CK MB fraction). Outcome measures included the rate of admission to the inpatient cardiology service and length of stay in the emergency department.

RESULTS

Of the 296 patients, 34 (11.5%) received a diagnosis of AMI in the emergency department, and 92 (31.1%) had chest pain of noncardiac cause. Patients in the intervention group were less likely than those in the control group to be admitted to the cardiology service (67 [45.9%] v. 81 [54.0%]). The absolute difference in the proportion (8.1% [95% confidence interval -3.3 to 19.5]), although potentially important clinically, was not statistically significant. The length of stay in the emergency department was essentially the same in the 2 study groups. At 30 days, the proportions of patients with a diagnosis of recurrent angina (58.2% in the intervention group and 58.0% in the control group) and AMI (12.3% and 14.7%) were also similar.

INTERPRETATION

The optimal cardiac marker panel to be used in the emergency department remains unknown. The addition of serial testing of myoglobin with cTnI confirmation to the standard panel did not substantially change the clinical management or outcomes of patients presenting with chest pain and nondiagnostic ECGs.

Epidural catheter breakage: a possible mechanism

The breakage of an epidural catheter within a patient is an uncommon but troublesome complication of continuous epidural block, and its cause is rarely discovered. Several possible mechanisms for catheter breakage have been proposed, but few can be reproduced experimentally. Review of two recent medicolegal cases concerning catheters that were severed at the time of insertion led to laboratory studies in an attempt to find an explanation. The results of this work demonstrated that it was possible to break or severely damage an epidural catheter by heavy contact between the tip of the epidural needle and a bony surface, if a length of the catheter was protruding from the tip.

Linking community-based blood pressure measurement to clinical care: a randomized controlled trial of outreach and tracking by community health workers

OBJECTIVES

This study assessed the effectiveness of enhanced tracking and follow-up services provided by community health workers in promoting medical follow-up of persons whose elevated blood pressures were detected during blood pressure measurement at urban community sites.

METHODS

In a randomized controlled trial, 421 participants received either enhanced or usual referrals to care. Participants were 18 years or older, were either Black or White, and had blood pressure greater than or equal to 140/90 mm Hg and income equal to or less than 200% of poverty. The primary outcome measure was completion of a medical follow-up visit within 90 days of referral.

RESULTS

The enhanced intervention increased follow-up by 39.4% (95% confidence interval [CI] = 14%, 71%; P = .001) relative to usual care. Follow-up visits were completed by 65.1% of participants in the intervention group, compared with 46.7% of those in the usual-care group. The number needed to treat was 5 clients (95% CI = 3, 13) per additional follow-up visit realized.

CONCLUSIONS

Enhanced tracking and outreach increased the proportion of persons with elevated blood pressure detected during community measurement who followed up with medical care.

Acute asthma epidemics, weather and pollen in England, 1987-1994

Recent epidemics of acute asthma have caused speculation that, if their causes were known, early warnings might be feasible. In particular, some epidemics seemed to be associated with thunderstorms. We wondered what risk factors predicting epidemics could be identified. Daily asthma admissions counts during 1987-1994, for two age groups (0-14 yrs and > or = 15 yrs), were measured using the Hospital Episodes System (HES). Epidemics were defined as combinations of date, age group and English Regional Health Authority (RHA) with exceptionally high asthma admission counts compared to the predictions of a log-linear autoregression model. They were compared with control days 1 week before and afterwards, regarding seven meteorological variables and 5 day average pollen counts for four species. Fifty six asthma epidemics were identified. The mean density of sferics (lightning flashes), temperature and rainfall on epidemic days were greater than those on control days. High sferics densities were overrepresented in epidemics. Simultaneously high sferics and grass pollen further increased the probability of an epidemic, but only to 15% (95% confidence interval 2-45%). Two thirds of epidemics were not preceded by thunderstorms. Thunderstorms and high grass pollen levels precede asthma epidemics more often than expected by chance. However, most epidemics are not associated with thunderstorms or unusual weather conditions, and most thunderstorms, even following high grass pollen levels, do not precede epidemics. An early warning system based on the indicators examined here would, therefore, detect few epidemics and generate an unacceptably high rate of false alarms.

Acute asthma epidemics, weather and pollen in England, 1987-1994

Recent epidemics of acute asthma have caused speculation that, if their causes were known, early warnings might be feasible. In particular, some epidemics seemed to be associated with thunderstorms. We wondered what risk factors predicting epidemics could be identified. Daily asthma admissions counts during 1987-1994, for two age groups (0-14 yrs and > or = 15 yrs), were measured using the Hospital Episodes System (HES). Epidemics were defined as combinations of date, age group and English Regional Health Authority (RHA) with exceptionally high asthma admission counts compared to the predictions of a log-linear autoregression model. They were compared with control days 1 week before and afterwards, regarding seven meteorological variables and 5 day average pollen counts for four species. Fifty six asthma epidemics were identified. The mean density of sferics (lightning flashes), temperature and rainfall on epidemic days were greater than those on control days. High sferics densities were overrepresented in epidemics. Simultaneously high sferics and grass pollen further increased the probability of an epidemic, but only to 15% (95% confidence interval 2-45%). Two thirds of epidemics were not preceded by thunderstorms. Thunderstorms and high grass pollen levels precede asthma epidemics more often than expected by chance. However, most epidemics are not associated with thunderstorms or unusual weather conditions, and most thunderstorms, even following high grass pollen levels, do not precede epidemics. An early warning system based on the indicators examined here would, therefore, detect few epidemics and generate an unacceptably high rate of false alarms.

Application of AN69 hydrogel to islet encapsulation. Evaluation in streptozotocin-induced diabetic rat model

The polymer AN69 (polyacrylonitrile-sodium methallylsulfonate) is a reference in biocompatibility in the field of hemodialysis. Its use for the encapsulation of living cells has been already described, but this study is the first description of AN69 hydrogel-encapsulated islet isograft in streptozotocin (STZ) diabetic rats. The aim of this work is to evaluate the biocompatibility of the AN69 hydrogel by comparison of the efficacy of free versus encapsulated islets transplanted to balance diabetes. Pancreatic islets are isolated from adult male Lewis rats by a standard collagenase digestion and purified on Ficoll density gradients. The AN69 hollow fiber is obtained by coextrusion of an 8% AN69 collodion. The hollow fiber is filled with islets suspended in agarose at the final concentration of 10,000 islets/ml, closed with surgical clips and implanted. The recipients are rendered diabetic by intravenous injection of STZ. The experimental design includes 4 groups of 8 rats: group 1: control, group 2: diabetic rats intraperitoneally implanted with 6000 free islets, group 3: diabetic rats intraperitoneally implanted with 9000 encapsulated islets, group 4: diabetic control. Weight and fasting glycemia are evaluated twice a week, diuresis once a week. After free islet implantation, rat survival is improved with glycemia below 250 mg/dl during 22 days. Compared to group 2, the status of group 3 is better, with a glycemia below 250 mg/dl during at least 70 days. This tends to demonstrate the biocompatibility of AN69 and is the first step of the validation of the use of AN69 for living cell encapsulation.

Transdermal fentanyl as treatment for chronic low back pain

Management of chronic low back pain often includes oral opioid use. The effectiveness of therapy is dependent upon compliance, which in turn is dependent upon response, side effects, access, and convenience. Our hypothesis was that a transdermal fentanyl system would provide more effective pain management than oral opioids. Fifty patients with chronic low back pain were examined. After litration to levels corresponding to current oral opioid use, each patient was maintained on transdermal fentanyl for one month. Oral opioid therapy was then resumed. Their experience was assessed with the a visual analogue scale for pain intensity, a numerical pain score, the Oswestry disability questionnaire, the pain disability index, and the Verran Snyder-Halpern sleep scale. Significant improvement in pain relief and disability was found with transdermal fentanyl compared with oral opioids. Mild opioid side effects were common, but easily controlled. Use of transdermal fentanyl is an effective alternative to oral opioids for managing chronic low back pain.

Effect of thunderstorms and airborne grass pollen on the incidence of acute asthma in England, 1990-94

BACKGROUND

Thunderstorms and prior grass pollen counts were investigated as predictors of daily hospital admissions for asthma in England. This study was motivated by reports in the literature of spectacular asthma epidemics associated with thunderstorms, particularly in the grass pollen season.

METHODS

Asthma admissions for two age groups (0-14 years and 15 and over) were measured using the Hospital Episodes System (HES) in the 14 regional health authorities (RHAs) in England. Thunderstorms were measured daily in each RHA using densities of sferics (lightning flashes). Relative asthma excesses for moderate positive and exceptionally high sferic densities, with or without previous high grass pollen counts, were measured using log linear autoregression--allowing for weekly, seasonal, and longer term background variation--and pooled over RHAs by calculating geometric means.

RESULTS

Relative risks from all RHAs were pooled to form geometric means. Exceptional sferic densities were associated with a relative excess risk of around 25% in both age groups. Moderate sferic densities were associated with a smaller excess, statistically significant in the two age groups taken together. In five RHAs in which grass pollen counts were available, high pollen counts for the previous five days were associated with an amplification of the excess associated with thunderstorms.

CONCLUSION

Very large sferic densities are associated with moderate rises in hospital admissions for acute asthma. However, typical thunderstorm days are not associated with spectacular asthma epidemics of the scale previously reported in the literature. Thunderstorm-associated excesses are amplified after a run of high pollen counts.

Factors associated with client-reported HIV infection among clients entering methadone treatment

To determine demographic and behavioral factors associated with client-reported HIV infection among new enrollees in methadone maintenance treatment programs (MMTPs) in Massachusetts and Connecticut, we examined ethnographic data and interview data from MMTP clients (N = 674). Clients responded to questions about behaviors in the 30 days before drug treatment. ETHNOGRAPH was used to analyze qualitative data, and logistic regression analysis was used to identify variables associated with client-reported HIV infection. Statistical significance was set at p < .05. The client-reported HIV infection rate was 20% (132/674). Odds ratios for factors associated with client-reported HIV infection were being white (0.53), increase in age (1.07), use of non-injected heroin (0.12), use of injected heroin (6.24), cocaine injection (1.78), sharing of "works" with strangers (2.15), and "safer sex" behavior (4.04). Additionally, 35% of those who did not use illicit drugs reported being seropositive. The qualitative data suggested HIV positive clients were concerned about protecting sex partners, and learning of HIV infection motivated some to stop using drugs. Although some clients engaged in low-risk behaviors, others did not, therefore the potential for HIV transmission among injection drug users (IDUs) in Connecticut and Massachusetts exists. HIV prevention and drug treatment program personnel should reinforce and build on the low-risk behaviors that are acceptable and adopted by some in this population.

A community waterborne outbreak of salmonellosis and the effectiveness of a boil water order

OBJECTIVES

A 1993 large water-borne outbreak of Salmonella typhimurium infections in Gideon, Mo, a city of 1100 with an unchlorinated community water supply, was investigated to determine the source of contamination and the effectiveness of an order to boil water.

METHODS

A survey of household members in Gideon and the surrounding township produced information on diarrheal illness, water consumption, and compliance with the boil water order.

RESULTS

More than 650 persons were ill; 15 were hospitalized, and 7 died. Persons consuming city water were more likely to be ill (relative risk [RR] = 9.1, 95% confidence interval [CI] = 2.9, 28.4), and the attack rate increased with increased water consumption. S. typhimurium was recovered from samples taken from a city fire hydrant and a water storage tower. Persons in 31% (30/ 98) of city households had drunk unboiled water after being informed about the boil water order, including 14 individuals who subsequently became ill. Reasons for noncompliance included "not remembering" (44%) and "disbelieving" (25%) the order.

CONCLUSIONS

Communities with deteriorating water systems risk widespread illness unless water supplies are properly operated and maintained. Effective education to improve compliance during boil water orders is needed.

An in vitro investigation of the efficacy of CPC for use in toothbrush decontamination

PURPOSE

A product designed as a toothbrush disinfectant containing cetylpyridinium chloride (CPC), a quaternary ammonium compound, recently was introduced. The purpose of this study was to provide additional evidence that CPC provides a practical solution for destroying residual microorganisms on air-dried toothbrushes and toothbrushes stored in a travel container.

METHODS

Sterile synthetic toothbrushes were inoculated with optical density standardized laboratory cultures of Staphylococcus epidermidis or Candida albicans. Half were then disinfected with CPC and half were used as untreated controls. The toothbrushes were vortexed in sterile saline solution, diluted in a ten-fold series, and plated on 5% blood agar or Sabouraud dextrose agar. The plates were incubated at 37 degrees C in a normal atmosphere for 48 hours, and colonies were counted.

RESULTS

CPC produced significant decreases in residual microorganisms. Using the CPC spray treatment on air-dried toothbrushes, Staphylococcus epidermidis essentially was reduced 100-fold, while Candida albicans had a 94% reduction of growth. Bacterial counts were higher in the samples stored in closed containers as compared to the air-dried samples.

CONCLUSION

CPC appeared to be an effective toothbrush disinfectant for the organisms evaluated. It is practical and economical. CPC could easily fit into the recommendations of a practice committed to infection control.

Preoperative chemoradiation for adenocarcinoma of the pancreas: excessive toxicity of prophylactic hepatic irradiation

PURPOSE

In an effort to reduce relapse in the liver and improve survival in patients with potentially resectable adenocarcinoma of the pancreatic head, we combined whole-liver irradiation with our standard preoperative chemoradiation regimen.

METHODS AND MATERIALS

Eleven patients with biopsy-proven, potentially resectable adenocarcinoma of the pancreatic head were treated with 50.4 Gy of external beam irradiation to the pancreas (1.8 Gy/day, 5 days/week) and concurrent continuous infusion 5-fluorouracil (300 mg/m2 per day). The liver was treated with 23.4 Gy on Days 8 through 21 (13 fractions; 1.8 Gy/fraction). Patients, who upon restaging with radiography and computed tomography were considered to have resectable tumors, were subsequently taken to surgery. If, at surgery, tumors were resectable, pancreaticoduodenectomy was performed, and 10 Gy of intraoperative electron-beam radiation therapy was delivered to the bed of the resected pancreas.

RESULTS

All 11 patients completed chemoradiation. Two treatment-related deaths occurred following chemoradiation, prompting premature termination of the study. Of seven patients taken to surgery, four underwent resection. Seven patients have died of disease, five with liver metastases.

CONCLUSIONS

Prophylactic hepatic chemoradiation, as given in this study, was associated with two treatment-related deaths and a higher than expected incidence of subsequent liver metastases. Our data do not support the use of this treatment program in patients with adenocarcinoma of the pancreas.