Psychological impact of lung cancer screening using a novel antibody blood test followed by imaging: the ECLS randomized controlled trial.

BACKGROUND: The Early CDT®-Lung antibody blood test plus serial computed tomography scans for test-positives (TPGs) reduces late-stage lung cancer presentation. This study assessed the psychological outcomes of this approach. METHODS: Randomized controlled trial (n = 12 208) comparing psychological outcomes 1-12 months post-recruitment in a subsample (n = 1032) of TPG, test-negative (TNG) and control groups (CG). RESULTS: Compared to TNG, TPG had lower positive affect (difference between means (DBM), 3 months (3m: -1.49 (-2.65, - 0.33)), greater impact of worries (DBM 1m: 0.26 (0.05, 0.47); 3m: 0.28 (0.07, 0.50)), screening distress (DBM 1m: 3.59 (2.28, 4.90); 3m: 2.29 (0.97, 3.61); 6m: 1.94 (0.61, 3.27)), worry about tests (odds ratio (OR) 1m: 5.79 (2.66, 12.63) and more frequent lung cancer worry (OR 1m: 2.52 (1.31, 4.83); 3m: 2.43 (1.26, 4.68); 6m: 2.87 (1.48, 5.60)). Compared to CG, TPG had greater worry about tests (OR 1m: 3.40 (1.69, 6.84)). TNG had lower negative affect (log-transformed DBM 3m: -0.08 (-0.13, -0.02)), higher positive affect (DBM 1m: 1.52 (0.43, 2.61); 3m: 1.43 (0.33, 2.53); 6m: 1.27 (0.17, 2.37)), less impact of worries (DBM 3m: -0.27 (-0.48, -0.07)) and less-frequent lung cancer worry (OR 3m: 0.49 (0.26, 0.92)). CONCLUSIONS: Negative psychological effects in TPG and positive effects in TNG were short-lived and most differences were small.

Canine MAS1: monoallelic expression is suggestive of an imprinted gene.

Imprinted genes are epigenetically modified in a parent-of-origin dependent manner and as a consequence are differentially expressed, with one allele typically expressed while the other is repressed. In canine, the insulin like growth factor 2 receptor gene (IGF2R) is imprinted with predominant expression of the maternally inherited allele. Because imprinted genes usually occur in clusters, we examined the allelic expression pattern of the gene encoding the canine Mas receptor (MAS1), which is located upstream of IGF2R on canine chromosome 1 and is highly conserved in mammals. In this report we describe monoallelic expression of canine MAS1 in the neonatal umbilical cord of several individuals and we identify the expressed allele as maternally inherited. These data suggest that canine MAS1 is an imprinted gene.

Detection in blood of autoantibodies to tumour antigens as a case-finding method in lung cancer using the EarlyCDT®-Lung Test (ECLS): study protocol for a randomized controlled trial.

BACKGROUND: Lung cancer is the most common cause of cancer related death worldwide. The majority of cases are detected at a late stage when prognosis is poor. The EarlyCDT®-Lung Test detects autoantibodies to abnormal cell surface proteins in the earliest stages of the disease which may allow tumour detection at an earlier stage thus altering prognosis. The primary research question is: Does using the EarlyCDT®-Lung Test to identify those at high risk of lung cancer, followed by X-ray and computed tomography (CT) scanning, reduce the incidence of patients with late-stage lung cancer (III & IV) or unclassified presentation (U) at diagnosis, compared to standard practice? METHODS: A randomised controlled trial of 12 000 participants in areas of Scotland targeting general practices serving patients in the most deprived quintile of the Scottish Index of Multiple Deprivation. Adults aged 50-75 who are at high risk of lung cancer and healthy enough to undergo potentially curative therapy (Performance Status 0-2) are eligible to participate. The intervention is the EarlyCDT®-Lung Test, followed by X-ray and CT in those with a positive result. The comparator is standard clinical practice in the UK. The primary outcome is the difference, after 24 months, between the rates of patients with stage III, IV or unclassified lung cancer at diagnosis. The secondary outcomes include: all-cause mortality; disease specific mortality; a range of morbidity outcomes; cost-effectiveness and measures examining the psychological and behavioural consequences of screening. Participants with a positive test result but for whom the CT scan does not lead to a lung cancer diagnosis will be offered 6 monthly thoracic CTs for 24 months. An initial chest X-ray will be used to determine the speed and the need for contrast in the first screening CT. Participants who are found to have lung cancer will be followed-up to assess both time to diagnosis and stage of disease at diagnosis. DISCUSSION: The study will determine the clinical and cost effectiveness of EarlyCDT®-Lung Test for early lung cancer detection and assess its suitability for a large-scale, accredited screening service. The study will also assess the potential psychological and behavioural harms arising from false positive or false negative results, as well as the potential benefits to patients of true negative EarlyCDT lung test results. A cost-effectiveness model of lung cancer screening based on the results of the EarlyCDT Lung Test study will be developed. TRIAL REGISTRATION: NCT01925625 . August 19, 2013.

Aspirin use and survival after the diagnosis of breast cancer: a population-based cohort study.

BACKGROUND: Aspirin use has been associated with a reduced cancer incidence and fewer deaths from cancer. This study examined whether women with breast cancer prescribed aspirin postdiagnosis had improved survival. METHODS: An observational, population cohort study was undertaken using data linkage of cancer registry, dispensed prescriptions and death records in Tayside, Scotland. All community prescriptions for aspirin in women with breast cancer were extracted and use postdiagnosis for each individual examined using Cox's proportional hazard models. The main outcome measures were all-cause mortality and breast cancer-specific mortality. RESULTS: Four thousand six hundred and twenty-seven patients diagnosed with breast cancer between 1 January 1998 and 31 December 2008 were followed up until 28 February 2010. Median age at diagnosis was 62 (IQR 52-74). One thousand eight hundred and two (39%) deaths were recorded, with 815 (18%) attributed to breast cancer. One thousand and thirty-five (22%) patients were prescribed aspirin postdiagnosis. Such aspirin use was associated with lower risk of all-cause mortality (HR=0.53, 95% CI=0.45-0.63, P<0.001) and breast cancer-specific mortality (HR=0.42, 95% CI=0.31-0.55, P<0.001) after adjusting for age, socioeconomic status, TNM stage, tumour grade, oestrogen receptor status, surgery, radiotherapy, chemotherapy, adjuvant endocrine therapy and aspirin use prediagnosis. CONCLUSIONS: Aspirin use postdiagnosis of breast cancer may reduce both all-cause and breast cancer-specific mortality. Further investigation seeking a causal relationship and which subgroups of patients benefit most await ongoing randomised controlled trials.

Hospitalised hip fracture risk with rosiglitazone and pioglitazone use compared with other glucose-lowering drugs.

AIMS/HYPOTHESIS: Current drug labels for thiazolidinediones (TZDs) warn of increased fractures, predominantly for distal fractures in women. We examined whether exposure to TZDs affects hip fracture in women and men and compared the risk to that found with other drugs used in diabetes. METHODS: Using a nationwide database of prescriptions, hospital admissions and deaths in those with type 2 diabetes in Scotland we calculated TZD exposure among 206,672 individuals. Discrete-time failure analysis was used to model the effect of cumulative drug exposure on hip fracture during 1999-2008. RESULTS: There were 176 hip fractures among 37,479 exposed individuals. Hip fracture risk increased with cumulative exposure to TZD: OR per year of exposure 1.18 (95% CI 1.09, 1.28; p = 3 × 10(-5)), adjusted for age, sex and calendar month. Hip fracture increased with cumulative exposure in both men (OR 1.20; 95% CI 1.03, 1.41) and women (OR 1.18; 95% CI 1.07, 1.29) and risks were similar for pioglitazone (OR 1.18) and rosiglitazone (OR 1.16). The association was similar when adjusted for exposure to other drugs for diabetes and for other potential confounders. There was no association of hip fracture with cumulative exposure to sulfonylureas, metformin or insulin in this analysis. The 90-day mortality associated with hip fractures was similar in ever-users of TZD (15%) and in never-users (13%). CONCLUSIONS/INTERPRETATION: Hip fracture is a severe adverse effect with TZDs, affecting both sexes; labels should be changed to warn of this. The excess mortality is at least as much as expected from the reported association of pioglitazone with bladder cancer.

A randomised controlled trial of the use of aciclovir and/or prednisolone for the early treatment of Bell's palsy: the BELLS study.

OBJECTIVE: To determine whether oral prednisolone or aciclovir, used separately or in combination, early in the course of Bell's palsy, improves the chances of recovery at 3 and 9 months. DESIGN: A 2 x 2 factorial randomised double-blind trial. Patients were randomly assigned to treatment by an automated telephone service using a permuted block randomisation technique with block sizes of four or eight, and no stratification. SETTING: Mainland Scotland, with referrals mainly from general practice to 17 hospital trial sites. PARTICIPANTS: Adults (aged 16 years or older) with unilateral facial nerve weakness of no identifiable cause presenting to primary care, the emergency department or NHS24 within 72 hours of symptom onset. INTERVENTIONS: Patients were randomised to receive active preparations or placebo for 10 days: (1) prednisolone (50 mg per day, 2 x 25-mg capsules) and aciclovir (2000 mg per day, 5 x 400-mg capsules); (2) prednisolone and placebo (lactose, indistinguishable); (3) aciclovir and placebo; and (4) placebo and placebo. OUTCOME MEASURES: The primary outcome was recovery of facial function assessed by the House-Brackmann scale. Secondary outcomes included health status, pain, self-perceived appearance and cost-effectiveness. RESULTS: Final outcomes were available for 496 patients, balanced for gender; mean age 44 years; initial facial paralysis moderate to severe. One half of patients initiated treatment within 24 hours of onset of symptoms, one-third within 24-48 hours and the remainder within 48-72 hours. Of the completed patients, 357 had recovered by 3 months and 80 at 9 months, leaving 59 with a residual deficit. There were significant differences in complete recovery at 3 months between the prednisolone comparison groups (83.0% for prednisolone, 63.6% for no prednisolone, a difference of + 19.4%; 95% confidence interval (CI): + 11.7% to + 27.1%, p < 0.001). The number needed to treat (NNT) in order to achieve one additional complete recovery was 6 (95% CI: 4 to 9). There was no significant difference between the aciclovir comparison groups (71.2% for aciclovir and 75.7% for no aciclovir). Nine-month assessments of patients recovered were 94.4% for prednisolone compared with 81.6% for no prednisolone, a difference of + 12.8% (95% CI: + 7.2% to + 18.4%, p < 0.001); the NNT was 8 (95% CI: 6 to 14). Proportions recovered at 9 months were 85.4% for aciclovir and 90.8% for no aciclovir, a difference of -5.3%. There was no significant prednisolone-aciclovir interaction at 3 months or at 9 months. Outcome differences by individual treatment (the four-arm model) showed significant differences. At 3 months the recovery rate was 86.3% in the prednisolone treatment group, 79.7% in the aciclovir-prednisolone group, 64.7% in the placebo group and 62.5% in the aciclovir group. At 9 months the recovery rates were respectively 96.1%, 92.7%, 85.3% and 78.1%. The increase in recovery rate conferred by the addition of prednisolone (both for prednisolone over placebo and for aciclovir-prednisolone over aciclovir) is highly statistically significant (p < 0.001). There were no significant differences in secondary measures apart from Health Utilities Index Mark 3 (HUI3) at 9 months in those treated with prednisolone. CONCLUSIONS: This study provided robust evidence to support the early use of oral prednisolone in Bell's palsy as an effective treatment which may be considered cost-effective. Treatment with aciclovir, either alone or with steroids, had no effect on outcome.

Genomic imprinting in Canis familiaris.

For the vast majority of mammalian genes, maternally- and paternally-derived alleles behave identically and are either expressed or repressed, regardless of whether they were inherited from egg or sperm. For imprinted genes, however, this is not the case. The alleles of imprinted genes are epigenetically modified in a parent-of-origin-specific manner and, as a consequence, maternally- and paternally-derived alleles behave differently. Typically one allele is expressed while the other is silent. Although relatively few in number, imprinted genes are the focus of intensive study, as they have important roles in embryonic development. Abnormal expression of imprinted genes results in growth disorders and is implicated in several clinical conditions. Most studies of imprinted genes have been performed in rodents or primates, with limited studies in other mammals such as bovine and opossum. We have recently demonstrated the existence of imprinted genes in the canine, by showing that the canine insulin-like growth factor 2 receptor gene (IGF2R) is monoallelically expressed, with predominant expression of the maternally-derived allele and repression of the paternally-inherited allele. Our ultimate goal is to characterize all imprinted genes in the canine, and to understand how they contribute to canine reproduction, development and disease. Such knowledge will be vital for optimizing the success of most reproductive strategies in the canine.

The accuracy of symptoms, signs and diagnostic tests in the diagnosis of left ventricular dysfunction in primary care: a diagnostic accuracy systematic review.

BACKGROUND: To assess the accuracy of findings from the clinical history, symptoms, signs and diagnostic tests (ECG, CXR and natriuretic peptides) in relation to the diagnosis of left ventricular systolic dysfunction (LVSD) in a primary care setting. METHODS: Diagnostic accuracy systematic review, we searched Medline (1966 to March 2008), EMBASE (1988 to March 2008), Central, Cochrane and ZETOC using a diagnostic accuracy search filter. We included cross-sectional or cohort studies that assess the diagnostic utility of clinical history, symptoms, signs and diagnostic tests, against a reference standard of echocardiography. We calculated pooled positive and negative likelihood ratios and assessed heterogeneity using the I2 index. RESULTS: 24 studies incorporating 10,710 patients were included. The median prevalence of LVSD was 29.9% (inter-quartile range 14% to 37%). No item from the clinical history or symptoms provided sufficient diagnostic information to "rule in" or "rule out" LVSD. Displaced apex beat shows a convincing diagnostic effect with a pooled positive likelihood ratio of 16.0 (8.2-30.9) but this finding occurs infrequently in patients. ECG was the most widely studied diagnostic test, the negative likelihood ratio ranging from 0.06 to 0.6. Natriuretic peptide results were strongly heterogeneous, with negative likelihood ratios ranging from 0.02 to 0.80. CONCLUSION: Findings from the clinical history and examination are insufficient to "rule in" or "rule out" a diagnosis of LVSD in primary care settings. BNP and ECG measurement appear to have similar diagnostic utility and are most useful in "ruling out" LVSD with a normal test result when the probability of LVSD is in the intermediate range.

Impact on mortality following first acute myocardial infarction of distance between home and hospital: cohort study.

OBJECTIVE: To investigate the effect of distance between home and acute hospital on mortality outcome of patients experiencing an incident myocardial infarction (MI). DESIGN: Cohort study using a record linkage database. SETTING: Tayside, Scotland, UK. PATIENTS: 10,541 patients with incident acute MI between 1994 and 2003 were identified from Tayside hospital discharge data and from death certification data. MAIN OUTCOME MEASURES: MI mortality in the community, all-cause mortality in hospital and all-cause mortality during follow-up. RESULTS: 4133 subjects died following incident MI in the community (that is, were not hospitalised), 6408 patients survived to be hospitalised and 1010 of these (15.8%) died in hospital. Of 5398 discharged from hospital, 1907 (35.3%) died during a median of 3.2 years of follow-up. After adjustment for rurality and other known risk factors, distance between home and admitting hospital was significantly associated with increased mortality both before hospital admission (adjusted odds ratio (OR), 2.05, 95% CI 1.00 to 4.21 for >9 miles and 1.46, 1.09 to 1.95 for 3-9 miles when compared to <3 miles) and after hospitalisation (adjusted hazard ratio (HR) 1.90, 1.19 to 3.02 and 1.27, 0.96 to 1.68). However, there was no effect of distance on in-hospital mortality (adjusted OR 0.95, 0.45 to 2.03 and 1.02, 0.66 to 1.58). CONCLUSION: The distance between home and hospital of admission may predict mortality in subjects experiencing a first acute MI. This association was found both before and after hospitalisation. Further studies are needed to explore the reasons for this association. However these data provide support for policies that locate services for acute MI closer to where patients live.

Diagnosis of left ventricular systolic dysfunction (LVSD): development and validation of a clinical prediction rule in primary care.

BACKGROUND: Diagnosing suspected left ventricular systolic dysfunction (LVSD) in the community is a challenge for GPs. We developed and validated a clinical prediction rule (CPR) for LVSD based on history, examination and electrocardiogram (ECG). METHODS: Prospective cohort studies of 458 symptomatic patients (derivation cohort) and 535 patients (validation cohort) in 26 general practices in Tayside and Fife, Scotland. All patients underwent a structured clinical examination and ECG and the 'reference standard' investigation of echocardiography to establish the presence of LVSD. RESULTS: Four elements from the clinical history and examination were all independently associated with LVSD--male sex [adjusted odds ratio (OR) 2.5; 95% CI 1.1, 5.0], presence of orthopnoea (OR 5.4; 1.9, 13.8) history of myocardial infarction (OR 5.6; 2.3, 13.6) and elevated jugular venous pulsations (OR 15.1; 4.6, 49.3). Addition of ECG (OR 20.6; 2.7, 158.6) provides important diagnostic information in terms of probability of LVSD. A CPR based on the presence or absence of these five elements will generate probabilities ranging from 1% to 97% for LVSD when applied to an individual patient. In the validation cohort, the model under-predicted the probability of LVSD, particularly at lower levels of expected risk, reflecting differences in the risk-factor profiles of the derivation and validation cohorts. CONCLUSIONS: The derived CPR provides quantitative estimates of post-test probability for LVSD. This rule requires further validation in other populations and settings because of the difficulties encountered in the validation cohort.

Agreement between community echocardiography and hospital echocardiography in patients suspected of having left ventricular systolic dysfunction.

BACKGROUND: Smaller echocardiography machines, when used in hospitals, are accurate for detecting left ventricular dysfunction and valvular disease. This paper assessed the detection of left ventricular dysfunction and of valvular disease in the community setting by a smaller machine. AIMS: To measure the agreement in patients with suspected heart failure between community echocardiography and traditional echocardiography in the hospital in detecting left ventricular dysfunction and significant valve disease. METHODS: Suspected heart failure patients were referred to one of the authors (SJ) for community echocardiography using a Siemens Cypress machine. The patients had a second echocardiogram in the hospital by another sonographer who was blinded to the results of the first echocardiogram. The reports of the two sonographers were assessed for agreement using kappa statistics. RESULTS: 458 patients had a community echocardiogram and 136 agreed to a second echocardiogram in the hospital. There was excellent agreement, kappa = 0.87 (0.06 SE), for the detection of left ventricular dysfunction between community echocardiography and the hospital machine. The detection of significant valvular disease was good, kappa = 0.75 (0.06) between the community echocardiogram and hospital machines. CONCLUSIONS: In suspected heart failure patients, community echocardiography gives comparable results to traditional hospital echocardiography for left ventricular dysfunction detection and for significant valvular disease detection.

The Tayside children's sleep questionnaire: a simple tool to evaluate sleep problems in young children.

BACKGROUND: Behavioural sleep problems in young children are relatively common with between 20% and 40% of those aged 1 to 5 years being affected. This paper describes the development of a simple questionnaire to assess disorders of initiating and maintaining sleep (DIMS) in children aged between 1 and 5 years for use as a selection tool for research purposes or as a screening instrument in primary care. METHODS: A subsection of the Sleep Disturbance Scale for Children was adapted and piloted with a small sample of children in two inner city GP practices (n = 81). Face and content validity were initially established by expert review. Discriminant validity was assessed qualitatively using interviews with mothers of identified cases and non-cases. The validity of the cut-off score was assessed by blinded case note reviews off known cases; inter-rater reliability was also calculated. Following modifications, the final questionnaire was posted to a representative sample of parents across the region with children in the appropriate age band (n = 1023). Internal reliability was assessed using Cronbach's alpha and factor analysis was undertaken to identify significant factors within the questionnaire. RESULTS: The response rate to the population questionnaire was 61.5% (n = 628) with 218 of the children having sleep scores that were indicative of DIMS (35%), echoing other figures reported in the literature. There was good internal consistency for the items (Cronbach's alpha = 0.85) with two main factors accounting for 58% of the variance. CONCLUSION: The Tayside Children's Sleep Questionnaire (TCSQ) is an easy-to-read and reliable tool that could be used both as a clinical and research instrument to assess the severity and prevalence of DIMS in young children.

Presence of bacteriuria caused by trimethoprim resistant bacteria in patients prescribed antibiotics: multilevel model with practice and individual patient data.

OBJECTIVE: To look for evidence of a relation between antibiotic resistance and prescribing by general practitioners by analysis of prescribing at both practice and individual patient level. DESIGN: Repeated cross-sectional study in 1995 and 1996. SETTING: 28 general practices in the Ninewells Hospital laboratory catchment area, Tayside, Scotland. SUBJECTS REVIEWED: 8833 patients registered with the 28 practices who submitted urine samples for analysis. MAIN OUTCOME MEASURES: Resistance to trimethoprim in bacteria isolated from urine samples at practice and individual level simultaneously in a multilevel model. RESULTS: Practices showed considerable variation in both the prevalence of trimethoprim resistance (26-50% of bacteria isolated) and trimethoprim prescribing (67-357 prescriptions per 100 practice patients). Although variation in prescribing showed no association with resistance at the practice level after adjustment for other factors (P = 0.101), in the multilevel model resistance to trimethoprim was significantly associated with age, sex, and individual-level exposure to trimethoprim (P < 0.001) or to other antibiotics (P = 0.002). The association with trimethoprim resistance was strongest for people recently exposed to trimethoprim, and there was no association for people with trimethoprim exposure more than six months before the date of the urine sample. DISCUSSION: Analysis of practice level data obscured important associations between antibiotic prescribing and resistance. The results support efforts to reduce unnecessary prescribing of antibiotics in the community and show the added value of individual patient data for research on the outcomes of prescribing.

The RCP's 'Three Key Questions' for asthma: review of practical use.

Assessment tools are a vital component of chronic disease management. The Royal College of Physicians has developed a patient-focused outcome measure for the treatment of asthma, the 'Three Key Questions'. However, in a study investigating the goals of people with asthma, several issues related to the tool emerged. Forty-seven adults of a range of ages and asthma severity but with no significant co-morbidity were interviewed. It emerged that the outcome measure may be subject to recall bias. Also, symptom reports may be conflated if daytime symptoms also occur with activity. 'Interference with activity' is a subjective term the interpretation of which varies considerably. Changes in the level of activity undertaken may be reported rather than changes in symptom severity. The 'Three Key Questions' are not fully patient-centred because they assess the presence of symptoms rather than their importance to the individual. The use of the 'Three Key Questions' as an outcome measure may not allow valid comparisons to be made between settings.

What Scottish primary care researchers are doing to recover their standing in the UK.

OBJECTIVE: To compare the outputs of Scottish PC research with the rest of the UK. DESIGN: Bibliometric analysis of the research level and potential impact of research publications. Papers are categorised by level (RL) from basic research to clinical observation and potential impact category (PIC), a 5 year impact factor on a numerical scale. SETTING: Interrogation of the Wellcome Trust's Research Outputs Database 1988-97. SUBJECTS: 17,303 papers, 2,280 arising from Scottish primary care. RESULTS: Scottish primary care publications totalled 14% of the published research in the UK during 1988, by 1997 it had fallen to 10%. PC researchers in the rest of the UK produced a 60% increase (1169 to 1866 per annum) in publications compared to our 25% increase (201 to 251 per annum) over the same period. Scottish papers were less likely to be presenting basic science. The mean potential impact was slightly lower than the rest of the UK (1.89 compared to 1.94, s.e.m.0.02). CONCLUSION: Scottish PC research outputs grew more slowly than the rest of the UK during 1988-97. The research interests and journals selected by the research community contributed to this pattern. The climate, infrastructure and skills required for more effective PC research during this period were also significant factors. The Scottish School of Primary Care provides a mechanism for everyone in NHSScotland and Higher Education Institutions to address the underlying issues identified in this analysis. As a 'baseline' analysis, this report will allow progress to be monitored as the SSPC becomes increasingly effective.

Review of risk factors for sudden infant death syndrome.

Sudden infant death syndrome (SIDS) accounts for the largest number of deaths during the first year of life in developed countries. The possible causes of SIDS are numerous and, to date, there is no adequate unifying pathological explanation for SIDS. Epidemiological studies have played a key role in identifying risk factors, knowledge of which has underpinned successful preventive programmes. This review critically assesses information on the main risk factors and causal hypotheses put forward for SIDS, focusing on research published since 1994. The overall picture that emerges from this review is that affected infants are not completely normal in development, but possess some inherent weakness, which may only become obvious when the infant is subjected to stress. Initially there may be some minor impairment or delay in development of respiratory, cardiovascular or neuromuscular function. None of these is likely to be sufficient, in isolation, to cause death and, provided the infant survives the first year of life, may no longer be of any significance. However, when a compromised infant is confronted with one or more stressful situations, several of which are now clearly identified as risk factors, and from which the majority of infants would normally escape, the combination may prove fatal.

Risk assessment of the use of deltamethrin on bednets for the prevention of malaria.

Risk assessments covering the use of the pyrethroid, deltamethrin, on bednets for the prevention of malaria have been conducted The toxicity of deltamethrin in humans and animals is reviewed following both dermal and oral exposure. The no-adverse-effect level (NOEL) for exposure via the dermal route was 1000 mg/kg body weight/day. From this an acceptable exposure level (AEL) of 10 mg/kg body weight/day has been derived. The NOEL for exposure via the oral route was 1 mg/kg body weight/day, with exposures above this causing neurotoxic effects in animals. This NOEL has been used to derive margins of safety compared with predicted exposures. While direct skin contact does not seem to cause systemic toxicity in humans, it can cause burning, numbness and tingling of the skin, which is a local effect. This too is taken into account in the risk assessments. The risk assessments cover those treating bednets, on an intermittent or regular basis, the washing of treated nets, sleeping under treated nets (infants, children and adults). Worst case scenarios for each of these situations show that dermal exposures are low (one-tenth or less of the AEL) and the margins of safety for systemic exposure derived from oral data are acceptable, ranging from 10 to 3300. The benefits of the use of treated bednets in reducing morbidity and mortality from malaria are considerable and it can be concluded that the risk:benefit ratio is very favourable.