Risk of post-traumatic stress disorder following traumatic events in a community sample.

AIMS: Post-traumatic stress disorder (PTSD) is typically associated with high-risk population groups, but the risk of PTSD that is associated with trauma experienced in the community, and effect of changes in diagnostic criteria in DSM-5 on prevalence in the general population, is unknown. METHODS: Cross-sectional analysis of population-based data from 4558 adults aged 25-83 years resident in Caerphilly county borough, Wales, UK. Exposure to different traumatic events was assessed using categorisation of free-text descriptions of trauma. PTSD caseness was determined using items assessing Diagnostic and Statistical Manual IV (DSM-IV) and DSM-5 A criteria and the Traumatic Screening Questionnaire. RESULTS: Of the 4558 participants, 1971 (47.0%) reported a traumatic event. The most common DSM-IV A1 qualifying trauma was life-threatening illnesses and injuries (13.6%). The highest risk of PTSD was associated with assaultive violence [34.1%]. The prevalence of PTSD using DSM-IV A criteria was 14.3% (95% confidence interval [CI] = 12.8, 15.9%). Using DSM-5 A criteria reduced the prevalence to 8.0 (95% CI = 6.9, 9.4%), primarily due to exclusion of DSM-IV A1 qualifying events, such as life-threatening illnesses. CONCLUSIONS: Nearly one-half of a general community sample had experienced a traumatic event and of these around one in seven was a DSM-IV case of PTSD. Although the majority of research has concentrated on combat, rape and assaultive violence, life threatening illness is a more common cause of PTSD in the community. Removal of this traumatic event in DSM-5 could reduce the number of cases of PTSD by around 6.0%.

Central arterial stiffness and diastolic dysfunction are associated with insulin resistance and abdominal obesity in young women but polycystic ovary syndrome does not confer additional risk.

STUDY QUESTION: Are arterial stiffness, carotid intima-media thickness and diastolic dysfunction increased in young women with polycystic ovary syndrome (PCOS) independently of the effects of obesity? SUMMARY ANSWER: Insulin resistance and central obesity are associated with subclinical cardiovascular dysfunction in young women, but a diagnosis of PCOS does not appear to confer additional risk at this age. WHAT IS KNOWN ALREADY: Some studies have shown that young women with PCOS may have increased measures of cardiovascular risk, including arterial stiffness, carotid intima-media thickness and myocardial dysfunction. However, it is difficult to establish how much of this risk is due to PCOS per se and how much is due to obesity and insulin resistance, which are common in PCOS and themselves associated with greater vascular risk. STUDY DESIGN, SIZE, DURATION: This cross-sectional study comprised 84 women with PCOS and 95 healthy volunteers, aged 16-45 years. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study was conducted in a university hospital. Subjects underwent a comprehensive assessment of body composition (including computed tomography (CT) assessment of visceral fat; VF), measurements of arterial stiffness (aortic pulse wave velocity; aPWV), common carotid intima-media thickness (ccIMT), diastolic function (longitudinal tissue velocity; e':a') and endocrinological measures. A sample size of 80 in each group gave 80% power for detecting a difference of 0.45 m/s in aPWV or a difference of 0.25 in e':a'. MAIN RESULTS AND THE ROLE OF CHANCE: After adjustment for age and body mass index (BMI), PCOS subjects had a greater insulin response (insulin area under the curve-IAUC) following glucose challenge (adjusted difference [AD] 35 900 pmol min/l, P < 0.001) and higher testosterone (AD 0.57 nmol/l, P < 0.001) and high molecular weight adiponectin than controls (AD 3.01 µg/ml, P = 0.02), but no significant differences in aPWV (AD -0.13 m/s, P = 0.33), ccIMT (AD -0.01 mm, P = 0.13), or e':a' (AD -0.01, P = 0.86) were observed. After adjustment for age, height and central pulse pressure, e':a' and aPWV were associated with logVF and IAUC. ccIMT was not related to logVF. The relationships between e':a' or aPWV and insulin resistance were only partly attenuated by adjusting for logVF. There was no significant relationship between aPWV or e':a' and either testosterone or adiponectin. LIMITATIONS, REASONS FOR CAUTION: The study recruited young women meeting the Rotterdam criteria for PCOS diagnosis; hence our findings may not be generalizable to older patients or those meeting other definitions of the syndrome. Biochemical hyperandrogenism was based solely on measurement of total testosterone. Cases and controls were not matched in advance for age and BMI, although the influence of these variables on the cardiovascular outcome measures was adjusted for. WIDER IMPLICATIONS OF THE FINDINGS: This study shows that central arterial stiffness and diastolic dysfunction are not increased in young women with PCOS, whereas they are associated with both insulin resistance and central obesity. Obesity thus represents the greatest modifiable risk factor for cardiovascular disease in young women with PCOS and lifestyle measures which target weight reduction are critical. STUDY FUNDING/COMPETING INTERESTS: This study received no specific grant support from any funding body. The authors have no conflicts of interest to declare.

Effect of neighbourhood deprivation and social cohesion on mental health inequality: a multilevel population-based longitudinal study.

BACKGROUND: The common mental disorders (CMDs) of anxiety and depression are the most common form of poor mental health in the general population. Evidence from the small number of previous cohort studies on the role of neighbourhood factors in mental health is inconclusive. We tested the hypothesis that high levels of neighbourhood social cohesion modify an adverse association between change in individual mental health and neighbourhood deprivation. METHOD: We carried out a longitudinal multilevel analysis using data from the Caerphilly Health and Social Needs Cohort Study with a 7-year follow-up (n = 4426; age range 18-74 years at baseline). Neighbourhood deprivation and neighbourhood social cohesion were assessed at baseline and change in mental health between follow-up and baseline was assessed using the five-item Mental Health Inventory (MHI-5). RESULTS: Residence in the most deprived neighbourhoods was negatively associated with change in mental health, after adjusting for baseline individual socio-economic risk factors and transitions in life events. This negative effect was significantly reduced in high social cohesion neighbourhoods. The predicted change in mental health score was calculated for the 10th and 90th centiles of the household low-income distribution. The difference between them was -2.8 in the low social cohesion group and 1.1 in the high cohesion group. The difference between the groups was 3.9 [95% confidence interval (CI) 0.2-7.6]. CONCLUSIONS: The public health burden of poor mental health and mental health inequality could potentially be reduced by strengthening social cohesion in deprived neighbourhoods. This offers a mechanism to address the adverse effect of neighbourhood deprivation on population mental health.

The natural history of eczema from birth to adult life: a cohort study.

BACKGROUND: Eczema is common in infancy; however, there is little evidence about its natural history to adulthood. OBJECTIVES: To study the natural history of eczema from birth to young adult life with particular reference to its relation to atopy. METHODS: A birth cohort of children with atopic family histories was followed for 23 years. Clinical examinations were conducted until the age of 7 years, skin-prick tests and serum total IgE were recorded in infancy and at ages 7 and 23 years, and questionnaires about eczema symptoms were completed at 15 and 23 years. RESULTS: Information was obtained on 497 subjects at birth, 482 at 1 year, 440 at 7 years, 363 at 15 years and 304 at 23 years. Eczema usually remitted from age 1 to 7 years but became more persistent from the age of 15 years, especially in those who were atopic. The prevalence of eczema rose in women from age 15 to 23 years but declined in men. Adults with eczema had higher IgE than those without at 3 months (geometric mean 3·0 vs. 1·7 kU L(-1); P=0·01), 7 years (107·9 vs. 45·2 kU L(-1); P=0·01) and 23 years (123·4 vs. 42·3 kU L(-1); P=0·01), and were more likely to have had positive skin-prick tests at 1 year of age. Current eczema was associated with raised IgE in infancy and adulthood but not in childhood. CONCLUSIONS: Predisposed infants and children with eczema usually grow out of the disease, but in adolescence it is more likely to persist. Adult eczema is related to atopy from the age of 3 months.

Incidence of diabetic retinopathy in people with type 2 diabetes mellitus attending the Diabetic Retinopathy Screening Service for Wales: retrospective analysis.

OBJECTIVES: To determine the incidence of any and referable diabetic retinopathy in people with type 2 diabetes mellitus attending an annual screening service for retinopathy and whose first screening episode indicated no evidence of retinopathy. DESIGN: Retrospective four year analysis. SETTING: Screenings at the community based Diabetic Retinopathy Screening Service for Wales, United Kingdom. PARTICIPANTS: 57,199 people with type 2 diabetes mellitus, who were diagnosed at age 30 years or older and who had no evidence of diabetic retinopathy at their first screening event between 2005 and 2009. 49,763 (87%) had at least one further screening event within the study period and were included in the analysis. MAIN OUTCOME MEASURES: Annual incidence and cumulative incidence after four years of any and referable diabetic retinopathy. Relations between available putative risk factors and the onset and progression of retinopathy. RESULTS: Cumulative incidence of any and referable retinopathy at four years was 360.27 and 11.64 per 1000 people, respectively. From the first to fourth year, the annual incidence of any retinopathy fell from 124.94 to 66.59 per 1000 people, compared with referable retinopathy, which increased slightly from 2.02 to 3.54 per 1000 people. Incidence of referable retinopathy was independently associated with known duration of diabetes, age at diagnosis, and use of insulin treatment. For participants needing insulin treatment with a duration of diabetes of 10 years or more, cumulative incidence of referable retinopathy at one and four years was 9.61 and 30.99 per 1000 people, respectively. CONCLUSIONS: Our analysis supports the extension of the screening interval for people with type 2 diabetes mellitus beyond the currently recommended 12 months, with the possible exception of those with diabetes duration of 10 years or more and on insulin treatment.

Prescribing competence of junior doctors: does it add up?

BACKGROUND: Prescribing errors complicate a significant number of paediatric admissions. Ongoing training and monitoring of prescribing competency in junior doctors has occurred in Cardiff since 2001, alongside national measures aimed at improving training and competency. AIM: Ongoing monitoring of junior doctors' prescribing competency to assess the effect of these national and local initiatives. METHODS: Junior doctors receive training and subsequent assessment on prescribing competency at induction. A 1 h bleep-free session concerning paediatric prescribing precedes completion of four prescribing tasks. British National Formulary for children and calculators are provided. Those scoring 0 or 1 are retrained before prescribing is permitted. Our previously published data of doctors between 2001 and 2004 was compared with assessment in 2007. RESULTS: 30 junior doctors were assessed in 2007 (32 in 2001-2004). All four questions were answered correctly by 22/30, compared to 10/32 (31%) in 2001-2004. The mean score in 2007 was 93.3% compared to 57.8% previously (see table 1). Comparison of means with previous results demonstrated statistically significant improvement with a mean difference of 36% (95% CI 24 to 47). In 2007, eight (27%) doctors got just one question wrong and no doctor answered all questions incorrectly. In 2001-2004, 22/32 (67%) made at least one error during previous assessment, and one doctor answered all questions incorrectly. Table 1Prescribing assessment scores in 2001-2004 and 2007 Answer scores2001-2004 (n=32)2007 (n=30)All questions correct10 (31%)22 (73%)One incorrect08 (27%)Two incorrect13 (41%)0Three incorrect8 (25%)0All questions incorrect1 (3%)0 CONCLUSION: Ongoing monitoring of junior doctors' prescribing ability has demonstrated improvements which may be due to local and national training initiatives.

The incidence and aetiology of epistaxis in infants: a population-based study.

OBJECTIVE: To estimate the incidence and describe the aetiology of epistaxis in infants. DESIGN: Population-based study including a retrospective hospital admission database analysis and a postal questionnaire to clinicians. SETTING: Wales, United Kingdom. METHODS: Cases of epistaxis over a 6-year period (1999-2004) were identified from the Patient Episode Dataset for Wales (PEDW) and validated using clinical information to calculate the population-based incidence and ascertain the causes of epistaxis in infants in Wales. RESULTS: 36 confirmed cases were identified over the 6-year period giving an estimated annual incidence of epistaxis of 19.3 (95% CI 14.0 to 26.7) per 100,000 infants. The median age at admission was 12 weeks (interquartile range 4-33) (min 1 week, max 49 weeks). 23 of the infants had a recognised cause for their epistaxis (trauma (five), coagulation disorder (four), congenital anomaly (two), acute rhinitis or coryza (11), abusive smothering event (one)). No cause for the epistaxis was identified for 13 cases. Coagulation disorder was excluded in seven of these 13 infants but in the other six no attempt was made to exclude this disorder. Child abuse was suspected but excluded in four of the 13 cases. CONCLUSION: Hospital admission for epistaxis is a rare event. In the majority of cases in this study a simple explanation was available and proven physical abuse was rare. A bleeding disorder should always be considered and, if additional evidence suggests physical abuse, this must be excluded.

Prevalence and pattern of cognitive impairment in a community cohort of men in South Wales: methodology and findings from the Caerphilly Prospective Study.

BACKGROUND/AIMS: The prevalence of dementia and cognitive impairment not dementia was investigated in the Caerphilly Prospective Study cohort (men currently aged 65-84 years). METHODS: Of 1,633 men eligible for cognitive screening, 1,225 (75%) were seen, with those failing the screening criteria (CAMCOG <83 or decline in CAMCOG >9) being neurologically examined. RESULTS: For dementia, diagnosed by DSM-IV criteria, the population prevalence was 5.2% rising to 6.1% in the screened population. For cognitive impairment not dementia, the prevalence in the screened population was 15.6% giving an overall prevalence of cognitive impairment of 21.8%. Prevalence rose fivefold between ages of 65 and 84 years to reach over 50%. CONCLUSION: These figures are likely to underestimate actual prevalence in this population, and developing effective interventions should be a public health priority.

Effects on patients with asthma of eradicating visible indoor mould: a randomised controlled trial.

BACKGROUND: It is not clear whether associations between respiratory symptoms and indoor mould are causal. A randomised controlled trial was conducted to see whether asthma improves when indoor mould is removed. METHODS: Houses of patients with asthma were randomly allocated into two groups. In one group, indoor mould was removed, fungicide was applied and a fan was installed in the loft. In the control group, intervention was delayed for 12 months. Questionnaires were administered and peak expiratory flow rate was measured at baseline, 6 months and 12 months. RESULTS: Eighty-one houses were allocated to the intervention group and 83 to the control group; 95 participants in 68 intervention houses and 87 in 63 control houses supplied follow-up information. Peak expiratory flow rate variability declined in both groups, with no significant differences between them. At 6 months, significantly more of the intervention group showed a net improvement in wheeze affecting activities (difference between groups 25%, 95% CI 3% to 47%; p = 0.028), perceived improvement of breathing (52%, 95% CI 30% to 74%; p<0.0001) and perceived reduction in medication (59%, 95% CI 35% to 81%; p<0.0001). By 12 months the intervention group showed significantly greater reductions than the controls in preventer and reliever use, and more improvement in rhinitis (24%, 95% CI 9% to 39%; p = 0.001) and rhinoconjunctivitis (20%, 95% CI 5% to 36%; p = 0.009). CONCLUSIONS: Although there was no objective evidence of benefit, symptoms of asthma and rhinitis improved and medication use declined following removal of indoor mould. It is unlikely that this was entirely a placebo effect.

A randomised controlled trial of clinical outreach education to rationalise antibiotic prescribing for acute dental pain in the primary care setting.

OBJECTIVE: To assess the effect of educational outreach visits on antibiotic prescribing for acute dental pain in primary care. STUDY DESIGN: RCT. SETTING: General dental practices in four health authority areas in Wales. SUBJECTS AND METHODS: General dental practitioners were recruited to the study and randomly allocated to one of the three study groups (control group, guideline group or intervention group). Following the intervention, practitioners completed a standardised questionnaire for each patient that presented with acute dental pain. INTERVENTIONS: The control group received no intervention. The guideline group received educational material by post. The intervention group received educational material by post and an academic detailing visit by a trained pharmacist. The educational material included evidence-based guidelines on prescribing for acute dental pain and patient information leaflets. MAIN OUTCOME MEASURES: The number of antibiotic prescriptions issued to patients presenting with dental pain and the number of 'inappropriate' antibiotic prescriptions. Antibiotics were considered to be inappropriate if the patient did not have symptoms indicative of spreading infection. RESULTS: A total of 1,497 completed questionnaires were received from 23, 20 and 27 general dental practitioners in the control, guideline and intervention group respectively. Patients in the intervention group received significantly fewer antibiotic prescriptions than patients in the control group (OR (95% CI) 0.63 (0.41, 0.95)) and significantly fewer inappropriate antibiotic prescriptions (OR (95% CI) 0.33 (0.21, 0.54)). However, antibiotic and inappropriate antibiotic prescribing were not significantly different in the guideline group compared to the control group (OR (95% CI) 0.83 (0.55, 1.21) and OR (95% CI) 0.82 (0.53, 1.29) respectively). CONCLUSIONS: Strategies based upon educational outreach visits may be successfully employed to rationalise antibiotic prescribing by dental practitioners.

Selecting specialist registrars by station interview.

Appointments to the specialist registrar (SpR) grade depend almost entirely on performance at interview, yet standard panel interviews do not directly assess the competences required of a medical trainee. In this study, station interviews were used to select neurology SpRs. Eighteen candidates were assessed in three interviews, each involving three stations: a curriculum vitae (CV)-based interview, an interview with a simulated patient, and a discussion of scenarios based upon teaching, audit and research. Two or three assessors at each station ranked candidates independently before discussing the pooled rankings and reading written references. The CV-based interview rankings (resembling a traditional panel interview) correlated less well with the overall rankings (r=0.54) than did research (r=0.83), information giving (r=0.75), audit (r=0.70) or teaching presentation (r=0.59). Station interviews appear fairer (providing more time, more independent examiners, fresh starts at each station), although they require more planning and expense. Competency-based assessments should be more widely used in selecting medical trainees.

Variability of antiepileptic medication taking behaviour in sudden unexplained death in epilepsy: hair analysis at autopsy.

BACKGROUND: Variable compliance with antiepileptic drugs (AEDs) is a potentially preventable cause of sudden unexplained death in epilepsy (SUDEP). Hair AED concentrations provide a retrospective insight into AED intake variability. METHODS: We compared hair AED concentration variability in patients with SUDEP (n = 16), non-SUDEP epilepsy related deaths (n = 9), epilepsy outpatients (n = 31), and epilepsy inpatients (n = 38). AED concentrations were measured in 1 cm hair segments using high performance liquid chromatography. Individual patient hair AED concentration profiles were corrected for "washout" using linear regression analysis. The coefficient of variation (CV) of the corrected mean hair AED concentration provided an index of variability of an individual's AED taking behaviour. Hair sample numbers varied between subjects, and so weighted regression estimates of the CV were derived for each group. RESULTS: The CV regression estimates for each group were: SUDEP 20.5% (standard error 1.9), non-SUDEP 15.0% (3.9), outpatients 9.6% (1.4), and inpatients 6.2% (2.7). The SUDEP group therefore showed greater hair AED concentration variability than either the outpatient or the inpatient groups (p<0.0001). CONCLUSION: Observed variability of hair AED concentrations, reflecting variable AED ingestion over time, is greater in patients dying from SUDEP than in either epilepsy outpatients or inpatients. SUDEP, at least in a proportion of cases, appears preventable.

Asthma prevalence in 1973, 1988 and 2003.

BACKGROUND: A study was undertaken to see whether the prevalence of asthma has changed since a survey was conducted in 1988, using the same methods that showed an increase during the previous 15 years. METHODS: A survey of 12 year old children was conducted in schools in South Wales where surveys had taken place in 1973 and 1988. The survey comprised a parentally completed questionnaire and an exercise challenge test, performed when no bronchodilator had been recently used. RESULTS: In 1973, 1988, and 2003, questionnaires were obtained for 817, 965 and 1148 children, respectively; the exercise test was performed by 812, 960 and 1019 children, respectively. The prevalence of reported wheeze in the last year rose during each 15 year period (9.8%, 15.2%, 19.7%), with an even steeper rise in reported asthma ever (5.5%, 12.0%, 27.3%). There was a continued increase in wheeze attributed to running, in terms of all children (5.8%, 10.5%, 16.0%) and also as the proportion of those with a history of wheeze (34.1%, 47.0%, 57.3%). The use of inhaled corticosteroids (not available in 1973) increased fourfold between 1988 and 2003. The prevalence of exercise induced bronchoconstriction rose between 1973 and 1988 but had declined by 2003. CONCLUSIONS: The rise in the prevalence of asthmatic symptoms has continued since 1988. This appears to conflict with a reported recent decline, unless asthma prevalence peaked in the 1990s. The decline in exercise induced bronchoconstriction is probably attributable to better control of the disease as more children are now using inhaled corticosteroids as preventive treatment.

Drowning of British children abroad.

AIMS: To quantify the risks of British children drowning abroad. METHODS: The numbers of British children drowning abroad were estimated for 1996-2003 using the RoSPA/RLSS press cutting database. We compared these figures with the numbers of British children going abroad from the International Passenger Survey from the Office of National Statistics. RESULTS: Sixty-eight children (45 boys-23 Girls) drowned in the eight-year period: 48 (71%) in swimming pools (mostly in hotels). Allowing for exposure, the rate was higher in North America [5.2 (CI 2.9-9.4)/million tourists] than the European Union [1.9 (CI 1.4-2.5)/million tourists] p = 0.002. DISCUSSION: On average eight British children drown each year abroad. This is therefore a rare but tragic event. Most of these episodes happen in swimming pools and this needs to be compared to the one child that dies each year in municipal swimming pools in the United Kingdom where there is adequate lifeguarding. It may be that parents have a false sense of security for their children in pools abroad. We believe that there needs to be action from the European Union on this important event.

Differences in risk of mortality under 1 year of age between rural and urban areas: an ecological study.

OBJECTIVE: To investigate differences in risk of categories and causes of death before 1 year of age between rural and urban areas. METHODS: Population-based ecological study using Poisson regression analysis of data from all enumeration districts in Wales. Data included all 243,223 registrable births to women resident in Wales, 809 therapeutic and spontaneous abortions, 1302 stillbirths and 1418 infant deaths occurring between 1993 and 1999. MAIN RESULTS: The relative risk of mortality in rural areas compared with urban areas for all deaths before 1 year of age was 0.89 (95% confidence interval 0.82, 0.98, P=0.02). The risk of mortality in rural areas was significantly lower than in urban areas for all categories of deaths occurring after 7 days of life. The relative risk of death due to infection was significantly lower in rural areas compared with urban areas (P=0.04), with similar results for deaths due to sudden infant death syndrome (P=0.03). After adjusting for social deprivation, there were no significant differences in the risk of death between rural and urban areas. CONCLUSIONS: While there were significant differences in crude risk between rural and urban enumeration districts for some causes and age groups before 1 year, after adjusting for social deprivation, these differences were not significant. The lack of significant interaction between rurality and deprivation indicated that the relationship between social deprivation and death before 1 year of age was not significantly different in rural areas compared with urban areas. Collaborative public health programmes to tackle deprivation are necessary in both rural and urban areas.

Is fish oil good or bad for heart disease? Two trials with apparently conflicting results.

Two successive randomized trials examined the effect of an increased intake of fatty fish, or the use of fish oil supplements, in reducing mortality in men with heart disease. The Diet and Reinfarction Trial (DART) was conducted in 2033 men who were recovering from acute myocardial infarction (MI). Those who were advised to eat fatty fish (or who opted to take fish oil capsules instead) had a 29% reduction in all-cause mortality over the following two years compared with those not so advised. The effect appeared in the first few months of the trial. The Diet and Angina Randomized Trial (DART 2) involved 3114 men with stable angina. Advice to eat fatty fish did not reduce mortality, and taking fish oil capsules was associated with a higher risk of cardiac and sudden death. The adverse effects of fish or fish oil were restricted to men not taking beta-blockers or dihydropyridine calcium-channel blockers, and were greater in those taking digoxin. Evidence from other sources strongly suggests an anti-arrhythmic action of fish oil, particularly after MI or in the presence of acute ischemia. The apparently conflicting results of the two trials may reflect different actions of n-3 fatty acids in acute and chronic conditions, together with different effects of eating fish and taking fish oil capsules. A mechanism is proposed that could account for these findings.

Are abused babies protected from further abuse?

A cohort of 69 physically abused babies under 1 year was followed for three years after the incident. Of the 49 babies who returned home following child protection investigations, 15 were further abused in the three year period, a re-abuse rate of 31%, which is grossly higher than the abuse rate in the general population.

Evaluating the cost-effectiveness of orthodontic provision.

The assessment of orthodontic provision is important to determine if treatment was necessary and undertaken appropriately. The ICON objectively quantifies orthodontic treatment need, complexity and outcome and is a valuable occlusal index in the assessment effectiveness of orthodontic care. It is possible to develop cost-effectiveness models by analysing the costs and effectiveness of orthodontic treatment. Several methods are illustrated to compare the orthodontic provision of specialist orthodontists.

Laboratory testing policies and their effects on routine surveillance of community antimicrobial resistance.

OBJECTIVE: To investigate the effects of laboratory testing policies, particularly selective testing, rule-based reporting and isolate identification, on estimates of community antimicrobial resistance. MATERIALS AND METHODS: Antibiotic resistance estimates were analysed from an all-Wales dataset for approximately 300 000 community isolates of common pathogens. RESULTS: Selective testing policies were often associated with markedly increased resistance, particularly for second-line testing. Site-specific testing tended to yield variant resistance estimates for eye and ear isolates. Estimates from rule-based reporting deviated markedly from test-result-based reporting. Urinary isolates reported as Escherichia coli showed greater susceptibility than those reported as undifferentiated urinary 'coliforms'. The proportion of isolates tested for an antibiotic by a laboratory was a useful indicator of selective testing in this dataset. Selective testing policies had invariably been applied where the proportion of isolates of a species tested against an antibiotic was <90%. As this proportion fell with increasingly selective policies, divergence from pooled-all-Wales non-selective estimates tended to increase, with a bias to increased resistance. CONCLUSIONS: Selective testing, rule-based reporting and urinary coliform identification policies all had significant effects upon resistance estimates. Triage based upon the proportion of isolates tested seemed a useful tool in assigning analysis resources. Where <20% of isolates were tested, selective policies with inherent bias to increased resistance were common, the low number of isolates gave high potential sampling errors, and little confidence could be placed in the resistance estimate. Where 20-90% of isolates were tested, detailed analysis sometimes revealed resistance estimates that might be usefully retrieved. Where >/=90% of isolates were tested, there was no evidence of selective testing, and inter-laboratory variation in estimates appeared to be safely ascribable to other effects, e.g. methodology or real variation in resistance levels.