Computer-aided National Early Warning Score to predict the risk of sepsis following emergency medical admission to hospital: a model development and external validation study

BACKGROUND

In hospitals in England, patients' vital signs are monitored and summarized into the National Early Warning Score (NEWS); this score is more accurate than the Quick Sepsis-related Organ Failure Assessment (qSOFA) score at identifying patients with sepsis. We investigated the extent to which the accuracy of the NEWS is enhanced by developing and comparing 3 computer-aided NEWS (cNEWS) models (M0 = NEWS alone, M1 = M0 + age + sex, M2 = M1 + subcomponents of NEWS + diastolic blood pressure) to predict the risk of sepsis.

METHODS

We included all emergency medical admissions of patients 16 years of age and older discharged over 24 months from 2 acute care hospital centres (York Hospital [YH] for model development and a combined data set from 2 hospitals [Diana, Princess of Wales Hospital and Scunthorpe General Hospital] in the Northern Lincolnshire and Goole National Health Service Foundation Trust [NH] for external model validation). We used a validated Canadian method for defining sepsis from administrative hospital data.

RESULTS

The prevalence of sepsis was lower in YH (4.5%, 1596/35 807) than in NH (8.5%, 2983/35 161). The C statistic increased across models (YH: M0 0.705, M1 0.763, M2 0.777; NH: M0 0.708, M1 0.777, M2 0.791). For NEWS of 5 or higher, sensitivity increased (YH: 47.24% v. 50.56% v. 52.69%; NH: 37.91% v. 43.35% v. 48.07%), the positive likelihood ratio increased (YH: 2.77 v. 2.99 v. 3.06; NH: 3.18 v. 3.32 v. 3.45) and the positive predictive value increased (YH: 11.44% v. 12.24% v. 12.49%; NH: 22.75% v. 23.55% v. 24.21%).

INTERPRETATION

From the 3 cNEWS models, model M2 is the most accurate. Given that it places no additional burden of data collection on clinicians and can be automated, it may now be carefully introduced and evaluated in hospitals with sufficient informatics infrastructure.

Does achieving the 'Best Practice Tariff' criteria for fractured neck of femur patients improve one year outcomes?

INTRODUCTION

'Best Practice Tariff' (BPT) criteria have been developed to improve peri-operative care for hip fracture patients. This paper aims to explore the impact of BPT criteria on 1-year outcomes.

PATIENTS AND METHODS

Anonymised data were acquired from the National Hip Fracture Database (NHFD) for patients presenting to Bradford Royal Infirmary with a fractured neck of femur during the period April 2011 to December 2015. Two study groups were defined: those that achieved the BPT uplift criteria, and those that did not. Three primary outcome measures were identified: one year survival, mobility status and residential status. Further analysis was performed to ascertain whether achieving any individual BPT criterion significantly affected 1-year outcomes.

RESULTS

1414 cases were included, 784 (55%) of whom met the BPT criteria. The 1-year survival rate of the BPT-achieved group was 67.7%, compared with 61.4% in the non-BPT group (relative risk reduction 10.3%, p = 0.014). Mobility status declined by at least one grade in 50.8% of the BPT-achieved group, compared with 60.8% of the non-BPT group (risk reduction 16.4%, p = 0.003). BPT achievement had no significant effect on residential status at one year. Multivariate analysis identified that post-operative Abbreviated Mental Test Score (AMTS) and falls assessment were significantly associated with reduced 1-year mortality. Similarly, both pre- and post-operative AMTS assessments resulted in greater potential to return to pre-morbid mobility level. When controlling for potential confounders (age, gender, ASA grade, pre-morbid mobility and residential status) logistic regression modelling showed that achieving the BPT criteria was associated with a 30% increase in the odds of survival at one year (p = 0.046).

DISCUSSION

Achieving the BPT requirements has a significant impact on 1-year mortality and return to pre-morbid mobility level. The effect of AMTS and falls assessments on these outcomes may be due to their properties as surrogate markers for more thorough and considered peri-operative assessment.

CONCLUSIONS

Few studies describe the effect of BPT criteria on 1-year outcomes; therefore the results presented here help to vindicate the investments made in the scheme. Furthermore, these results may help steer subsequent revisions to BPT requirements by encouraging greater focus on peri-operative assessment and interventions.

Understanding and applying practitioner and patient views on the implementation of a novel automated Computer-Aided Risk Score (CARS) predicting the risk of death following emergency medical admission to hospital: qualitative study

OBJECTIVES

The Computer-Aided Risk Score (CARS) estimates the risk of death following emergency admission to medical wards using routinely collected vital signs and blood test data. Our aim was to elicit the views of healthcare practitioners (staff) and service users and carers (SU/C) on (1) the potential value, unintended consequences and concerns associated with CARS and practitioner views on (2) the issues to consider before embedding CARS into routine practice.

SETTING

This study was conducted in two National Health Service (NHS) hospital trusts in the North of England. Both had in-house information technology (IT) development teams, mature IT infrastructure with electronic National Early Warning Score (NEWS) and were capable of integrating NEWS with blood test results. The study focused on emergency medical and elderly admissions units. There were 60 and 39 acute medical/elderly admissions beds at the two NHS hospital trusts.

PARTICIPANTS

We conducted eight focus groups with 45 healthcare practitioners and two with 11 SU/Cs in two NHS acute hospitals.

RESULTS

Staff and SU/Cs recognised the potential of CARS but were clear that the score should not replace or undermine clinical judgments. Staff recognised that CARS could enhance clinical decision-making/judgments and aid communication with patients. They wanted to understand the components of CARS and be reassured about its accuracy but were concerned about the impact on intensive care and blood tests.

CONCLUSION

Risk scores are widely used in healthcare, but their development and implementation do not usually involve input from practitioners and SU/Cs. We contributed to the development of CARS by eliciting views of staff and SU/Cs who provided important, often complex, insights to support the development and implementation of CARS to ensure successful implementation in routine clinical practice.

Development and validation of a novel computer-aided score to predict the risk of in-hospital mortality for acutely ill medical admissions in two acute hospitals using their first electronically recorded blood test results and vital signs: a cross-sectional study

OBJECTIVES

There are no established mortality risk equations specifically for emergency medical patients who are admitted to a general hospital ward. Such risk equations may be useful in supporting the clinical decision-making process. We aim to develop and externally validate a computer-aided risk of mortality (CARM) score by combining the first electronically recorded vital signs and blood test results for emergency medical admissions.

DESIGN

Logistic regression model development and external validation study.

SETTING

Two acute hospitals (Northern Lincolnshire and Goole NHS Foundation Trust Hospital (NH)-model development data; York Hospital (YH)-external validation data).

PARTICIPANTS

Adult (aged ≥16 years) medical admissions discharged over a 24-month period with electronic National Early Warning Score(s) and blood test results recorded on admission.

RESULTS

The risk of in-hospital mortality following emergency medical admission was 5.7% (NH: 1766/30 996) and 6.5% (YH: 1703/26 247). The C-statistic for the CARM score in NH was 0.87 (95% CI 0.86 to 0.88) and was similar in an external hospital setting YH (0.86, 95% CI 0.85 to 0.87) and the calibration slope included 1 (0.97, 95% CI 0.94 to 1.00).

CONCLUSIONS

We have developed a novel, externally validated CARM score with good performance characteristics for estimating the risk of in-hospital mortality following an emergency medical admission using the patient's first, electronically recorded, vital signs and blood test results. Since the CARM score places no additional data collection burden on clinicians and is readily automated, it may now be carefully introduced and evaluated in hospitals with sufficient informatics infrastructure.

Test-retest reproducibility of accommodative facility measures in primary school children

BACKGROUND

To determine the test-retest reproducibility of accommodative facility (AF) measures in an unselected sample of UK primary school children.

METHODS

Using ±2.00 DS flippers and a viewing distance of 40 cm, AF was measured in 136 children (range 4-12 years, average 8.1 ± 2.1) by five testers on three occasions (average interval between successive tests: eight days, range 1-21 days). On each occasion, AF was measured monocularly and binocularly, for two minutes. Full datasets were obtained in 111 children (81.6 per cent).

RESULTS

Intra-individual variation in AF was large (standard deviation [SD] = 3.8 cycles per minute [cpm]) and there was variation due to the identity of the tester (SD = 1.6 cpm). On average, AF was greater: (i) in monocular compared to binocular testing (by 1.4 cpm, p < 0.001); (ii) in the second minute of testing compared to the first (by 1.3 cpm, p < 0.001); (iii) in older compared to younger children (for example, AF for 4/5-year-olds was 3.3 cpm lower than in children ≥ 10 years old, p = 0.009); and (iv) on subsequent testing occasions (for example, visit-2 AF was 2.0 cpm higher than visit-1 AF, p < 0.001). After the first minute of testing at visit-1, only 36.9 per cent of children exceeded published normative values for AF (≥ 11 cpm monocularly and ≥ 8 cpm binocularly), but this rose to 83.8 per cent after the third test. Using less stringent pass criteria (≥ 6 cpm monocularly and ≥ 3 cpm binocularly), the equivalent figures were 82.9 and 96.4 per cent, respectively. Reduced AF did not co-exist with abnormal near point of accommodation or reduced visual acuity.

CONCLUSIONS

The results reveal considerable intra-individual variability in raw AF measures in children. When the results are considered as pass/fail, children who initially exhibit normal AF continued to do so on repeat testing. Conversely, the vast majority of children with initially reduced AF exhibit normal performance on repeat testing. Using established pass/fail criteria, the prevalence of persistently reduced AF in this sample is 3.6 per cent.

Factors influencing accuracy of referral and the likelihood of false positive referral by optometrists in Bradford, United Kingdom

AIMS

Levels of false positive referral to ophthalmology departments can be high. This study aimed to evaluate commonality between false positive referrals in order to find the factors which may influence referral accuracy.

METHODS

In 2007/08, a sample of 431 new Ophthalmology referrals from the catchment area of Bradford Royal Infirmary were retrospectively analysed.

RESULTS

The proportion of false positive referrals generated by optometrists decreases with experience at a rate of 6.2% per year since registration (p<0.0001). Community services which involved further investigation done by the optometrist before directly referring to the hospital were 2.7 times less likely to refer false positively than other referral formats (p=0.007). Male optometrists were about half as likely to generate a false positive referral than females (OR=0.51, p=0.008) and as multiple/corporate practices in the Bradford area employ less experienced and more female staff, independent practices generate about half the number of false positive referrals (OR=0.52, p=0.005).

CONCLUSIONS

Clinician experience has the greatest effect on referral accuracy although there is also a significant effect of gender with women tending to refer more false positives. This may be due to a different approach to patient care and possibly a greater sensitivity to litigation. The improved accuracy of community services (which often refer directly after further investigation) supports further growth of these schemes.

Dizziness, but not falls rate, improves after routine cataract surgery: the role of refractive and spectacle changes

Purpose

To determine whether dizziness and falls rates change due to routine cataract surgery and to determine the influence of spectacle type and refractive factors.

Methods

Self‐reported dizziness and falls were determined in 287 patients (mean age of 76.5 ± 6.3 years, 55% females) before and after routine cataract surgery for the first (81, 28%), second (109, 38%) and both eyes (97, 34%). Dizziness was determined using the short‐form of the Dizziness Handicap Inventory. Six‐month falls rates were determined using self‐reported retrospective data.

Results

The number of patients with dizziness reduced significantly after cataract surgery (52% vs 38%; χ² = 19.14^,p < 0.001), but the reduction in the number of patients who fell in the 6‐months post surgery was not significant (23% vs 20%; χ² = 0.87, p = 0.35). Dizziness improved after first eye surgery (49% vs 33%, p = 0.01) and surgery on both eyes (58% vs 35%, p < 0.001), but not after second eye surgery (52% vs 45%, p = 0.68). Multivariate logistic regression analyses found significant links between post‐operative falls and change in spectacle type (increased risk if switched into multifocal spectacles). Post‐operative dizziness was associated with changes in best eye visual acuity and changes in oblique astigmatic correction.

Conclusions

Dizziness is significantly reduced by first (or both) eye cataract surgery and this is linked with improvements in best eye visual acuity, although changes in oblique astigmatic correction increased dizziness. The lack of improvement in falls rate may be associated with switching into multifocal spectacle wear after surgery.

Effectiveness of fluoroscopy-guided intra-articular steroid injection for hip osteoarthritis

AIM

To demonstrate the benefits of fluoroscopy-guided intra-articular steroid injection in the hip with varying degrees of disease severity, and to investigate the financial aspects of the procedure and impact on waiting time.

MATERIALS AND METHODS

A prospective study was undertaken of patients who underwent fluoroscopic intra-articular steroid injection over the 9-month study period. Comparative analysis of the Oxford hip pain score pre- and 6-8 weeks post-intra-articular injection was performed. Hip radiographs of all patients were categorised as normal, mild, moderate, or severe disease (four categories) based on the modified Kellgren-Lawrence severity scale, and improvement on the Oxford hip pain score on each of these four severity categories were assessed.

RESULTS

Within the study cohort of 100 patients, the mean increase in post-procedure hip score of 7.32 points confirms statistically significant benefits of the therapy (p<0.001, 95% confidence interval: 5.55-9.09). There was no significant difference in pre-injection hip score or change in score between the four severity categories (p=0.51). Significant improvement in hip score (p<0.05) was demonstrated in each of the four severity categories 6-8 weeks post-injection. No associated complications were observed.

CONCLUSION

The present study confirms that fluoroscopy-guided intra-articular steroid injection is a highly effective therapeutic measure for hip osteoarthritis across all grades of disease severity with significant cost savings and the potential to reduce waiting times.

Intermediate addition multifocals provide safe stair ambulation with adequate 'short-term' reading

Purpose

A recent randomised controlled trial indicated that providing long‐term multifocal wearers with a pair of distance single‐vision spectacles for use outside the home reduced falls risk in active older people. However, it also found that participants disliked continually switching between using two pairs of glasses and adherence to the intervention was poor. In this study we determined whether intermediate addition multifocals (which could be worn most of the time inside and outside the home and thus avoid continual switching) could provide similar gait safety on stairs to distance single vision spectacles whilst also providing adequate ‘short‐term’ reading and near vision.

Methods

Fourteen healthy long‐term multifocal wearers completed stair ascent and descent trials over a 3‐step staircase wearing intermediate and full addition bifocals and progression‐addition lenses (PALs) and single‐vision distance spectacles. Gait safety/caution was assessed using foot clearance measurements (toe on ascent, heel on descent) over the step edges and ascent and descent duration. Binocular near visual acuity, critical print size and reading speed were measured using Bailey‐Lovie near charts and MNRead charts at 40 cm.

Results

Gait safety/caution measures were worse with full addition bifocals and PALs compared to intermediate bifocals and PALs. The intermediate PALs provided similar gait ascent/descent measures to those with distance single‐vision spectacles. The intermediate addition PALs also provided good reading ability: Near word acuity and MNRead critical print size were better with the intermediate addition PALs than with the single‐vision lenses (p < 0.0001), with a mean near visual acuity of 0.24 ± 0.13 logMAR (~N5.5) which is satisfactory for most near vision tasks when performed for a short period of time.

Conclusions

The better ability to ‘spot read’ with the intermediate addition PALs compared to single‐vision spectacles suggests that elderly individuals might better comply with the use of intermediate addition PALs outside the home. A lack of difference in gait parameters for the intermediate addition PALs compared to distance single‐vision spectacles suggests they could be usefully used to help prevent falls in older well‐adapted full addition PAL wearers. A randomised controlled trial to investigate the usefulness of intermediate multifocals in preventing falls seems warranted.

Analysis of lower limb movement to determine the effect of manipulating the appearance of stairs to improve safety: a linked series of laboratory-based, repeated measures studies

Background

Falls on stairs are a common and dangerous problem for older people. This series of studies evaluated whether or not selected changes to the appearance of stairs could make them safer for older people to negotiate.

Objectives

To determine the effect of (1) a step edge highlighter and its position and (2) an optimised horizontal–vertical (H–V) visual illusion placed on a step riser on gait safety during stair descent and ascent.

Design

A series of studies using a repeated measures, laboratory-based design, investigating gait control and safety in independently mobile older people.

Setting

The University of Bradford Vision and Mobility Laboratory.

Participants

Fit and healthy older people aged 60 years of age or more, independently mobile, reasonably active and with normal healthy eyes and corrected vision.

Interventions

A step edge highlighter in a variety of offsets from the stair edge and an optimised H–V visual illusion placed on the stair riser. The H–V illusion was provided on a staircase by horizontal step edge highlighters on the tread edges and vertical stripes on the step risers.

Main outcome measures

Gait parameters that are important for safe stepping in ascent and descent, particularly toe clearance during stair ascent and heel clearance during stair descent.

Results

The step edge highlighter increased the precision of heel clearance during stepping and its positioning relative to the tread edge determined the extent of heel clearance over the tread edge. Positioning the highlighter away from the tread edge, as is not uncommonly provided by friction strips, decreased heel clearance significantly and led to greater heel scuffs. Although psychophysics experiments suggested that higher spatial frequencies of the H–V illusion might provide greater toe clearance on stair ascent, gait trials showed similar increased toe clearances for all spatial frequencies. When a 12 cycle per step spatial frequency H–V illusion was used, toe clearance increases of approximately 1 cm (17.5%) occurred without any accompanying changes in other important gait parameters or stability measures.

Conclusions

High-contrast tread edge highlighters present on steps and stairs and positioned flush with the edge of the tread or as near to this as possible should improve stair descent safety in older people. A H–V illusion positioned on the riser of a raised surface/walkway (e.g. kerbs) and/or the top and/or bottom of a stairway is likely to increase foot clearance over the associated step/stair edge, and appears not to lead to any decrement in postural stability. Thus, their use is likely to reduce trip risk and hence improve stair ascent safety. The effect of the step and stair modifications should be assessed in older people with visual impairment. The only other remaining assessment that could be made would be to assess fall prevalence on steps and stairs, perhaps in public buildings, with and without these modifications.

Funding

The National Institute for Health Research Public Health Research programme.

Sensitivity and specificity of the empirical lymphocyte genome sensitivity (LGS) assay: implications for improving cancer diagnostics

Lymphocyte responses from 208 individuals: 20 with melanoma, 34 with colon cancer, and 4 with lung cancer (58), 18 with suspected melanoma, 28 with polyposis, and 10 with COPD (56), and 94 healthy volunteers were examined. The natural logarithm of the Olive tail moment (OTM) was plotted for exposure to UVA through 5 different agar depths (100 cell measurements/depth) and analyzed using a repeated measures regression model. Responses of patients with cancer plateaued after treatment with different UVA intensities, but returned toward control values for healthy volunteers. For precancerous conditions and suspected cancers, intermediate responses occurred. ROC analysis of mean log OTMs, for cancers plus precancerous/suspect conditions vs. controls, cancer vs. precancerous/suspect conditions plus controls, and cancer vs. controls, gave areas under the curve of 0.87, 0.89, and 0.93, respectively (P<0.001). Optimization allowed test sensitivity or specificity to approach 100% with acceptable complementary measures. This modified comet assay could represent a stand-alone test or an adjunct to other investigative procedures for detecting cancer.

Associations of circulating calcium and 25-hydroxyvitamin D with glucose metabolism in pregnancy: a cross-sectional study in European and South Asian women

BACKGROUND

Vitamin D deficiency is thought to impair insulin action and glucose metabolism; however, previous studies have not examined ethnic differences or the influence of calcium and parathyroid hormone. We investigated this in a cohort of predominantly white European and south Asian women during pregnancy.

METHODS

In this cross-sectional study from an urban population in northern England (53.8°N), 1467 women were recruited when undergoing glucose tolerance testing (75 g oral glucose tolerance test) at 26 weeks' gestation.

RESULTS

Gestational diabetes mellitus (GDM) was diagnosed in 137 women (9.3%). Median 25-hydroxyvitamin D concentration for the study population was 9.3 ng/mL (interquartile range 5.2, 16.9) and was higher in European [15.2 ng/mL (10.7, 23.5)] than in south Asian women [5.9 ng/mL (3.9, 9.4), P < .001]. After appropriate adjustment for confounders, 25-hydroxyvitamin D showed a weak inverse association with fasting plasma glucose (FPG; mean difference 1.0% per 1 SD; the ratio of geometric means (RGM) 0.99, 95% confidence interval (CI) 0.98, 1.00), and PTH was weakly associated with FPG (RGM 1.01, 95% CI 1.00, 1.02), but neither was associated with fasting insulin, postchallenge glucose, or GDM. Serum calcium (albumin adjusted) was strongly associated with fasting insulin (RGM 1.06; 95% CI 1.03, 1.08), postchallenge glucose (RGM 1.03, 95% CI 1.01, 1.04), and GDM (odds ratio 1.33, 95% CI 1.06, 1.66) but not with FPG. Associations were similar in European and south Asian women.

CONCLUSIONS

These findings do not indicate any important association between vitamin D status and glucose tolerance in pregnancy. Relationships between circulating calcium and glucose metabolism warrant further investigation.

Binocular summation and other forms of non-dominant eye contribution in individuals with strabismic amblyopia during habitual viewing

BACKGROUND

Adults with amblyopia ('lazy eye'), long-standing strabismus (ocular misalignment) or both typically do not experience visual symptoms because the signal from weaker eye is given less weight than the signal from its fellow. Here we examine the contribution of the weaker eye of individuals with strabismus and amblyopia with both eyes open and with the deviating eye in its anomalous motor position.

METHODOLOGY/RESULTS

The task consisted of a blue-on-yellow detection task along a horizontal line across the central 50 degrees of the visual field. We compare the results obtained in ten individuals with strabismic amblyopia with ten visual normals. At each field location in each participant, we examined how the sensitivity exhibited under binocular conditions compared with sensitivity from four predictions, (i) a model of binocular summation, (ii) the average of the monocular sensitivities, (iii) dominant-eye sensitivity or (iv) non-dominant-eye sensitivity. The proportion of field locations for which the binocular summation model provided the best description of binocular sensitivity was similar in normals (50.6%) and amblyopes (48.2%). Average monocular sensitivity matched binocular sensitivity in 14.1% of amblyopes' field locations compared to 8.8% of normals'. Dominant-eye sensitivity explained sensitivity at 27.1% of field locations in amblyopes but 21.2% in normals. Non-dominant-eye sensitivity explained sensitivity at 10.6% of field locations in amblyopes but 19.4% in normals. Binocular summation provided the best description of the sensitivity profile in 6/10 amblyopes compared to 7/10 of normals. In three amblyopes, dominant-eye sensitivity most closely reflected binocular sensitivity (compared to two normals) and in the remaining amblyope, binocular sensitivity approximated to an average of the monocular sensitivities.

CONCLUSIONS

Our results suggest a strong positive contribution in habitual viewing from the non-dominant eye in strabismic amblyopes. This is consistent with evidence from other sources that binocular mechanisms are frequently intact in strabismic and amblyopic individuals.

Test-retest reproducibility of accommodation measurements gathered in an unselected sample of UK primary school children

PURPOSE

To determine the test-retest reproducibility of accommodation measurements gathered in an unselected sample of primary school children.

METHODS

Monocular and binocular amplitudes of accommodation (AA) were collected by five different Testers using the push-up method in an unselected sample of school children (n=137, age: 8.1±2.1 years). Testing was conducted on three occasions (average testing interval: 8 days) in 91.2% of the children.

RESULTS

The median AA was 19.1D, the variation due to the identity of the Tester was 3.1D (p<0.001) and the within-subject variation (which takes the variation due to Tester identity into account) was 5.2D. Around 75-79% of children exhibited monocular AAs≥12D when tested on the first occasion, but more than 90% exhibited an AA≥12D when subsequently tested. Around 74-80% of those with an AA<12D on the first occasion had values≥12D on subsequent testing even though no treatment had been undertaken. Poorer initial AA measurements were less likely to improve on repeat testing.

CONCLUSIONS

Our results reveal substantial intra-individual variation in AA measurements, raising questions about the usefulness of this test in children aged 4-12 years. We suggest that AA assessment may prove most useful in children in this age range as a pass/fail check for substantially reduced AA, for example, where the AA is <12D. Our sample would suggest that the prevalence of persistently reduced AA may be around 3.2% when tested under binocular conditions and 4-6.4% when tested monocularly.

A limited role for suppression in the central field of individuals with strabismic amblyopia

Background

Although their eyes are pointing in different directions, people with long-standing strabismic amblyopia typically do not experience double-vision or indeed any visual symptoms arising from their condition. It is generally believed that the phenomenon of suppression plays a major role in dealing with the consequences of amblyopia and strabismus, by preventing images from the weaker/deviating eye from reaching conscious awareness. Suppression is thus a highly sophisticated coping mechanism. Although suppression has been studied for over 100 years the literature is equivocal in relation to the extent of the retina that is suppressed, though the method used to investigate suppression is crucial to the outcome. There is growing evidence that some measurement methods lead to artefactual claims that suppression exists when it does not.

Methodology/Results

Here we present the results of an experiment conducted with a new method to examine the prevalence, depth and extent of suppression in ten individuals with strabismic amblyopia. Seven subjects (70%) showed no evidence whatsoever for suppression and in the three individuals who did (30%), the depth and extent of suppression was small.

Conclusions

Suppression may play a much smaller role in dealing with the negative consequences of strabismic amblyopia than previously thought. Whereas recent claims of this nature have been made only in those with micro-strabismus our results show extremely limited evidence for suppression across the central visual field in strabismic amblyopes more generally. Instead of suppressing the image from the weaker/deviating eye, we suggest the visual system of individuals with strabismic amblyopia may act to maximise the possibilities for binocular co-operation. This is consistent with recent evidence from strabismic and amblyopic individuals that their binocular mechanisms are intact, and that, just as in visual normals, performance with two eyes is better than with the better eye alone in these individuals.

Test--retest variability of Randot stereoacuity measures gathered in an unselected sample of UK primary school children

AIM

To determine the test-retest reliability of the Randot stereoacuity test when used as part of vision screening in schools.

METHODS

Randot stereoacuity (graded-circles) and logMAR visual acuity measures were gathered in an unselected sample of 139 children (aged 4-12, mean 8.1±2.1 years) in two schools. Randot testing was repeated on two occasions (average interval between successive tests 8 days, range: 1-21 days). Three Randot scores were obtained in 97.8% of children.

RESULTS

Randot stereoacuity improved by an average of one plate (ie, one test level) on repeat testing but was little changed when tested on the third occasion. Within-subject variability was up to three test levels on repeat testing. When stereoacuity was categorised as 'fine', 'intermediate' or 'coarse', the greatest variability was found among younger children who exhibited 'intermediate' or 'coarse'/nil stereopsis on initial testing. Whereas 90.8% of children with 'fine' stereopsis (≤50 arc-seconds) on the first test exhibited 'fine' stereopsis on both subsequent tests, only ∼16% of children with 'intermediate' (>50 but ≤140 arc-seconds) or 'coarse'/nil (≥200 arc-seconds) stereoacuity on initial testing exhibited stable test results on repeat testing.

CONCLUSIONS

Children exhibiting abnormal stereoacuity on initial testing are very likely to exhibit a normal result when retested. The value of a single, abnormal Randot graded-circles stereoacuity measure from school screening is therefore questionable.

The enriched opportunities programme for people with dementia: a cluster-randomised controlled trial in 10 extra care housing schemes

OBJECTIVES

The Enriched Opportunities Programme (EOP) is a multi-level intervention focussing on improved quality of life for people with dementia. This study compared the experience of people living with dementia and other mental health problems in extra care housing schemes that utilised EOP with schemes that employed an active control intervention.

METHOD

Ten extra care housing schemes were cluster randomised to receive either the EOP intervention or an active control intervention for an 18-month period. Residents with dementia or other significant mental health problems (20-30 per scheme) were assessed on a number of outcome measures at baseline, six months, one year and 18 months. The primary outcome measure was quality of life. Self-reported depression was an important secondary outcome.

RESULTS

The EOP-participating residents rated their quality of life more positively over time (4.0 (SE 0.6) units; 14% p < 0.001) than the active control (1.3 (SE 0.6) units; 4% p = 0.003). There was also a significant group-time interaction for depressive symptoms (p = 0.003). The EOP-participating residents reported a reduction of 25% at both six and 12 months and a 37% reduction at 18 months (all p's < 0.001). EOP residents were less likely than residents in the active control sites to move to a care home or to be admitted to a hospital inpatient bed. They were more likely to be seen by a range of community health professionals.

CONCLUSION

The EOP had a positive impact on the quality of life of people with dementia in well-staffed extra care housing schemes.

Survival of patients with hematological malignancy admitted to the intensive care unit: prognostic factors and outcome compared to unselected medical intensive care unit admissions, a parallel group study

Improved survival in patients with hematological malignancy (HM) admitted to the intensive care unit (ICU) has largely been reported in uncontrolled cohorts from single academic institutions. We compared hospital mortality between 147 patients with HM and 147 general medical admissions to five non-specialist ICUs. The proportion of patients surviving to hospital discharge was significantly worse in patients with HM (27% vs. 56%; p < 0.001). Six-month and 1-year survival in patients with HM was 21% and 18%, respectively. HM, greater age, mechanical ventilation (MV) and acute physiology and chronic health evaluation (APACHE) II score were independent predictors of poor outcome. For patients with HM, culture proven infection, age, MV and inotropes were negative predictors. Disease-specific factors including hematological diagnosis, neutropenia, remission status, prior stem cell transplant, time from diagnosis to admission and degree of prior treatment were not predictive. Overall survival of patients with HM was worse than that recently reported from specialist units.

Spectacle prescribing II: practitioner experience is linked to the likelihood of suggesting a partial prescription

PURPOSE

A follow up study to investigate whether UK optometrists partially prescribe significant changes in refractive correction to assist patient adaptation and whether various aspects of practitioner profiles are linked to the nature of these prescribing decisions.

METHOD

A case scenario type questionnaire was distributed by post and via the internet to UK optometrists. Five case scenarios were described that included information on patient age, symptoms, habitual refractive correction (if any), subjective refraction and any other relevant clinical information. In each case respondents were asked to indicate and justify what refractive correction they would prescribe.

RESULTS

A total of 592 questionnaires were completed. Between 41% and 84% prescribed the subjective refraction result depending on the scenario. The likelihood of partial prescribing increased by 34% for every 10 years following qualification and thus after a typical 40 year career, respondents were now over three times more likely to partially prescribe. There were no other links with the propensity to partially prescribe.

CONCLUSION

The subjective refraction result exerted a strong hold on the reported prescribing outcome, particularly for newly qualified optometrists. Partial prescribing was increasingly proposed the greater the number of years the respondent had been qualified. This suggests that with increasing exposure to patients who return dissatisfied with their spectacles, a greater appreciation of partial prescribing is gained. This link seems to be an important finding that provides significant support for the prescribing rules suggested by textbooks, which are not yet supported by research evidence.

Lipidomic analysis reveals prostanoid profiles in human term pregnant myometrium

Prostanoids modulate the activity of human pregnant myometrium and their functional role can be appreciated through characterisation of prostanoid receptors and tissue concentration of prostanoids. We have applied a lipidomic approach to elucidate the profile of prostanoids in human non-labouring and labouring myometrium. We have identified a total of nineteen prostanoids including prostacyclin, thromboxanes, prostaglandins and dihydro-prostaglandins. Prostacyclin was the predominant prostanoid in both non-labouring and labouring myometria, with PGD(2) and PGF(2alpha) being the second most abundant. Although the total amount of prostanoids was increased in the labouring tissue, PGE(2) and 13,14-dihydro-15-keto-PGE(2) were the only prostanoids to increase significantly at early and late labour (p< or =0.001). Our data suggest that PGF(2alpha) plays an important role in parturition, whilst the increase in PGE(2) could occur to facilitate cervical dilation and relaxation of the lower myometrium during labour. Although the elevation in TXA(2) was less marked than expected, in terms of translation to function even a relatively small increase in the level of this potent spasmogen may have significant effects.

Response of multiple recurrent TaT1 bladder cancer to intravesical apaziquone (EO9): comparative analysis of tumor recurrence rates

OBJECTIVES

Previous studies have demonstrated that intravesical administration of apaziquone (EOquin) has ablative activity against superficial bladder cancer marker lesions with 8 out of 12 complete responses recorded. We present a comparison between the rates of tumor recurrence before and after treatment with apaziquone.

METHODS

The rate of tumor recurrence after treatment with apaziquone was compared with each patient's historical record of recurrences obtained from a retrospective analysis of the patients' case notes. The time to each recurrence event before apaziquone treatment and the time to the first recurrence after apaziquone treatment were recorded, and the data were analyzed using a population-averaged linear regression model using Stata Release, version 9.2, software.

RESULTS

Of the eight complete responses obtained in the Phase I study, tumor recurrence occurred in 4 patients and the remaining 4 patients remained disease free after a median follow-up of 31 months. The time to the first recurrence after apaziquone treatment was significantly longer (P <0.001) compared with the historical pattern and recurrence interval before apaziquone. Before apaziquone instillation, the mean +/- SE recurrence rate and tumor rate per year was 1.5 +/- 0.2 and 4.8 +/- 1.2, respectively, and these decreased to 0.6 +/- 0.25 and 1.5 +/- 0.8, respectively, after apaziquone treatment (P <0.05).

CONCLUSIONS

The results of this study indicate that early recurrences after treatment with apaziquone are infrequent and the interval to recurrence is significantly greater compared with the historical recurrence times for these patients. Larger prospective randomised trials are warranted to confirm these results.

Does breastfeeding method influence infant weight gain?

OBJECTIVE

To compare the effect of traditional and "baby-led" breastfeeding advice on early infant weight gain and exclusive breastfeeding rates.

DESIGN

Longitudinal cohort study: part prospective, part retrospective.

SETTING

One UK general practice.

PARTICIPANTS

63 exclusively breastfed infants in two cohorts: 32 babies born before and 31 babies born after a change in breastfeeding advice.

INTERVENTION

A change from baby-led to traditional breastfeeding advice.

MAIN OUTCOME MEASURES

Primary analysis: comparison of the effectiveness of the intervention (ie, weight gain expressed as standard deviation score gain (SDSG) between birth and 6-8 weeks) and exclusive breastfeeding rates between babies whose mothers received traditional advice and those whose mothers received baby-led advice. Secondary analysis: relevance of feed length (ie, weight gain expressed as SDSG between birth and 6-8 weeks in babies feeding for 10 min or less from the first breast and those feeding for longer than 10 min).

RESULTS

The two groups were equivalent with respect to birth weight, gestational age, and parity.

PRIMARY OUTCOME

babies whose mothers received the traditional advice were more likely to be exclusively breast fed up to 12 weeks (log rank chi2 = 9.68, p = 0.002) and gained more weight up to 6-8 weeks than those given baby-led advice (mean SDSG 0.41 (95% CI 0.13 to 0.69) vs -0.23 (95% CI -0.72 to 0.27)). Secondary outcome: irrespective of feeding advice given, babies feeding for 10 min or less from the first breast gained more weight by 6-8 weeks than babies feeding for longer than 10 min (mean SDSG 0.42 (95% CI 0.11 to 0.73) vs -0.19 (95% CI -0.64 to 0.26)).

CONCLUSIONS

In this study, traditional breastfeeding advice resulted in increased weight gain and increased exclusive breastfeeding rates compared with baby-led advice. Exclusively breastfed babies who had shorter feeds (10 min or less from the first breast) gained more weight.

Prevalence of bacterial vaginosis in lesbians and heterosexual women in a community setting

OBJECTIVES

High prevalence of bacterial vaginosis (BV) has been reported in lesbians but most studies were based in sexually transmitted infection clinic settings; therefore, we wished to determine the prevalence and risk factors of BV in lesbians and heterosexual women in a community setting in the UK.

METHODS

A cross-sectional study recruiting lesbian women volunteers from community groups, events, clubs and bars. Heterosexual women were recruited from a community family planning clinic. They self-swabbed to create a vaginal smear, which was Gram-stained and categorised as BV, intermediate or normal flora. They completed a questionnaire about age, ethnic group, smoking, genital hygiene practices and sexual history.

RESULTS

Of 189 heterosexuals and 171 lesbians recruited, 354 had gradeable flora. BV was identified in 43 (25.7%) lesbians and 27 (14.4%) heterosexuals (adjusted OR 2.45, 95% CI 1.25 to 4.82; p = 0.009). Concordance of vaginal flora within lesbian partnerships was significantly greater than expected (27/31 (87%) couples, kappa = 0.63; p<0.001). Smoking significantly increased the risk of BV regardless of sexuality (adjusted OR 2.65; p = 0.001) and showed substantial concordance in lesbian partnerships but less than for concordance of flora.

CONCLUSIONS

Women who identified as lesbians have a 2.5-fold increased likelihood of BV compared with heterosexual women. The prevalence is slightly lower than clinic-based studies and as volunteers were recruited in community settings, this figure may be more representative of lesbians who attend gay venues. Higher concordance of vaginal flora within lesbian partnerships may support the hypothesis of a sexually transmissible factor or reflect common risk factors such as smoking.

Evidence of reference standard related bias in studies of plain radiograph reading performance: a meta-regression

The aim is to determine the effect of reference standard related bias on estimates of plain radiograph reading performance using studies conducted in clinical practice. Data were extracted on study eligibility, clinical and reference standard characteristics and reading performance. The choice of reference standards and the prevalence of bias are presented descriptively. Associations between bias and reading performance are estimated using a regression model that produces relative diagnostic odds ratios (RDOR) with 95% confidence intervals (CIs). Three of the 20 eligible studies addressed all five reference standard related biases; 15 studies addressed three or more. When the reference standard report is influenced by knowledge of an observer's opinion this is associated with a significant overestimation in reading performance (RDOR, 3.7; 95% CI, 1.6 to 8.3; p = 0.01). There is limited evidence that reading performance is inflated when the observer is aware of the reference standard report before commenting on the radiograph (RDOR, 1.7; 95% CI, 0.6 to 5.1) and deflated when a less valid reference standard is used (RDOR, 0.5; 95% CI, 0.1 to 2.5). There is no evidence that reading performance is affected by application of the reference standard depending on an observer's opinion and using different reference standards in the same study. In conclusion we found variation in the choice and application of reference standards in studies of plain radiograph reading performance, but only when reference standards report in the knowledge of an observer's opinion does this contribute to a significant overestimation in reading performance.

HIV enteropathy: crypt stem and transit cell hyperproliferation induces villous atrophy in HIV/Microsporidia-infected jejunal mucosa

OBJECTIVES

The study aim was to analyse the kinetics of stem and transit cells in the crypts of jejunal mucosa infected with HIV and Microsporidia.

DESIGN

The size of villi, depth of crypts and proliferative activity of transit and stem cells in jejunal mucosa were measured using morphometric techniques.

METHODS

The surface area/volume ratio (S/V) of jejunal biopsies was estimated under light microscopy using a Weibel graticule. Crypt length was measured by counting enterocytes along the crypt side from the base to the villus junction, and the mean crypt length was calculated. The S/V and crypt lengths of the jejunal mucosa of 21 HIV and Microsporidia-infected test cases were compared with 14 control cases. The labelling index in relation to the crypt cell position of 10 of the test cases was analysed compared with 13 control cases.

RESULTS

Differences were found in the S/V and crypt length, and there was a negative correlation between S/V and crypt length in test and control cases combined. Cell labelling indices fell into low and high proliferation groups. There were significant differences in labelling indices between low proliferation test cases and controls, between high proliferation test cases and controls, and between high and low proliferation test cases.

CONCLUSION

Villous atrophy induced by HIV and Microsporidia is attributed to crypt cell hyperplasia and the encroachment of crypt cells onto villi. These infections induce crypt hypertrophy by stimulating cell mitosis predominantly in transit cells but also in stem cells. Increased stem cell proliferation occurs only in high proliferation cases.

Reducing the cost of screening novel agents using the hollow fibre assay

Although the in vivo hollow fibre assay (HFA) as utilised by the National Cancer Institute is a highly effective screening tool, it has not been adopted en masse in the cancer pharmacology field. However, in laboratories which have adopted it, the effectiveness of HFA has also been confirmed. If immunocompetent mice could be used with the HFA, thereby reducing the cost of the assay, accessibility would increase and reductions in the cost of selecting appropriate agents for early clinical trials would result. It was demonstrated here that there was no difference in terms of cell growth and response to chemotherapy for cancer cells in hollow fibres in immunocompetent compared with immunodeficient mice. The HFA can thus be performed in these less expensive and more easily available mice with the implication of considerable savings to the preclinical cancer pharmacology community.

Comparative study of the subjective and objective grading of ptosis surgery outcomes

AIMS

To assess the results of blepharoptosis surgery in our hospital by subjective and objective grading of the outcome and comparing them to determine their degree of corelation.

METHODS

Retrospective interventional case series report supplemented by postal questionnaires and telephonic patient surveys. The study included 107 eyelids of 78 patients. Using a simple grading system, surgical outcome was objectively graded as good, suboptimal, or poor. Outcome was also defined according to the patients' perspective as good, suboptimal, or poor. Level of agreement between the subjective and objective grading of the outcome was measured using a weighted kappa analysis.

RESULTS

The objective results were classed as good-68/107 (63.5%), suboptimal--18 eyelids (16.8%), and poor--21 eyelids (19.6%). The subjective results were obtainable in 91 eyelids and were good--54/91 (59.3%), suboptimal--8/91 (8.7%), and poor--29/91 (32%). A mismatch between objective and subjective outcomes was seen in 16 eyelids. We saw a statistically significant corelation between the objective grading and the patients' perspective (P<0.001).

CONCLUSION

Our overall ptosis surgery results are comparable with rates previously reported. The subjective and objective outcomes of ptosis surgery may sometimes vary, but nevertheless exhibit substantive agreement when measured by this simple grading system.

The mechanics of landing when stepping down in unilateral lower-limb amputees

BACKGROUND

The ability to successfully negotiate stairs and steps is an important factor for functional independence. While work has been undertaken to understand the biomechanics of gait in lower-limb amputees, little is known about how amputees negotiate stairs and steps. This study aimed to determine the mechanics of landing in unilateral lower-limb amputees when stepping down to a new level. A secondary aim was to assess the effects of using a shank-mounted shock-absorbing device (Tele-Torsion Pylon) on the mechanics of landing.

METHODS

Ten unilateral amputees (five transfemoral and five transtibial) and eight able-bodied controls performed single steps down to a new level (73 and 219 mm). Trials were repeated in amputees with the Tele-Torsion Pylon active and inactive. The mechanics of landing were evaluated by analysing peak limb longitudinal force, maximal limb shortening, lower extremity stiffness, and knee joint angular displacement during the initial contact period, and limb and ankle angle at the instant of ground-contact. Data were collected using a Vicon 3D motion analysis system and two force platforms.

FINDINGS

Amputees landed on a straightened and near vertical limb. This limb position was maintained in transfemoral amputees, whereas in transtibial amputees knee flexion occurred. As a result lower extremity stiffness was significantly greater in transfemoral amputees compared to transtibial amputees and able-bodied controls (P<0.001). The Tele-Torsion Pylon had little effect on the mechanics of landing in transtibial amputees, but brought about a reduction in lower extremity stiffness in transfemoral amputees (P<0.05).

INTERPRETATION

Amputees used a stepping strategy that ensured the direction of the ground reaction force vector was kept anterior of the knee joint centre. Using a Tele-Torsion Pylon may improve the mechanics of landing during downward stepping in transfemoral amputees.

Comparison of transplant listing strategy in two renal dialysis centers within a regional transplant alliance

AIMS

An increasing dialysis population and insufficient supply of transplant organs necessitate that patients are carefully evaluated prior to registration on the national waiting list to ensure effective utilization of a scarce resource. We have assessed listing practice in two renal units within the North of England Transplant Alliance.

METHODS

Demographic, ethnic and clinical data were recorded at initiation of dialysis for patients from two northern English cities, Bradford (n = 209) and Hull (n = 202) between 1994-2000. Patients were stratified by two co-morbidity scoring systems. Multivariate and survival analyses were undertaken by registration status.

RESULTS

Overall, 159 patients were registered onto the waiting list. Stratification by co-morbidity predicted listing at high and low risk, but with overlap at medium scores. There was no difference in overall co-morbid burden between the two centers (p = 0.161 and 0.316, respectively, for two scoring systems). Logistic regression analysis demonstrated a center effect, Hull having an odds ratio for listing of 0.48 compared to Bradford (p = 0.041). Short- and medium-term survival in the listed group was high regardless of co-morbid score (22 vs 174 deaths in the non-listed group). In this cohort, five patients died with grafts, another three died whilst active on the waiting list. The remaining 14 patients had been removed from the list prior to death.

SUMMARY

Co-morbidity scoring schemes are unlikely to be sophisticated enough to accurately identify those who would most benefit from transplantation, and the value of clinical judgment is well-shown in this study. Standardization of registration will result in more equitable allocation of organs. However, this study has demonstrated that there are differences in listing practices even within a single alliance. Continuous assessment will allow judicious removal from the waiting list of patients who have developed an unacceptable co-morbid burden.

The gait initiation process in unilateral lower-limb amputees when stepping up and stepping down to a new level

BACKGROUND

Unilateral lower-limb amputees lead with their intact limb when stepping up and with their prosthesis when stepping down; the gait initiation process for the different stepping directions has not previously been investigated.

METHODS

Ten unilateral amputees (5 transfemoral and 5 transtibial) and 8 able-bodied controls performed single steps up and single steps down to a new level (73 and 219 mm). Duration, a-p and m-l centre of mass and centre of pressure peak displacements and centre of mass peak velocity of the anticipatory postural adjustment and step execution phase were evaluated for each stepping direction by analysing data collected using a Vicon 3D motion analysis system.

FINDINGS

There were significant differences (in the phase duration, peak a-p and m-l centre of pressure displacement and peak a-p and m-l centre of mass velocity at heel-off and at foot-contact) between both amputee sub-groups and controls (P<0.05), but not between amputee sub-groups. These group differences were mainly a result of amputees adopting a different gait initiation strategy for each stepping direction.

INTERPRETATION

Findings indicate the gait initiation process utilised by lower-limb amputees was dependent on the direction of stepping and more particularly by which limb the amputee led with; this suggests that the balance and postural control of gait initiation is not governed by a fixed motor program, and thus that becoming an amputee will require time and training to develop alternative neuromuscular control and coordination strategies. These findings should be considered when developing training/rehabilitation programs.

NAD(P)H:Quinone oxidoreductase-1 C609T polymorphism analysis in human superficial bladder cancers: relationship of genotype status to NQO1 phenotype and clinical response to Mitomycin C

NAD(P)H:Quinone oxidoreductase-1 (NQO1) has been implicated in the bioreductive activation of the clinically active anticancer drug Mitomycin C (MMC) and a polymorphic variant of NQO1 which lacks functional enzyme activity (NQO1*2) has been linked with poor survival in patients treated with MMC. The relationship between NQO1 activity and cellular response to MMC is however controversial and the aim of this study was to determine whether the response of bladder cancer patients to MMC can be forecast on the basis of NQO1*2 genotype status. Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissue from 148 patients with low to intermediate grade (G1/G2) superficial (Ta/T1) bladder cancers and NQO1*2 genotype status determined by PCR-RFLP. NQO1*2 genotype status was retrospectively compared with clinical response to intravesical administered MMC with the primary end-point being time to first recurrence. NQO1 phenotype was determined by immunohistochemistry. Of the 148 patients genotyped, 85 (57.4%) were NQO1*1 (wild-type), 59 (39.8%) were NQO1*1/*2 (heterozygotes) and 4 (2.7%) were NQO1*2/*2. No NQO1 protein expression was detected in NQO1*2/*2 tumours. A broad spectrum of NQO1 protein expression existed in tumours genotyped as NQO1*1 and NQO1*1/*2 although tumours with NQO1*1 typically expressed higher NQO1 protein. A poor correlation existed between NQO1*2 genotype status and clinical response to MMC. The results of this retrospective study suggest that tailoring MMC therapy to individual patients with superficial bladder cancer on the basis of NQO1 genotype status is unlikely to be of clinical benefit.

Immunohistochemical analysis of NAD(P)H:quinone oxidoreductase and NADPH cytochrome P450 reductase in human superficial bladder tumours: Relationship between tumour enzymology and clinical outcome following intravesical mitomycin C therapy

A central theme within the concept of enzyme-directed bioreductive drug development is the potential to predict tumour response based on the profiling of enzymes involved in the bioreductive activation process. Mitomycin C (MMC) is the prototypical bioreductive drug that is reduced to active intermediates by several reductases including NAD(P)H:quinone oxidoreductase (NQO1) and NADPH cytochrome P450 reductase (P450R). The purpose of our study was to determine whether NQO1 and P450R protein expression in a panel of low-grade, human superficial bladder tumours correlates with clinical response to MMC. A retrospective clinical study was conducted in which the response to MMC of 92 bladder cancer patients was compared to the immunohistochemical expression of NQO1 and P450R protein in archived paraffin-embedded bladder tumour specimens. A broad spectrum of NQO1 protein levels exists in bladder tumours between individual patients, ranging from intense to no immunohistochemical staining. In contrast, levels of P450R were similar with most tumours having moderate to high levels. All patients were chemotherapy naïve prior to receiving MMC and clinical response was defined as the time to first recurrence. A poor correlation exists between clinical response and NQO1, P450R or the expression patterns of various combinations of the 2 proteins. The results of our study demonstrate that the clinical response of superficial bladder cancers to MMC cannot be predicted on the basis of NQO1 and/or P450R protein expression and suggest that other factors (other reductases or post DNA damage events) have a significant bearing on tumour response.

Confidence intervals and sample size calculations for studies of film-reading performance

The relaxation of restrictions on the type of professions that can report films has resulted in radiographers and other healthcare professionals becoming increasingly involved in image interpretation in areas such as mammography, ultrasound and plain-film radiography. Little attention, however, has been given to sample size determinations concerning film-reading performance characteristics such as sensitivity, specificity and accuracy. Illustrated with hypothetical examples, this paper begins by considering standard errors and confidence intervals for performance characteristics and then discusses methods for determining sample size for studies of film-reading performance. Used appropriately, these approaches should result in studies that produce estimates of film-reading performance with adequate precision and enable investigators to optimize the sample size in their studies for the question they seek to answer.

Review article: methodological standards in radiographer plain film reading performance studies

The objectives of this paper are to raise awareness of the methodological standards that can affect the quality of radiographer plain-film reading performance studies and to determine the frequency with which these standards are fulfilled. Multiple search methods identified 30 such studies from between 1971 and the end of June 1999. The percentage of studies that fulfilled criteria for the 10 methodological standards were as follows. (1) Performance of a sample size calculation, 3%; (2) definition of a normal and abnormal report, 97%; (3) description of the sequence of events through which films passed before reporting, 94%; (4) analysis of individual groups of observers within a combination of groups, 50% (5) appropriate choice of reference standard, 80%; (6) appropriate choice of arbiter, 57%; (7) appropriate use of a control, 22%; (8) analysis of pertinent clinical subgroups, e.g. body areas, patient type, 44%; (9) availability of data for re-calculation, 59%; and (10) presentation of indeterminate results, 69%. These findings indicate variation in the application of the methodological standards to studies of radiographer's film reading performance. Careful consideration of these standards is an essential component of study quality and hence the validity of the evidence base used to underpin radiographic reporting policy.

Bias in plain film reading performance studies

Radiographers and other healthcare professionals are becoming increasingly involved in radiological reporting, for instance plain radiographs, mammography and ultrasound. Systematic reviews of research evidence can help to assimilate a knowledge base by ordering and evaluating the available evidence on the reporting accuracy of different professional groups. This article reviews the biases that can undermine the results of plain film reading performance studies. These biases are subdivided into three categories. The first category refers to the selection of subjects, including both films and professionals, and covers the validity of generalizing results beyond the study population. The other two categories are concerned with study design and the interpretation both of films and of reports and the effect on study validity. An understanding of these biases is essential when designing such studies and when interpreting the results of existing studies.

Do animals bite more during a full moon? Retrospective observational analysis

OBJECTIVE

To test the hypothesis that the incidence of animal bites increases at the time of a full moon.

DESIGN

Retrospective observational analysis.

SETTING

Accident and emergency department at a general hospital in an English city.

SUBJECTS

1621 consecutive patients, irrespective of age and sex.

MAIN OUTCOME MEASURES

Number of patients who attended an accident and emergency department during 1997 to 1999 after being bitten by an animal. The number of bites in each day was compared with the lunar phase in each month.

RESULTS

The incidence of animal bites rose significantly at the time of a full moon. With the period of the full moon as the reference period, the incidence rate ratio of the bites for all other periods of the lunar cycle was significantly lower (P <0.001).

CONCLUSIONS

The full moon is associated with a significant increase in animal bites to humans.