Lack of attentional retraining effects in cigarette smokers attempting cessation: a proof of concept double-blind randomised controlled trial

BACKGROUND

Observational studies have shown that attentional bias for smoking-related cues is associated with increased craving and relapse. Laboratory experiments have shown that manipulating attentional bias may change craving. Interventions to reduce attentional bias could reduce relapse in smokers seeking to quit. We report a clinical trial of attentional retraining in treatment-seeking smokers.

METHODS

This was a double-blind randomised controlled trial that took place in UK smoking cessation clinics. Smokers interested in quitting were randomised to five weekly sessions of attentional retraining (N=60) or placebo training (N = 58) using a modified visual probe task from one week prior to quit day. Both groups received 21 mg nicotine patches (from quit day onwards) and behavioural support. Primary outcomes included change in attentional bias reaction times four weeks after quit day on the visual probe task and craving measured weekly using the Mood and Physical Symptoms Scale. Secondary outcomes were changes in withdrawal symptoms, time to first lapse and prolonged abstinence.

RESULTS

No attentional bias towards smoking cues was found in the sample at baseline (mean difference = 3 ms, 95% CI = -2, 9). Post-training bias was not significantly lower in the retraining group compared with the placebo group (mean difference = -9 ms, 95% CI = -20, 2). There was no difference between groups in change in craving (p = 0.89) and prolonged abstinence at four weeks (risk ratio = 1.00, 95% CI = 0.70, 1.43).

CONCLUSIONS

Taken with one other trial, there appears to be no effect from clinic-based attentional retraining using the visual probe task. Attentional retraining conducted out of clinic may prove more effective.

CLINICAL TRIAL REGISTRATION

UK Clinical Trials ISRCTN 54375405.

Is screening for AF worthwhile? Stroke risk in a screened population from the SAFE study

INTRODUCTION

Atrial fibrillation (AF) is an important independent risk factor for stroke and oral anticoagulation therapy provides a highly effective treatment to reduce this risk. Active screening strategies improve detection of AF in comparison with routine care; however, whether screen-detected patients have stroke risk profiles favouring anticoagulation is unclear. Using data derived from the screening for AF in the elderly (SAFE) study, the aim of this article was to determine if patients with AF detected via active screening have stroke risk profiles that warrant prophylactic anticoagulation.

METHODS

Secondary analysis of data derived from 25 general practices within which cohorts of 200 patients were randomly allocated to opportunistic [pulse and electrocardiogram (ECG)] or systematic screening (postal invitation for ECG). Stroke risk assessment was undertaken using baseline data extracted from medical records and CHADS2 criteria. CHADS2 scores were compared between the screening groups.

RESULTS

One hundred and forty-nine new cases of AF were detected, 75 via opportunistic screening and 74 via systematic screening. CHADS2 scores were ≥1 in 83% [95% confidence interval (CI) 72.6-89.6] of patients detected via opportunistic screening and 78% (95% CI 67.7-86.2) detected via systematic screening. There were no significant differences in stroke risk profiles of patients detected via opportunistic and systematic screenings.

CONCLUSION

Stroke risk profiles of patients detected via opportunistic and systematic screenings were similar. Data derived from the SAFE study suggest that active screening for AF in patients aged ≥65 years in primary care is a useful screening programme with 78-83% of patients identified eligible for anticoagulation treatment according to the CHADS2 criteria.

Attentional bias retraining in cigarette smokers attempting smoking cessation (ARTS): study protocol for a double blind randomised controlled trial

BACKGROUND

Smokers attend preferentially to cigarettes and other smoking-related cues in the environment, in what is known as an attentional bias. There is evidence that attentional bias may contribute to craving and failure to stop smoking. Attentional retraining procedures have been used in laboratory studies to train smokers to reduce attentional bias, although these procedures have not been applied in smoking cessation programmes. This trial will examine the efficacy of multiple sessions of attentional retraining on attentional bias, craving, and abstinence in smokers attempting cessation.

METHODS/DESIGN

This is a double-blind randomised controlled trial. Adult smokers attending a 7-session weekly stop smoking clinic will be randomised to either a modified visual probe task with attentional retraining or placebo training. Training will start 1 week prior to quit day and be given weekly for 5 sessions. Both groups will receive 21 mg transdermal nicotine patches for 8-12 weeks and withdrawal-orientated behavioural support for 7 sessions. Primary outcome measures are the change in attentional bias reaction time and urge to smoke on the Mood and Physical Symptoms Scale at 4 weeks post-quit. Secondary outcome measures include differences in withdrawal, time to first lapse and prolonged abstinence at 4 weeks post-quit, which will be biochemically validated at each clinic visit. Follow-up will take place at 8 weeks, 3 months and 6 months post-quit.

DISCUSSION

This is the first randomised controlled trial of attentional retraining in smokers attempting cessation. This trial could provide proof of principle for a treatment aimed at a fundamental cause of addiction.

TRIAL REGISTRATION

Current Controlled Trials: ISRCTN54375405.

The relationship between serum TSH and free T4 in older people

The frequency distribution of serum thyroid stimulating hormone (TSH) shows a skewed pattern that may change with age. The set point of the hypothalamic-pituitary-thyroid axis for an individual is thought to be genetically determined and has been described as a log-linear relationship of serum TSH to free thyroxine (T4); however, the validity of this hypothesis has yet to be established in older people. The aim of the study was to describe the relationship between serum TSH and free T4 in older people and define factors influencing this relationship. We conducted a cross-sectional, observational study of thyroid function in a community population of older subjects over 65 years of age. The relationship between serum TSH and free T4 was not linear as previously described, but is best described as a fourth-order polynomial. Both gender and smoking status affected the relationship. This suggests that more complex modelling is required when investigating the hypothalamic-pituitary-thyroid axis.

Inverted BMI rather than BMI is a better proxy for percentage of body fat

BACKGROUND

Percentage of body fat (BF%) is a known risk factor for a range of healthcare problems but is difficult to measure. An easy to measure proxy is the weight/height(2) ratio known as the Body Mass Index (BMI kg/m(2)). However, BMI does have some inherent weaknesses which are readily overcome by its inverse iBMI (1000/BMI, cm(2)/kg).

METHODS

The association between BF% and both BMI and iBMI together with their distributional properties was explored using previously published data from healthy (n = 2993) and diseased populations (n = 298).

RESULTS

BMI is skewed whereas iBMI is symmetrical and so is better approximated by the normal distribution. The relationship between BF% and BMI is curved, but that of iBMI and BF% is linear and thus iBMI explains more of the variation in BF% than BMI. For example a unit increase in BMI for a group of thin women represents an increase of 2.3% in BF, but for obese women this represents only a 0.3% increase in BF-a 7-fold difference. The curvature stems from body mass being the numerator in BMI but the denominator in BF% resulting in a form of hyperbolic curve which is not the case with iBMI. Furthermore, BMI and iBMI have different relationships (interaction) with BF% for men and women, but these differences are less marked with iBMI.

CONCLUSIONS

Overall, these characteristics of iBMI favour its use over BMI, especially in statistical models.

Iodine status of UK schoolgirls: a cross-sectional survey

BACKGROUND

Iodine deficiency is the most common cause of preventable mental impairment worldwide. It is defined by WHO as mild if the population median urinary iodine excretion is 50-99 μg/L, moderate if 20-49 μg/L, and severe if less than 20 μg/L. No contemporary data are available for the UK, which has no programme of food or salt iodination. We aimed to assess the current iodine status of the UK population.

METHODS

In this cross-sectional survey, we systematically assessed iodine status in schoolgirls aged 14-15 years attending secondary school in nine UK centres. Urinary iodine concentrations and tap water iodine concentrations were measured in June-July, 2009, and November-December, 2009. Ethnic origin, postcode, and a validated diet questionnaire assessing sources of iodine were recorded.

FINDINGS

810 participants provided 737 urine samples. Data for dietary habits and iodine status were available for 664 participants. Median urinary iodine excretion was 80·1 μg/L (IQR 56·9-109·0). Urinary iodine measurements indicative of mild iodine deficiency were present in 51% (n=379) of participants, moderate deficiency in 16% (n=120), and severe deficiency in 1% (n=8). Prevalence of iodine deficiency was highest in Belfast (85%, n=135). Tap water iodine concentrations were low or undetectable and were not positively associated with urinary iodine concentrations. Multivariable general linear model analysis confirmed independent associations between low urinary iodine excretion and sampling in summer (p<0·0001), UK geographical location (p<0·0001), low intake of milk (p=0·03), and high intake of eggs (p=0·02).

INTERPRETATION

Our findings suggest that the UK is iodine deficient. Since developing fetuses are the most susceptible to adverse effects of iodine deficiency and even mild perturbations of maternal and fetal thyroid function have an effect on neurodevelopment, these findings are of potential major public health importance. This study has drawn attention to an urgent need for a comprehensive investigation of UK iodine status and implementation of evidence-based recommendations for iodine supplementation.

FUNDING

Clinical Endocrinology Trust.

Does self-management of oral anticoagulation therapy improve quality of life and anxiety?

BACKGROUND

Research related to service requirements for anticoagulation management has focussed on clinical and health economic outcomes and paid little attention to the impact of treatment and service delivery on patients' quality of life. This was the first large UK study to evaluate the effect of patient self-management (PSM) of oral anticoagulation on treatment-related quality of life (TRQoL) and anxiety in comparison with routine care (RC) and to explore the effect of level of therapeutic control on TRQoL and anxiety across and within each model of care.

METHODS

A quantitative survey, set in primary care in the West Midlands. The subjects were 517 randomized controlled trial participants, 242 receiving PSM and 275 RC. Postal questionnaires at baseline and 12 months comprised the State Trait Anxiety Inventory and a treatment-specific measure of positive (satisfaction and self-efficacy) and negative aspects (daily hassles, strained social network and psychological distress) of TRQoL. Change in anxiety and TRQoL scores were compared between PSM and RC. Subgroup analysis was based upon level of therapeutic control (high, medium and low).

RESULTS

Overall, 83% (n = 202) PSM and 55% (n = 161) RC patients contributed data. Anxiety scores were similar in both groups. PSM demonstrated greater improvement in self-efficacy than RC across the study period. A statistically significant between-group difference (PSM versus RC) in the self-efficacy also existed in subgroups with medium and high levels of therapeutic control.

CONCLUSIONS

PSM is not associated with increased anxiety and has a positive effect upon some aspects of TRQoL compared to RC.

The bone-anchored hearing aid in the rehabilitation of single-sided deafness: experience with 58 patients

OBJECTIVES

To assess the efficacy of the bone-anchored hearing aid (BAHA) in the rehabilitation of single-sided deafness (SSD).

STUDY DESIGN

Retrospective case-control series review.

SETTING

Tertiary referral unit.

PATIENTS

Fifty-eight consecutive patients that had a bone-anchored hearing aid for single-sided deafness completed outcome questionnaires, building upon earlier audiological assessment of 19 patients. Single-sided deafness controls (n = 49) were mainly acoustic neuroma patients.

MAIN OUTCOME MEASUREMENTS

speech discrimination testing in directional noise, speech and spatial qualities of hearing questionnaire and the Glasgow Benefit Inventory (GBI).

RESULTS

The mean follow-up time was 28.4 months. Five (13%) of the bone-anchored hearing aid patients were non-users because of lack of benefit. The audiometric testing confirmed that when noise was on the bone-anchored hearing aid side speech perception was reduced but benefited when noise was on the side of the hearing ear. There was no difference between the Speech and Spatial Qualities of Hearing Scores in bone-anchored hearing aid users and controls. In particular there was no difference in the spatial subscores. In the bone-anchored hearing aid users the median Glasgow Benefit Inventory score was 11. If the non-users are included then 13 (22%) patients had no or detrimental (negative) Benefit scores. No or negative benefit scores were more frequent in those deaf for <10 years. In open-field questions, patients felt the bone-anchored hearing aid was most useful in small groups or in 'one-to-one' conversation.

CONCLUSIONS

Bone-anchored hearing aid rehabilitation for single-sided deafness is less successful than for other indications, reflected here by relatively low median Glasgow Benefit Inventory scores. There was also no significant difference between controls and bone-anchored hearing aid users in the Speech and Spatial Qualities of Hearing Questionnaire. Patients with a longer duration of deafness report greater subjective benefit than those more recently deafened, perhaps due to differing expectations.

Comparison of imputation methods for handling missing covariate data when fitting a Cox proportional hazards model: a resampling study

BACKGROUND

The appropriate handling of missing covariate data in prognostic modelling studies is yet to be conclusively determined. A resampling study was performed to investigate the effects of different missing data methods on the performance of a prognostic model.

METHODS

Observed data for 1000 cases were sampled with replacement from a large complete dataset of 7507 patients to obtain 500 replications. Five levels of missingness (ranging from 5% to 75%) were imposed on three covariates using a missing at random (MAR) mechanism. Five missing data methods were applied; a) complete case analysis (CC) b) single imputation using regression switching with predictive mean matching (SI), c) multiple imputation using regression switching imputation, d) multiple imputation using regression switching with predictive mean matching (MICE-PMM) and e) multiple imputation using flexible additive imputation models. A Cox proportional hazards model was fitted to each dataset and estimates for the regression coefficients and model performance measures obtained.

RESULTS

CC produced biased regression coefficient estimates and inflated standard errors (SEs) with 25% or more missingness. The underestimated SE after SI resulted in poor coverage with 25% or more missingness. Of the MI approaches investigated, MI using MICE-PMM produced the least biased estimates and better model performance measures. However, this MI approach still produced biased regression coefficient estimates with 75% missingness.

CONCLUSIONS

Very few differences were seen between the results from all missing data approaches with 5% missingness. However, performing MI using MICE-PMM may be the preferred missing data approach for handling between 10% and 50% MAR missingness.

Older subjects with hyperthyroidism present with a paucity of symptoms and signs: a large cross-sectional study

CONTEXT

The absence of classical symptoms and signs of hyperthyroidism often results in delayed diagnosis and treatment.

OBJECTIVES

The objective of the study was to determine the prevalence of symptoms and signs of hyperthyroidism according to patients' age and gender as well as severity and type of hyperthyroidism.

DESIGN, PARTICIPANTS AND SETTING

This was a cross-sectional study of 3049 consecutive patients with hyperthyroidism presenting to a single secondary/tertiary care clinic.

MAIN OUTCOME MEASURES

Calculation of adjusted odds ratios for presence/absence of symptoms/signs of hyperthyroidism simultaneously analyzing the influence of patients' age/gender, disease etiology/severity, symptom duration, and smoking.

RESULTS

The majority of patients older than 61 yr had two or more symptoms. The lowest proportion of subjects reporting five or more symptoms was found in those older than 61 yr. Increasing age was associated with reduced adjusted odds ratio for the presence of most classical symptoms except for weight loss and shortness of breath, independent of disease severity. Those with more severe hyperthyroidism and smokers had increased odds ratios for most symptoms. Older age, higher serum free T(4) concentrations at diagnosis, male gender, and toxic nodular hyperthyroidism were independently associated with risk of atrial fibrillation. Signs of ophthalmopathy were associated with increasing age, smoking, longer symptom duration, and female gender.

CONCLUSIONS

Classical symptoms and signs of hyperthyroidism are significantly less prevalent in older patients and more prevalent in smokers and subjects with higher free T(4) concentrations. We propose a lower threshold for performing thyroid function tests in patients older than 60 yr, especially in those presenting with atrial fibrillation, weight loss, or shortness of breath.

Comparison of techniques for handling missing covariate data within prognostic modelling studies: a simulation study

BACKGROUND

There is no consensus on the most appropriate approach to handle missing covariate data within prognostic modelling studies. Therefore a simulation study was performed to assess the effects of different missing data techniques on the performance of a prognostic model.

METHODS

Datasets were generated to resemble the skewed distributions seen in a motivating breast cancer example. Multivariate missing data were imposed on four covariates using four different mechanisms; missing completely at random (MCAR), missing at random (MAR), missing not at random (MNAR) and a combination of all three mechanisms. Five amounts of incomplete cases from 5% to 75% were considered. Complete case analysis (CC), single imputation (SI) and five multiple imputation (MI) techniques available within the R statistical software were investigated: a) data augmentation (DA) approach assuming a multivariate normal distribution, b) DA assuming a general location model, c) regression switching imputation, d) regression switching with predictive mean matching (MICE-PMM) and e) flexible additive imputation models. A Cox proportional hazards model was fitted and appropriate estimates for the regression coefficients and model performance measures were obtained.

RESULTS

Performing a CC analysis produced unbiased regression estimates, but inflated standard errors, which affected the significance of the covariates in the model with 25% or more missingness. Using SI, underestimated the variability; resulting in poor coverage even with 10% missingness. Of the MI approaches, applying MICE-PMM produced, in general, the least biased estimates and better coverage for the incomplete covariates and better model performance for all mechanisms. However, this MI approach still produced biased regression coefficient estimates for the incomplete skewed continuous covariates when 50% or more cases had missing data imposed with a MCAR, MAR or combined mechanism. When the missingness depended on the incomplete covariates, i.e. MNAR, estimates were biased with more than 10% incomplete cases for all MI approaches.

CONCLUSION

The results from this simulation study suggest that performing MICE-PMM may be the preferred MI approach provided that less than 50% of the cases have missing data and the missing data are not MNAR.

Combining estimates of interest in prognostic modelling studies after multiple imputation: current practice and guidelines

Background

Multiple imputation (MI) provides an effective approach to handle missing covariate data within prognostic modelling studies, as it can properly account for the missing data uncertainty. The multiply imputed datasets are each analysed using standard prognostic modelling techniques to obtain the estimates of interest. The estimates from each imputed dataset are then combined into one overall estimate and variance, incorporating both the within and between imputation variability. Rubin's rules for combining these multiply imputed estimates are based on asymptotic theory. The resulting combined estimates may be more accurate if the posterior distribution of the population parameter of interest is better approximated by the normal distribution. However, the normality assumption may not be appropriate for all the parameters of interest when analysing prognostic modelling studies, such as predicted survival probabilities and model performance measures.

Methods

Guidelines for combining the estimates of interest when analysing prognostic modelling studies are provided. A literature review is performed to identify current practice for combining such estimates in prognostic modelling studies.

Results

Methods for combining all reported estimates after MI were not well reported in the current literature. Rubin's rules without applying any transformations were the standard approach used, when any method was stated.

Conclusion

The proposed simple guidelines for combining estimates after MI may lead to a wider and more appropriate use of MI in future prognostic modelling studies.

Scaling concept II rowing ergometer performance for differences in body mass to better reflect rowing in water

We investigated whether the concept II indoor rowing ergometer accurately reflects rowing on water. Forty-nine junior elite male rowers from a Great Britain training camp completed a 2000 m concept II model C indoor rowing ergometer test and a water-based 2000 m single-scull rowing test. Rowing speed in water (3.66 m/s) was significantly slower than laboratory-based rowing performance (4.96 m/s). The relationship between the two rowing performances was found to be R2=28.9% (r=0.538). We identified that body mass (m) made a positive contribution to concept II rowing ergometer performance (r=0.68, P<0.001) but only a small, non-significant contribution to single-scull water rowing performance (r=0.039, P=0.79). The contribution that m made to single-scull rowing in addition to ergometer rowing speed (using allometric modeling) was found to be negative (P<0.001), confirming that m has a significant drag effect on water rowing speed. The optimal allometric model to predict single-scull rowing speed was the ratio (ergometer speed xm(-0.23))1.87 that increased R2 from 28.2% to 59.2%. Simply by dividing the concept II rowing ergometer speed by body mass (m0.23), the resulting "power-to-weight" ratio (ergometer speed xm(-0.23)) improves the ability of the concept II rowing performance to reflect rowing on water.

Screening for dyslexia, dyspraxia and Meares-Irlen syndrome in higher education

This study reports a comparison of screening tests for dyslexia, dyspraxia and Meares-Irlen (M-I) syndrome in a Higher Education setting, the University of Worcester. Using a sample of 74 volunteer students, we compared the current tutor-delivered battery of 15 subtests with a computerized test, the Lucid Adult Dyslexia Screening test (LADS), and both of these with data on assessment outcomes. The sensitivity of this tutor battery was higher than LADS in predicting dyslexia, dyspraxia or M-I syndrome (91% compared with 66%) and its specificity was lower (79% compared with 90%). Stepwise logistic regression on these tests was used to identify a better performing subset of tests, when combined with a change in practice for M-I syndrome screening. This syndrome itself proved to be a powerful discriminator for dyslexia and/or dyspraxia, and we therefore recommend it as the first stage in a two-stage screening process. The specificity and sensitivity of the new battery, the second part of which comprises LADS plus four of the original tutor delivered subtests, provided the best overall performance: 94% sensitivity and 92% specificity. We anticipate that the new two-part screening process would not take longer to complete.

Prediction of cure and risk of hypothyroidism in patients receiving 131I for hyperthyroidism

CONTEXT

There is little consensus regarding the most appropriate dose of radioiodine ((131)I) to be administered to patients with hyperthyroidism.

OBJECTIVE

To compare the efficacy of fixed dose regimens of (131)I in curing hyperthyroidism and to define simple clinical and biochemical factors that predict outcome in individual patients.

DESIGN

Consecutive series of hyperthyroid subjects treated with (131)I.

SETTING

Single Secondary/Tertiary Care Hospital Clinic.

PARTICIPANTS

A total of 1278 patients (1013 females and 262 males, mean age 49.7 years) presenting with hyperthyroidism between 1984 and 2006.

INTERVENTION

Treatment with (131)I using a fixed dose regimen.

MAIN OUTCOME MEASURES

Probability of cure and risk of development of hypothyroidism following a single dose of (131)I.

RESULTS

Patients given a single dose of (131)I of 600 MBq (n = 485) had a higher cure rate (84.1%) compared with those receiving either 370 MBq (74.9%, P < 0.001) or those given 185 Bq (63%, P < 0.001). An increased incidence of hypothyroidism by 1 year was evident with higher doses (600 MBq: 60.4%; 370 MBq: 49.2%, P = 0.001; 185 Bq: 38.1%, P < 0.001). Binary logistic regression analysis identified a 600 Bq dose of (131)I [adjusted odds ratio, AOR 3.33 (2.28-4.85), P < 0.001], female gender [AOR 1.75 (1.23-2.47), P = 0.002], lower presenting serum free T4 concentration [AOR 1.01 (1.01-1.02), P < 0.001] and absence of a palpable goitre [AOR 3.33 (2.00-5.56), P < 0.001] to be independent predictors of cure. Similarly, a 600 MBq dose [AOR 3.79 (2.66-5.38), P < 0.001], female gender [AOR 1.46 (1.05-2.02), P = 0.02], younger age [AOR 1.03 (1.02-1.04), P < 0.001], absence of a palpable goitre [AOR 3.85 (2.38-5.88), P < 0.001] and presence of ophthalmopathy [AOR 1.57 (1.06-2.31), P = 0.02] were identified as independent factors predicting the probability of development of hypothyroidism at one year. Based on these findings, formulae to indicate probability of cure and risk of hypothyroidism for application to individual patients were derived.

CONCLUSIONS

Simple clinical/biochemical criteria can be used to predict outcome after (131)I treatment. These factors determine that males, those with severe biochemical hyperthyroidism, and those with a palpable goitre require larger doses (600 MBq) in order to achieve cure.

Standardisation of rates using logistic regression: a comparison with the direct method

Background

Standardisation of rates in health services research is generally undertaken using the direct and indirect arithmetic methods. These methods can produce unreliable estimates when the calculations are based on small numbers. Regression based methods are available but are rarely applied in practice. This study demonstrates the advantages of using logistic regression to obtain smoothed standardised estimates of the prevalence of rare disease in the presence of covariates.

Methods

Step by step worked examples of the logistic and direct methods are presented utilising data from BETS, an observational study designed to estimate the prevalence of subclinical thyroid disease in the elderly. Rates calculated by the direct method were standardised by sex and age categories, whereas rates by the logistic method were standardised by sex and age as a continuous variable.

Results

The two methods produce estimates of similar magnitude when standardising by age and sex. The standard errors produced by the logistic method were lower than the conventional direct method.

Conclusion

Regression based standardisation is a practical alternative to the direct method. It produces more reliable estimates than the direct or indirect method when the calculations are based on small numbers. It has greater flexibility in factor selection and allows standardisation by both continuous and categorical variables. It therefore allows standardisation to be performed in situations where the direct method would give unreliable results.

Conservative versus primary surgical treatment of acoustic neuromas: a comparison of rates of facial nerve and hearing preservation

OBJECTIVES

To determine whether patients with small to medium sized acoustic neuromas managed conservatively suffer reduced rates of facial nerve and hearing preservation when compared with patients undergoing primary surgery.

DESIGN

An intention-to-treat comparison between patients managed conservatively at first presentation and those managed with primary surgery.

SETTING

Tertiary referral neurotological centre in Birmingham, UK.

PARTICIPANTS

Data were drawn from our database of 487 sporadic acoustic neuromas managed from 1997 to present day.

MAIN OUTCOME MEASURES

Facial nerve status (assessed using the House-Brackmann system) was collated for all conservatively managed patients (n = 167) and compared with that expected when calculated from primarily surgically managed tumours of equivalent size (n = 121). A chi-square test was employed to test the statistical significance of any difference. Hearing preservation (maintenance of AAO-HNS Class) in patients presenting with Class A or B hearing was compared between conservatively managed patients and those with primary surgical management.

RESULTS

Observed facial nerve preservation in conservatively managed patients was significantly better (P < 0.001) than expected when calculated from rates of facial nerve preservation in surgically managed patients. Hearing preservation was also significantly more successful in conservatively managed patients (Pearson chi-square: P < 0.000).

CONCLUSIONS

An initial period of conservative management is a safe and reasonable management policy in all acoustic neuromas up to 2 cm in size at the cerebello-pontine angle. Given that there are no failsafe ways of deciding potential for growth in acoustic neuromas, initial conservative management of these tumours offers superior hearing and facial nerve preservation when compared with primary surgical treatment.

Self-testing for cancer: a community survey

BACKGROUND

Cancer-related self-tests are currently available to buy in pharmacies or over the internet, including tests for faecal occult blood, PSA and haematuria. Self-tests have potential benefits (e.g. convenience) but there are also potential harms (e.g. delays in seeking treatment). The extent of cancer-related self-test use in the UK is not known. This study aimed to determine the prevalence of cancer-related self-test use.

METHODS

Adults (n = 5,545) in the West Midlands were sent a questionnaire that collected socio-demographic information and data regarding previous and potential future use of 18 different self-tests. Prevalence rates were directly standardised to the England population. The postcode based Index of Multiple Deprivation 2004 was used as a proxy measure of deprivation.

RESULTS

2,925 (54%) usable questionnaires were returned. 1.2% (95% CI 0.83% to 1.66%) of responders reported having used a cancer related self test kit and a further 36% reported that they would consider using one in the future. Logistic regression analyses suggest that increasing age, deprivation category and employment status were associated with cancer-related self-test kit use.

CONCLUSION

We conclude that one in 100 of the adult population have used a cancer-related self-test kit and over a third would consider using one in the future. Self-test kit use could alter perceptions of risk, cause psychological morbidity and impact on the demand for healthcare.

Are There Limits to Swimming World Records?

The purpose of this article was to investigate whether swimming world records are beginning to plateau and whether the inequality between men and women's swimming performances is narrowing, similar to that observed in running world records. A flattened "S-shaped curve" logistic curve is fitted to 100-m, 200-m, and 400-m front-crawl world-record swimming speeds for men and women from 1 May 1957 to the present time, using the non-linear least-squares regression. The inequality between men and women's world records is also assessed using the ratio, Women's/Men's world record speeds. The results confirm that men and women's front-crawl swimming world-record speeds are plateauing and the ratio between women's and men's world records has remained stable at approximately 0.9. In conclusion, the logistic curves provide evidence that swimming world-record speeds experienced a period of "accelerated" growth/improvements during the 1960 - 1970s, but are now beginning to plateau. The period of acceleration corresponded with numerous advances in science and technology but also coincided with the anecdotal evidence for institutionalised doping. Also noteworthy, however, is the remarkably consistency in the women's/men's world record ratio, circa 0.9, similar to those observed in middle and long distance running performances. These finding supports the notion that a 10 % gender inequality exists for both swimming and running.

Short stay emergency admissions to a West Midlands NHS Trust: a longitudinal descriptive study, 2002 2005

OBJECTIVES

To describe changes and characteristics in emergency admissions to a West Midlands National Health Service Trust, 2002-2005, with a focus on short stay emergency admissions.

METHODS

A longitudinal descriptive study using retrospective analysis of routine admissions data. Admissions were categorised as short (0/1 day) or long (>or=2 days) and examined separately using a General Linear Model. Factors favouring short stays as opposed to long stays were examined using multivariable logistic regression.

RESULTS

There were 151 478 emergency admissions to the Trust between 1 April 2002 and 31 December 2005, of which 2910 (1.92%) had no discharge date recorded. Adjusted means showed a 7.76% increase in emergency admissions in winter months (October-January) and a 14.50% increase across the study period. Increases were greater in short stay (34.03%) than long stay emergency admissions (8.38%). Odds of short stays in admitted patients increased by 25%. Higher odds of short stays were also associated with younger age, winter month and medical admitting specialty (p<0.001).

CONCLUSIONS

Increases in emergency admissions were greater in short stay than long stay cases. Reasons for this may be both appropriate (increased use of clinical protocols and falling average length of stay) and detrimental (pressure to meet 4 h emergency department target, changing primary care provision). Further research is needed before generalising findings to other Trusts.

Association between serum free thyroxine concentration and atrial fibrillation

BACKGROUND

Previous studies have suggested that minor changes in thyroid function are associated with risk of atrial fibrillation (AF). Our objective was to determine the relationship between thyroid function and presence of atrial fibrillation (AF) in older subjects.

METHODS

A population-based study of 5860 subjects 65 years and older, which excluded those being treated for thyroid dysfunction and those with previous hyperthyroidism. Main outcome measures included tests of thyroid function (serum free thyroxine [T(4)] and thyrotropin [TSH]) and the presence of AF on resting electrocardiogram.

RESULTS

Fourteen subjects (0.2%) had previously undiagnosed overt hyperthyroidism and 126 (2.2%), subclinical hyperthyroidism; 5519 (94.4%) were euthyroid; and 167 (2.9%) had subclinical hypothyroidism and 23 (0.4%), overt hypothyroidism. The prevalence of AF in the whole cohort was 6.6% in men and 3.1% in women (odds ratio, 2.23; P<.001). After adjusting for sex, logistic regression showed a higher prevalence of AF in those with subclinical hyperthyroidism compared with euthyroid subjects (9.5% vs 4.7%; adjusted odds ratio, 2.27; P=.01). Median serum free T(4) concentration was higher in those with AF than in those without (1.14 ng/dL; interquartile range [IQR], 1.05-1.27 ng/dL [14.7 pmol/L; IQR, 13.5-16.4 pmol/L] vs 1.10 ng/dL; IQR, 1.00-1.22 ng/dL [14.2 pmol/L; IQR, 12.9-15.7 pmol/L]; P<.001), and higher in those with AF when analysis was limited to euthyroid subjects (1.13 ng/dL; IQR, 1.05-1.26 ng/dL [14.6 pmol/L; IQR, 13.5-16.2 pmol/L] vs 1.10 ng/dL; IQR, 1.01-1.21 ng/dL [14.2 pmol/L; IQR, 13.0-15.6 pmol/L]; P=.001). Logistic regression showed serum free T(4) concentration, increasing category of age, and male sex all to be independently associated with AF. Similar independent associations were observed when analysis was confined to euthyroid subjects with normal TSH values.

CONCLUSIONS

The biochemical finding of subclinical hyperthyroidism is associated with AF on resting electrocardiogram. Even in euthyroid subjects with normal serum TSH levels, serum free T(4) concentration is independently associated with AF.

Different faecal sampling methods alter the acceptability of faecal occult blood testing: A cross sectional community survey

BACKGROUND

A bowel cancer screening programme is being introduced in the UK. The programme will screen men and women aged 60-69 using faecal occult blood testing (FOBt). Uptake rates in the pilot evaluation were <60%. This study aimed to determine whether the acceptability of FOBt is associated with the sampling method or previous exposure to FOBt.

METHODS

Postal questionnaire assessing the perceived acceptability of three potential methods of FOBt sampling: (1) sterile transport swab; (2) smear card [as used in the national screening roll-out]; (3) faecal specimen pot [routinely used in the NHS for stool samples]. Study population comprised those aged 50-69.

RESULTS

Response rate was 63%. FOBt was reported as acceptable by 94.5%. Acceptability fell significantly when sampling methods were detailed. The swab was rated more acceptable than the card or the pot (90.2% versus 62.9% versus 63.0%, p<0.0005). FOBt acceptability did not vary with previous experience of FOBt.

CONCLUSIONS

The acceptability of FOBt varied by the sampling method described. The smear card, such as that used in the national screening programme, was the least preferred method. To increase the uptake of screening, alternative methods of faecal sampling should be considered.

Origin of Human Bipedalism As an Adaptation for Locomotion on Flexible Branches

Human bipedalism is commonly thought to have evolved from a quadrupedal terrestrial precursor, yet some recent paleontological evidence suggests that adaptations for bipedalism arose in an arboreal context. However, the adaptive benefit of arboreal bipedalism has been unknown. Here we show that it allows the most arboreal great ape, the orangutan, to access supports too flexible to be negotiated otherwise. Orangutans react to branch flexibility like humans running on springy tracks, by increasing knee and hip extension, whereas all other primatesdothe reverse. Human bipedalism is thus less an innovation than an exploitation of a locomotor behavior retained from the common great ape ancestor.

The effect of walking on fitness, fatness and resting blood pressure: a meta-analysis of randomised, controlled trials

OBJECTIVE

The purpose of this review was to perform a meta-analysis on walking intervention studies in order to quantify the magnitude and direction of walking-induced changes that may alter selected cardiovascular risk factors.

METHOD

Twenty-four randomised controlled trials of walking were assessed for quality on a three-point scale. Data from these studies were pooled and treatment effects (TEs) were calculated for six traditional cardiovascular risk variables: body weight, body mass index (BMI), percentage body fat, aerobic fitness (V(O(2) )max in ml kg(-1) min(-1)) and resting systolic and diastolic blood pressure. Weighted TEs were analysed using a random effects model with weights obtained using the inverse of the individual TE variances. Random effects models were used to investigate the influence of both study quality and exercise volume (<150 vs. > or =150 min week(-1)).

RESULTS

Random effects modelling showed that walking interventions increased V(O(2) )max and decreased body weight, BMI, percent body fat and resting diastolic blood pressure in previously sedentary adults (p<0.05 for all).

CONCLUSION

The results of this study provide evidence that healthy but sedentary individuals who take up a programme of regular brisk walking improves several known risk factors for cardiovascular disease.

The design of simulation studies in medical statistics

Simulation studies use computer intensive procedures to assess the performance of a variety of statistical methods in relation to a known truth. Such evaluation cannot be achieved with studies of real data alone. Designing high-quality simulations that reflect the complex situations seen in practice, such as in prognostic factors studies, is not a simple process. Unfortunately, very few published simulation studies provide sufficient details to allow readers to understand fully all the processes required to design a simulation study. When planning a simulation study, it is recommended that a detailed protocol be produced, giving full details of how the study will be performed, analysed and reported. This paper details the important considerations necessary when designing any simulation study, including defining specific objectives of the study, determining the procedures for generating the data sets and the number of simulations to perform. A checklist highlighting the important considerations when designing a simulation study is provided. A small review of the literature identifies the current practices within published simulation studies.

Patient self management of oral anticoagulation in routine care in the UK

BACKGROUND

Self management of anticoagulation: a randomised trial (SMART) was the first large scale UK trial to assess clinical and cost effectiveness of patient self management (PSM) of oral anticoagulation therapy compared to routine care. SMART showed that while PSM was as clinically effective as routine care, it was not as cost effective. SMART adds to the growing body of trial data to support PSM; however there are no data on clinical effectiveness and cost of PSM in routine care.

AIM

To evaluate clinical effectiveness of PSM compared to routine care outside trial conditions.

METHODS

A retrospective multicentre matched control study. 63 PSM patients from primary care in the West Midlands were matched by age and international normalised ratio (INR) target with controls. INR results were collected for the period 1 July 2003-30 June 2004. The primary outcome measure was INR control.

RESULTS

38 PSM and 40 control patients were recruited. INR percentage time in range was 70% PSM vs 64% controls. 60% PSM were having a regular clinical review, 45% were performing an internal quality control (IQC) test and 82% were performing external quality assurance (EQA) on a regular basis.

CONCLUSION

PSM outside trial conditions is as clinically effective as routine UK care.

Estimating the rate of oxygen consumption during submersion from the heart rate of diving animals

How animals manage their oxygen stores during diving and other breath-hold activities has been a topic of debate among physiologists for decades. Specifically, while the behavior of free-ranging diving animals suggests that metabolism during submersion must be primarily aerobic in nature, no studies have been able to determine their rate of oxygen consumption during submersion (Vo(2)d) and hence prove that this is the case. In the present study, we combine two previously used techniques and develop a new model to estimate Vo(2)d accurately and plausibly in a free-ranging animal and apply it to data for macaroni penguins (Eudyptes chrysolophus) as an example. For macaroni penguins at least, Vo(2)d can be predicted by measuring heart rate during the dive cycle and the subsequent surface interval duration. Including maximum depth of the dive improves the accuracy of these predictions. This suggests that energetically demanding locomotion events within the dive combine with the differing buoyancy and locomotion costs associated with traveling to depth to influence its cost in terms of oxygen use. This will in turn effect the duration of the dive and the duration of the subsequent recovery period. In the present study, Vo(2)d ranged from 4 to 28 ml.min(-1).kg(-1), indicating that, at least as far as aerobic metabolism was concerned, macaroni penguins were often hypometabolic, with rates of oxygen consumption usually below that for this species resting in water (25.6 ml.min(-1).kg(-1)) and occasionally lower than that while resting in air (10.3 ml.min(-1).kg(-1)).

Cardiovascular manifestations of hyperthyroidism before and after antithyroid therapy: a matched case-control study

OBJECTIVES

This study sought to prospectively evaluate the prevalence of cardiovascular abnormalities in patients with overt hyperthyroidism before and after antithyroid therapy.

BACKGROUND

Overt hyperthyroidism is associated with recognized cardiovascular effects believed to be reversed by antithyroid therapy; however, increasing data suggest significant long-term cardiovascular mortality.

METHODS

A total of 393 (312 women, 81 men) consecutive unselected patients with overt hyperthyroidism were recruited and compared with 393 age- and gender-matched euthyroid control subjects. Hyperthyroid patients were re-evaluated after antithyroid therapy. Findings in patients and matched control subjects were compared at presentation, after treatment when patients had subclinical hyperthyroidism biochemically, and when patients were rendered biochemically euthyroid. All had a structured cardiovascular history and examination, including measurements of blood pressure (BP) and pulse rate. All had resting 12-lead electrocardiogram and 24-h digital Holter monitoring of cardiac rhythm.

RESULTS

A higher prevalence of cardiovascular symptoms and signs, as well as abnormal hemodynamic parameters, was noted among hyperthyroid patients at recruitment compared with control subjects. Cardiac dysrhythmias, especially supraventricular, were more prevalent among patients than among control subjects. Palpitation and dyspnea, postural decrease in systolic pressure, and atrial fibrillation (AF) remained more prevalent in treated hyperthyroid subjects with subclinical hyperthyroidism compared with control subjects, and remained more prevalent after restoration of euthyroidism. Predictors for successful reversion to sinus rhythm in those with AF associated with hyperthyroidism were lower BP measurements at recruitment and an initial hypothyroid state induced by antithyroid therapy. Mortality was higher in hyperthyroid subjects than in control subjects after a mean period of follow-up of 66.6 months.

CONCLUSIONS

Cardiovascular abnormalities are common in patients with overt hyperthyroidism at presentation, but some persist despite effective antithyroid therapy.

Cluster analysis as a method for determining size ranges for spinal implants: disc lumbar replacement prosthesis dimensions from magnetic resonance images

STUDY DESIGN

Statistical analysis of clinical radiologic data.

OBJECTIVE

To develop an objective method for finding the number of sizes for a lumbar disc replacement.

SUMMARY OF BACKGROUND DATA

Cluster analysis is a well-established technique for sorting observations into clusters so that the "similarity level" is maximal if they belong to the same cluster and minimal otherwise.

METHODS

Magnetic resonance scans from 69 patients, with no abnormal discs, yielded 206 sagittal and transverse images of 206 discs (levels L3-L4-L5-S1). Anteroposterior and lateral dimensions were measured from vertebral margins on transverse images; disc heights were measured from sagittal images. Hierarchical cluster analysis was performed to determine the number of clusters followed by nonhierarchical (K-means) cluster analysis. Discriminant analysis was used to determine how well the clusters could be used to classify an observation.

RESULTS

The most successful method of clustering the data involved the following parameters: anteroposterior dimension; lateral dimension (both were the mean of results from the superior and inferior margins of a vertebral body, measured on transverse images); and maximum disc height (from a midsagittal image). These were grouped into 7 clusters so that a discriminant analysis was capable of correctly classifying 97.1% of the observations. The mean and standard deviations for the parameter values in each cluster were determined.

CONCLUSIONS

Cluster analysis has been successfully used to find the dimensions of the minimum number of prosthesis sizes required to replace L3-L4 to L5-S1 discs; the range of sizes would enable them to be used at higher lumbar levels in some patients.

Serum thyrotropin concentration as a novel predictor of malignancy in thyroid nodules investigated by fine-needle aspiration

CONTEXT

Thyroid nodules and goiter are common, and fine-needle aspiration biopsy (FNAB) is the first investigation of choice in distinguishing benign from malignant disease.

OBJECTIVE

The objective of the study was to assess whether simple clinical and biochemical parameters can predict the likelihood of thyroid malignancy in subjects undergoing FNAB.

DESIGN

The design was a prospective cohort.

SETTING

The study was conducted at a single secondary/tertiary care clinic.

PARTICIPANTS

One thousand five hundred consecutive patients without overt thyroid dysfunction (1304 females and 196 males, mean age 47.8 yr) presenting with palpable thyroid enlargement between 1984 and 2002 were evaluated by FNAB of the thyroid.

INTERVENTION(S)

There were no interventions.

MAIN OUTCOME MEASURES

Goiter type was assessed clinically and classified as diffuse in 183, multinodular in 456, or solitary nodule in 861 cases. Serum TSH concentration at presentation was measured in a sensitive assay in patients presenting after 1988 (n = 1183). The final cytological or histological diagnosis was determined after surgery (n = 553) or a minimum 2-yr clinical follow-up period (mean 9.5 yr, range 2-18 yr).

RESULTS

The overall sensitivity and specificity of FNAB in predicting malignancy were 88 and 84%, respectively. The risk of diagnosis of malignancy rose in parallel with the serum TSH at presentation, with significant increases evident in patients with serum TSH greater than 0.9 mU/liter, compared with those with lower TSH. Binary logistic regression analysis revealed significantly increased adjusted odds ratios (AORs) for the diagnosis of malignancy in subjects with serum TSH 1.0-1.7 mU/liter, compared with TSH less than 0.4 mU/liter [AOR 2.72, 95% confidence interval (CI) 1.02-7.27, P = 0.046], with further increases evident in those with TSH 1.8-5.5 mU/liter (AOR 3.88, 95% CI 1.48-10.19, P = 0.006, compared with TSH < 0.4 mU/liter) and greater than 5.5 mU/liter (AOR 11.18, 95% CI 3.23-8.63, P < 0.001, compared with TSH < 0.4 mU/liter). Males (AOR 1.8, 95% CI 1.04-3.1, P = 0.04), younger patients (AOR 1.1, 95% CI 1.01-1.15, P = 0.025), and those with clinically solitary nodules (AOR 2.53, 95% CI 1.5-4.28, P = 0.001) were also at increased risk. Based on these findings, a formula to predict the risk of the diagnosis of thyroid malignancy in individual patients, taking into account their gender, age, goiter type determined clinically, and serum TSH, was calculated.

CONCLUSIONS

The risk of malignancy in a thyroid nodule increases with serum TSH concentrations within the normal range. In addition to patient's gender, age, and goiter type, the serum TSH concentration at presentation is an independent predictor of the presence of thyroid malignancy. We propose that these simple clinical and biochemical factors can serve as an adjunct to FNAB in predicting risk of malignancy.

Modeling physiological and anthropometric variables known to vary with body size and other confounding variables

This review explores the most appropriate methods of identifying population differences in physiological and anthropometric variables known to differ with body size and other confounding variables. We shall provide an overview of such problems from a historical point of view. We shall then give some guidelines as to the choice of body-size covariates as well as other confounding variables, and show how these might be incorporated into the model, depending on the physiological dependent variable and the nature of the population being studied. We shall also recommend appropriate goodness-of-fit statistics that will enable researchers to confirm the most appropriate choice of model, including, for example, how to compare proportional allometric models with the equivalent linear or additive polynomial models. We shall also discuss alternative body-size scaling variables (height, fat-free mass, body surface area, and projected area of skeletal bone), and whether empirical vs. theoretical scaling methodologies should be reported. We shall offer some cautionary advice (limitations) when interpreting the parameters obtained when fitting proportional power function or allometric models, due to the fact that human physiques are not geometrically similar to each other. In conclusion, a variety of different models will be identified to describe physiological and anthropometric variables known to vary with body size and other confounding variables. These include simple ratio standards (e.g., per body mass ratios), linear and additive polynomial models, and proportional allometric or power function models. Proportional allometric models are shown to be superior to either simple ratio standards or linear and additive polynomial models for a variety of different reasons. These include: 1) providing biologically interpretable models that yield sensible estimates within and beyond the range of data; and 2) providing a superior fit based on the Akaike information criterion (AIC), Bayes information criterion (BIC), or maximum log-likelihood criteria (resulting in a smaller error variance). As such, these models will also: 3) naturally lead to a more powerful analysis-of-covariance test of significance, which will 4) subsequently lead to more correct conclusions when investigating population (epidemiological) or experimental differences in physiological and anthropometric variables known to vary with body size.

Lack of association between serum TSH or free T4 and body mass index in euthyroid subjects

BACKGROUND

There is ongoing debate regarding the influence of minor changes in thyroid status within the normal range and body mass index (BMI). Overt thyroid dysfunction is well recognized to affect weight, but the influence of minor perturbations of thyroid function remains unclear.

AIM OF THE STUDY

To examine in euthyroid subjects the association of serum concentrations of TSH and free T4 within the normal range and BMI. To compare serum TSH and free T4 concentrations in nonobese and obese subjects.

SUBJECTS AND METHODS

A cohort of 401 euthyroid subjects with normal serum TSH (361 females, 40 males, mean age 48.2 years) who had been referred to a Thyroid Clinic due to the presence of a thyroid nodule or goitre. Measurements of serum TSH and free T4 were recorded, together with BMI (calculated from weight and height). Associations between measures of TSH, free T4 and BMI were investigated.

RESULTS

There was no association between either serum TSH or free T4 concentration when considered as a continuous variable and BMI, and no difference in BMI when subjects were categorized according to serum TSH or free T4. There was also no difference in serum TSH or free T4 between lean and obese euthyroid subjects. Evidence of thyroid autoimmunity indicated by the presence of antibodies to thyroid peroxidase was likewise not associated with a difference in BMI.

CONCLUSION

This study provides no evidence for an association between thyroid status within the normal range and BMI.

Analysis of an administrative database of half a million restorations over 11 years

AIM

This paper describes the analytical approach used to extract empirical distributions of the interval from the date of placement of a direct restoration to the date when the next intervention took place on the same tooth, that is, an estimate of restoration survival.

METHODS

Data, based on the complete attendance and treatment history, over the eleven years from 1991 to 2001, of a statistically representative sample of 82,537 General Dental Services' patients in England and Wales, all of whom received at least one directly placed restoration during the observation period, have been analysed. The patients on the database received a total of 719,009 courses of treatment, and there were 503,965 occasions when a tooth was directly restored. The method of analysis involved, first, the estimation of the probability that the patient will eventually return, given an interval without attending, by analysing the observed patterns of re-attendance. This estimated probability of re-attendance was then used to modify the standard Kaplan-Meier procedure to produce realistic estimates of the hazard of re-intervention.

RESULTS

The results demonstrate that the newly developed methodology has produced robust estimates of the distribution of survival intervals to next intervention on the same tooth. Regarding attendance patterns, re-attendance probability varies with length of interval since last attendance. There is also a strong association with patient age. The older the patient, the more likely it is that a gap in attendance is indicative that the patient will never return. The detailed cumulative survival curve over eleven years has been plotted and forty-seven per cent of restorations, overall, survived without re-intervention for at least ten years. The entire analysis was then successfully replicated on a second, independently selected, sample of attendance and treatment records, confirming the ten-year survival estimate.

CONCLUSIONS

This newly developed methodology has produced robust estimates of the distribution of survival intervals to next intervention on the same tooth. Patient re-attendance probability varies with length of interval since last attendance and with patient age. The ten-year overall survival rate to next intervention on the same tooth for direct restorations placed within the GDS in England and Wales is circa 47%.

Outcome of direct restorations placed within the general dental services in England and Wales (Part 3): Variation by dentist factors

AIM

It is the aim of this paper to investigate the survival of direct-placement restorations provided within the General Dental Services in England and Wales, in relation to the dentist factors which may affect this.

METHODS

For this work, survival of a restoration was considered to be the time between the date of completion of the course of treatment in which it was placed and the date of acceptance of the course of treatment when the next tooth-specific treatment was carried out on the same tooth. A modified version of Kaplan-Meier statistical methodology was used to plot survival curves for restorations placed by different subgroups of dentists.

RESULTS

The age and experience of the dentist who placed the original restoration were found to be related to restoration survival, with older dentists having shorter intervals from placement of restorations to re-intervention (P<0.001). Country of qualification seems not to be relevant within Europe in terms of restoration survival, but dentists who qualified outside Europe achieve different restoration survival times for the restorations that they place. Dentist's gender has no relationship with time from restoration to re-intervention.

CONCLUSIONS

Dentist factors such as age, country of qualification, and employment status, but not the gender of the dentist, have been found to influence the survival of directly placed restorations.

Outcome of direct restorations placed within the general dental services in England and Wales (Part 2): Variation by patients' characteristics

AIM

It is the purpose of this paper to investigate the outcome of direct-placement restorations provided within the General Dental Services in England and Wales, and to identify the patient factors which may affect this using a database derived from patient treatment data at the Dental Practice Board.

METHODS

For this work, survival of a restoration was considered to be the time between the date of completion of the course of treatment in which it was placed and the date of acceptance of the course of treatment when the next tooth-specific treatment was carried out on the same tooth. A modified version of Kaplan-Meier statistical methodology was used to plot survival curves for restorations in different subgroups of patients within the population of patients for whom data were available.

RESULTS

The results indicated that patients' gender was of little significance in the long-term survival of restorations, but patient age had a significant effect, with the restorations of older patients surviving less well than those of younger patients (P<0.001). The charge-paying status of the patient had a statistically significant but small effect (P<0.001), with survival for charge-payers being slightly higher throughout the observation period. There was a strong relationship between attendance frequency and survival time, with restorations of more frequent attenders performing less well than those of less frequent attenders (P<0.001).

CONCLUSIONS

Patient factors such as age, charge-paying status, interval between courses of treatment, continuity of care by one dentist, and annual gross fees incurred, have all been found to influence the survival of directly placed restorations.

Outcome of direct restorations placed within the general dental services in England and Wales (Part 1): Variation by type of restoration and re-intervention

AIM

It is the aim of this paper to consider the dental factors associated with the need for re-intervention on a restoration, such as the tooth position, size of cavity, and restoration material.

METHODS

Patients whose data were included in this study were those whose birthdays were included within a set of randomly selected dates, one of which was chosen in each possible year of birth. The restoration records consisted of all those records containing directly placed restorations which related to courses of treatment of patients 18 years or older with last date on the claim form after 31st December 1990, and with date of acceptance after September 1990 and before January 2002. For each tooth treated with a direct restoration the subsequent history of intervention on that tooth was consulted, and the next date of intervention, if any could be found in the extended data set, was obtained. Thus a data set was created of direct restorations with their dates of placement and their dates, if any, of re-intervention.

RESULTS

Data for over 80,000 different adult patients were analyzed, of whom 46% were male and 54% female. A total of 503,965 tooth restoration occasions were obtained from the data over a period of eleven years. Single surface amalgam restorations were found to have the longest survival --58% at 10 years, and glass ionomer the shortest 38% at 10 years. Factors which were found to reduce restoration outcome included involvement of the incisal angle in composite restorations--this resulted in a reduction in median survival of around two years--and the placement of pins in a restoration. The presence of a root filling was also found to reduce the survival of restorations in the crown of the root filled tooth.

CONCLUSIONS

Small amalgam restorations have longer survival times before re-intervention than large amalgam restorations such as MOD. Composite and glass ionomer restorations perform less well than amalgam restorations. Pin placement and root filling reduce the survival time of restorations.

Lymphocyte telomere dynamics and telomerase activity in inflammatory bowel disease: effect of drugs and smoking

BACKGROUND

The chromosome instability observed in peripheral blood lymphocytes in ulcerative colitis could be a biomarker of cancer susceptibility.

AIM

To determine whether accelerated telomere shortening could explain chromosome instability and assess the effect of drugs and smoking on telomere dynamics in these cells.

METHODS

Peripheral blood lymphocytes were isolated from ulcerative colitis, Crohn's disease and non-inflammatory bowel disease control patients. Telomere lengths were measured by quantitative real-time polymerase chain reaction. After activation and cell separation, telomerase activity and human telomerase reverse transcriptase messenger ribonucleic acid were measured by telomerase repeat amplification protocol enzyme-linked immunosorbent serological assay and quantitative real-time polymerase chain reaction, respectively.

RESULTS

Age-related telomere loss in peripheral blood lymphocytes was similar in ulcerative colitis, Crohn's disease and control patients. Telomerase activity decreased with age in all groups and correlated positively with telomere length (r = 0.489, P = 0.006). Among Crohn's disease patients, azathioprine was associated with decreased telomerase activity (0.66 vs. 1.54, P = 0.026, P < 0.05) and smoking was associated with decreased human telomerase reverse transcriptase mRNA expression (10.5 vs. 33.3, P = 0.036, P < 0.05).

CONCLUSIONS

Telomere shortening is not accelerated and therefore cannot be the cause of the chromosome instability observed in ulcerative colitis peripheral blood lymphocytes. Azathioprine and cigarette smoking modify telomerase expression in these cells.

Heart rate variability and turbulence in hyperthyroidism before, during, and after treatment

Patients with subclinical and treated overt hyperthyroidism have an excess vascular mortality rate. Several symptoms and signs in overt hyperthyroidism suggest abnormality of cardiac autonomic function that may account in part for this excess mortality rate, but few studies have examined cardiac autonomic function in untreated and treated hyperthyroidism. We assessed heart rate turbulence (HRT) and time-domain parameters of heart rate variability in a large, unselected cohort of patients with overt hyperthyroidism referred to our thyroid clinic (n = 259) and compared findings with a group of normal subjects with euthyroidism (n = 440). These measures were also evaluated during antithyroid therapy (when serum-free thyroxine and triiodothyronine concentrations returned to normal but thyrotropin remained suppressed (i.e., subclinical hyperthyroidism, n = 110) and when subjects were rendered clinically and biochemically euthyroid (normal serum thyrotropin, free thyroxine and triiodothyronine concentrations, n = 219). We found that overall measures of heart rate variability and those specific for cardiac vagal modulation were attenuated in patients with overt hyperthyroidism compared with normal subjects; measurements of overall heart rate variability remained low in those with low levels of serum thyrotropin but returned to normal in patients with biochemical euthyroidism. Measurements of HRT (onset and slope) were also decreased in patients with overt hyperthyroidism, but HRT slope returned to normal values with antithyroid treatment. This study is the first to evaluate HRT in overt and treated hyperthyroidism.

Does Lower-Body BMD Develop at the Expense of Upper-Body BMD in Female Runners?

PURPOSE

Evidence suggests that exercise plays an important role in stimulating site-specific bone mineral density (BMD). However, what is less well understood is how these benefits dissipate throughout the body. Hence, the purpose of the present study was to compare the levels of, and the correlation between, BMD recorded at 10 sites in female endurance runners, and to investigate possible determinants responsible for any inter-site differences observed.

METHODS

Repeated measures ANOVA was used to compare the BMD between sites and factor analysis was used to describe the pattern of intersite correlations. Allometric ANCOVA was used to identify the primary determinants of bone mass and how these varied between sites.

RESULTS

The ANOVA and factor analysis identified systematic differences in BMD between sites, with the greatest BMD being observed in the lower-body sites, in particular the legs. An investigation into the possible mechanisms responsible for these differences revealed "distances run" (km.wk-1) as a positive, and "years of training" as a negative determinant of bone mass (P < 0.001). However, the effect of a number of determinants varied between sites (P < 0.05). Specifically, the ANCOVA identified that running further distances resulted in higher bone mass in the arms and legs. In contrast, training for additional years appeared to result in lower bone mass in the arms and lumbar spine. Calcium intake was also found to be positively associated with bone mass in the legs but negatively associated at all other sites.

CONCLUSIONS

A combination of running exercise and calcium intake would appear to stimulate the bone mass of women endurance runners at lower-body sites but at the expense of bone mass at upper-body sites.

Pituitary tumor transforming gene and fibroblast growth factor-2 expression: potential prognostic indicators in differentiated thyroid cancer

Differentiated thyroid cancers are the most common endocrine cancers, but there are no reliable molecular markers of prognosis. Pituitary tumor transforming gene (PTTG) plays several potential roles in tumor initiation and progression, including regulating mitosis and stimulating expression of fibroblast growth factor (FGF)-2. Increased expression of PTTG has been demonstrated in follicular thyroid lesions, and expression of this oncogene has been identified as a potential prognostic marker in pituitary adenomas and colon carcinomas. We assessed the expression of PTTG and FGF-2 and its receptor FGF-R-1 in 27 differentiated thyroid cancers, and we compared this with expression in 11 normal thyroids, 25 multinodular goiters, and 13 Graves' disease specimens. We also examined the relationship between gene expression and clinical markers of tumor behavior. PTTG and FGF-2 were overexpressed in thyroid carcinomas (9.5-fold increase, P = 0.003, and 5.0-fold increase, P < 0.001, respectively) compared with normal thyroid. Increased FGF-2 mRNA expression was independently associated with the findings of lymph node invasion (R(2) = 0.71; P < 0.001) and distant metastasis (R(2) = 0.55; P = 0.009) at tumor presentation, after taking into account known prognostic factors such as age and gender of the patient and size and type of the tumor. High PTTG expression was independently associated with tumor recurrence (R(2) = 0.64; P = 0.003). We conclude that PTTG and FGF-2 expression are potential prognostic markers (and perhaps therapeutic targets) for differentiated thyroid cancer.

A comparison of Bayesian and maximum likelihood methods to determine the performance of a point of care test for Helicobacter pylori in the office setting

OBJECTIVE

Evaluations of point of care tests (PCT) are often hampered by a lack of appropriate gold standards. This study aimed to compare the results of a Bayesian statistical analysis and a maximum likelihood method to evaluate the performance of a PCT for Helicobacter pylori in primary care.

METHODS

The Helisal Rapid Blood Test (Cortecs Diagnostics) was performed in 311 patients from 6 primary care centers, and a concurrent venous sample was taken for 2 enzyme-linked immunosorbent assays (ELISA) performed at the laboratory, blind to the PCT result. The Bayesian analysis was conducted using Markov Chain Monte Carlo methods (WinBUGS). The performance characteristics of the PCT and the 2 ELISA tests were estimated together with 95% credible intervals (95% CIs).

RESULTS

The estimate of prevalence of H. pylori in this population was 64% (95% CI, 59% to 70%), the sensitivity and specificity of the PCT were 89% (84% to 94%) and 84% (77% to 91%), respectively (likelihood ratios positive 5.6, negative 0.13). The equivalent maximum likelihood results were prevalence, 65%; sensitivity, 90%; and specificity, 83%.

CONCLUSIONS

The Helisal Rapid Blood Test performed as well as laboratory-based ELISA tests in this cohort of patients. The Bayesian analysis and the maximum likelihood method gave similar results, the Bayesian method also simultaneously estimating 95% CIs.

Modeling elite male athletes' peripheral bone mass, assessed using regional dual x-ray absorptiometry

There is still considerable debate as to whether bone mineral content (BMC) increases in proportion to the projected bone area, A(p), or an estimate of the skeletal bone volume, (A(p))(3/2), being assessed. The results from this study suggest that the bone mass acquisition of elite athletes' arms and legs increases in proportion to the projected bone area, A(p), having simultaneously controlled/removed the effect of the confounding variables of body mass and body fat. Although this supports the use of the traditional bone mineral density ratio (BMD=BMC/A(p)), it also highlights the dangers of overlooking the effect of known confounding variables. Ignoring the effect of such confounding variables, athletic groups whose activities involve upper body strength (rugby, rock climbing, kayaking, weight lifting) had the highest arm BMD, while runners were observed to have the lowest arm BMD (lower than that of the controls). Similarly, leg BMD was highest in rugby players, whose activities included both running and strength training. However, the rugby players were also observed to have the greatest body mass. When the important determinants of body mass, body fat, as well as projected bone area, A(p), were incorporated as covariates into a proportional allometric ANCOVA model for BMC, different conclusions were obtained. The introduction of these covariates had the effect of reducing the sporting differences on adjusted arm BMC, although the "sport" by "side" interaction still identified racket players as the only group with a greater dominant arm BMC (P < 0.05). In contrast, sporting differences in adjusted leg BMC remained highly significant, but with a rearranged hierarchy. The runners replaced the rugby players as having the greatest adjusted leg BMC. The results confirm the benefits of activity on peripheral bone mass as being site-specific but reinforce the dangers of making generalizations about the relative benefits of different exercises ignoring the effects of known confounding variables, such as body size, body composition, and age.

Oxygen uptake during post dive recovery in a diving birdAythya fuligula: implications for optimal foraging models

The rate of oxygen uptake at the surface between dives was measured for four tufted ducks, Aythya fuligula, during bouts of foraging dives to a depth of 1.8 m. The ducks surfaced into a respirometer box after each dive so that the rate of oxygen uptake(V̇O2) could be measured. V̇O2decreased over time at the surface and there was a particularly rapid phase of oxygen uptake for approximately the first 3s. The specific shape of the oxygen uptake curve is dependent upon the duration of the preceding dive. The uptake curve after longer dives was significantly steeper during the first 3s at the surface than after shorter dives, although V̇O2 after the first 3s was not significantly different between these two dive duration bins. Thus, the mean total oxygen uptake (VO2) was higher after surface periods following longer dives. Due to the high V̇O2 during the initial part of the surface period, the curve associated with longer dives was statistically biphasic, with the point of inflection at 3.3s. The curve for shorter dives was not statistically biphasic. The birds may increase their respiratory frequency during the first 3s after longer dives, producing the increased V̇O2,which would enable the birds to resaturate their oxygen stores more rapidly in response to the increased oxygen depletion of the longer submergence time.

Adjusting bone mass for differences in projected bone area and other confounding variables: an allometric perspective

The traditional method of assessing bone mineral density (BMD; given by bone mineral content [BMC] divided by projected bone area [Ap], BMD = BMC/Ap) has come under strong criticism by various authors. Their criticism being that the projected bone "area" (Ap) will systematically underestimate the skeletal bone "volume" of taller subjects. To reduce the confounding effects of bone size, an alternative ratio has been proposed called bone mineral apparent density [BMAD = BMC/(Ap)3/2]. However, bone size is not the only confounding variable associated with BMC. Others include age, sex, body size, and maturation. To assess the dimensional relationship between BMC and projected bone area, independent of other confounding variables, we proposed and fitted a proportional allometric model to the BMC data of the L2-L4 vertebrae from a previously published study. The projected bone area exponents were greater than unity for both boys (1.43) and girls (1.02), but only the boy's fitted exponent was not different from that predicted by geometric similarity (1.5). Based on these exponents, it is not clear whether bone mass acquisition increases in proportion to the projected bone area (Ap) or an estimate of projected bone volume (Ap)3/2. However, by adopting the proposed methods, the analysis will automatically adjust BMC for differences in projected bone size and other confounding variables for the particular population being studied. Hence, the necessity to speculate as to the theoretical value of the exponent of Ap, although interesting, becomes redundant.