Real-World Estimates of Adrenal Insufficiency-Related Adverse Events in Children With Congenital Adrenal Hyperplasia

BACKGROUND

Although congenital adrenal hyperplasia (CAH) is known to be associated with adrenal crises (AC), its association with patient- or clinician-reported sick day episodes (SDE) is less clear.

METHODS

Data on children with classic 21-hydroxylase deficiency CAH from 34 centers in 18 countries, of which 7 were Low or Middle Income Countries (LMIC) and 11 were High Income (HIC), were collected from the International CAH Registry and analyzed to examine the clinical factors associated with SDE and AC.

RESULTS

A total of 518 children-with a median of 11 children (range 1, 53) per center-had 5388 visits evaluated over a total of 2300 patient-years. The median number of AC and SDE per patient-year per center was 0 (0, 3) and 0.4 (0.0, 13.3), respectively. Of the 1544 SDE, an AC was reported in 62 (4%), with no fatalities. Infectious illness was the most frequent precipitating event, reported in 1105 (72%) and 29 (47%) of SDE and AC, respectively. On comparing cases from LMIC and HIC, the median SDE per patient-year was 0.75 (0, 13.3) vs 0.11 (0, 12.0) (P < 0.001), respectively, and the median AC per patient-year was 0 (0, 2.2) vs 0 (0, 3.0) (P = 0.43), respectively.

CONCLUSIONS

The real-world data that are collected within the I-CAH Registry show wide variability in the reported occurrence of adrenal insufficiency-related adverse events. As these data become increasingly used as a clinical benchmark in CAH care, there is a need for further research to improve and standardize the definition of SDE.

Evidence synthesis for constructing directed acyclic graphs (ESC-DAGs): a novel and systematic method for building directed acyclic graphs

Background

Directed acyclic graphs (DAGs) are popular tools for identifying appropriate adjustment strategies for epidemiological analysis. However, a lack of direction on how to build them is problematic. As a solution, we propose using a combination of evidence synthesis strategies and causal inference principles to integrate the DAG-building exercise within the review stages of research projects. We demonstrate this idea by introducing a novel protocol: ‘Evidence Synthesis for Constructing Directed Acyclic Graphs’ (ESC-DAGs)’.

Methods

ESC-DAGs operates on empirical studies identified by a literature search, ideally a novel systematic review or review of systematic reviews. It involves three key stages: (i) the conclusions of each study are ‘mapped’ into a DAG; (ii) the causal structures in these DAGs are systematically assessed using several causal inference principles and are corrected accordingly; (iii) the resulting DAGs are then synthesised into one or more ‘integrated DAGs’. This demonstration article didactically applies ESC-DAGs to the literature on parental influences on offspring alcohol use during adolescence.

Conclusions

ESC-DAGs is a practical, systematic and transparent approach for developing DAGs from background knowledge. These DAGs can then direct primary data analysis and DAG-based sensitivity analysis. ESC-DAGs has a modular design to allow researchers who are experienced DAG users to both use and improve upon the approach. It is also accessible to researchers with limited experience of DAGs or evidence synthesis.

MON-170 Real World Estimates of Adrenal Insufficiency Related Adverse Events in Children with Congenital Adrenal Hyperplasia: On Behalf of the I-CAH Consortium

Background Although congenital adrenal hyperplasia (CAH) is a rare condition, it is the commonest cause of early-onset primary adrenal insufficiency and places the patient at a life-long risk of sick day episodes (SDE) and adrenal crises (AC). Objective To investigate the epidemiology of SDE and AC in an international cohort of patients <18 yrs old with 21-OH deficiency CAH. Methods Multi-level logistic model analysis of data in the International CAH (I-CAH) registry (www.i-cah.org) to examine the clinical associations of SDE, AC, stress-dose days and hospitalisations. Results 518 patients (F, 53%) from 34 centres in 18 countries with a median number of cases per centre of 12 (IQR 1-26), had a total of 5388 reported visits with a median duration of follow-up per patient of 3.1 yrs (IQR 2.5-5.8). Of the 518 patients, 334 (64%) had ≥1 SDE; the median number of SDE per patient year per centre was 1.0 (IQR 0.4-2.2) and the median duration of SDE was 3.0 days (IQR 2.0-5.0). Children between 1-4 yrs and adolescents (15-18 yrs) had a greater risk of SDE [OR 2.02 (95%CI:1.60,2.56) and OR 1.64 (95%CI:1.34,2.02), respectively] and stress-dosing [OR 2.03 (95%CI:1.56,2.60) and OR 1.63 (95%CI:1.32,2.02), respectively] compared to children <1 yr old. Males were more likely to have a SDE [OR 1.40 (95%CI:1.13,1.73) and stress-dosing [OR 1.40 (95%CI:1.12,1.76) than females. An AC was reported in 4% of SDE (62/1544) with 92% of visits associated with hospital admission. Infectious illness was the most frequent associated event and was reported in 72% (1105/1544) of SDE and 47% (29/62) of AC. Males had a higher risk of AC compared to females [OR 1.03 (95%CI:1.03,1.03). Children with salt-wasting CAH were more likely to be hospitalised during a SDE, compared with those with simple-virilising CAH [OR 2.08 (95%CI:0.99,7.91)]. Children receiving glucocorticoid (GC) doses within the hydrocortisone (HC) equivalent dose (ED) of 10-15mg/m²/d were more likely to have SDE [OR 1.66 (95%CI:1.31,2.10), stress-dosing [OR 1.85 (95%CI:1.44,2.37) and AC [OR 1.08 (95%CI:1.08,1.08), p<0.001] than children on HC ED >15mg/m²/day. Similarly, children on HC ED <10mg/m²/d were more likely to have SDE [OR 2.20 (95%CI:1.66,2.90)], stress-dosing [OR 2.37 (95%CI:1.77,3.19)] and AC [OR 8.34 (95%CI:8.33,8.35), p<0.001] than those on higher doses. Children on FC doses between 50-200mcg/day and lower than 50 mcg were less likely to have AC [OR 4.54 (95%CI:4.54,4.55) and OR 8.58 (95%CI:8.57,8.59), respectively] than those on higher doses (>200mcg/day). Oral GC were increased in 74% (1147/1544) of SDE whilst HC injection was administered in 11% (176/1544) of SDE. Conclusions The real-world data within the I-CAH registry are a valuable resource for identifying factors that place a child with CAH at a higher risk of adverse events and can be used in prediction models for calculating individual risk.

Urinary Sodium Excretion, Blood Pressure, and Risk of Future Cardiovascular Disease and Mortality in Subjects Without Prior Cardiovascular Disease

Hypertension is a risk factor for cardiovascular disease. Increased urinary sodium excretion, representing dietary sodium intake, is associated with hypertension. Low sodium intake has been associated with increased mortality in observational studies. Further studies should assess whether confounding relationships explain associations between sodium intake and outcomes. We studied UK Biobank participants (n=457 484; mean age, 56.3 years; 44.7% men) with urinary electrolytes and blood pressure data. Estimated daily urinary sodium excretion was calculated using Kawasaki formulae. We analyzed associations between sodium excretion and blood pressure in subjects without cardiovascular disease, treated hypertension, or diabetes mellitus at baseline (n=322 624). We tested relationships between sodium excretion, incidence of fatal and nonfatal cardiovascular disease, heart failure, and mortality. Subjects in higher quintiles of sodium excretion were younger, with more men and higher body mass index. There was a linear relationship between increasing urinary sodium excretion and blood pressure. During median follow-up of 6.99 years, there were 11 932 deaths (1125 cardiovascular deaths) with 10 717 nonfatal cardiovascular events. There was no relationship between quintile of sodium excretion and outcomes. These relationships were unchanged after adjustment for comorbidity or excluding subjects with events during the first 2 years follow-up. No differing risk of incident heart failure (1174 events) existed across sodium excretion quintiles. Urinary sodium excretion correlates with elevated blood pressure in subjects at low cardiovascular risk. No pattern of increased cardiovascular disease, heart failure, or mortality risk was demonstrated with either high or low sodium intake.

Cost-effectiveness Analysis in R Using a Multi-state Modeling Survival Analysis Framework: A Tutorial

This tutorial provides a step-by-step guide to performing cost-effectiveness analysis using a multi-state modeling approach. Alongside the tutorial, we provide easy-to-use functions in the statistics package R. We argue that this multi-state modeling approach using a package such as R has advantages over approaches where models are built in a spreadsheet package. In particular, using a syntax-based approach means there is a written record of what was done and the calculations are transparent. Reproducing the analysis is straightforward as the syntax just needs to be run again. The approach can be thought of as an alternative way to build a Markov decision-analytic model, which also has the option to use a state-arrival extended approach. In the state-arrival extended multi-state model, a covariate that represents patients' history is included, allowing the Markov property to be tested. We illustrate the building of multi-state survival models, making predictions from the models and assessing fits. We then proceed to perform a cost-effectiveness analysis, including deterministic and probabilistic sensitivity analyses. Finally, we show how to create 2 common methods of visualizing the results-namely, cost-effectiveness planes and cost-effectiveness acceptability curves. The analysis is implemented entirely within R. It is based on adaptions to functions in the existing R package mstate to accommodate parametric multi-state modeling that facilitates extrapolation of survival curves.

Estimation of Survival Probabilities for Use in Cost-effectiveness Analyses: A Comparison of a Multi-state Modeling Survival Analysis Approach with Partitioned Survival and Markov Decision-Analytic Modeling

Modeling of clinical-effectiveness in a cost-effectiveness analysis typically involves some form of partitioned survival or Markov decision-analytic modeling. The health states progression-free, progression and death and the transitions between them are frequently of interest. With partitioned survival, progression is not modeled directly as a state; instead, time in that state is derived from the difference in area between the overall survival and the progression-free survival curves. With Markov decision-analytic modeling, a priori assumptions are often made with regard to the transitions rather than using the individual patient data directly to model them. This article compares a multi-state modeling survival regression approach to these two common methods. As a case study, we use a trial comparing rituximab in combination with fludarabine and cyclophosphamide v. fludarabine and cyclophosphamide alone for the first-line treatment of chronic lymphocytic leukemia. We calculated mean Life Years and QALYs that involved extrapolation of survival outcomes in the trial. We adapted an existing multi-state modeling approach to incorporate parametric distributions for transition hazards, to allow extrapolation. The comparison showed that, due to the different assumptions used in the different approaches, a discrepancy in results was evident. The partitioned survival and Markov decision-analytic modeling deemed the treatment cost-effective with ICERs of just over £16,000 and £13,000, respectively. However, the results with the multi-state modeling were less conclusive, with an ICER of just over £29,000. This work has illustrated that it is imperative to check whether assumptions are realistic, as different model choices can influence clinical and cost-effectiveness results.

Scottish Keep Well health check programme: an interrupted time series analysis

BACKGROUND

Effective interventions are available to reduce cardiovascular risk. Recently, health check programmes have been implemented to target those at high risk of cardiovascular disease (CVD), but there is much debate whether these are likely to be effective at population level. This paper evaluates the impact of wave 1 of Keep Well, a Scottish health check programme, on cardiovascular outcomes.

METHODS

Interrupted time series analyses were employed, comparing trends in outcomes in participating and non-participating practices before and after the introduction of health checks. Health outcomes are defined as CVD mortality, incident hospitalisations and prescribing of cardiovascular drugs.

RESULTS

After accounting for secular trends and seasonal variation, coronary heart disease mortality and hospitalisations changed by 0.4% (95% CI -5.2% to 6.3%) and -1.1% (-3.4% to 1.3%) in Keep Well practices and by -0.3% (-2.7% to 2.2%) and -0.1% (-1.8% to 1.7%) in non-Keep Well practices, respectively, following the intervention. Adjusted changes in prescribing in Keep Well and non-Keep Well practices were 0.4% (-10.4% to 12.5%) and -1.5% (-9.4% to 7.2%) for statins; -2.5% (-12.3% to 8.4%) and -1.6% (-7.1% to 4.3%) for antihypertensive drugs; and -0.9% (-6.5% to 5.0%) and -2.4% (-10.1% to 6.0%) for antiplatelet drugs.

CONCLUSIONS

Any impact of the Keep Well health check intervention on CVD outcomes and prescribing in Scotland was very small. Findings do not support the use of the screening approach used by current health check programmes to address CVD. We used an interrupted time series method, but evaluation methods based on randomisation are feasible and preferable and would have allowed more reliable conclusions. These should be considered more often by policymakers at an early stage in programme design when there is uncertainty regarding programme effectiveness.

A cardiovascular disease policy model: part 2-preparing for economic evaluation and to assess health inequalities

Objectives

This is the second of the two papers introducing a cardiovascular disease (CVD) policy model. The first paper described the structure and statistical underpinning of the state-transition model, demonstrating how life expectancy estimates are generated for individuals defined by ASSIGN risk factors. This second paper describes how the model is prepared to undertake economic evaluation.

Design

To generate quality-adjusted life expectancy (QALE), the Scottish Health Survey was used to estimate background morbidity (health utilities) and the impact of CVD events (utility decrements). The SF-6D algorithm generated utilities and decrements were modelled using ordinary least squares (OLS). To generate lifetime hospital costs, the Scottish Heart Health Extended Cohort (SHHEC) was linked to the Scottish morbidity and death records (SMR) to cost each continuous inpatient stay (CIS). OLS and restricted cubic splines estimated annual costs before and after each of the first four events. A Kaplan-Meier sample average (KMSA) estimator was then used to weight expected health-related quality of life and costs by the probability of survival.

Results

The policy model predicts the change in QALE and lifetime hospital costs as a result of an intervention(s) modifying risk factors. Cost-effectiveness analysis and a full uncertainty analysis can be undertaken, including probabilistic sensitivity analysis. Notably, the impacts according to socioeconomic deprivation status can be made.

Conclusions

The policy model can conduct cost-effectiveness analysis and decision analysis to inform approaches to primary prevention, including individually targeted and population interventions, and to assess impacts on health inequalities.

Characterization of subgroups of heart failure patients with preserved ejection fraction with possible implications for prognosis and treatment response

BACKGROUND

Patients with heart failure and preserved ejection fraction (HFpEF) have a poor prognosis, and no therapies have been proven to improve outcomes. It has been proposed that heart failure, including HFpEF, represents overlapping syndromes that may have different prognoses. We present an exploratory study of patients enrolled in the Irbesartan in Heart Failure with Preserved Ejection Fraction Study (I-PRESERVE) using latent class analysis (LCA) with validation using the Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity (CHARM)-Preserved study to identify HFpEF subgroups.

METHODS AND RESULTS

In total, 4113 HFpEF patients randomized to irbesartan or placebo were characterized according to 11 clinical features. The HFpEF subgroups were identified using LCA. Event-free survival and effect of irbesartan on the composite of all-cause mortality and cardiovascular hospitalization were determined for each subgroup. Subgroup definitions were applied to 3203 patients enrolled in CHARM-Preserved to validate observations regarding prognosis and treatment response. Six subgroups were identified with significant differences in event-free survival (P < 0.001). Clinical profiles and prognoses of the six subgroups were similar in CHARM-Preserved. The two subgroups with the worst event-free survival in both studies were characterized by a high prevalence of obesity, hyperlipidaemia, diabetes mellitus, anaemia, and renal insufficiency (Subgroup C) and by female predominance, advanced age, lower body mass index, and high rates of atrial fibrillation, valvular disease, renal insufficiency, and anaemia (Subgroup F).

CONCLUSION

Using a data-driven approach, we identified HFpEF subgroups with significantly different prognoses. Further development of this approach for characterizing HFpEF subgroups is warranted.

HMG-coenzyme A reductase inhibition, type 2 diabetes, and bodyweight: evidence from genetic analysis and randomised trials

BACKGROUND

Statins increase the risk of new-onset type 2 diabetes mellitus. We aimed to assess whether this increase in risk is a consequence of inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the intended drug target.

METHODS

We used single nucleotide polymorphisms in the HMGCR gene, rs17238484 (for the main analysis) and rs12916 (for a subsidiary analysis) as proxies for HMGCR inhibition by statins. We examined associations of these variants with plasma lipid, glucose, and insulin concentrations; bodyweight; waist circumference; and prevalent and incident type 2 diabetes. Study-specific effect estimates per copy of each LDL-lowering allele were pooled by meta-analysis. These findings were compared with a meta-analysis of new-onset type 2 diabetes and bodyweight change data from randomised trials of statin drugs. The effects of statins in each randomised trial were assessed using meta-analysis.

FINDINGS

Data were available for up to 223 463 individuals from 43 genetic studies. Each additional rs17238484-G allele was associated with a mean 0·06 mmol/L (95% CI 0·05-0·07) lower LDL cholesterol and higher body weight (0·30 kg, 0·18-0·43), waist circumference (0·32 cm, 0·16-0·47), plasma insulin concentration (1·62%, 0·53-2·72), and plasma glucose concentration (0·23%, 0·02-0·44). The rs12916 SNP had similar effects on LDL cholesterol, bodyweight, and waist circumference. The rs17238484-G allele seemed to be associated with higher risk of type 2 diabetes (odds ratio [OR] per allele 1·02, 95% CI 1·00-1·05); the rs12916-T allele association was consistent (1·06, 1·03-1·09). In 129 170 individuals in randomised trials, statins lowered LDL cholesterol by 0·92 mmol/L (95% CI 0·18-1·67) at 1-year of follow-up, increased bodyweight by 0·24 kg (95% CI 0·10-0·38 in all trials; 0·33 kg, 95% CI 0·24-0·42 in placebo or standard care controlled trials and -0·15 kg, 95% CI -0·39 to 0·08 in intensive-dose vs moderate-dose trials) at a mean of 4·2 years (range 1·9-6·7) of follow-up, and increased the odds of new-onset type 2 diabetes (OR 1·12, 95% CI 1·06-1·18 in all trials; 1·11, 95% CI 1·03-1·20 in placebo or standard care controlled trials and 1·12, 95% CI 1·04-1·22 in intensive-dose vs moderate dose trials).

INTERPRETATION

The increased risk of type 2 diabetes noted with statins is at least partially explained by HMGCR inhibition.

FUNDING

The funding sources are cited at the end of the paper.

A cardiovascular disease policy model that predicts life expectancy taking into account socioeconomic deprivation

Objectives

A policy model is a model that can evaluate the effectiveness and cost-effectiveness of interventions and inform policy decisions. In this study, we introduce a cardiovascular disease (CVD) policy model which can be used to model remaining life expectancy including a measure of socioeconomic deprivation as an independent risk factor for CVD.

Design

A state transition model was developed using the Scottish Heart Health Extended Cohort (SHHEC) linked to Scottish morbidity and death records. Individuals start in a CVD-free state and can transit to three CVD event states plus a non-CVD death state. Individuals who have a non-fatal first event are then followed up until death. Taking a competing risk approach, the cause-specific hazards of a first event are modelled using parametric survival analysis. Survival following a first non-fatal event is also modelled parametrically. We assessed discrimination, validation and calibration of our model.

Results

Our model achieved a good level of discrimination in each component (c-statistics for men (women)—non-fatal coronary heart disease (CHD): 0.70 (0.74), non-fatal cerebrovascular disease (CBVD): 0.73 (0.76), fatal CVD: 0.77 (0.80), fatal non-CVD: 0.74 (0.72), survival after non-fatal CHD: 0.68 (0.67) and survival after non-fatal CBVD: 0.65 (0.66)). In general, our model predictions were comparable with observed event rates for a Scottish randomised statin trial population which has an overlapping follow-up period with SHHEC. After applying a calibration factor, our predictions of life expectancy closely match those published in recent national life tables.

Conclusions

Our model can be used to estimate the impact of primary prevention interventions on life expectancy and can assess the impact of interventions on inequalities.

Time trends in 30 day case-fatality following hospitalisation for asthma in adults in Scotland: a retrospective cohort study from 1981 to 2009

BACKGROUND

The risk of case-fatality following hospitalisation for asthma has not been well characterised. We describe trends in 30 day case-fatality following hospitalisation for asthma in adults in Scotland from 1981 to 2009.

METHODS

Using the Scottish Morbidity Record Scheme (SMR01) with all asthma hospitalisations for adults (≥18 years) with ICD9 493 and ICD10 J45-J46 in the principal diagnostic position at discharge (1981-2009). These data were linked to mortality data from the General Register Office for Scotland (GROS), with asthma case-fatality defined as death within 30 days of asthma admission (in or out of hospital). Logistic regression was used to explore the impact of age, sex, previous asthma admission (in the 12 months prior to hospitalisation), socioeconomic deprivation, year of admission and co-morbidity on 30-day case-fatality.

RESULTS

There were a total of 116,457 asthma hospitalisations; a total of 1000 (0.9%) hospitalisations resulted in a post-admission death (within 30 days of admission). Odds ratios for unadjusted and adjusted case-fatality showed a decreased risk of case-fatality from the mid-1990s onwards when compared to case-fatality in 1981. Advancing age and co-morbid diagnoses of respiratory failure, cancer, renal failure, cor pulmonale, coronary heart disease and respiratory infection were associated with increased likelihood of death.

CONCLUSIONS

30 day case-fatality has declined over the last three decades, comparable to case-fatality reported in other parts of the U.K. This decline may be in part due to improved guidelines, protocols and disease management for asthma over the last 30 years. The likelihood of death 30 days following an asthma admission increased with age group and was associated with respiratory failure, renal failure and cancer.

Angina and intermittent claudication in 7403 participants of the 2003 Scottish Health Survey: impact on general and mental health, quality of life and five-year mortality

BACKGROUND

Angina and intermittent claudication impair function and mobility and reduce health-related quality of life. Both symptoms have similar etiology, yet the physical and psychological impacts of these symptoms are rarely studied in community-based cohorts or in individuals with isolated symptoms.

METHODS

The 2003 Scottish Health Survey was a cross-sectional survey which enrolled a random sample of individuals aged 16-95 years living in Scotland. The Rose Angina Questionnaire, the Edinburgh Claudication Questionnaire, the Short Form-12 (SF-12) and the General Health Questionnaire were completed. Self-assessed general health was reported. Survey results were linked to national death records and mortality at five years was calculated. Subjects with isolated angina or intermittent claudication and neither symptom were compared (22 participants with both symptoms were excluded); 7403 participants (aged ≥ 16 years) were included.

RESULTS

Participants with angina (n=205; 60 ± 15 years; 45% male) rated their general health worse and were more likely to have a potential mental-health problem than those with intermittent claudication (n=173; 61 ± 15 years; 41% male). Mean (standard deviation) physical and mental component scores on the SF-12 were higher for participants with intermittent claudication relative to those with angina (physical component score: 42.3 (10.6) vs. 35.0 (11.7), p<0.001; mental component score: 52.3 (8.5) vs. 46.5 (11.7), p=0.001). There was an observed absolute difference in five-year mortality of 4.8% (angina 12.3%, 95% CI 8.5-17.6; intermittent claudication 7.5%, 95% CI 4.4-12.6) although not statistically significant (p=0.16).

CONCLUSIONS

Both intermittent claudication and angina adversely impact general and mental health and survival, even in a relatively young, community-based cohort.

Sex-specific time trends in first admission to hospital for peripheral artery disease in Scotland 1991–2007

Background

This study examined trends for all first hospital admissions for peripheral artery disease (PAD) in Scotland from 1991 to 2007 using the Scottish Morbidity Record.

Methods

First admissions to hospital for PAD were defined as an admission to hospital (inpatient and day-case) with a principal diagnosis of PAD, with no previous admission to hospital (principal or secondary diagnosis) for PAD in the previous 10 years.

Results

From 1991 to 2007, 41 593 individuals were admitted to hospital in Scotland for the first time for PAD. Some 23 016 (55·3 per cent) were men (mean(s.d.) age 65·7(11·7) years) and 18 577 were women (aged 70·4(12·8) years). For both sexes the population rate of first admissions to hospital for PAD declined over the study interval: from 66·7 per 100 000 in 1991-1993 to 39·7 per 100 000 in 2006-2007 among men, and from 43·5 to 29·1 per 100 000 respectively among women. After adjustment, the decline was estimated to be 42 per cent in men and 27 per cent in women (rate ratio for 2007 versus 1991: 0·58 (95 per cent confidence interval 0·55 to 0·62) in men and 0·73 (0·68 to 0·78) in women). The intervention rate fell from 80·8 to 74·4 per cent in men and from 77·9 to 64·9 per cent in women. The proportion of hospital admissions as an emergency or transfer increased, from 23·9 to 40·7 per cent among men and from 30·0 to 49·5 per cent among women.

Conclusion

First hospital admission for PAD in Scotland declined steadily and substantially between 1991 and 2007, with an increase in the proportion that was unplanned.

Estimating the impact of stroke unit care in a whole population: an epidemiological study using routine data

BACKGROUND AND PURPOSE

Randomised trials indicate that organised inpatient (stroke unit) care has an important impact on patient outcomes with an absolute risk difference (ARD) of 3% for survival and 5% for returning home. However, it is unclear what impact this complex intervention actually has in routine practice. A comprehensive national dataset was used to study the impact of stroke unit implementation.

METHODS

The Scottish linked discharge database was used to identify all patients admitted to hospital with an incident stroke. Analyses compared case fatality and discharge home (adjusted for age, sex, deprivation and comorbidity) for hospitals with or without a stroke unit during four consecutive study periods: 1986-1990, 1991-1995, 1996-2000 and 2001-2005.

RESULTS

During the study period, the percentage of admissions to hospitals that had a stroke unit increased from 0% to 87%, the 6 month case fatality decreased from 45% to 29% and discharges home increased from 46% to 59%. Adjusted ORs (95% CI) for case fatality (stroke unit versus no unit) in each study period were as follows: not calculable (no units before 1991), 0.83 (0.78-0.89), 0.90 (0.86-0.94) and 0.87 (0.82-0.91). These equate to an ARD of 3.0% over the whole study period. Equivalent data for discharge home indicated an increased odds of discharge home: not calculable, 1.23 (1.15-1.31), 1.15 (1.10-1.21) and 1.17 (1.11-1.23) with an overall ARD of 5%.

CONCLUSIONS

These results indicate a positive impact of a policy of stroke unit care on case fatality and discharge home. The estimated impact, after adjusting for case mix, appears very similar to that calculated using clinical trial data.

Treatment of type 2 diabetes and outcomes in patients with heart failure: a nested case-control study from the U.K. General Practice Research Database

OBJECTIVE

Diabetes and heart failure commonly coexist, and prior studies have suggested better outcomes with metformin than other antidiabetic agents. We designed this study to determine whether this association reflects a beneficial effect of metformin or a harmful effect of other agents.

RESEARCH DESIGN AND METHODS

We performed a case-control study nested within the U.K. General Practice Research Database cohort in which diagnoses were assigned by each patient's primary care physician. Case subjects were patients 35 years or older, newly diagnosed with both heart failure and diabetes after January 1988, and who died prior to October 2007. Control subjects were matched to case subjects based on age, sex, clinic site, calendar year, and duration of follow-up. Analyses were adjusted for comorbidities, A1C, renal function, and BMI.

RESULTS

The duration of concurrent diabetes and heart failure was 2.8 years (SD 2.6) in our 1,633 case subjects and 1,633 control subjects (mean age 78 years, 53% male). Compared with patients who were not exposed to antidiabetic drugs, the current use of metformin monotherapy (adjusted odds ratio 0.65 [0.48-0.87]) or metformin with or without other agents (0.72 [0.59-0.90]) was associated with lower mortality; however, use of other antidiabetic drugs or insulin was not associated with all-cause mortality. Conversely, the use of ACE inhibitors/angiotensin receptor blockers (0.55 [0.45-0.68]) and beta-blockers (0.76 [0.61-0.95]) were associated with reduced mortality.

CONCLUSIONS

Our results confirm the benefits of trial-proven anti-failure therapies in patients with diabetes and support the use of metformin-based strategies to lower glucose.

Mathematical coupling may account for the association between baseline severity and minimally important difference values

OBJECTIVE

To generate anchor-based values for the "minimally important difference" (MID) for a number of commonly used patient-reported outcome (PRO) measures and to examine whether these values could be applied across the continuum of preoperative patient severity.

STUDY DESIGN AND SETTING

Six prospective cohort studies of patients undergoing elective surgery at hospitals in England and Wales. Patients completed questionnaires about their health and health-related quality of life before and after surgery. MID values were calculated using the mean change score for a reference group of patients who reported they were "a little better" after surgery minus the mean change score for those who said they were "about the same." Pearson's correlation was used to examine the association between baseline severity and change scores in the reference group. Baseline severity was expressed in two ways: first in terms of preoperative scores and second in terms of the average of pre- and postoperative scores (Oldham's method).

RESULTS

Of the 10 PRO measures examined, eight demonstrated a moderate or high positive association between preoperative scores and MID values. Only two measures demonstrated such an association when Oldham's measure of baseline severity was used.

CONCLUSION

In general, there is little association between baseline severity and MID values. However, a moderate association persists for some measures, and it is recommended that researchers continue to test for this relationship when generating anchor-based MID values from change scores.

Aldosterone status associated with insulin resistance in patients with heart failure--data from the ALOFT study

BACKGROUND

Aldosterone has a key role in the pathophysiology of heart failure. In around 50% of such patients, aldosterone "escapes" from inhibition by drugs that interrupt the renin-angiotensin axis; such patients have a worse clinical outcome. Insulin resistance is a risk factor in heart failure and cardiovascular disease. The relation between aldosterone status and insulin sensitivity was investigated in a cohort of heart failure patients.

METHODS

302 patients with New York Heart Association (NYHA) class II-IV heart failure on conventional therapy were randomised in the ALiskiren Observation of heart Failure Treatment study (ALOFT), designed to test the safety of a directly acting renin inhibitor. Plasma aldosterone and 24-hour urinary aldosterone excretion, as well as fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were measured. Subjects with aldosterone escape and high urinary aldosterone were identified according to previously accepted definitions.

RESULTS

20% of subjects demonstrated aldosterone escape and 34% had high urinary aldosterone levels. At baseline, there was a positive correlation between fasting insulin and plasma (r = 0.22 p<0.01) and urinary aldosterone(r = 0.19 p<0.03). Aldosterone escape and high urinary aldosterone subjects both demonstrated higher levels of fasting insulin (p<0.008, p<0.03), HOMA-IR (p<0.06, p<0.03) and insulin-glucose ratios (p<0.006, p<0.06) when compared to low aldosterone counterparts. All associations remained significant when adjusted for potential confounders.

CONCLUSIONS

This study demonstrates a novel direct relation between aldosterone status and insulin resistance in heart failure. This observation merits further study and may identify an additional mechanism that contributes to the adverse clinical outcome associated with aldosterone escape.

Age- and sex-specific trends in fatal incidence and hospitalized incidence of stroke in Scotland, 1986 to 2005

BACKGROUND

Temporal trends in stroke incidence are unclear. We aimed to examine age- and sex-specific temporal trends in incidence of fatal and nonfatal hospitalized stroke in Scotland from 1986 to 2005.

METHODS AND RESULTS

Mean age at the time of first stroke was 70.8 (SD, 12.9) years in men and 76.4 (12.9) years in women. Between 1986 and 2005, rates fell in men from 235 (95% CI, 229 to 242) to 149 (144 to 154) and in women from 299 (292 to 306) to 182 (177 to 188). Poisson modeling showed that temporal trends were influenced by age with declines in incidence of hospitalized stroke starting later in younger than older age groups. In both men and women aged under 55 years, the overall incidence rate of stroke was significantly higher in 2005 than in 1986.

CONCLUSIONS

We report in a whole country that the overall incidence of stroke declined steadily and substantially between 1986 and 2005, with a relative reduction in the risk of stroke of 31% in men and 42% in women. Reductions in rates of both hospitalized and nonhospitalized fatal stroke contributed to this overall decline. The increase in incident stroke rates in young people is of concern.

Sex Differences in Incidence, Mortality, and Survival in Individuals With Stroke in Scotland, 1986 to 2005

Background and Purpose— The aim of this study was to examine the effect of sex across different age groups and over time for stroke incidence, 30-day case-fatality, and mortality.

Methods— All first hospitalizations for stroke in Scotland (1986 to 2005) were identified using linked morbidity and mortality data. Age-specific rate ratios (RRs) for comparing women with men for both incidence and mortality were modeled with adjustment for study year and socioeconomic deprivation. Logistic regression was used to model 30-day case-fatality.

Results— Women had a lower incidence of first hospitalization than men and size of effect varied with age (55 to 64 years, RR=0.65, 95% CI 0.63 to 0.66; ≥85 years, RR=0.94, 95% CI 0.91 to 0.96). Women aged 55 to 84 years had lower mortality than men and again size of effect varied with age (65 to 74 years, RR=0.79, 95% CI 0.76 to 0.81); 75 to 84 years, RR=0.94, 95% CI 0.92 to 0.95). Conversely, women aged ≥85 years had 15% higher stroke mortality than men (RR=1.15, 95% CI 1.12 to 1.18). Adjusted risk of death within 30 days was significantly higher in women than men, and this difference increased over the 20-year period in all age groups (adjusted OR in 55 to 64 year olds 1.23, 95% CI 1.14 to 1.33 in 1986 and 1.51, 95% CI 1.39 to 1.63 in 2005).

Conclusions— We observed lower rates of incidence and mortality in younger women than men. However, higher numbers of older women in the population mean that the absolute burden of stroke is greater in women. Short-term case-fatality is greater in women of all ages and, worryingly, these differences have increased from 1986 to 2005.

Diathermy power settings as a risk factor for hemorrhage after tonsillectomy

OBJECTIVE

To investigate bipolar diathermy power settings as a risk factor for postoperative hemorrhage following tonsillectomy.

STUDY DESIGN AND SETTING

A prospective cohort study was undertaken between July 2003 and September 2004 in National Health Service (NHS) and independent hospitals in England and Northern Ireland. Data were collected on patient characteristics, tonsillectomy technique, and postoperative hemorrhage within 28 days of surgery.

RESULTS

Among the 9572 patients who had a tonsillectomy performed with bipolar diathermy dissection and hemostasis, the overall rate of hemorrhage was 4.6 percent and the risk of hemorrhage was not associated with the diathermy power setting. Among the 8465 patients who had tonsillectomy with cold steel dissection and bipolar diathermy hemostasis, the rate of hemorrhage increased from 1.8% in patients with the lowest power settings (6 to 8 watts) to 3.7% in those with settings above 18 watts (P value for trend = 0.005).

CONCLUSION

In tonsillectomies using cold steel dissection and bipolar diathermy for hemostasis, the risk of postoperative hemorrhage becomes greater as diathermy power increases.

Long-term trends in first hospitalization for heart failure and subsequent survival between 1986 and 2003: a population study of 5.1 million people

BACKGROUND

We examined whether population-level hospitalization rates for heart failure (HF) and subsequent survival have continued to improve since the turn of the century. We also examined trends in the prescribing of evidence-based pharmacological treatment for HF.

METHODS AND RESULTS

All patients in Scotland hospitalized with a first episode of HF between 1986 and 2003 were followed up until death or the end of 2004. Prescriptions of evidence-based treatments issued from 1997 to 2003 by a sample of primary care practices were also examined. A total of 116 556 individuals (52.6% women) had a first hospital discharge for HF. Age-adjusted first hospitalization rates for HF (per 100 000; 95% CI in parentheses) rose from 124 (119 to 129) in 1986 to 162 (157 to 168) in 1994 and then fell to 105 (101 to 109) in 2003 in men; in women, they rose from 128 (123 to 132) in 1986 to 160 (155 to 165) in 1993, falling to 101 (97 to 105) in 2003. Case-fatality rates fell steadily over the period. Adjusted 30-day case-fatality rates fell after discharge (adjusted odds [2003 versus 1986] 0.59 [95% CI 0.45 to 0.63] in men and 0.77 [95% CI 0.67 to 0.88] in women). Adjusted 1- and 5-year survival improved similarly. Median survival increased from 1.33 to 2.34 years in men and from 1.32 to 1.79 years in women. Age-adjusted prescribing rates for angiotensin-converting enzyme inhibitors, beta-blockers, and spironolactone increased from 1997 to 2003 (all P<0.0001 for trend).

CONCLUSIONS

After rising between 1986 and 1994, rates of first hospitalization for HF declined. Case-fatality rates also fell. Prescribing rates for HF therapies increased from 1997 to 2003. These findings suggest that improvements in the prevention and treatment of HF may have had progressive, sustained effects on outcomes at the population level; however, prognosis remains poor in HF.

Survival after liver transplantation in the United Kingdom and Ireland compared with the United States

BACKGROUND AND OBJECTIVE

Surgical mortality in the US is widely perceived to be superior to that in the UK. However, previous comparisons of surgical outcome in the two countries have often failed to take sufficient account of case-mix or examine long-term outcome. The standardised nature of liver transplantation practice makes it uniquely placed for undertaking reliable international comparisons of surgical outcome. The objective of this study is to undertake a risk-adjusted disease-specific comparison of both short- and long-term survival of liver transplant recipients in the UK and Ireland with that in the US.

METHODS

A multicentre cohort study using two high quality national databases including all adults who underwent a first single organ liver transplant in the UK and Ireland (n = 5925) and the US (n = 41,866) between March 1994 and March 2005. The main outcome measures were post-transplant mortality during the first 90 days, 90 days to 1 year and beyond the first year, adjusted for recipient and donor characteristics.

RESULTS

Risk-adjusted mortality in the UK and Ireland was generally higher than in the US during the first 90 days (HR 1.17; 95% CI 1.07 to 1.29), both for patients transplanted for acute liver failure (HR 1.27; 95% CI 1.01 to 1.60) and those transplanted for chronic liver disease (HR 1.18; 95% CI 1.07 to 1.31). Between 90 days and 1 year post-transplantation, no statistically significant differences in overall risk-adjusted mortality were noted between the two cohorts. Survivors of the first post-transplant year in the UK and Ireland had lower overall risk-adjusted mortality than those transplanted in the US (HR 0.88; 95% CI 0.81 to 0.96). This difference was observed among patients transplanted for chronic liver disease (HR 0.88; 95% CI 0.81 to 0.96), but not those transplanted for acute liver failure (HR 1.02; 95% CI 0.70 to 1.50).

CONCLUSIONS

Whilst risk-adjusted mortality is higher in the UK and Ireland during the first 90 days following liver transplantation, it is higher in the US among those liver transplant recipients who survived the first post-transplant year. Our results are consistent with the notion that the US has superior acute perioperative care whereas the UK appears to provide better quality chronic care following liver transplantation surgery.

Continuous monitoring tools for pediatric surgical outcomes: an example using biliary atresia

PURPOSE

Continuous monitoring tools can be used to monitor surgical outcomes over time. We illustrate the use of CUmulative SUM (CUSUM) charts in monitoring outcomes of Kasai portoenterostomy for treatment of biliary atresia at a supraregional unit.

METHODS

Data on 57 consecutive infants who underwent a Kasai portoenterostomy performed by a single surgeon between June 1994 and June 2006 were collected. A procedure was defined as successful if clearance of jaundice (plasma bilirubin level <20 micromol/l) was achieved within 6 months of surgery. We applied cumulative observed-minus-expected, sequential probability ratio test (SPRT), and zero-resetting SPRT CUSUM charts and compared the results with those of standard aggregate data analyses. An expected failure rate of 43.0%, based on the national average failure rate, was used.

RESULTS

The failure rate observed after 57 operations was 29.8%. The zero-resetting SPRT chart indicated a lower-than-expected failure rate earlier than did the aggregate data analyses and any of the other continuous monitoring techniques.

CONCLUSIONS

The CUSUM chart method provides ongoing feedback that can be used for continuous monitoring of the outcome of a procedure to ensure that standards of care are maintained. Its use as a routine monitoring tool in pediatric surgery deserves wider recognition.

The impact of serum sodium concentration on mortality after liver transplantation: a cohort multicenter study

Modification of the current allocation system for donor livers in the United States to incorporate recipient serum sodium concentration ([Na]) has recently been proposed. However, the impact of this parameter on posttransplantation mortality has not been previously examined in a large risk-adjusted analysis. We assessed the effect of recipient [Na] on the survival of all adults with chronic liver disease who received a first single organ liver transplant in the UK and Ireland during the period March 1, 1994 to March 31, 2005 (n=5,152) at 3 years, during the first 90 days, and beyond the first 90 days, adjusting for a wide range of recipient, donor, and graft characteristics. Compared to those with normal [Na] (135-145 meq/L; n=3,066), severely hyponatremic recipients ([Na]<130 meq/L, n=541), had a higher risk-adjusted mortality at 3 years (hazard ratio [HR] 1.28; 95% confidence interval [CI], 1.04-1.59; P<0.02). The excess mortality was, however, confined to the first 90 days (HR 1.55; 95% CI, 1.18-2.04; P<0.002) with no significant difference thereafter. This was also true for hypernatremic recipients ([Na]>45 meq/L, n=81), who had an even greater risk-adjusted mortality compared to normonatremic recipients (overall: HR 1.85; 95% CI, 1.25-2.73; P<0.002; <or=90 days: HR 2.29; 95% CI, 1.42-3.70; P<0.001; >90 days: HR 1.12; 95% CI, 0.55-2.29; P=0.8), whereas mildly hyponatremic recipients ([Na] 130-134 meq/L, n=1,127) had similar risk-adjusted mortality to those with normal [Na] at the same time points. In conclusion, recipient [Na] is an independent predictor of death following liver transplantation. Attempts to correct the [Na] toward the normal reference range are an important aspect of pretransplantation management.

Continuous monitoring of long-term outcomes with application to hip prostheses

The CUSUM continuous monitoring method could be a valuable tool in evaluating the performance (revision experience) of prostheses used in hip replacement surgery. The dilemma when applying the CUSUM in this context is the choice of statistical model for the outcome (revision). The Bernoulli model is perhaps the most straightforward approach but the Poisson model is a plausible, and could be argued, preferable alternative for long-term outcomes such as this, provided the rate of revision with time from surgery can be assumed to be constant. However, a rate (or hazard) varying according to the Weibull distribution appears to be a better representation of a prosthesis lifetime. We show how to adapt the Poisson approach to allow for the hazard to vary according to the Weibull model as well as other parametric survival models. Application to data on a known poorly performing prosthesis shows both the Poisson and Weibull CUSUMs could have given early warning of the poor performance, with the Weibull chart alerting before the Poisson. Simulation work to investigate the robustness of the Poisson and Weibull CUSUM to departures from the underlying survival model highlights the need for correct specification of the model for the outcome.

Developing a prognostic model for 90-day mortality after liver transplantation based on pretransplant recipient factors

BACKGROUND

Current statistical prognostic models for mortality after liver transplantation do not have good discriminatory ability. Furthermore, the methodology used to develop these models is often flawed. The objective of this paper is to develop a prognostic model for 90-day mortality after liver transplantation based on pretransplant recipient factors, employing a rigorous model development method.

METHODS

We used data on 4,829 patient that were prospectively collected for the UK & Ireland Liver Transplant Audit. Switching regression was employed to impute missing values combined with a bootstrapping approach for variable selection.

RESULTS

In all, 452 patients (9.4%) died within 90 days of their transplantation. The final prognostic model was well calibrated and discriminated moderately well between patients who did and who did not die (c-statistic 0.65, 95% CI [0.63, 0.68]). Although discrimination was not excellent overall, the results showed that those patients with a "low" chance of dying within 90 days of their transplant and those with a "high" chance of dying could be differentiated from patients with a "intermediate" chance.

CONCLUSIONS

Our model can provide transplant candidates with predictions of their early posttransplantation prospects before any donor information is known, which is essential information for patients with end-stage liver disease for whom liver transplantation is a treatment option.

Continuous monitoring of the performance of hip prostheses

New brands of joint prosthesis are released for general implantation with limited evidence of their long-term performance in patients. The CUSUM continuous monitoring method is a statistical testing procedure which could be used to provide prospective evaluation of brands as soon as implantation in patients begins and give early warning of poor performance. We describe the CUSUM and illustrate the potential value of this monitoring tool by applying it retrospectively to the 3M Capital Hip experience. The results show that if the clinical data and methodology had been available, the CUSUM would have given an alert to the underperformance of this prosthesis almost four years before the issue of a Hazard Notice by the Medical Devices Agency. This indicates that the CUSUM can be a valuable tool in monitoring joint prostheses, subject to timely and complete collection of data. Regional or national joint registries provide an opportunity for future centralised, continuous monitoring of all hip and knee prostheses using these techniques.

Dental caries experience and use of dental services among preschool children in Ajman, UAE

OBJECTIVE

The aim of this study was to estimate the prevalence and severity of dental caries in the primary dentition of young children in Ajman, UAE, and investigate its association with sociodemographic characteristics and use of dental services.

METHODS

A cluster-sampling approach was used to randomly select children aged 5 or 6 years who were enrolled in public or private schools. Clinical examinations for caries were conducted by a single examiner using World Health Organization criteria. Parents completed questionnaires seeking information on socioeconomic background and dental service utilization. Zero-inflated negative binomial (ZINB) regression modelling was used to identify risk markers and risk indicators for caries experience.

RESULTS

The prevalence of dental caries in the sample was high 76.1%. The average dmfs score 10.2. Caries severity was greater among older children and among male children of less educated mothers. Emirati (local) children had higher caries severity than others. Children who had higher level of caries visited the dentist more frequently than other children whose visits were for check-up only.

CONCLUSIONS

Dental caries prevalence and severity in young children in Ajman are high, and socioeconomic characteristics and dental utilization are important determinants of their dental caries experience. There is an urgent need for oral health programmes targeted at the treatment and underlying causes of dental caries in these children.

Functional status of patients before liver transplantation as a predictor of posttransplant mortality

BACKGROUND

Risk models for mortality after liver transplantation have poor predictive ability. We examined whether the performance of these risk models can be improved by including information about patients' functional status (i.e., their ability to carry out activities of daily living) in addition to conventional clinical risk factors.

METHODS

The UK and Ireland Liver Transplant Audit has data on all liver transplantations carried out in both countries since 1994. We examined the association of functional status measures taken immediately before transplantation on a 5-point scale (modified version of the Eastern Cooperative Oncology Group performance status) and mortality 90 days after transplantation. Logistic regression was used to adjust for other risk factors.

RESULTS

Posttransplant mortality increased from 5.3% in patients able to carry out normal activity without restriction (functional status 1) to 24.8% in patients completely reliant on nursing and medical care (functional status 5; P for trend 0.003). This association remained after adjustment for conventional risk factors (adjusted P for trend 0.003). Adjusted odds ratios with functional status 3 (the most frequent functional status) as baseline category were 0.60 (95% confidence interval 0.29-1.25) for functional status 1, 0.70 (0.50-0.97) for functional status 2, 1.00 (0.71-1.41) for functional status 4, and 1.85 (1.07-3.19) for functional status 5.

CONCLUSIONS

Considering a patient's functional status or more general measures of a patient's health status before transplantation in addition to conventional clinical factors may help to improve our ability to predict posttransplant survival.

Systematic review and validation of prognostic models in liver transplantation

A model that can accurately predict post-liver transplant mortality would be useful for clinical decision making, would help to provide patients with prognostic information, and would facilitate fair comparisons of surgical performance between transplant units. A systematic review of the literature was carried out to assess the quality of the studies that developed and validated prognostic models for mortality after liver transplantation and to validate existing models in a large data set of patients transplanted in the United Kingdom (UK) and Ireland between March 1994 and September 2003. Five prognostic model papers were identified. The quality of the development and validation of all prognostic models was suboptimal according to an explicit assessment tool of the internal, external, and statistical validity, model evaluation, and practicality. The discriminatory ability of the identified models in the UK and Ireland data set was poor (area under the receiver operating characteristic curve always smaller than 0.7 for adult populations). Due to the poor quality of the reporting, the methodology used for the development of the model could not always be determined. In conclusion, these findings demonstrate that currently available prognostic models of mortality after liver transplantation can have only a limited role in clinical practice, audit, and research.

Effectiveness of electrochemically activated water as an irrigant in an infected tooth model

AIM

To test the effectiveness of electrochemically activated aqueous solutions in the debridement of Enterococcus faecalis biofilms in root canals of extracted teeth.

METHODOLOGY

Extracted, human, single-rooted teeth (198) assembled into 11 sets (n = 18) with matching anatomical characteristics were randomly assigned to eight experimental groups. After decoronation, the root canals were prepared to a standard size. Enterococcus faecalis biofilms were grown in the root canals of autoclaved, individually mounted teeth over 48 h. Electrolysed saline collected as anolyte at the anode and catholyte at the cathode were the test agents. The four ultrasonication and four without ultrasonication irrigant groups included: neutral anolyte (NA) (pH 6.5), acidic anolyte (AA) (pH 3.0), catholyte (C) (pH 11.5) and C alternated with neutral anolyte (C/NA). Phosphate-buffered saline (PBS) with and without ultrasonication formed negative and NaOCl (3%) positive control groups. After irrigation, root canal samples were serially diluted, cultured and enumerated. The data were analysed as ratios of residual colony-forming units (CFUs) in PBS versus the test irrigants and using multivariate regression.

RESULTS

The NA and NA (ultrasonicated, U), C/NA and AA (U) groups had significantly (alpha = 0.05) less and C (U) and C/NA (U) significantly (alpha = 0.05) more bacteria (CFUs mL(-1)) compared with their respective PBS controls. Ultrasonicated C/NA had significantly (alpha = 0.05) higher CFU counts than the nonultrasonicated solution. Other comparisons between ultrasonic and nonultrasonic groups were not significant. Of the nonultrasonicated groups, C/NA and NA were most effective, whilst of the ultrasonicated groups, AA and NA were most effective. None of these was as effective as 3% NaOCl.

CONCLUSIONS

All but two groups (AA and C) were significantly different from their PBS controls. There was a significant difference between the C/NA groups with and without ultrasonication but not between other combinations. NA (U) and AA (U) were the most effective test solutions but NaOCl (3%) gave by far the highest bacterial kills.

Pretransplant MELD score and post liver transplantation survival in the UK and Ireland

It has been shown that the model for end-stage liver disease (MELD) score is an accurate predictor of survival in patients with liver disease without transplantation. Four recent studies carried out in the United States have demonstrated that the MELD score obtained immediately prior to transplantation is also associated with post-transplant patient survival. Our aim was to evaluate how accurately the MELD score predicts 90-day post-transplant survival in adult patients with chronic liver disease in the UK and Ireland. The UK and Ireland Liver Transplant Audit has data on all liver transplants since 1994. We studied survival of 3838 adult patients after first elective liver transplantation according to United Network for Organ Sharing categories of their MELD scores (< or = 10, 11-18, 19-24, 25-35, > or =36). The overall survival at 90-days was 90.2%. The 90-day survival varied according to the United Network for Organ Sharing MELD categories (92.6%, 91.9%, 89.7%, 89.7%, and 70.8%, respectively; P < 0.01). Therefore, only those patients with a MELD score of 36 or higher (3% of the patients) had a survival that was markedly lower than the rest. As a consequence, the ability of the MELD score to discriminate between patients who were dead or alive was poor (c-statistic 0.58). Re-estimating the coefficients in the MELD regression model, even allowing for nonlinear relationships, did not improve its discriminatory ability. In conclusion, in the UK and Ireland the MELD score is significantly associated with post-transplant survival, but its predictive ability is poor. These results are in agreement with results found in the United States. Therefore, the most appropriate system to support patient selection for transplantation will be one that combines a pretransplant survival model (e.g., MELD score) with a properly developed post-transplant survival model.

The utility of the zero-inflated Poisson and zero-inflated negative binomial models: a case study of cross-sectional and longitudinal DMF data examining the effect of socio-economic status

OBJECTIVES

To examine the utility of the zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) modelling approaches for modelling four sets of dental caries data from the same cohort study [with particular attention to the influence of childhood socioeconomic status (SES)]: cross-sectional data on the deciduous dentition at age 5 years; cross-sectional data on the permanent dentition at age 18 and 26 years; and longitudinal data on caries increment between ages 18 and 26 years.

METHODS

Data on dental caries occurrence at ages 5, 18 and 26 years were obtained from the Dunedin Multidisciplinary Health and Development Study (DMHDS). ZIP and ZINB models were fitted to the cross-sectional (n = 745) and longitudinal (n = 809) data sets using Stata (Intercooled Stata 7.0). The dependent variables for the three cross-sectional analyses were the DMFS indices at age 5, 18, and 26 years, and net DFS increment (NETDFS) was the dependent variable for the longitudinal analysis.

RESULTS

The empty ZIP model was a poor fit for all four data sets, whereas the empty ZINB model showed good fit; consequently both the cross-sectional and longitudinal analyses were conducted using ZINB modelling. Being in the high-SES group during childhood was associated with a greater probability of being caries-free by age 18 years, over and above that which would be expected from the negative binomial process. Low childhood SES also had the largest coefficient in the modelling of the negative binomial process, but at age 5 years, where the adjusted mean dmfs score in the low-SES group was 6.8 (compared with 4.7 and 2.9 in the medium- and high-SES groups, respectively). The substantial SES differences which existed at age 5 years (in the deciduous dentition) had reduced somewhat by age 18 years, and had widened again by age 26 years. In the longitudinal analysis, "baseline" caries experience (age 18-year DMFS) was a predictor both of being an extra zero and of caries severity.

CONCLUSION

This investigation of the utility of the zero-inflated approach for modelling both cross-sectional and longitudinal caries data has shown that ZIP/ZINB models can provide new insight into disease patterns. It is anticipated that they will become increasingly useful in epidemiological studies that use the DMF index as the outcome measure.

Comparing completely and stratified randomized designs in cluster randomized trials when the stratifying factor is cluster size: a simulation study

Stratified randomized designs are popular in cluster randomized trials (CRTs) because they increase the chance of the intervention groups being well balanced in terms of identified prognostic factors at baseline and may increase statistical power. The objective of this paper is to assess the gains in power obtained by stratifying randomization by cluster size, when cluster size is associated with an important cluster level factor which is otherwise unaccounted for in data analysis. A simulation study was carried out using a CRT where UK general practices were the randomized units as a template. The results show that when cluster size is strongly associated with a cluster level factor which is predictive of outcome, the stratified randomized design has superior power results to the completely randomized design and that the superiority is related to the number of clusters.

Fluticasone propionate spray and betamethasone sodium phosphate mouthrinse: a randomized crossover study for the treatment of symptomatic oral lichen planus

BACKGROUND

Symptomatic oral lichen planus (OLP) has been palliated with a wide spectrum of topical and systemic therapies. Although the majority of management strategies include corticosteroids, few have been evaluated in randomized controlled trials.

OBJECTIVE

We investigated the acceptability and efficacy of topical fluticasone propionate spray (FP) and betamethasone sodium phosphate mouthrinse (BSP) upon the signs and symptoms of OLP, assessing patient quality of life changes as a consequence of these therapies.

METHODS

We implemented a randomized, crossover study in which each drug was administered for a period of 6 weeks with an intervening washout period of 2 weeks at an outpatient oral medicine unit in London, United Kingdom. We treated 48 patients with biopsy-proven symptomatic OLP, and 44 patients (92%) completed the study. The dosage was 50 microg two dose unit sprays and BSP 500 microg, each 4 times daily. Symptomatic improvement was evaluated by means of a visual analogue scale (VAS), the McGill pain score, the Oral Health Impact Profile (OHIP), and Oral Health Quality of Life (OHQoL) questionnaires. The total surface area of the lesions, including all white, erythematous, and ulcerative lesions was measured at each visit. The efficacy, ease of application, and adverse effects associated with each medication were recorded.

RESULTS

Both FP and BSP mouthwash caused both a statistically significant reduction in painful symptoms as measured by the VAS and improvement in quality of life as measured by the OHIP and OHoQL indices. There was no significant difference between the two corticosteroids in their efficacy in reducing painful symptoms (measured by the VAS) or in their effect on patient quality of life. Both FP and BSP significantly reduced the surface area of oral lesions. However, FP was statistically significantly better than BSP in reducing lesion surface area. There was no statistically significant difference between the patient-assessed effects of the 2 therapies.

CONCLUSIONS

FP and BSP are both effective in the short-term clinical management of symptomatic OLP. FP is more acceptable to patients than BSP because of the convenience of the spray form.

Management of recalcitrant ulcerative oral lichen planus with topical tacrolimus

OBJECTIVE

Our purpose was to investigate the efficacy and safety of 0.1% topical tacrolimus in erosive or ulcerative oral lichen planus.

METHODS

This was an open-label, noncomparative study conducted in an outpatient oral medicine unit in London, United Kingdom. The study covered an 8-week period with a 22-week follow-up after cessation of therapy. Nineteen patients, aged 28 to 87 years with biopsy-proven oral lichen planus refractory to, or dependent on, systemic immunosuppressive agents, were enrolled. Seventeen patients (89%) completed the study. Application of 0.1% tacrolimus was administered to all symptomatic oral mucosal lesions. Clinical review took place 1, 3, 5, 7, and 8 weeks after commencing therapy. Alleviation of symptoms was evaluated by using a visual analogue scale as well as the McGill Pain and Oral Health Impact profile questionnaires. The extent of the oral mucosal erosion or ulceration was directly measured by the same clinician at all visits. Safety assessments included monitoring of adverse events, complete blood cell count, renal and hepatic clinical chemistry, and tacrolimus blood concentrations.

RESULTS

Tacrolimus caused a statistically significant improvement in symptoms within 1 week of commencement of therapy. A mean decrease of 73.3% occurred in the area of ulceration over the 8-week study period. Local irritation (in 6 subjects, 35%) was the most commonly reported adverse effect. Laboratory values showed no significant changes with time. Therapeutic levels of tacrolimus were demonstrated in 8 subjects but were unrelated to the extent of oral mucosal involvement. Thirteen of 17 patients suffered a relapse of oral lichen planus within 2 to 15 weeks of cessation of tacrolimus therapy.

CONCLUSION

Topical tacrolimus is effective therapy for erosive or ulcerative oral lichen planus.

An introduction to meta-analysis within the framework of multilevel modelling using the probability of success of root canal treatment as an illustration

OBJECTIVE

To introduce the statistical methodology of meta-analysis within the framework of multilevel modelling (MLM) using an illustrative example.

BASIC RESEARCH DESIGN

In meta-analysis it is important that the quantitative pooling of study results should be carried out in conjunction with careful consideration of the variation apparent between studies. If statistical heterogeneity is found to be significant, it is due, at least in part, to clinical heterogeneity. It is possible to account for clinical heterogeneity by including covariates that are thought to be responsible, using meta-regression.

CLINICAL SETTING

A total of 38 studies of root canal treatment outcome were identified as being suitable for introducing the meta-analysis methodology. Two covariates were considered for modelling: a 'loose' or 'strict' (loose--incomplete radiographic healing; strict--complete radiographic healing) criterion for judging outcome of treatment and the year in which the study was performed.

RESULTS

There was considerable statistical heterogeneity between the study results. The effect of employing loose criteria for judging success significantly increased the probability of success when compared to employing strict criteria. Furthermore, the variance between studies was significantly reduced when this covariate was included in the modelling process when compared to the variation estimated in the model which did not consider covariates.

CONCLUSION

MLM is a good facilitator for meta-analysis and meta-regression.

Perceptions of vocational trainees on gender and racial disadvantage within the Thames vocational training programme

BACKGROUND

A recent report has suggested that vocational trainees within London experienced racial or gender disadvantage during their selection. This exploratory study did not investigate the extent or the nature of this disadvantage.

AIM

To undertake a survey using a pre-tested questionnaire with dental vocational trainees on the Thames Scheme. The questionnaire explored perceived and experienced aspects of gender and racial disadvantage during their vocational training programme.

RESULTS

127 trainees completed the questionnaire (response rate 92%). Minority ethnic respondents were more than twice as likely to feel their selection was influenced by gender (odds ratio [OR] 2.25, 95% Confidence Interval [CI] 1.02, 5.10) and more than three times likely to feel selection was influenced by their race when compared with their white colleagues (OR 3.05, 95%; CI 1.01,11.45). The majority of trainees did not perceive any disadvantage whilst on the vocational training course. For example, only five respondents (4%) felt that minority ethnic individuals were treated less favourably during the vocational training course.

CONCLUSION

In conclusion, this preliminary study has attempted to explore inter-ethnic differences within the profession on perceived racial disadvantage and possible strategies for change. It is clear that the perception of disadvantage is greater than the reality within the experience of most trainees.

Using routine data to complement and enhance the results of randomised controlled trials

BACKGROUND

Randomised controlled trials (RCTs) are widely accepted as the best way to assess the outcomes and safety of medical interventions, but are sometimes not ethical, not feasible, or limited in the generalisability of their results. In such circumstances, routinely available data could help in several ways. Routine data could be used, for example, to conduct 'pseudo-trials', to estimate likely outcomes and required sample size to help design and conduct trials, or to examine whether the expected outcomes observed in an RCT will be realised in the general population.

OBJECTIVES

The project was undertaken to explore how routinely assembled hospital data might complement or supplement RCTs to evaluate medical interventions: in contexts where RCTs are not feasible for defining the context and design of an RCT for assessing whether the benefits indicated by RCTs are achieved in wider clinical practice.

METHODS

The project was based on the system of linked Scottish morbidity records, which cover 100% of acute hospital care episodes and statutory death records from 1981 to 1995. Three case studies were undertaken as a way of investigating the utility of these records in different applications. First, an attempt was made to analyse the link between the timing of surgery for subarachnoid haemorrhage (SAH) and subsequent outcomes (a question not easily susceptible to RCT design). A subsample was derived by excluding patients for which a diagnosis of SAH may not have been established or that may not have been admitted to a neurosurgical unit, and the data were assessed to attempt to inform the design of a trial of early versus late surgery. Transurethral prostatectomy (TURP), the second case study, has become the surgery of choice for benign prostatic hyperplasia without systematic assessment of its effectiveness and safety, and an RCT would now be considered unethical. However, there is a need to investigate long-term effects and the influence of co-morbidities on outcomes. A retrospective comparison of mortality and re-operation following either open prostatectomy (OPEN) or TURP was, therefore, undertaken. Patients for whom it was not possible to establish the initial procedure were excluded. The third case study compared coronary artery bypass grafting (CABG) with percutaneous transluminal angioplasty (PTCA) for coronary revascularisation. RCTs have been conducted in limited patient subgroups with short follow-up periods. A meta-analysis of RCTs could be augmented by routine data, which are available for large populations. This would allow assessment of subgroup effects, and outcomes over a long period. A subgroup of patients was therefore constructed for whom relevant routine data were available and who reflected the entry criteria for major RCTs, thus enabling a comparison between the results expected from this subgroup and those of the general population.

RESULTS AND CONCLUSIONS

The uses of routine data in these contexts had strengths and weaknesses. The SAH study suggested a means of assessing outcomes and survival rates following haemorrhage, which could have value in informing the design of more precise trials and in evaluating changes in outcome following the introduction of new treatments such as embolisation. However, the potential of the data was not realised because their scope and content were insufficient. For example, lack of data on the time of onset of symptoms and patients' conditions at hospital admission made it difficult to establish the link between timing of surgery and the outcome, and there was insufficient information on patients' conditions at discharge to enable a comparison of outcomes. The prostatectomy study was able to address questions not answered by RCT literature because the large number of cases it included allowed exploration of subgroup effects. (ABSTRACT TRUNCATED)

Is modelling dental caries a 'normal' thing to do?

OBJECTIVE

To introduce and encourage the use of generalised linear models (GLMs) in analysing caries data that do not require the response to be treated necessarily as a sample from a normal distribution.

BASIC RESEARCH DESIGN

At the present time, it is most likely that the sampling distribution of dmf/DMF in industrialised countries will not approximate normality. Generalised linear modelling can be conducted assuming many underlying distributions which, in fact, includes the normal distribution. In this paper three GLMs are employed (normal, Poisson, negative binomial) for modelling an example caries data set. In addition, a binomial model is used to model the dichotomous outcome of caries-free/caries-present.

CLINICAL SETTING

The data comprised 871 Old Trafford, Manchester primary school children aged between 4 years 0 months and 5 years 11 months.

RESULTS

The effect of one study covariate was prominent in a normal model applied to all available dmf data but not in two non-normal models which used dmf > 0 data only. Furthermore, the same covariate was significant at the 5% level in a binomial model indicating that it influenced whether or not caries was present and not the level of dmf.

CONCLUSION

A suitable modelling approach for caries data is to employ a Poisson or a negative binomial model for the dmf/DMF response and a binomial model for the caries-free/caries-present outcome. This allows separate estimation of those factors which influence the magnitude of caries and those factors which influence whether caries is actually present or not.

The initial dental health status of British Army Gurkha recruits

AIM

To describe the initial dental health status of British Army Gurkhas who were recruited in 1999 and to compare the present caries data with previous unpublished data from before 1970 and 1983.

DESIGN AND SETTING

A clinical examination was conducted on the 228 Gurkhas, the entire UK intake for 1999, during their second week of military training. The focus of the examinations was on caries experience. A questionnaire was employed to collect demographic data as well as information on the recruits' reported dental behaviour and beliefs.

RESULTS

1999 recruits who reported a dental problem within the past year were significantly more likely to have visited a dentist before compared to those recruits who reported no dental problems. The frequency distributions of D3MFT for the 1983 and 1999 recruits were very similar.

CONCLUSIONS

Gurkha men are at relatively low risk of dental caries and predicted treatment time suggests a relatively small use of resources would be needed to make this group dentally fit. These recruits are an extremely homogeneous group who remain discernible from the general Nepalese population.

Changes in oral health over ten years amongst UK children aged 4-5 years living in a deprived multiethnic area

OBJECTIVE

To examine the changes over a decade in caries experience amongst children aged 4-5 years living in a deprived multiethnic community in the United Kingdom.

DESIGN

Cross-sectional surveys.

SETTING

Schools and nurseries in the Old Trafford area, Manchester, England, 1989, 1990, 1991 and 1998.

MAIN OUTCOME MEASURES

Mean dmft, oral cleanliness and proportion of children with rampant caries.

RESULTS

The unadjusted Odds Ratio for caries free children examined in 1998 compared with children examined prior to 1998, was only significant amongst the white group. White children examined in 1998 were over three times more likely to be caries free than white children examined previously. South Asian children whose mothers were non English speaking examined in 1998 were almost twice as likely to have good/fair oral cleanliness than those examined prior to 1998. Moreover, South Asian children whose mothers were non-English speaking in 1998 were over three times more likely not to have rampant caries than their counterparts in the earlier years.

CONCLUSION

There were significant improvements in caries and oral health amongst white children over the decade, and although less marked these were mirrored amongst South Asian children.

Comparing outcomes of percutaneous transluminal coronary angioplasty with coronary artery bypass grafting; can routine health service data complement and enhance randomized controlled trials?

AIM

To compare outcomes of percutaneous transluminal coronary angioplasty (PTCA) with coronary artery bypass graft surgery (CABG) for a population stemming from routinely collected data, in order to assess the merits of such data sources as a complement, and possible enhancement, to randomized controlled trial results.

METHODS AND RESULTS

A population of Scottish patients were taken from a routine discharge summary and from this data source patients comparable to those from randomized controlled trial settings were identified. Between 1989 and 1995, 12 238 pseudo randomized controlled trial patients were identified from the routine data set, of which 3714 (30.3%) received PTCA and 8524 (69.7%) received CABG. The baseline characteristics of the pseudo randomized controlled trial and randomized controlled trial patients were similar. The evidence from both the randomized controlled trials and routine data indicate that for 1 year follow-up the risk of cardiac death and/or non-fatal myocardial infarction is not significantly different between the two treatment groups.

CONCLUSION

The outcomes expected of PTCA and CABG following trial evidence have been realized in the routine data which are representative of a complete, non-selective population. Due to the size of the routine data set it would be possible to set up hypotheses for potential subgroup effects at the outset.