Developing a Natural History Model for Duchenne Muscular Dystrophy.

BACKGROUND: The aim of this study was to pool multiple data sets to build a patient-centric, data-informed, natural history model (NHM) for Duchenne muscular dystrophy (DMD) to estimate disease trajectory across patient lifetime under current standard of care in future economic evaluations. The study was conducted as part of Project HERCULES, a multi-stakeholder collaboration to develop tools to support health technology assessments of new treatments for DMD. METHODS: Health states were informed by a review of NHMs for DMD and input from clinicians, patients and caregivers, and defined using common outcomes in clinical trials and real-world practice. The primary source informing the NHM was the Critical Path Institute Duchenne Regulatory Science Consortium (D-RSC) database. This was supplemented with expert input obtained via an elicitation exercise, and a systematic literature review and meta-analysis of mortality data. RESULTS: The NHM includes ambulatory, transfer and non-ambulatory phases, which capture loss of ambulation, ability to weight bear and upper body and respiratory function, respectively. The NHM estimates patients spend approximately 9.5 years in ambulatory states, 1.5 years in the transfer state and the remainder of their lives in non-ambulatory states. Median predicted survival is 34.8 years (95% CI 34.1-35.8). CONCLUSION: The model includes a detailed disease pathway for DMD, including the clinically and economically important transfer state. The NHM may be used to estimate the current trajectory of DMD in economic evaluations of new treatments, facilitating inclusion of a lifetime time horizon, and will help identify areas for further research.

Jointly modelling longitudinally measured urinary human chorionic gonadotrophin and early pregnancy outcomes.

Human chorionic gonadotrophin (hCG) is largely used to confirm pregnancy. Yet evidence shows that longitudinal hCG profiles are distinguishable between healthy and failing pregnancies. We retrospectively fitted a joint longitudinal-survival model to data from 127 (85 healthy and 42 failing pregnancies) US women, aged 18-45, who were attempting to conceive, to quantify the association between longitudinally measured urinary hCG and early miscarriage. Using subject-specific predictions, obtained uniquely from the joint model, we investigated the plausibility of adaptively monitoring early pregnancy outcomes based on updating hCG measurements. Volunteers collected daily early morning urine samples for their menstrual cycle and up to 28 days post day of missed period. The longitudinal submodel for log hCG included a random intercept and slope and fixed linear and quadratic time terms. The survival submodel included maternal age and cycle length covariates. Unit increases in log hCG corresponded to a 63.9% (HR 0.36, 95% CI 0.16, 0.47) decrease in the risk of miscarriage, confirming a strong association between hCG and miscarriage. Outputted conditional survival probabilities gave individualised risk estimates for the early pregnancy outcomes in the short term. However, longer term monitoring would require a larger sample size and prospectively followed up data, focusing on emerging extensions to the joint model, which allow assessment of the specificity and sensitivity.

Assessing causal treatment effect estimation when using large observational datasets.

BACKGROUND: Recently, there has been a heightened interest in developing and evaluating different methods for analysing observational data. This has been driven by the increased availability of large data resources such as Electronic Health Record (EHR) data alongside known limitations and changing characteristics of randomised controlled trials (RCTs). A wide range of methods are available for analysing observational data. However, various, sometimes strict, and often unverifiable assumptions must be made in order for the resulting effect estimates to have a causal interpretation. In this paper we will compare some common approaches to estimating treatment effects from observational data in order to highlight the importance of considering, and justifying, the relevant assumptions prior to conducting an observational analysis. METHODS: A simulation study was conducted based upon a small cohort of patients with chronic obstructive pulmonary disease. Two-stage least squares instrumental variables, propensity score, and linear regression models were compared under a range of different scenarios including different strengths of instrumental variable and unmeasured confounding. The effects of violating the assumptions of the instrumental variables analysis were also assessed. Sample sizes of up to 200,000 patients were considered. RESULTS: Two-stage least squares instrumental variable methods can yield unbiased treatment effect estimates in the presence of unmeasured confounding provided the sample size is sufficiently large. Adjusting for measured covariates in the analysis reduces the variability in the two-stage least squares estimates. In the simulation study, propensity score methods produced very similar results to linear regression for all scenarios. A weak instrument or strong unmeasured confounding led to an increase in uncertainty in the two-stage least squares instrumental variable effect estimates. A violation of the instrumental variable assumptions led to bias in the two-stage least squares effect estimates. Indeed, these were sometimes even more biased than those from a naïve linear regression model. CONCLUSIONS: Instrumental variable methods can perform better than naïve regression and propensity scores. However, the assumptions need to be carefully considered and justified prior to conducting an analysis or performance may be worse than if the problem of unmeasured confounding had been ignored altogether.

Two-stage estimation to adjust for treatment switching in randomised trials: a simulation study investigating the use of inverse probability weighting instead of re-censoring.

BACKGROUND: Treatment switching is common in randomised trials of oncology treatments, with control group patients switching onto the experimental treatment during follow-up. This distorts an intention-to-treat comparison of the treatments under investigation. Two-stage estimation (TSE) can be used to estimate counterfactual survival times for patients who switch treatments - that is, survival times that would have been observed in the absence of switching. However, when switchers do not die during the study, counterfactual censoring times are estimated, inducing informative censoring. Re-censoring is usually applied alongside TSE to resolve this problem, but results in lost longer-term information - a major concern if the objective is to estimate long-term treatment effects, as is usually the case in health technology assessment. Inverse probability of censoring weights (IPCW) represents an alternative technique for addressing informative censoring but has not before been combined with TSE. We aim to determine whether combining TSE with IPCW (TSEipcw) represents a valid alternative to re-censoring. METHODS: We conducted a simulation study to compare TSEipcw to TSE with and without re-censoring. We simulated 48 scenarios where control group patients could switch onto the experimental treatment, with switching affected by prognosis. We investigated various switching proportions, treatment effects, survival function shapes, disease severities and switcher prognoses. We assessed the alternative TSE applications according to their estimation of control group restricted mean survival (RMST) that would have been observed in the absence of switching up to the end of trial follow-up. RESULTS: TSEipcw performed well when its weights had a low coefficient of variation, but performed poorly when the coefficient of variation was high. Re-censored analyses usually under-estimated control group RMST, whereas non-re-censored analyses usually produced over-estimates, with bias more serious when the treatment effect was high. In scenarios where TSEipcw performed well, it produced low bias that was often between the two extremes associated with the re-censoring and non-recensoring options. CONCLUSIONS: Treatment switching adjustment analyses using TSE should be conducted with re-censoring, without re-censoring, and with IPCW to explore the sensitivity in results to these application options. This should allow analysts and decision-makers to better interpret the results of adjustment analyses.

Causal inference for long-term survival in randomised trials with treatment switching: Should re-censoring be applied when estimating counterfactual survival times?

Treatment switching often has a crucial impact on estimates of effectiveness and cost-effectiveness of new oncology treatments. Rank preserving structural failure time models (RPSFTM) and two-stage estimation (TSE) methods estimate 'counterfactual' (i.e. had there been no switching) survival times and incorporate re-censoring to guard against informative censoring in the counterfactual dataset. However, re-censoring causes a loss of longer term survival information which is problematic when estimates of long-term survival effects are required, as is often the case for health technology assessment decision making. We present a simulation study designed to investigate applications of the RPSFTM and TSE with and without re-censoring, to determine whether re-censoring should always be recommended within adjustment analyses. We investigate a context where switching is from the control group onto the experimental treatment in scenarios with varying switch proportions, treatment effect sizes, treatment effect changes over time, survival function shapes, disease severity and switcher prognosis. Methods were assessed according to their estimation of control group restricted mean survival that would be observed in the absence of switching, up to the end of trial follow-up. We found that analyses which re-censored usually produced negative bias (i.e. underestimating control group restricted mean survival and overestimating the treatment effect), whereas analyses that did not re-censor consistently produced positive bias which was often smaller in magnitude than the bias associated with re-censored analyses, particularly when the treatment effect was high and the switching proportion was low. The RPSFTM with re-censoring generally resulted in increased bias compared to the other methods. We believe that analyses should be conducted with and without re-censoring, as this may provide decision-makers with useful information on where the true treatment effect is likely to lie. Incorporating re-censoring should not always represent the default approach when the objective is to estimate long-term survival times and treatment effects.

Adjusting for treatment switching in randomised controlled trials - A simulation study and a simplified two-stage method.

Estimates of the overall survival benefit of new cancer treatments are often confounded by treatment switching in randomised controlled trials (RCTs) - whereby patients randomised to the control group are permitted to switch onto the experimental treatment upon disease progression. In health technology assessment, estimates of the unconfounded overall survival benefit associated with the new treatment are needed. Several switching adjustment methods have been advocated in the literature, some of which have been used in health technology assessment. However, it is unclear which methods are likely to produce least bias in realistic RCT-based scenarios. We simulated RCTs in which switching, associated with patient prognosis, was permitted. Treatment effect size and time dependency, switching proportions and disease severity were varied across scenarios. We assessed the performance of alternative adjustment methods based upon bias, coverage and mean squared error, related to the estimation of true restricted mean survival in the absence of switching in the control group. We found that when the treatment effect was not time-dependent, rank preserving structural failure time models (RPSFTM) and iterative parameter estimation methods produced low levels of bias. However, in the presence of a time-dependent treatment effect, these methods produced higher levels of bias, similar to those produced by an inverse probability of censoring weights method. The inverse probability of censoring weights and structural nested models produced high levels of bias when switching proportions exceeded 85%. A simplified two-stage Weibull method produced low bias across all scenarios and provided the treatment switching mechanism is suitable, represents an appropriate adjustment method.

Validation of the Patient Global Impression scales for use in detrusor overactivity: secondary analysis of the RELAX study.

OBJECTIVE: To assess construct validity of the Patient Global Impression scales (Severity [PGI-S], Bother [PGI-B] and Improvement [PGI-I]) for symptoms of detrusor overactivity (DO). DESIGN: Secondary analysis of a randomised trial of onabotulinum toxin A. SETTING: Eight UK urogynaecology departments. POPULATION: A total of 240 women with DO refractory to medical treatment randomised to receive 200 iu onabotulinum toxin A or placebo in the RELAX trial and followed up for 6 months. MAIN OUTCOME MEASURES: Urinary diaries and disease-specific quality of life (QoL) questionnaires were completed at baseline and during follow up. Discriminatory ability of the PGI-S, PGI-B and PGI-I scales to identify symptom severity and change in severity was assessed by comparing mean diary and QoL outcomes across the response categories, analysed by one-way analysis of variance. RESULTS: Data were available from 237 women (98.8%) for validation of PGI-S and PGI-B at baseline, and 192 women (80%) at 6 weeks follow up for validation of PGI-I. Leakage episodes (P = 0.01), urgency episodes (P = 0.019), urgency severity (P = 0.012), and QoL scores (all P < 0.001) were greater in women with more severe problems on PGI-S. Similar results were seen for PGI-B: leakage (P = 0.051), urgency episodes (P < 0.001), urgency severity (P < 0.001), and QoL scores (all P < 0.001). PGI-I responses demonstrated significant relationships with size of change of all variables (P < 0.001). The generic instrument EQ-5D had weaker relationships (PGI-S, P = 0.09; PGI-B, P = 0.004; PGI-I, P = 0.06), suggesting that it was less sensitive. CONCLUSIONS: The PGI scales are robust and valid instruments to assess disease severity, bother and improvement after treatment in women with detrusor overactivity.

Esophageal stents for benign refractory strictures: a meta-analysis.

BACKGROUND AND AIMS: Fully covered self-expanding removable stents (SERS) have been considered a viable alternative to serial bougienage. The primary aim of this meta-analysis was to determine the efficacy of SERS for refractory esophageal strictures. METHODS: Medline, Embase, and PubMed databases were searched using the keywords "esophageal stricture," "esophageal stents," "benign stricture," "dysphagia," "caustic," "peptic stricture," "anastomotic," "radiation," and "dysphagia" for the period from January 1965 to June 2010. Articles were selected for review independently by two authors (T. T. and J. M.) on the basis of predefined inclusion criteria, and the data collected. A meta-analysis using a random effects model was done. RESULTS: Eight studies with a total of 199 patients were included in the final analysis (104-males, average age 56 years, range: 49 - 68 years). Overall, 46.2 % of patients (95 %CI: 38.3 % - 54.1 %) had dysphagia improvement at an average follow up of 74 weeks. There was a significant difference ( P = 0.019) in dysphagia improvement for patients with Polyflex stents (55.3 %; 95 %CI: 44.4 % - 65.9 %) versus nitinol stents (21.8 %; 95 %CI: 13.7 % - 33.7 %). On meta-regression, patient sex ( P = 0.80), patient age ( P = 0.725), corrosive etiology ( P = 0.30), stricture location ( P = 0.273), stricture length ( P = 0.32), time of removal ( P = 0.056), and duration of follow-up (0.35) had no significance influence on the outcome. The migration rate was 26.4 % (95 %CI: 25.3 % - 39.3 %). CONCLUSIONS: Although the efficacy of SERS placement in benign refractory strictures is 46.2 %, it is associated with migration rate of 26.4 %. Nevertheless, the use of these temporary stents, which can be successfully removed in 87 % of patients, is an alluring prospect for treating patients with this difficult condition.

Temporal trends in primary total hip and knee arthroplasty surgery: results from a UK regional joint register, 1991-2004.

INTRODUCTION: The aim of this study was to evaluate temporal trends in the prevalence of primary total hip and knee replacements (THRs and TKRs) throughout the Trent region from 1991 to 2004. PATIENTS AND METHODS: The Trent Regional Arthroplasty Study records details of primary THR and TKR prospectively and data from the register were examined. Age and gender population data were provided by the Office for National Statistics. RESULTS: A total of 26,281 THRs and 23,606 TKRs were recorded during this period. Analysis showed that females had an increased incidence rate ratio (IRR) for both primary THR (IRR = 1.29; 95% CI 1.26-1.33; P < 0.001) and TKR (IRR = 1.17; 95% CI 1.14-1.20; P < 0.001). Patients aged 74-85 years had the largest IRR for both primary THR (IRR = 6.7; 95% CI 6.4-7.0; P < 0.001) and TKR (IRR = 15.3; 95% CI 14.4-16.3; P < 0.001). CONCLUSIONS: The prevalence of primary TKR increased significantly over time whereas THR remained steady in the Trent region between 1991 and 2004.

A randomised, partially observer blind, multicentre, head-to-head comparison of a two-dose regimen of Baxter and GlaxoSmithKline H1N1 pandemic vaccines, administered 21 days apart.

OBJECTIVES: To evaluate the immunogenicity of a two-dose schedule of Baxter cell-cultured, non-adjuvanted, whole-virion H1N1 vaccine, and GlaxoSmithKline AS03(A)-adjuvanted split-virion H1N1 vaccine with respect to the EU Committee for Medicinal Products for Human Use (CHMP) and the US Food and Drug Administration (FDA) licensing criteria. DESIGN: An age-stratified, randomised, observer-blind, parallel-group, multicentre controlled trial was carried out in volunteers aged ≥ 18-44, ≥ 45-64 and ≥ 65 years. SETTING: Three teaching hospitals in the UK (Leicester Royal Infirmary, Leicester; Nottingham City Hospital, Nottingham; and Royal Hallamshire Hospital, Sheffield). PARTICIPANTS: Three hundred and forty-seven subjects were identified and randomised to AS03(A)-adjuvanted split-virion H1N1 vaccine or whole-virion (WV) vaccine in age groups [≥ 18-44 years (n = 140), ≥ 45-64 years (n = 136) and ≥ 65 years (n = 71)]. INTERVENTIONS: Vaccine was administered by intramuscular injection into the deltoid muscle of the non-dominant arm. One hundred and seventy-five randomised subjects were allocated AS03(A)-adjuvanted split H1N1 vaccine; one hundred and sixty-nine subjects had a second dose of the same vaccine 21 days later. One hundred and seventy-two subjects were allocated WV vaccine; one hundred and seventy-one subjects had a second dose of the same vaccine 21 days later. Serum samples for antibody measurements were collected on days 0 (before the first vaccination), 7, 14, 21 (before the second vaccination), 28, 35, 42 and 180. Subjects were observed for local and systemic reactions for 30 minutes after each injection, and for the next 7 days they recorded, in self-completed diaries, the severity of solicited local (pain, bruising, erythema and swelling) and systemic symptoms (chills, malaise, muscle aches, nausea and headache), oral temperature and use of analgesic medications. MAIN OUTCOME MEASURES: Vaccine immunogenicity using the CHMP and the FDA licensing criteria. Antibody titres were measured using haemagglutination inhibition (HI) and microneutralisation (MN) assays at baseline and 7, 14 and 21 days after each vaccination and at day 180. The three immunogenicity criteria end points were the seroprotection rate, the seroconversion rate and the mean-fold titre elevation. RESULTS: Both vaccine doses were given in 340 subjects (98%). Data from 680 (99%) of 687 issued diary cards were returned. Sera were obtained from 340 (98.0%), 333 (96.0%), 341 (98.3%), 331 (95.4%), 329 (94.8%) and 332 (95.7%) subjects on days 7, 14, 21, 28, 35 and 42, respectively. Three hundred and forty-six and 345 subjects were included in the safety and immunogenicity analyses, respectively. Prevaccination antibody was detected by HI (titre ≥ 1 : 8) and MN (titre ≥ 1 : 10) in 14% and 31% of subjects, respectively. Among the 298 (85.9%) subjects without baseline antibody on HI assay, a titre of ≥ 1 : 40 (seroprotection) was achieved after a single dose of AS03(A)-adjuvanted vaccine and WV vaccine by day 21 in 93.0% and 65.5%, respectively, of subjects between 18 and 44 years, 76.4% and 36.1% of subjects between 45 and 64 years, and 53.1% and 30.0% of subjects ≥ 65 years. Among all 347 subjects, a titre of ≥ 1 : 40 was achieved after a single dose of AS03(A)-adjuvanted vaccine and WV vaccine by day 21 in 94.0% and 71.4%, respectively, of subjects between 18 and 44 years, 77.3% and 38.8% of subjects between 45 and 64 years, and 51.4% and 32.4% of subjects ≥ 65 years. The age-adjusted odds ratio (OR) for adjuvanted compared with WV vaccine, in terms of seroprotection, was 4.42 [95% confidence interval (CI) 2.63 to 7.44, p < 0.001]. On day 42, among subjects without baseline antibody on HI assay, a titre of ≥ 1 : 40 was achieved after the second dose of AS03(A)-adjuvanted vaccine and WV vaccine by 100% and 67.9%, respectively, of subjects between 18 and 44 years, 89.3% and 41% of subjects between 45 and 64 years, and 76.5% and 34.5% of subjects ≥ 65 years. Among all 347 subjects, a titre of ≥ 1 : 40 was achieved on day 42 after the second dose of AS03(A)-adjuvanted vaccine and WV vaccine in 100% and 73.1%, respectively, of subjects between 18 and 44 years, 90.8% and 43.9% of subjects between 45 and 64 years, and 75.7% and 36.4% of subjects ≥ 65 years. The age-adjusted OR for adjuvanted vaccine compared with WV vaccine, in terms of seroprotection, was 11.21 (95% CI 5.80 to 21.64, p < 0.001). Age-related decline in antibody response occurred after both doses of both vaccines. WV vaccine was associated with fewer local and systemic reactions and lower immune responses than was AS03(A)-adjuvanted vaccine. The most frequent solicited local event was pain, reported by 28% and 76% of subjects after either dose of WV or adjuvanted vaccine, respectively (OR 7.71, 95% CI 4.48 to 13.24, p < 0.0001). The most common systemic event was myalgia, reported by 24% and 49% of subjects after either dose of WV or adjuvanted vaccine (OR 2.99, 95% CI 1.86 to 4.80, p < 0.0001). CONCLUSIONS: AS03(A)-adjuvanted 2009 H1N1 vaccine is more immunogenic and provides greater antigen-sparing capacity than WV 2009 H1N1 vaccine. TRIAL REGISTRATION: Current Controlled Trials ISRCTN92328241. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 14, No. 55. See the HTA programme website for further project information.

Searching for the right outcome? A systematic review and meta-analysis of controlled trials using carotid intima-media thickness or pulse wave velocity to infer antiatherogenic properties of thiazolidinediones.

INTRODUCTION: Recent meta-analyses cast doubt over purported beneficial effects of Peroxisome Proliferator Activated Receptor-Gamma (PPAR-gamma) receptor agonists. Thiazolidinedione (TZD) trials using surrogate outcomes to postulate an antiatherogenic paradigm have been criticised as misinformative. We conducted an independent systematic review and meta-analysis of controlled TZD studies incorporating carotid intima-media thickness (CIMT) or pulse wave velocity (PWV) as primary outcome measures. The aim was to provide an evidence-based overview of TZD intervention studies using markers prospectively linked to vascular outcome in type 2 diabetes. METHODS: Systematic search of known databases for TZD intervention trials using mean thickness CIMT(n = 9) and ankle-brachial PWV(n = 6) as primary outcome measures was performed. CIMT and PWV pooled weighted mean difference was calculated using a random effects model accounting for heterogeneity and publication bias. An indirect meta-analysis provided a comparison of rosiglitazone and pioglitazone effects. RESULTS: A composite of combined placebo and comparator controlled trials demonstrated a significant weighted mean difference of-0.06 mm for CIMT (95% CI-0.09 to-0.02, p = 0.001) and-0.72 ms(-1) for PWV (95% CI-1.28 to-0.16, p = 0.011) in favour of thiazolidiendione treatment. No TZD intraclass variation in CIMT (p = 0.96) or PWV (p = 0.33) change was observed. CONCLUSION: TZDs exhibit significant beneficial effects on aorto-carotid atherosclerosis when assessed using prospectively validated non-invasive techniques. Inferring clinical benefit in the absence of confirmatory outcome trials is questionable and caution should be exercised when interpreting intervention data with surrogate endpoints. TZD-induced congestive cardiac failure or other unknown PPAR-gamma adverse effects are plausible explanations for the conflicting results of intervention trials using markers of atherosclerosis and clinical event outcomes.

Systematic review and meta-analysis of mortality in crop protection product manufacturing workers.

OBJECTIVES: The potential health effects of the manufacture and use of crop protection chemicals were investigated through systematic review and meta-analysis of studies of cohorts of workers in the crop protection product manufacturing industry. METHODS: Several computerised literature databases were searched from inception until December 2003, with references listed in identified articles checked for further relevant articles. Random effects meta-analyses of log standardised mortality ratios (SMRs) were carried out. Heterogeneity was explored through subgroup analyses and meta-regression; sensitivity analyses of different approaches for zero events were performed. RESULTS: 21 references reporting information on 37 separate cohorts for mortality were identified. The meta-SMR for all cause mortality was 0.94 (95% CI 0.88 to 1.00) (37 cohorts). Significantly raised mortality was found for cancers of the buccal cavity and pharynx, oesophagus, rectum, larynx, lung, and lymphatic and haematopoietic system with little heterogeneity being observed. Excluding studies with zero events identified additional excesses. CONCLUSIONS: Evidence of multiple excesses, particularly in subgroups exposed to phenoxy herbicides contaminated with dioxins, substantiates previous findings. The importance of careful treatment of zero cases was highlighted. Future systematic reviews and meta-analyses would benefit from availability of results for a standard list of causes of disease.

Etanercept therapy in rheumatoid arthritis and the risk of malignancies: a systematic review and individual patient data meta-analysis of randomised controlled trials.

PURPOSE: Tumour necrosis factor (TNF) plays an important role in inflammation and may affect tumour growth control. To assess the risk of malignancy with etanercept, a fusion protein that inhibits TNF action, a meta-analysis was performed using individual patient data from randomised controlled trials (RCT) in patients with rheumatoid arthritis (RA). METHODS: A search was conducted of bibliographic databases, abstracts from annual meetings and any unpublished studies on file with manufacturers of etanercept to December 2006. Only RCT of etanercept used for 12 weeks or more in patients with RA were included. Nine trials met the inclusion criteria. To adjudicate endpoints, the case narratives of potential cases were reviewed. Patient-level data were extracted from the clinical trials databases. RESULTS: The nine trials included 3316 patients, 2244 who received etanercept (contributing 2484 person-years of follow-up) and 1072 who received control therapy (1051 person-years). Malignancies were diagnosed in 26 patients in the etanercept group (incidence rate (IR) 10.47/1000 person-years) and seven patients in the control group (IR 6.66/1000 person-years). A Cox's proportional hazards, fixed-effect model stratified by trial yielded a hazard ratio of 1.84 (95% CI 0.79 to 4.28) for the etanercept group compared with the control group. CONCLUSIONS: In this analysis, the point estimate of malignancy risk was higher in etanercept-treated patients, although the results were not statistically significant. The approach of obtaining individual patient data of RCT in cooperation with trial sponsors allowed important insights into the methodological advantages and challenges of sparse adverse event data meta-analysis.

Meta-analysis of the efficacy and tolerability of pramipexole versus ropinirole in the treatment of restless legs syndrome.

OBJECTIVE: In the absence of comparative trials a meta-analysis was performed to compare the efficacy and tolerability of the non-ergot derived dopamine agonists, pramipexole and ropinirole, in restless legs syndrome (RLS). METHODS: Frequentist fixed and random-effects models were pre-specified for the direct comparisons and a Bayesian approach for the indirect comparison. Efficacy outcomes included the mean change from baseline in the International RLS Study Group Rating Scale (IRLS) score and the percentage of responders on the clinical global impressions - improvement scale (CGI-I). Safety outcomes included the incidence of withdrawal and adverse events. RESULTS: The direct meta-analysis confirmed superior efficacy for both treatments versus placebo for the IRLS (pramipexole: -5.45; 95% CI: -7.70; -3.20; ropinirole: -3.16; 95% CI: -4.26; -2.05) and the CGI-I (pramipexole: OR=2.98; 95% CI: 2.08; 4.26; ropinirole: OR=1.99; 95% CI: 1.52; 2.60). Placebo comparisons showed a significantly higher incidence of nausea for pramipexole (p<0.01), whereas nausea, vomiting, dizziness, and somnolence were significantly higher for ropinirole (all p<0.01). The indirect comparison showed with a probability of > or = 95%, a superior reduction in the mean IRLS score (-2.33; 95% credibility interval [CrI]: -4.23; -0.41), higher CGI-I response rate (OR=1.50; 95% CrI: 0.97; 2.32) and significantly lower incidence of nausea, vomiting, and dizziness for pramipexole compared to ropinirole. CONCLUSION: Differences in efficacy and tolerability favouring pramipexole over ropinirole can be observed. These findings should be further confirmed in head-to-head clinical trials.

Access to dental services for people with a physical disability: a survey of general dental practitioners in Leicestershire, UK.

OBJECTIVE: To investigate the availability of facilities, including parking, accessibility and toilet amenities, for physically disabled people at dental practices in Leicestershire, and views relating to the provision of treatment, as reported by general dental practitioners. BASIC RESEARCH DESIGN: A cross-sectional postal questionnaire-based study. SETTING: General Dental Service practices in Leicestershire, United Kingdom. PARTICIPANTS: Questionnaires were sent to all General Dental Service practices (n=123) within Leicestershire. MAIN OUTCOME MEASURES: Facilities for physically disabled people as reported by general dental practitioners and views of practitioners in relation to provision of treatment. RESULTS: The response rate from general dental practices was 80%. The views of 120 (42%) of the 284 dentists approached relating to the provision of treatment to people with a physical disability were recorded. Although up to 77% of the dental practices were considered by practitioners to be accessible to someone using a wheelchair, only 7% also had suitable parking and toilet facilities. The majority of responding dentists treated patients with a physical disability, but 76% of practitioners found it difficult to provide treatment to this group. Concerns regarding the financial cost of providing treatment were raised. There is evidence that conditions are less than optimal in general practice settings for patients with a physical disability receiving treatment. Only nine of the 123 practices in Leicestershire had appropriate parking, access and toilet facilities for physically disabled people. CONCLUSION(S): Facilities for physically disabled people at general practices in Leicestershire are limited. If inequalities in dental health among the physically disabled are to be successfully reduced, steps must be taken to make practices more easily accessible with suitable facilities, and to increase awareness of services offered by appropriate dental practices.

Meta analysis: Cancer risk in Barrett's oesophagus.

BACKGROUND: Risk of cancer in Barrett's oesophagus is reported to vary between studies and also between countries, where the studies were conducted as per several systematic reviews. Cancer incidence has implications on surveillance strategies. AIM: To perform a meta-analysis to determine the incidence of oesophageal cancer in Barrett's oesophagus. METHODS: Articles retrieved by MEDLINE search (English language, 1966-2004). Studies had to necessarily include verified Barrett's oesophagus surveillance patients, documented follow-up and cancer identified as the outcome measure. A random effects model of meta-analysis was chosen and results were expressed as mean (95% CI). RESULTS: Forty-one articles selected for conventional Barrett's oesophagus (length >3 cm); eight included short segment Barrett's oesophagus (one additional article including only short segment Barrett's oesophagus). Cancer incidence was 7/1000 (6-9) person-years duration of follow-up (pyd), with no detectable geographical variation [UK 7/1000 (4-12) pyd, USA 7/1000 (5-9) pyd and Europe 8/1000 (5-12) pyd]. Cancer incidence in the UK was 10/1000 (7-14), when two large studies were excluded. Cancer incidence in SSBO was 6/1000 (3-12) pyd. When short segment Barrett's oesophagus compared to conventional Barrett's oesophagus, there was a trend towards reduced cancer risk [OR 0.55, (95% CI: 0.19-1.6), P = 0.25]. CONCLUSION: We found no geographical variations in Barrett's oesophagus cancer risk, but observed a trend towards reduced cancer risk in short segment Barrett's oesophagus. There is a time trend of decreasing cancer incidence.