PLEASANT: Preventing and Lessening Exacerbations of Asthma in School-age children Associated with a New Term - a cluster randomised controlled trial and economic evaluation

Evaluation of the cost-effectiveness of a multicomponent fall prevention program in hospitalized patients

The aim of this pre- and post-interventional study was to analyze the cost-effectiveness of the multicomponent fall prevention program in hospitalized patients. To achieve this aim, cost-effectiveness analysis performed using decision tree modeling was compared with the implementation of the fall prevention program and usual care. The primary outcome was the number of patient falls. The uncertainty in cost and effectiveness data was evaluated using one-way sensitivity analysis, best-worst-case scenario analysis, and probabilistic sensitivity analysis. According to cost-effectiveness analysis, implementation of the fall prevention program was dominantly cost-effective. As a result of the probabilistic sensitivity analysis, it was revealed that, even if willing-to-pay per-fall prevented value was 0, the probability of being cost-effective was 54.4% for the fall prevention program. Economic evaluation results showed that implementing the multicomponent fall prevention program was dominantly cost-effective in hospitalized patients. Nurses and nurse managers can benefit from economic evaluations in their decision-making processes to implement fall prevention programs.

Predisposing factors for a second fragile hip fracture in a population of 1130 patients with hip fractures, treated at Oulu University Hospital in 2013-2016: a retrospective study

OBJECTIVE

The life-time risk of a second fragile hip fracture is 8.4%, but the risk factors that predispose to a second hip fracture remain unresolved. This study aimed to define risk factors that predisposed patients to a second hip fracture.

METHODS

For this retrospective study, we retrieved clinical data on 1130 patients with fragile hip fractures (67.2% female, mean age: 79.3 years) that underwent surgery at the Oulu University Hospital in 2013-2016. These data included the fracture risk assessment score (measured with the FRAX tool), the bone-mass T-score, laboratory values, ambulatory capacity, and the time of death.

RESULTS

In this population, 12.4% of patients sustained a second hip fracture. The predisposing factors for a second hip fracture were: female (p = 0.016), a high FRAX score (p = 0.020), and low physical capacity (p < 0.001). The vitamin D level recommended for treating osteoporosis (i.e., vitamin D > 75 nmol/l) was observed in only 24% of patients, and 42% of patients had ionized calcium levels below the reference range. According to the level of the cross-linked carboxy-terminal telopeptide of type I collagen (ICTP), 37% of patients did not have high bone turnover. We found a positive correlation between age and ICTP (p = 0.001). The risk of death was higher after the second hip fracture (p = 0.005), but we found no difference in age between patients with first and second hip fractures (p = 0.11).

CONCLUSION

After a hip fracture, a second hip fracture is a well-known risk. Nevertheless, we found that only one-third of patients with a second hip fracture had used anti-osteoporosis medication at any time previously. These findings suggested that second hip fractures were most likely to occur in patients with osteopenic T-score values, in women more often than men, and in patients with high FRAX scores and low ambulatory capacity.

Cost-effectiveness analysis of five drugs for treating postmenopausal women in the United States with osteoporosis and a very high fracture risk

PURPOSE

Five strategies were recommended by the American Association of Clinical Endocrinologists/American College of Endocrinology (AACE/ACE) guidelines for the treatment of postmenopausal osteoporosis (PMO) patients with a very high fracture risk. We aimed to assess their cost-effectiveness in the United States (US).

METHODS

A microsimulation Markov model was created to compare the cost-effectiveness of five treatment strategies, including zoledronate, denosumab, abaloparatide, teriparatide, and romosozumab in PMO patients with a recent fracture from the healthcare perspective of the US. The data used in the model were obtained from published studies or online resources. Base-case analysis, one-way deterministic sensitivity analysis (DSA) and probability sensitivity analysis (PSA) were conducted for 65-, 70-, 75-, and 80-year-old patients.

RESULTS

In base case, at 65 years, zoledronate was the cheapest strategy. The incremental cost-effectiveness ratios (ICER, which represent incremental costs per QALY gained) of denosumab, teriparatide, abaloparatide, and romosozumab against zoledronate were $13,020/QALY (quality-adjusted years), $477,331 /QALY, $176,287/QALY, and $98,953/QALY, respectively. Under a willing-to-pay (WTP, which means the highest price a consumer will pay for one unit of a good of service) threshold of $150,000/QALY, denosumab and romosozumab were cost-effective against zoledronate. The PSA results showed that denosumab was the most cost-effective option with WTP thresholds of $50,000/QALY, $100,000/QALY and $150,000/QALY. The results were similar in other age groups. The DSA results indicated that the most common parameters that have important influence on the outcome were drug persistence, incidence of adverse events, the efficacy of drugs on hip fractures and the cost of the drug.

CONCLUSION AND RELEVANCE

Among PMO patients with a very high fracture risk in the US, zoledronate is the cheapest strategy and denosumab is the most cost-effective choice among these five strategies.

TRial to Assess Implementation of New research in a primary care Setting (TRAINS): study protocol for a pragmatic cluster randomised controlled trial of an educational intervention to promote asthma prescription uptake in general practitioner practices

Background

There is a marked increase in unscheduled care visits in school-aged children with asthma after returning to school in September. This is potentially associated with children not taking their asthma preventer medication during the school summer holidays. A cluster randomised controlled trial (PLEASANT) was undertaken with 1279 school-age children in 141 general practices (71 on intervention and 70 on control) in England and Wales. It found that a simple letter sent from the family doctor during the school holidays to a parent with a child with asthma, informing them of the importance of taking asthma preventer medication during the summer relatively increased prescriptions by 30% in August and reduced medical contacts in the period September to December. Also, it is estimated there was a cost-saving of £36.07 per patient over the year. We aim to conduct a randomised trial to assess if informing GP practices of an evidence-based intervention improves the implementation of that intervention.

Methods/design

The TRAINS study—TRial to Assess Implementation of New research in a primary care Setting—is a pragmatic cluster randomised implementation trial using routine data. A total of 1389 general practitioner (GP) practices in England will be included into the trial; 694 GP practices will be randomised to the intervention group and 695 control group of usual care. The Clinical Practice Research Datalink (CPRD) will send the intervention and obtain all data for the study, including prescription and primary care contacts data. The intervention will be sent in June 2021 by postal and email to the asthma lead and/or practice manager. The intervention is a letter to GPs informing them of the PLEASANT study findings with recommendations. It will come with an information leaflet about PLEASANT and a suggested reminder letter and SMS text template.

Discussion

The trial will assess if informing GP practices of the PLEASANT trial results will increase prescription uptake before the start of the school year. The hope is that the intervention will increase the implementation of PLEASANT work and then increase prescription uptake during the summer holiday prior to the start of school.

Trial registration

ClinicalTrials.gov ID: NCT05226091

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06864-y.

Features of successful interventions to improve adherence to inhaled corticosteroids in children with asthma: A narrative systematic review

INTRODUCTION

Nonadherence to inhaled corticosteroids (ICSs) in children with asthma leads to significant morbidity and mortality. Few adherence interventions have been effective and little is known about what contributes to intervention effectiveness. This systematic review summarizes the efficacy and the characteristics of effective interventions.

METHODS

Six databases were systematically searched on October 3, 2020 for randomized control trials measuring adherence to ICS in children with asthma. A narrative synthesis was conducted focusing on intervention efficacy and study reliability. Intervention content was coded based on the National Institute for Health and Care Excellence guidelines for medicines adherence (the Perceptions and Practicalities Approach, PAPA) and behavior change techniques (BCTs), to determine the effective aspects of the intervention.

RESULTS

Of 240 studies identified, 25 were eligible for inclusion. Thirteen of the 25 studies were categorized as being highly reliable. Nine of the 13 interventions were effective at increasing adherence and 6 of those met the criteria for a PAPA intervention. Techniques targeting perceptions and practicalities in successful interventions included rewards, reminders, feedback and monitoring of adherence, pharmacological support, instruction on how to take their ICS/adhere, and information about triggers for symptoms and nonadherence.

CONCLUSION

Adherence interventions in children with asthma have mixed effectiveness. Effective intervention studies were more frequently of higher quality, were tailored to individuals' perceptual and practical adherence barriers, and used multiple BCTs. However, due to the small number of included studies and varying study design quality, conclusions drawn here are preliminary. Future research is needed to test a PAPA-based intervention with a rigorous study design.

Improving adherence in chronic airways disease: are we doing it wrongly?

Non-adherence to medicines is a significant clinical and financial burden, but successful strategies to improve it, and thus bring about significant improvements in clinical outcome, remain elusive. Many barriers exist, including a lack of awareness amongst some healthcare professionals as to the extent and impact of non-adherence and a dearth of skills to address it successfully. Patients may not appreciate that they are non-adherent, feel they cannot disclose it or underestimate its impact on their health in the short and longer term. In describing the evidence-based frameworks that identify the causal factors behind medicines taking (or not taking) behaviours, we can start to personalise interventions to enable individuals to make informed decisions about their treatments and thus overcome real and perceived barriers to adherence.

Medicines non-adherence is common and associated with significant morbidity and mortality. @GrainnedAn and colleagues outline causal factors behind this behaviour and the appropriate individualised interventions available to support optimal medicines use.https://bit.ly/3ejJNTV

How I Do It: Transitioning Asthma Care From Adolescents to Adults

Children with asthma grow to become adults with asthma. Adolescents are not simply older children and do not automatically transform into independent adults, nor do they become proficient in self-management of their condition overnight. Adolescence is a high-risk time for many people with asthma, with increased risk of asthma-related morbidity and mortality. Children with high-risk asthma attend hospital-based asthma clinics with their parents until they reach young adulthood, and parents usually take on the significant burden of disease management on behalf of their children. Once patients are transferred to adult medical teams, many will continue to have limited knowledge about their asthma, limited understanding of how to manage their symptoms and comorbidities, and limited comprehension of how and why to take their regular medication. Adolescence is a critical time of change during which young people yearn for autonomy. Effective transition gives young people the skills and knowledge necessary to manage their health independently and provides the substrate for autonomous care, the bed rock of long-term conditions. This review focuses on the challenges of adolescent health care and provides guidance on how to take a planned, patient-centered approach to ensure each transition is effective and safe.

Electronically delivered interventions to reduce antibiotic prescribing for respiratory infections in primary care: cluster RCT using electronic health records and cohort study

BACKGROUND

Unnecessary prescribing of antibiotics in primary care is contributing to the emergence of antimicrobial drug resistance.

OBJECTIVES

To develop and evaluate a multicomponent intervention for antimicrobial stewardship in primary care, and to evaluate the safety of reducing antibiotic prescribing for self-limiting respiratory infections (RTIs).

INTERVENTIONS

A multicomponent intervention, developed as part of this study, including a webinar, monthly reports of general practice-specific data for antibiotic prescribing and decision support tools to inform appropriate antibiotic prescribing.

DESIGN

A parallel-group, cluster randomised controlled trial.

SETTING

The trial was conducted in 79 general practices in the UK Clinical Practice Research Datalink (CPRD).

PARTICIPANTS

All registered patients were included.

MAIN OUTCOME MEASURES

The primary outcome was the rate of antibiotic prescriptions for self-limiting RTIs over the 12-month intervention period.

COHORT STUDY

A separate population-based cohort study was conducted in 610 CPRD general practices that were not exposed to the trial interventions. Data were analysed to evaluate safety outcomes for registered patients with 45.5 million person-years of follow-up from 2005 to 2014.

RESULTS

There were 41 intervention trial arm practices (323,155 patient-years) and 38 control trial arm practices (259,520 patient-years). There were 98.7 antibiotic prescriptions for RTIs per 1000 patient-years in the intervention trial arm (31,907 antibiotic prescriptions) and 107.6 per 1000 patient-years in the control arm (27,923 antibiotic prescriptions) [adjusted antibiotic-prescribing rate ratio (RR) 0.88, 95% confidence interval (CI) 0.78 to 0.99; p = 0.040]. There was no evidence of effect in children aged < 15 years (RR 0.96, 95% CI 0.82 to 1.12) or adults aged ≥ 85 years (RR 0.97, 95% CI 0.79 to 1.18). Antibiotic prescribing was reduced in adults aged between 15 and 84 years (RR 0.84, 95% CI 0.75 to 0.95), that is, one antibiotic prescription was avoided for every 62 patients (95% CI 40 to 200 patients) aged 15-84 years per year. Analysis of trial data for 12 safety outcomes, including pneumonia and peritonsillar abscess, showed no evidence that these outcomes might be increased as a result of the intervention. The analysis of data from non-trial practices showed that if a general practice with an average list size of 7000 patients reduces the proportion of RTI consultations with antibiotics prescribed by 10%, then 1.1 (95% CI 0.6 to 1.5) more cases of pneumonia per year and 0.9 (95% CI 0.5 to 1.3) more cases of peritonsillar abscesses per decade may be observed. There was no evidence that mastoiditis, empyema, meningitis, intracranial abscess or Lemierre syndrome were more frequent at low-prescribing practices.

LIMITATIONS

The research was based on electronic health records that may not always provide complete data. The number of practices included in the trial was smaller than initially intended.

CONCLUSIONS

This study found evidence that, overall, general practice antibiotic prescribing for RTIs was reduced by this electronically delivered intervention. Antibiotic prescribing rates were reduced for adults aged 15-84 years, but not for children or the senior elderly.

FUTURE WORK

Strategies for antimicrobial stewardship should employ stratified interventions that are tailored to specific age groups. Further research into the safety of reduced antibiotic prescribing is also needed.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN95232781.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 11. See the NIHR Journals Library website for further project information.

Adherence to medication in children and adolescents with asthma: methods for monitoring and intervention

INTRODUCTION

Poor adherence in children with asthma is a major cause of asthma attacks and poor control, leads to large health-care costs, and has been identified as a factor in asthma deaths. However, it is difficult to detect and frequently overlooked leading to inappropriate escalation of asthma treatment. There is a need for cost effective ways to monitor adherence in order to intervene to change this modifiable behavior. Areas covered: Several measurement tools have been developed to assess adherence in adults and children with asthma. The current methods for measuring adherence, both subjective and objective, have several flaws and even the current gold standard, electronic monitoring devices (EMDs), has limitations. This review will outline and critique the adherence monitoring tools and highlight ways in which they have been used for the purpose of intervention. Expert commentary: Although advances have been made in adherence monitoring, we still have some way to go in creating the ideal monitoring tool. There are no validated tailored self-monitoring questionnaires for children with asthma and most objective measures, such as prescription refill rate and weighing canisters, overestimate adherence. Current EMDs, although useful, need improved accuracy to ensure that both actuation and inhalation are measured, and the devices need to be affordable for use in routine health-care practice.

Open-label, cluster randomised controlled trial and economic evaluation of a brief letter from a GP on unscheduled medical contacts associated with the start of the school year: the PLEASANT trial

BACKGROUND

Asthma is seasonal with peaks in exacerbation rates in school-age children associated with the return to school following the summer vacation. A drop in prescription collection in August is associated with an increase in the number of unscheduled contacts after the school return.

OBJECTIVE

To assess whether a public health intervention delivered in general practice reduced unscheduled medical contacts in children with asthma.

DESIGN

Cluster randomised trial with trial-based economic evaluation. Randomisation was at general practice level, stratified by size of practice. The intervention group received a letter from their general practitioner (GP) in late July outlining the importance of (re)taking asthma medication before the return to school. The control group was usual care.

SETTING

General practices in England and Wales.

PARTICIPANTS

12 179 school-age children in 142 general practices (70 randomised to intervention).

MAIN OUTCOME

Proportion of children aged 5-16 years who had an unscheduled contact in September. Secondary endpoints included collection of prescriptions in August and medical contacts over 12 months (September-August). Economic endpoints were quality-adjusted life-years gained and health service costs.

RESULTS

There was no evidence of effect (OR 1.09; 95% CI 0.96 to 1.25 against treatment) on unscheduled contacts in September. The intervention increased the proportion of children collecting a prescription in August by 4% (OR 1.43; 95% CI 1.24 to 1.64). The intervention also reduced the total number of medical contacts between September-August by 5% (incidence ratio 0.95; 95% CI 0.91 to 0.99).The mean reduction in medical contacts informed the health economics analyses. The intervention was estimated to save £36.07 per patient, with a high probability (96.3%) of being cost-saving.

CONCLUSIONS

The intervention succeeded in increasing children collecting prescriptions. It did not reduce unscheduled care in September (the primary outcome), but in the year following the intervention, it reduced the total number of medical contacts.

TRIAL REGISTRATION NUMBER

ISRCTN03000938; Results.

Interventions for autumn exacerbations of asthma in children

BACKGROUND

Asthma exacerbations in school-aged children peak in autumn, shortly after children return to school following the summer holiday. This might reflect a combination of risk factors, including poor treatment adherence, increased allergen and viral exposure, and altered immune tolerance. Since this peak is predictable, interventions targeting modifiable risk factors might reduce exacerbation-associated morbidity and strain upon health resources. The peak occurs in September in the Northern Hemisphere and in February in the Southern Hemisphere.

OBJECTIVES

To assess the effects of pharmacotherapy and behavioural interventions enacted in anticipation of school return during autumn that are designed to reduce asthma exacerbations in children during this period.

SEARCH METHODS

We searched the Cochrane Airways Group Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, reference lists of primary studies and existing reviews, and manufacturers' trial registries (Merck, Novartis and Ono Parmaceuticals). We searched databases from their inception to 1 December 2017, and imposed no restriction on language of publication.

SELECTION CRITERIA

We included all randomised controlled trials comparing interventions aimed specifically at reducing autumn exacerbations with usual care, (no systematic change in management in preparation for school return). We included studies providing data on children aged 18 years or younger.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently screened records identified by the search and then extracted data and assessed bias for trials meeting the inclusion criteria. A third review author checked for accuracy and mediated consensus on disagreements. The primary outcome was proportion of children experiencing one or more asthma exacerbations requiring hospitalisation or oral corticosteroids during the autumn period.

MAIN RESULTS

Our searches returned 546 trials, of which five met our inclusion criteria. These studies randomised 14,252 children to receive either an intervention or usual care. All studies were conducted in the Northern Hemisphere. Three interventions used a leukotriene receptor antagonist, one used omalizumab or a boost of inhaled corticosteroids, and the largest study, (12,179 children), used a medication reminder letter. Whilst the risk of bias within individual studies was generally low, we downgraded the evidence quality due to imprecision associated with low participant numbers, poor consistency between studies, and indirect outcome ascertainment.A US study of 513 children with mild/severe asthma and allergic sensitisation was the only study to provide data for our primary outcome. In this study, the proportion of participants experiencing an exacerbation requiring oral corticosteroids or hospital admission in the 90 days after school return was significantly reduced to 11.3% in those receiving omalizumab compared to 21.0% in those receiving placebo (odds ratio 0.48, 95% confidence interval 0.25 to 0.92, moderate-quality evidence). The remaining studies used alternative exacerbation definitions. When data from two leukotriene receptor antagonist studies with comparable outcomes were combined in a random-effects model, there was no evidence of an effect upon exacerbations. There was no evidence that a seasonal medication reminder letter decreased unscheduled contacts for a respiratory diagnosis between September and December.Four studies recorded adverse events. There was no evidence that the proportion of participants experiencing at least one adverse event differed between intervention and usual care groups. Lack of data prevented planned subgroup and sensitivity analyses.

AUTHORS' CONCLUSIONS

Seasonal omalizumab treatment from four to six weeks before school return might reduce autumn asthma exacerbations. We found no evidence that this strategy is associated with increased adverse effects other than injection site pain, but it is costly. There were no data upon which to judge the effect of this or other seasonal interventions on asthma control, quality of life, or asthma-related death. In future studies definitions of exacerbations should be provided, and standardised where possible. To investigate possible differential effects according to subgroup, participants in future trials should be well characterised with respect to baseline asthma severity and exacerbation history in addition to age and gender.

A cluster randomised controlled trial and evaluation and cost-effectiveness analysis of the Roots of Empathy schools-based programme for improving social and emotional well-being outcomes among 8- to 9-year-olds in Northern Ireland

Background

There is growing consensus regarding the importance of attending to children’s social and emotional well-being. There is now a substantial evidence base demonstrating the links between a child’s early social and emotional development and a range of key longer-term education, social and health outcomes. Universal school-based interventions provide a significant opportunity for early intervention in this area and yet the existing evidence base, particularly in relation to their long-term effects, is limited.

Objectives and main outcomes

To determine the effectiveness and cost-effectiveness of Roots of Empathy (ROE), a universal school-based programme that, through attempting to enhance children’s empathy, seeks to achieve the following two main outcomes: improvement in prosocial behaviour and reduction in difficult behaviour.

Design

A cluster randomised controlled trial and an economic evaluation. A total of 74 primary schools were randomly assigned to deliver ROE or to join a waiting list control group. Seven schools withdrew post randomisation and a further two withdrew before the immediate post-test time point. Children (n = 1278) were measured pre test and immediately post test, and then for 3 years following the end of the programme. Data were also collected from teachers and parents.

Setting and participants

The intervention schools delivered ROE to their Year 5 children (aged 8–9 years) as a whole class.

Intervention

ROE is delivered on a whole-class basis for one academic year (October–June). It consists of 27 lessons based around the monthly visit from a baby and parent who are usually recruited from the local community. Children learn about the baby’s growth and development and are encouraged to generalise from this to develop empathy towards others.

Results

Although it was developed in Canada, the programme was very well received by schools, parents and children, and it was delivered effectively with high fidelity. ROE was also found to be effective in achieving small improvements in children’s prosocial behaviour (Hedges’ g = 0.20; p = 0.045) and reductions in their difficult behaviour (Hedges’ g = –0.16; p = 0.060) immediately post test. Although the gains in prosocial behaviour were not sustained after the immediately post-test time point, there was some tentative evidence that the effects associated with reductions in difficult behaviour may have remained up to 36 months from the end of the programme. These positive effects of ROE on children’s behaviour were not found to be associated with improvements in empathy or other social and emotional skills (such as emotional recognition and emotional regulation), on which the trial found no evidence of ROE having an effect. The study also found that ROE was likely to be cost-effective in line with national guidelines.

Conclusions

These findings are consistent with those of other evaluations of ROE and suggest that it is an effective and cost-effective programme that can be delivered appropriately and effectively in regions such as Northern Ireland. A number of issues for further consideration are raised regarding opportunities to enhance the role of parents; how a time-limited programme such as ROE can form part of a wider and progressive curriculum in schools to build on and sustain children’s social and emotional development; and the need to develop a better theory of change for how ROE works.

Trial registration

Current Controlled Trials ISRCTN07540423.

Funding

This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 6, No. 4. See the NIHR Journals Library website for further project information.

Economic Evaluations Alongside Efficient Study Designs Using Large Observational Datasets: the PLEASANT Trial Case Study

BACKGROUND

Large observational datasets such as Clinical Practice Research Datalink (CPRD) provide opportunities to conduct clinical studies and economic evaluations with efficient designs.

OBJECTIVES

Our objectives were to report the economic evaluation methodology for a cluster randomised controlled trial (RCT) of a UK NHS-delivered public health intervention for children with asthma that was evaluated using CPRD and describe the impact of this methodology on results.

METHODS

CPRD identified eligible patients using predefined asthma diagnostic codes and captured 1-year pre- and post-intervention healthcare contacts (August 2012 to July 2014). Quality-adjusted life-years (QALYs) 4 months post-intervention were estimated by assigning utility values to exacerbation-related contacts; a systematic review identified these utility values because preference-based outcome measures were not collected. Bootstrapped costs were evaluated 12 months post-intervention, both with 1-year regression-based baseline adjustment (BA) and without BA (observed).

RESULTS

Of 12,179 patients recruited, 8190 (intervention 3641; control 4549) were evaluated in the primary analysis, which included patients who received the protocol-defined intervention and for whom CPRD data were available. The intervention's per-patient incremental QALY loss was 0.00017 (bias-corrected and accelerated 95% confidence intervals [BCa 95% CI] -0.00051 to 0.00018) and cost savings were £14.74 (observed; BCa 95% CI -75.86 to 45.19) or £36.07 (BA; BCa 95% CI -77.11 to 9.67), respectively. The probability of cost savings was much higher when accounting for BA versus observed costs due to baseline cost differences between trial arms (96.3 vs. 67.3%, respectively).

CONCLUSION

Economic evaluations using data from a large observational database without any primary data collection is feasible, informative and potentially efficient. Clinical Trials Registration Number: ISRCTN03000938.