Theophylline for irreversible chronic airflow limitation: a randomized study comparing n of 1 trials to standard practice

The use of N-of-1 trials to generate real-world evidence for optimal treatment of individuals and populations

Introduction

Ideally, real-world data (RWD) collected to generate real-world evidence (RWE) should lead to impact on the care and health of real-world patients. Deriving from care in which clinicians and patients try various treatments to inform therapeutic decisions, N-of-1 trials bring scientific methods to real-world practice.

Methods

These single-patient crossover trials generate RWD and RWE by giving individual patients various treatments in a double-blinded way in sequential periods to determine the most effective treatment for a given patient.

Results

This approach is most often used for patients with chronic, relatively stable conditions that provide the opportunity to make comparisons over multiple treatment periods, termed Type 1 N-of-1 trials. These are most helpful when there is heterogeneity of treatment effects among patients and no a priori best option. N-of-1 trials also can be done for patients with rare diseases, potentially testing only one treatment, to generate evidence for personalized treatment decisions, designated as Type 2 N-of-1 trials. With both types, in addition to informing individual's treatments, when uniform protocols are used for multiple patients with the same condition, the data collected in the individual N-of-1 trials can be aggregated to provide RWD/RWE to inform more general use of the treatments. Thereby, N-of-1 trials can provide RWE for the care of individuals and for populations.

Conclusions

To fulfill this potential, we believe N-of-1 trials should be built into our current healthcare ecosystem. To this end, we are building the needed infrastructure and engaging the stakeholders who should receive value from this approach.

A scoping review of randomized trials assessing the impact of n-of-1 trials on clinical outcomes

BACKGROUND

The single patient (n-of-1) trial can be used to resolve therapeutic uncertainty for the individual patient. Treatment alternatives are systematically tested against each other, generating patient-specific data used to inform an individualized treatment plan. We hypothesize that clinical decisions informed by n-of-1 trials improve patient outcomes compared to usual care. Our objective was to provide an overview of the clinical trial evidence on the effect of n-of-1 trials on clinical outcomes.

METHODS

A systematic search of medical databases, trial registries, and gray literature was performed to identify trials assessing clinical outcomes in a group of patients undergoing an n-of-1 trial compared to those receiving usual care for any clinical condition. We abstracted elements related to study design and results and assessed risk of bias for both the overall randomized trials and the n-of-1 trials. The review was registered on PROSPERO. (CRD: 42020166490).

FINDINGS

Twelve randomized trials of the n-of-1 approach were identified in conditions spanning chronic pain, osteoarthritis, chronic irreversible airflow limitation, attention-deficit hyperactivity disorder, hyperlipidemia, atrial fibrillation, statin intolerance, and hypertension. One trial showed a statistically significant benefit in the primary outcome. Only one reached the pre-specified sample size target. Secondary outcomes showed modest benefits, including decreasing medication use, fewer atrial fibrillation episodes, and improved patient satisfaction.

INTERPRETATION

Very few trials have been undertaken to assess the effectiveness of n-of-1 trials in improving clinical outcomes, and most trials were underpowered for the primary outcome. Barriers to enrollment and retention in these trials should be explored, as well-powered randomized trials are needed to clarify the clinical impact of n-of-1 trials and assess their utility in clinical practice.

Unblinded and Blinded N-of-1 Trials Versus Usual Care: A Randomized Controlled Trial to Increase Statin Uptake in Primary Care

BACKGROUND

The aim was to assess whether an intervention incorporating a practicable open-label n-of-1 trial would lead to greater uptake of statin than usual care and comparable uptake to a closed-label gold-standard n-of-1 trial.

METHODS

We enrolled patients who had stopped or declined statins into a 3-arm trial (usual care, unblinded, and blinded n-of-1 intervention arms). Physicians advised participants randomized to usual care to take statin therapy to prevent cardiovascular disease. In both intervention arms, physicians delivered a theoretically informed informed intervention endorsing the value of experimenting with medication in n-of-1 trials to assess whether it caused side-effects. In these trials, participants alternated between 4 weeks of medication and no medication (unblinded arm) or randomly sorted active and placebo (blinded arm) and recorded symptoms and symptom attributions for 6 months. Thereafter, physicians discussed participants' symptom reports during active/inactive treatment periods and asked participants to resume statins if appropriate.

RESULTS

Seventy-three were randomized to the intervention arms and 20 to the control group. Fifty-six of 73 (77%) attempted the n-of-1 experiment; 28/36 (78%) in the unblinded arm; and 28/37 (76%) in the blinded arm. Forty-three of 56 (77%) completed the 6-month experiment and received feedback from the physician; 20/28 (71%) in the unblinded arm and 23/28 (82%) in the blinded arm. Thirty-three of 76 (45%) people restarted statins in the n-of-1 arms compared with 4/20 (20%) in the control arm, difference 24% (95% CI, 5%-43%; P=0.041). There was no evidence this differed between blinded and unblinded arms, difference 2% (95% CI, -20% to 24%; P=0.86). Adverse events occurred at a similar rate on and off statin.

CONCLUSIONS

In patients refusing or intolerant of statin, supporting experimentation with n-of-1 trials increases medication uptake compared with usual care. Alternating on-off medication in unblinded n-of-1 experiments appears as effective as a blinded experiment.

REGISTRATION

URL: https://doi.org/10.1186/ISRCTN11142694; Unique identifier: ISRCTN11142694.

A Useful and Sustainable Role for N-of-1 Trials in the Healthcare Ecosystem

Clinicians and patients often try a treatment for an initial period to inform longer‐term therapeutic decisions. A more rigorous approach involves N‐of‐1 trials. In these single‐patient crossover trials, typically conducted in patients with chronic conditions, individual patients are given candidate treatments in a double‐blinded, random sequence of alternating periods to determine the most effective treatment for that patient. However, to date, these trials are rarely done outside of research settings and have not been integrated into general care where they could offer substantial benefit. Designating this classical, N‐of‐1 trial design as type 1, there also are new and evolving uses of N‐of‐1 trials that we designate as type 2. In these, rather than focusing on optimizing treatment for chronic diseases when multiple approved choices are available, as is typical of type 1, a type 2 N‐of‐1 trial tests treatments designed specifically for a patient with a rare disease, to facilitate personalized medicine. While the aims differ, both types face the challenge of collecting individual‐patient evidence using standard, trusted, widely accepted methods. To fulfill their potential for producing both clinical and research benefits, and to be available for wide use, N‐of‐1 trials will have to fit into the current healthcare ecosystem. This will require generalizable and accepted processes, platforms, methods, and standards. This also will require sustainable value‐based arrangements among key stakeholders. In this article, we review opportunities, stakeholders, issues, and possible approaches that could support general use of N‐of‐1 trials and deliver benefit to patients and the healthcare enterprise. To assess and expand the benefits of N‐of‐1 trials, we propose multistakeholder meetings, workshops, and the generation of methods, standards, and platforms that would support wider availability and the value of N‐of‐1 trials.

Chronic Obstructive Pulmonary Disease: A Palliative Medicine Review of the Disease, Its Therapies, and Drug Interactions

Despite significant advances in treatment, chronic obstructive pulmonary disease (COPD) remains a chronic and progressive disease that frequently leads to premature mortality. COPD is associated with a constellation of significant symptoms, including dyspnea, cough, wheezing, pain, fatigue, anxiety, depression, and insomnia, and is associated with increased morbidity. Palliative care is appropriate to support these patients. However, historically, palliative care has focused on supporting patients with malignant disease, rather than progressive chronic diseases such as COPD. Therapies for COPD often result in functional and symptomatic improvements, including health-related quality of life (HRQL), and palliative care may further improve symptoms and HRQL. Provision of usual palliative care therapies for this patient population requires understanding the pathogenesis of COPD and common disease-targeted pharmacotherapies, as well as an approach to balancing life-prolonging and HRQL care strategies. This review describes COPD and current targeted therapies and their effects on symptoms, exercise tolerance, HRQL, and survival. It is important to note that medications commonly used for symptom management in palliative care can interact with COPD medications resulting in increased risk of adverse effects, enhanced toxicity, or changes in clearance of medications. To address this, we review pharmacologic interactions with and precautions related to use of COPD therapies in conjunction with commonly used palliative care medications.

Introduction to precision medicine in COPD

Although there has been tremendous growth in our understanding of chronic obstructive pulmonary disease (COPD) and its pathophysiology over the past few decades, the pace of therapeutic innovation has been extremely slow. COPD is now widely accepted as a heterogeneous condition with multiple phenotypes and endotypes. Thus, there is a pressing need for COPD care to move from the current “one-size-fits-all” approach to a precision medicine approach that takes into account individual patient variability in genes, environment and lifestyle. Precision medicine is enabled by biomarkers that can: 1) accurately identify subgroups of patients who are most likely to benefit from therapeutics and those who will only experience harm (predictive biomarkers); 2) predict therapeutic responses to drugs at an individual level (response biomarkers); and 3) segregate patients who are at risk of poor outcomes from those who have relatively stable disease (prognostic biomarkers). In this essay, we will discuss the current concept of precision medicine and its relevance for COPD and explore ways to implement precision medicine for millions of patients across the world with COPD.

N of 1 trials and the optimal individualisation of drug treatments: a systematic review protocol

BACKGROUND

Guidelines and evidence-based drug treatment recommendations are usually based on the results of clinical trials, which have limited generalisability in routine clinical settings due to their restrictive eligibility criteria. These trials are also conducted in ideal and rigorously controlled settings. N of 1 trials, which are single patient multiple crossover studies, offer a means of increasing the evidence base and individualising care for individuals in clinical practice. This systematic review of the N of 1 drug treatment trial aims to investigate its usefulness for achieving optimal individualised patient care.

METHODS

The following databases will be searched for relevant articles: MEDLINE, EMBASE, PsycINFO (all via Ovid), AMED, CINAHAL (via EBSCO), The Cochrane Library (including CENTRAL, NHS EED, and DARE), and Web of Science (Thomson Reuters). Supplementary searches will include ongoing trial databases and organisational websites. All N of 1 trials in which patients have been treated with a drug will be considered. Outcomes will include information on the clinical usefulness of N of 1 trials-i.e. achievement of optimal individualised care, health-care utilisation of patients, frequently used practices, experiences of clinical care or participation in N of 1 trials, adherence to treatment plan, and unwanted effects of the treatment. Screening of included papers will be undertaken independently by two reviewers, while data extraction and the quality of reporting will be conducted by one reviewer and checked by another. Both quantitative and qualitative summaries will be reported using appropriate methods.

DISCUSSION

This review will provide new insights into the clinical utility of N of 1 drug trials in helping participants find the most acceptable treatment as defined by patients and clinicians based on the selected outcome measures and the perspectives of participants involved in such trials. Findings from this review will inform the development of a stakeholder workshop and guidance to help physicians find the optimum therapy for their patients and will help guide future research on N of 1 trials.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016032452.

N-of-1 Design and Its Applications to Personalized Treatment Studies

N-of-1 trial is a type of clinical trial which has been applied in chronic recurrent conditions that require long-term non-curative treatment. In this type of trials, each patient will be randomly assigned to one of the treatment sequences and repeatedly crossed over two or more treatments of interests. Through this cross-comparing method (cross-over phase), investigator can identify an optimal treatment (medicine or therapy) for the patient and treat the patient with the optimal treatment in an extension phase. This design could efficiently reduce the placebo effect, which is often seen in clinical trials, and maximize the true treatment effect. This type of design has been used in some traditional Chinese medicine (TCM) clinical trials lately. However, it brings some challenges for collecting and analyzing the data. Research on statistical methodology of this type of design is rarely found in the literature. The goal of this research is to discuss the application of the N-of-1 design to personalized treatment studies. We will demonstrate a real study conducted in TCM and present some theoretical and simulation results.

Espresso Coffee for the Treatment of Somnolence in Parkinson's Disease: Results of n-of-1 Trials

There is limited information available concerning the treatment of daytime somnolence associated with Parkinson’s disease (PD); the most frequently applied therapeutic strategies include decreasing the dose of dopamine agonists or adding potential wake-promoting agents. There is recent data from a placebo-controlled trial concluding on a non-significant trend in favor of caffeine. We aimed to evaluate the efficacy of espresso-coffee in the treatment of daytime somnolence in PD. To evaluate the efficacy of espresso-coffee in the treatment of daytime somnolence in PD, we have conducted multiple single-patient (n-of-1) clinical trials comparing regular espresso coffee to decaffeinated coffee in PD patients presenting moderate to severe daytime somnolence defined as an Epworth Sleepiness Scale score >9. Each single-patient (n-of-1) trial included a sequence of three crossovers (two treatment periods separated by two days of washout). Four patients were included in the studies and three completed the three pairs of treatment periods. In two of the four patients, espresso coffee was considered beneficial. This study concludes that multiple single patient trials are feasible in PD and suggests that espresso-coffee may have a beneficial effect on daytime somnolence in some patients. These results cannot be generalized beyond the patients included in these trials.

Comparative effectiveness of antihypertensive treatment for older children with primary hypertension: study protocol for a series of n-of-1 randomized trials

BACKGROUND

Children are increasingly being diagnosed with primary hypertension. The absence of comparative effectiveness research of antihypertensive medications in children has contributed to considerable differences in prescribing practices among physicians treating children with primary hypertension. Even if parallel-group trials had established a best overall choice for most of these children, the best medication for an individual may differ from the best overall medication.

METHODS/DESIGN

This project consists of a series of systematically administered n-of-1 trials among older children to verify the need for ongoing antihypertensive treatment and, if so, to identify the preferred single drug therapy from among the three major classes of drugs commonly used for primary hypertension (angiotensin-converting enzyme inhibitors, calcium channel blockers, and diuretics). We will determine whether one of these is the preferred therapy for the great majority of patients. The "preferred" therapy is the drug which produces normal ambulatory blood pressure, with the greatest reduction in blood pressure without unacceptable side effects. We will recruit 50 patients from the Houston Pediatric and Adolescent Hypertension Program clinic. For each patient, the three drugs will be prescribed in random order and each drug will be taken for 2 weeks. The effectiveness of each therapy will be measured with 24-h ambulatory blood pressure monitoring, and tolerability will be assessed using a side effect questionnaire. Participants will rotate through treatment periods, repeating drugs and adjusting doses until the preferred therapy is identified. In assessing whether one of the medications is most effective for the majority of subjects, the primary outcome will be the percentage of participants for whom each drug is selected as the preferred therapy. We hypothesize that no drug will be selected for the great majority of the subjects, a finding that would support consideration of clinical use of n-of-1 trials. Secondary analyses will explore whether patient characteristics predict which medication will be selected as a preferred drug.

DISCUSSION

This study will help optimize care of participating patients and provide evidence regarding the usefulness of n-of-1 trials in identifying appropriate treatment for children with hypertension and potentially other disorders.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02412761 (registered 4/8/2015).

Outcomes for patients with the same disease treated inside and outside of randomized trials: a systematic review and meta-analysis

BACKGROUND

It is unclear whether participation in a randomized controlled trial (RCT), irrespective of assigned treatment, is harmful or beneficial to participants. We compared outcomes for patients with the same diagnoses who did ("insiders") and did not ("outsiders") enter RCTs, without regard to the specific therapies received for their respective diagnoses.

METHODS

By searching the MEDLINE (1966-2010), Embase (1980-2010), CENTRAL (1960-2010) and PsycINFO (1880-2010) databases, we identified 147 studies that reported the health outcomes of "insiders" and a group of parallel or consecutive "outsiders" within the same time period. We prepared a narrative review and, as appropriate, meta-analyses of patients' outcomes.

RESULTS

We found no clinically or statistically significant differences in outcomes between "insiders" and "outsiders" in the 23 studies in which the experimental intervention was ineffective (standard mean difference in continuous outcomes -0.03, 95% confidence interval [CI] -0.1 to 0.04) or in the 7 studies in which the experimental intervention was effective and was received by both "insiders" and "outsiders" (mean difference 0.04, 95% CI -0.04 to 0.13). However, in 9 studies in which an effective intervention was received only by "insiders," the "outsiders" experienced significantly worse health outcomes (mean difference -0.36, 95% CI -0.61 to -0.12).

INTERPRETATION

We found no evidence to support clinically important overall harm or benefit arising from participation in RCTs. This conclusion refutes earlier claims that trial participants are at increased risk of harm.

Chronic obstructive pulmonary disease exacerbations: latest evidence and clinical implications

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and results in an economic and social burden that is both substantial and increasing. The natural history of COPD is punctuated by exacerbations which have major short- and long-term implications on the patient and healthcare system. Evidence-based guidelines stipulate that early detection and prompt treatment of exacerbations are essential to ensure optimal outcomes and to reduce the burden of COPD. Several factors can identify populations at risk of exacerbations. Implementing prevention measures in patients at risk is a major goal in the management of COPD.

N-of-1 trials in the medical literature: a systematic review

BACKGROUND

N-of-1 trials (multiple crossover studies conducted in single individuals) may be ideal for determining individual treatment effects and as a tool to estimate heterogeneity of treatment effects (HTE) in a population. However, comprehensive data on n-of-1 trial methodology and analysis is lacking. We performed this study to describe n-of-1 trial characteristics, examine treatment changes resulting from n-of-1 trial participation, and to determine if trial reporting is adequate for estimating HTE.

METHODS

We undertook a systematic review of n-of-1 trials published between 1985 and December 2010. Included trials were those having individual treatment episodes as the unit of randomization and reporting individual-specific treatment effects. We abstracted trial characteristics, treatment change information, and analytic methods.

RESULTS

We included 108 trials reporting on 2154 participants. Approximately half (49%) of the trials used a statistical cutoff to determine a superior treatment, whereas the remainder used a graphical comparison (25%) or a clinical significance cutoff (20%). Sixty-seven trials, reporting on 488 people, provided treatment change information: 54% of participants had subsequent treatment decisions consistent with the results of the trial, 8% had decisions inconsistent with trial results, and 38% had ambiguous results. Less than half of the trials (45%) reported adequate information to facilitate the calculation of HTE.

CONCLUSION

N-of-1 trials are a useful tool for enhancing therapeutic precision in a range of conditions and should be conducted more often. To facilitate future meta-analysis, and the estimation of HTE, researchers reporting n-of-1 trial results should clearly describe individual data.

The n-of-1 clinical trial: the ultimate strategy for individualizing medicine?

N-of-1 or single subject clinical trials consider an individual patient as the sole unit of observation in a study investigating the efficacy or side-effect profiles of different interventions. The ultimate goal of an n-of-1 trial is to determine the optimal or best intervention for an individual patient using objective data-driven criteria. Such trials can leverage study design and statistical techniques associated with standard population-based clinical trials, including randomization, washout and crossover periods, as well as placebo controls. Despite their obvious appeal and wide use in educational settings, n-of-1 trials have been used sparingly in medical and general clinical settings. We briefly review the history, motivation and design of n-of-1 trials and emphasize the great utility of modern wireless medical monitoring devices in their execution. We ultimately argue that n-of-1 trials demand serious attention among the health research and clinical care communities given the contemporary focus on individualized medicine.

Individual (N-of-1) trials can be combined to give population comparative treatment effect estimates: methodologic considerations

OBJECTIVE

To compare different statistical models for combining N-of-1 trials to estimate a population treatment effect.

STUDY DESIGN AND SETTING

Data from a published series of N-of-1 trials comparing amitriptyline (AMT) therapy and combination treatment (AMT+fluoxetine [FL]) were analyzed to compare summary and individual participant data meta-analysis; repeated-measure models; Bayesian hierarchical models; and single-period, single-pair, and averaged outcome crossover models.

RESULTS

The best-fitting model included a random intercept (response on AMT) and fixed treatment effect (added FL). Results supported a common, uncorrelated within-patient covariance structure that is equal between treatments and across patients. Assuming unequal within-patient variances, a random-effect model was favored. Bayesian hierarchical models improved precision and were highly sensitive to within-patient variance priors.

CONCLUSION

Optimal models for combining N-of-1 trials need to consider goals, data sources, and relative within- and between-patient variances. Without sufficient patients, between-patient variation will be hard to explain with covariates. N-of-1 data with few observations per patients may not support models with heterogeneous within-patient variation. With common variances, models appear robust. Bayesian models may improve parameter estimation but are sensitive to prior assumptions about variance components. With limited resources, improving within-patient precision must be balanced by increased participants to explain population variation.

Outcomes of patients who participate in randomized controlled trials compared to similar patients receiving similar interventions who do not participate

BACKGROUND

Some people believe that patients who take part in randomised controlled trials (RCTs) face risks that they would not face if they opted for non-trial treatment. Others think that trial participation is beneficial and the best way to ensure access to the most up-to-date physicians and treatments. This is an updated version of the original Cochrane review published in Issue 1, 2005.

OBJECTIVES

To assess the effects of patient participation in RCTs ('trial effects') independent both of the effects of the clinical treatments being compared ('treatment effects') and any differences between patients who participated in RCTs and those who did not. We aimed to compare similar patients receiving similar treatment inside and outside of RCTs.

SEARCH STRATEGY

In March 2007, we searched The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, The Cochrane Methodology Register, SciSearch and PsycINFO for potentially relevant studies. Our search yielded 7586 new references. In addition, we reviewed the reference lists of relevant articles.

SELECTION CRITERIA

Randomized studies and cohort studies with data on clinical outcomes of RCT participants and similar patients who received similar treatment outside of RCTs.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed studies for inclusion, assessed study quality and extracted data.

MAIN RESULTS

We identified 30 new non-randomized cohort studies (45 comparisons): no new RCTs were found. This update now includes five RCTs (yielding 6 comparisons) and 80 non-randomized cohort studies (130 comparisons), with 86,640 patients treated in RCTs and 57,205 patients treated outside RCTs. In the randomised studies, patients were invited to participate in an RCT or not; these comparisons provided limited information because of small sample sizes (a total of 412 patients) and the nature of the questions they addressed. When the results of RCTs and non-randomized cohorts that reported dichotomous outcomes were combined, there were 98 comparisons; there was also heterogeneity (P < 0.00001, I(2) = 42.2%) between studies. No statistical significant differences were found for 85 of the 98 comparisons. Eight comparisons reported statistically significant better outcomes for patients treated within RCTs, and five comparisons reported statistically significant worse outcomes for patients treated within RCTs. There was significant heterogeneity (P < 0.00001, I(2) = 58.2%) among the 38 continuous outcome comparisons. No statistically significant differences were found for 30 of the 38 comparisons. Three comparisons reported statistically significant better outcomes for patients treated within RCTs, and five comparisons reported statistically significant worse outcomes for patients treated within RCTs.

AUTHORS' CONCLUSIONS

This review indicates that participation in RCTs is associated with similar outcomes to receiving the same treatment outside RCTs. These results challenge the assertion that the results of RCTs are not applicable to usual practice.

Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary

Chronic obstructive pulmonary disease (COPD) remains a major public health problem. It is the fourth leading cause of chronic morbidity and mortality in the United States, and is projected to rank fifth in 2020 in burden of disease worldwide, according to a study published by the World Bank/World Health Organization. Yet, COPD remains relatively unknown or ignored by the public as well as public health and government officials. In 1998, in an effort to bring more attention to COPD, its management, and its prevention, a committed group of scientists encouraged the U.S. National Heart, Lung, and Blood Institute and the World Health Organization to form the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Among the important objectives of GOLD are to increase awareness of COPD and to help the millions of people who suffer from this disease and die prematurely of it or its complications. The first step in the GOLD program was to prepare a consensus report, Global Strategy for the Diagnosis, Management, and Prevention of COPD, published in 2001. The present, newly revised document follows the same format as the original consensus report, but has been updated to reflect the many publications on COPD that have appeared. GOLD national leaders, a network of international experts, have initiated investigations of the causes and prevalence of COPD in their countries, and developed innovative approaches for the dissemination and implementation of COPD management guidelines. We appreciate the enormous amount of work the GOLD national leaders have done on behalf of their patients with COPD. Despite the achievements in the 5 years since the GOLD report was originally published, considerable additional work is ahead of us if we are to control this major public health problem. The GOLD initiative will continue to bring COPD to the attention of governments, public health officials, health care workers, and the general public, but a concerted effort by all involved in health care will be necessary.

Canadian Thoracic Society recommendations for management of chronic obstructive pulmonary disease - 2007 update

Chronic obstructive pulmonary disease (COPD) is a major respiratory illness in Canada that is both preventable and treatable. Our understanding of the pathophysiology of this complex condition continues to grow and our ability to offer effective treatment to those who suffer from it has improved considerably. The purpose of the present educational initiative of the Canadian Thoracic Society (CTS) is to provide up to date information on new developments in the field so that patients with this condition will receive optimal care that is firmly based on scientific evidence. Since the previous CTS management recommendations were published in 2003, a wealth of new scientific information has become available. The implications of this new knowledge with respect to optimal clinical care have been carefully considered by the CTS Panel and the conclusions are presented in the current document. Highlights of this update include new epidemiological information on mortality and prevalence of COPD, which charts its emergence as a major health problem for women; a new section on common comorbidities in COPD; an increased emphasis on the meaningful benefits of combined pharmacological and nonpharmacological therapies; and a new discussion on the prevention of acute exacerbations. A revised stratification system for severity of airway obstruction is proposed, together with other suggestions on how best to clinically evaluate individual patients with this complex disease. The results of the largest randomized clinical trial ever undertaken in COPD have recently been published, enabling the Panel to make evidence-based recommendations on the role of modern pharmacotherapy. The Panel hopes that these new practice guidelines, which reflect a rigorous analysis of the recent literature, will assist caregivers in the diagnosis and management of this common condition.

Effect of theophylline on the rate of moderate to severe exacerbations among patients with chronic obstructive pulmonary disease

AIM

To determine the effectiveness of theophyllines in real clinical practice on moderate to severe exacerbations.

METHODS

A cohort of 36,492 chronic obstructive pulmonary disease (COPD) patients aged > or =50 years was reconstructed from the health administrative databases of the province of Quebec, Canada, between 1 January 1995 and 31 December 2002 to compare users of theophyllines with users of inhaled corticosteroids (ICS) and users of long-acting beta(2)-agonists (LABA) on their rate of moderate to severe COPD exacerbations.

RESULTS

Users of theophyllines were found to be less likely than users of LABA [crude rates 84 vs. 91 per 100 patient-years, adjusted rate ratio (RR) 0.89, 95% confidence interval (CI) 0.84, 0.95] and users of theophyllines plus ICS were found to be less likely than users of LABA plus ICS (crude rates 114 vs. 112 per 100 patient-years, adjusted RR 0.89, 95% CI 0.87, 0.92) to have moderate to severe COPD exacerbations. Users of theophyllines were found to be more likely than users of ICS to have a COPD exacerbation (crude rates 84 vs. 77 per 100 patient-years, adjusted RR 1.07, 95% CI 1.04, 1.10), and this association was even stronger among patients who had at least three exacerbations in the year prior to cohort entry (crude rates 273 vs. 213 per 100 patient-years, adjusted RR 1.28, 95% CI 1.19, 1.38).

CONCLUSION

The use of theophyllines was found to be associated with a reduction in the rate of COPD exacerbations among all COPD patients, but to be less effective than ICS among patients with frequent exacerbations.

Outcomes of patients who participate in randomised controlled trials compared to similar patients receiving similar interventions who do not participate

BACKGROUND

Some people believe that patients who take part in randomised controlled trials (RCTs) face risks that they would not face if they opted for non-trial treatment. Others think that trial participation is beneficial and the best way to ensure access to the most up to date physicians and treatments.

OBJECTIVES

To assess the effects of patient participation in RCTs ('trial effects') independent both of the effects of the clinical treatments being compared ('treatment effects') and any differences between patients who participated in RCTs and those who did not.

SEARCH STRATEGY

In May 2001, we searched The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, The Cochrane Methodology Register, SciSearch and PsycINFO for potentially relevant studies. Our search yielded over 10,000 references. In addition, we reviewed the reference lists of relevant articles and wrote to over 250 investigators to try to obtain further information.

SELECTION CRITERIA

Randomised studies and cohort studies with data on clinical outcomes of RCT participants and similar patients who received similar treatment outside of RCTs.

DATA COLLECTION AND ANALYSIS

At least two reviewers independently assessed studies for inclusion, assessed study quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

We included five randomised studies (yielding 6 comparisons) and 50 non-randomised cohort studies (85 comparisons), with 31,140 patients treated in RCTs and 20,380 patients treated outside RCTs. In the randomised studies, patients were invited to participate in an RCT or not; these comparisons provided limited information because of small sample sizes (a total of 412 patients) and the nature of the questions they addressed. There was statistically significant heterogeneity (P < 0.002, I(2) = 36.2%) among the 73 dichotomous outcome comparisons; none of the potential explanatory factors we investigated helped to explain this heterogeneity. No statistically significant differences were found for 63 of the 73 comparisons. Eight comparisons reported statistically significant better outcomes for patients treated within RCTs, and two comparisons reported statistically significant worse outcomes for patients treated within RCTs. There were no statistically significant differences in heterogeneity (P = 0.53, I(2) = 0%) or in outcomes (SMD 0.01, 95% CI -0.10 to 0.12) of patients treated within and outside RCTs in the 18 comparisons which had used continuous outcomes.

AUTHORS' CONCLUSIONS

This review indicates that participation in RCTs is not associated with greater risks than receiving the same treatment outside RCTs. These results challenge the assertion that the results of RCTs are not applicable to usual practice.

Conducting research in individual patients: lessons learnt from two series of N-of-1 trials

Background

Double-blind randomised N-of-1 trials (N-of-1 trials) may help with decisions concerning treatment when there is doubt regarding the effectiveness and suitability of medication for individual patients. The patient is his or her own control, and receives the experimental and the control treatment during several periods of time in random order. Reports of N-of-1 trials are still relatively scarce, and the research methodology is not as firmly established as that of RCTs. Recently, we have conducted two series of N-of-1 trials in general practice. Before, during, and after data-collection, difficulties regarding outcome assessment, analysis of the results, the withdrawal of patients, and the follow-up had to be dealt with. These difficulties are described and our solutions are discussed.

Discussion

To prevent or anticipate difficulties in N-of-1 trials, we argue that that it is important to individualise the outcome measures, and to carefully consider the objective, type of randomisation and the analysis. It is recommended to use the same dosages and dosage forms that the patient used before the trial, to start the trial with a run-in period, to formulate both general and individualised decision rules regarding the efficacy of treatment, to adjust treatment policies immediately after the trial, and to provide adequate instructions and support if treatment is adjusted.

Summary

Because of the specific characteristics of N-of-1 trials it is difficult to formulate general 'how to do it' guidelines for designing N-of-1 trials. However, when the design of each N-of-1 trial is tailored to the specific characteristics of each individual patient and the underlying medical problem, most difficulties in N-of-1 trials can be prevented or overcome. In this way, N-of-1 trials may be of help when deciding on drug treatment for individual patients.

N-of-1 trials: innovative methods to evaluate complementary and alternative medicines in pediatric cancer

N-of-1 randomized controlled trials (RCTs) are randomized trials conducted within individuals and may be an attractive methodology for conducting studies of complementary and alternative medicine (CAM) in pediatric oncology. These trials may be used to determine the efficacy of an intervention in an individual, or multiple N-of-1 RCTs may be combined to estimate a population effect. There are many potential advantages to the use of N-of-1 RCTs with CAM in pediatric cancer. These advantages include the ability to determine whether CAM is effective in a specific child. In addition, the N-of-1 RCT allows parents and children to voice preferences about treatment options and allows them to directly participate in balancing adverse events and therapeutic benefits. Also, in estimation of population effects, combining multiple N-of-1 RCTs tends to require smaller sample sizes than do traditional parallel-group designs. However, there also may be several challenges to the conduct of such a trial. The use of N-of-1 RCTs may be very beneficial in evaluating CAM therapies in pediatric cancer. However, careful consideration of the advantages and disadvantages of such a design should be undertaken prior to initiating an N-of-1 RCT.

Pharmacological treatment of chronic obstructive pulmonary disease

None of the drugs currently available for chronic obstructive pulmonary disease (COPD) are able to reduce the progressive decline in lung function which is the hallmark of this disease. Smoking cessation is the only intervention that has proved effective. The current pharmacological treatment of COPD is symptomatic and is mainly based on bronchodilators, such as selective beta2-adrenergic agonists (short- and long-acting), anticholinergics, theophylline, or a combination of these drugs. Glucocorticoids are not generally recommended for patients with stable mild to moderate COPD due to their lack of efficacy, side effects, and high costs. However, glucocorticoids are recommended for severe COPD and frequent exacerbations of COPD. New pharmacological strategies for COPD need to be developed because the current treatment is inadequate.

Systematic review to determine whether participation in a trial influences outcome

OBJECTIVE

To systematically compare the outcomes of participants in randomised controlled trials (RCTs) with those in comparable non-participants who received the same or similar treatment.

DATA SOURCES

Bibliographic databases, reference lists from eligible articles, medical journals, and study authors.

REVIEW METHODS

RCTs and cohort studies that evaluated the clinical outcomes of participants in RCTs and comparable non-participants who received the same or similar treatment.

RESULTS

Five RCTs (six comparisons) and 50 cohort studies (85 comparisons) provided data on 31,140 patients treated in RCTs and 20,380 comparable patients treated outside RCTs. In the five RCTs, in which patients were given the option of participating or not, the comparisons provided limited information because of small sample sizes (a total of 412 patients) and the nature of the questions considered. 73 dichotomous outcomes were compared, of which 59 reported no statistically significant differences. For patients treated within RCTs, 10 comparisons reported significantly better outcomes and four reported significantly worse outcomes. Significantly heterogeneity was found (I2 = 89%) among the comparisons of 73 dichotomous outcomes; none of our a priori explanatory factors helped explain this heterogeneity. The 18 comparisons of continuous outcomes showed no significant differences in heterogeneity (I2 = 0%). The overall pooled estimate for continuous outcomes of the effect of participating in an RCT was not significant (standardised mean difference 0.01, 95% confidence interval -0.10 to 0.12).

CONCLUSION

No strong evidence was found of a harmful or beneficial effect of participating in RCTs compared with receiving the same or similar treatment outside such trials.

n-of-1 randomized controlled trials: an opportunity for complementary and alternative medicine evaluation

Complementary and alternative medicine (CAM) practice has traditionally relied on expert opinion and case examples to evaluate the outcome of a particular therapeutic treatment. Such trials are subject to bias, leading to the formation of erroneous conclusions about the effectiveness of most treatments. This paper reviews the feasibility of n-of-1 trials to better evaluate the clinical and statistical significance of CAM therapies. In particular: (1) problems arising from the use of standard therapeutic trials; (2) the n-of-1 trial and data analysis; (3) clinical use and advantages of the n-of-1 trial in conventional medicine; (4) potential clinical uses of the n-of-1 trial in CAM; (5) preliminary guidelines for the use of the n-of-1 trial in CAM; (6) constraints on the use of the n-of-1 trial in CAM; and (7) ethical issues in the conduct of the n-of-1 trial.

What is evidence-based medicine?

Evidence-based practice requires clinical expertise, common sense, understanding of the circumstances and values of the patient, and judicious application of the best available evidence. This article discusses evidence-based medicine as an explicit and formal problem-solving strategy.

Review article: Single subject trials as a research instrument in gastrointestinal pharmacology

The single subject trial is a randomized controlled trial carried out in the individual patient, and the result obtained is specific to the individual patient and the drug being investigated. This type of trial offers a supplement to traditional parallel group trials, especially in patients with heterogeneous disorders, often characterized by varying treatment responses and/or high placebo response rates. Pooled results from several individual single subject trials could extend the conclusions beyond the individual patient, and help to characterize a subset of responders to a specific treatment or clarify the heterogeneity of the disease. The basic principles of the different single subject trial designs are described. Advantages and limitations are reviewed with a special focus on published trials in functional gastrointestinal disorders. The single subject trial may be a valuable supplement to traditional drug treatment trials, either used as isolated trials in individual patients to determine optimal therapy, or in groups of patients to identify those with a uniform response to treatment. However, the lack of validation and reliability studies limits the value of the single subject trials presented so far.

Oral theophylline for chronic obstructive pulmonary disease

BACKGROUND

Oral theophylline has, for many years, been used as a bronchodilator in patients with COPD. Despite the introduction of new drugs, and its narrow therapeutic index, theophylline is still recommended for COPD treatment.

OBJECTIVES

To determine the effectiveness of oral theophylline when compared to placebo in patients with stable COPD.

SEARCH STRATEGY

The Cochrane Airways Review Group and Cochrane Controlled Clinical Registers were searched.

SELECTION CRITERIA

All studies were randomised controlled trials (RCTs).

DATA COLLECTION AND ANALYSIS

Data were independently abstracted and the methodological quality assessed by two reviewers.

MAIN RESULTS

Twenty RCTs met the inclusion criteria. Concomitant therapy varied from none to any other bronchodilator plus corticosteroid (oral and inhaled). The following outcomes were significantly different when compared to placebo. FEV1 improved with treatment: Weighted Mean Difference (WMD) 100 ml; 95% Confidence Interval (95%CI) 40, 160 ml. Similarly for FVC: WMD 210 ml 95%CI 100, 320. Two studies reported an improvement in VO2max; WMD 195 ml/min, 95%CI 113,27). At rest, PaO2 and PaCO2 both improved with treatment (WMD 3.2 mmHg; 95%CI = 1.2, 5., and WMD -2.4 mmHg; 95%CI = -3.5, -1.2, respectively). Walking distance tests did not improve (4 studies, Standardised Mean Difference 0.30, 95%CI -0.01, 0.62), neither did Visual Analogue Score for breathlessness isn two small studies (WMD 3.6, 95%CI -4.6, 11.8). The Relative Risk (RR) of nausea was greater with theophylline (RR 7.7; 95%CI 1.5, 39.9). However, patients' preference for theophylline was greater than that for placebo (RR 2.27; 95%CI = 1.26, 4.11). Very few patient withdrew from these studies for any reason.

REVIEWER'S CONCLUSIONS

Theophylline has a modest effect on FEV1 and FVC and slightly improves arterial blood gas tensions in moderate to severe COPD. These benefits were seen in patients receiving a variety of different concomitant therapies. Improvement in exercise performance depended on the method of testing. There was a very low dropout rate in the studies that could be included in this review, which suggests that recruited patients may have been known by the investigators to be theophylline tolerant. This may limit the generalisability of these studies.

Management of Chronic Obstructive Pulmonary Disease: A Review

Chronic obstructive pulmonary disease (COPD) affects about 14 million persons in the United States and is the only common cause of death that is increasing in incidence. Chronic management of this disorder includes nonpharmacologic interventions such as smoking cessation, immunization, nutritional support, and pulmonary rehabilitation. The pharmacotherapy of COPD is based on regular administration of bronchodilators, when symptoms are persistent. Long-acting bronchodilators have been shown to improve quality of life in patients with COPD. Ipratropium remains the anticholinergic of choice, but more specific agents with a longer duration of action should become available. Four recent large clinical trials on the use of inhaled corticosteroids (ICS) have been published. The results demonstrate that ICS do not alter the decline in lung function in patients with COPD. Patients with more severe COPD and frequent exacerbations may have a better quality of life and a reduced rate of exacerbations with ICS. Management of acute exacerbations involves three major pharmacologic treatment modalities: antibiotics, short-acting bronchodilators, and systemic steroids. Recent data shows the benefits of systemic corticosteroids in the management of acute exacerbations.

Update on pharmacologic therapy for chronic obstructive pulmonary disease

As described throughout this article, significant improvements continue to occur in the pharmacologic management of COPD. These improvements range from improved medication targeting to better understanding of mechanisms of action, to better delivery of medications, to lower side effects. New areas of pharmacologic intervention, if not ready for use today, hold great promise for the not-too-distant future. In addition to the many agents described here, multiple mediator antagonists and anti-inflammatory agents are also under investigation for use in COPD. Interestingly, repair of alveolar tissue may be possible. Indeed, preliminary animal studies suggest that retinoic acid may be able to induce regeneration of lung alveoli. Overall, more effort is needed to broaden awareness and provide for the appropriate diagnosis of COPD, better explain pharmacologic therapies for COPD, simplify and disseminate guidelines, and highlight key differences between asthma and COPD, including their treatment strategies. As interest in COPD continues to grow, future updates on COPD management will continue to add new pharmacologic options for this devastating and preventable disease.

Bronchodilator therapy in chronic obstructive pulmonary disease

This paper reviews new developments in bronchodilator therapy for chronic obstructive pulmonary disease (COPD). Most patients with COPD respond to bronchodilators, but we have no reliable way to predict which patients will respond. When responsiveness is assessed, changes in lung volume as well as improvements in FEV1 should be considered. The combination of a beta-agonist and an anticholinergic agent produces greater improvement than either agent alone. Anticholinergic agents have few adverse side effects in patients with COPD, but concern remains about the possible cardiac side effects of beta-agonists. No clear answer exists about whether new, long-acting beta-agonists, such as salmeterol, should supplant anticholinergic agents as "first-line" therapy in COPD.

How should health-related quality of life be assessed in patients with COPD?

The traditional approach of caring for patients with chronic respiratory disease has been to rely on pulmonary function tests to quantify the severity and to assess response to therapy. However, patients with respiratory conditions seek medical attention because of symptoms, particularly dyspnea, and impaired ability to function, which clearly impact on an individual's health-related quality of life (HRQOL). Accordingly, instruments have been developed to provide a standardized method to measure health status and levels of impairment. One of the major reasons for measuring HRQOL is to detect how much HRQOL has changed in response to therapy (an evaluative instrument). A minimum clinically significant change has been established for some HRQOL instruments in order to indicate the relative value of any measured change and to guide the interpretation as to whether the change is "clinically meaningful." Selected studies using disease-specific instruments have demonstrated that beta(2)-agonist, anticholinergic, and theophylline medications can improve HRQOL, as compared with placebo therapy.