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Asthma Clinical Trials Network

Publications and source records attributed to Asthma Clinical Trials Network.

11 recordsLinked to original sources
PubMed2001

Summarizing methacholine challenges in clinical research.

In clinical trials in asthma, airway reactivity is commonly assessed by performing a methacholine challenge. Airway reactivity is thought to vary in proportion to asthma severity, and methacholine causes the airways of asthma subjects to constrict, thus lowering forced expiratory volume in 1 second (FEV(1)). A dose-response curve is obtained for each subject who meets standardized eligibility requirements to proceed with a methacholine challenge. When data from a methacholine challenge are used as an outcome variable in analysis, a univariate measure called the PC(20), the concentration of methacholine needed to produce a 20% fall in FEV(1) from baseline, is typically used to summarize the dose-response curve. Questions that arise regarding data generated from the methacholine challenge include: how to express data that do not yield a PC(20) value; whether PC(20) actually represents the best way to capture airway activity as expressed in a methacholine challenge; and whether the baseline FEV(1) is defined appropriately in calculation of PC(20). The impact of these issues on the statistical analysis of methacholine challenge data is described in this article. Some adjustments to the usual estimates of PC(20) and parametric modeling of the entire dose-response curve are proposed as alternatives that address some of the shortcomings of PC(20).

Asthma↗
PubMed2001

The organization of the Asthma Clinical Research Network: a multicenter, multiprotocol clinical trials team.

Asthma is an increasingly serious cause of morbidity and mortality in the United States, affecting approximately 12 million people, including men and women, children and adults, and all racial and ethnic groups. It is now recognized that asthma is a complex disease of varied etiology triggered by a number of factors such as allergens, drugs, chemicals, exercise, cold dry air, infections, and emotions. Asthma is a chronic disease requiring multiple medications to treat and control symptoms as well as medications thought to control the underlying inflammation. Despite major advances in understanding the etiology and pathophysiology of asthma and the development of new therapeutic modalities, the prevalence, severity, and mortality from asthma have all increased over the past decades in all age groups. Hospitalizations for asthma have doubled in adults and increased fivefold for children over the past 20 years. Mortality appears to be particularly high in urban and rural minority populations. Asthma continues to place a heavy burden on patients and their families as well as the health-care system. In an attempt to respond to the need for well-designed clinical trials to allow rapid evaluation of new and existing therapeutic approaches for asthma and for dissemination of laboratory and clinical findings to the health-care community, the Division of Lung Diseases, National Heart, Lung, and Blood Institute, established the Asthma Clinical Research Network.

Adult↗
PubMed2001

Implementing randomization procedures in the asthma clinical research network.

Randomization is a required component for the success of most controlled clinical trials. To ensure that the benefits of randomization are realized, well defined and carefully planned procedures must be put in place prior to the start of a trial. This paper presents a detailed account of the registration and randomization procedures implemented for the first four clinical trials of the Asthma Clinical Research Network.

Adolescent↗
PubMed2001

Genetic analysis in the Asthma Clinical Research Network.

Because there is reason to believe that genetic variants could account for different treatment responses in subjects with asthma, it is important to collect blood for genetic-analysis purposes when conducting clinical trials in asthma. This article describes issues related to maintaining subject confidentiality, tracking and shipping blood samples, quality control procedures at the laboratory performing the genotyping, and necessary data verification checks when implementing the genetic-analysis database for the Asthma Clinical Research Network.

Adrenergic beta-Agonists↗
PubMed2001

Quality control within the Asthma Clinical Research Network.

Quality control and assurance are very important issues for multicenter clinical investigation. Although such investigation usually states that those factors are part of the investigation, at best this occurs to a minimal extent. Indeed, to ensure the best possible investigatory results with the least amount of variance between centers, the Asthma Clinical Research Network (ACRN) instituted strict written criteria that were continually overviewed. This article describes the ACRN's quality control of: clinic procedures and equipment, training and certification of study personnel, site visit evaluations, and the procedures of bronchoscopy and sputum induction. The examples given in this report demonstrate how various aspects of our investigation are performed.

Asthma↗
PubMed2001

Modem remote support of pulmonary-function testing and quality control systems.

The data coordinating center (DCC) of the Asthma Clinical Research Network (ACRN) is responsible for the support of 11 pulmonary-function testing systems and two quality control systems. Pulmonary-function data from these systems are used as outcome indicators in studies conducted by the ACRN. Each of these systems is composed of a spirometer, a personal computer for data acquisition from the spirometer, a modem, and a printer. These systems are located at six clinical centers nationwide. An analysis conducted at the beginning of the first ACRN protocol identified the following requirements: (1) standard pulmonary-function testing, (2) standard methacholine-challenge testing, (3) the ability to handle simultaneous multiple protocols as well as have data from non-ACRN subjects, (4) the ability to separate data from different protocols as well as separate ACRN and non-ACRN data, (5) the ability to transmit data from the remote clinical centers to the DCC, (6) the ability to ensure quality data and to report on those results, and (7) the ability to provide remote support.

Asthma↗
PubMed2001

Data management procedures in the Asthma Clinical Research Network.

Well-designed data management processes are essential in ensuring the quality of data collected in multicenter clinical trials. This paper describes the data management processes and systems that were developed by the data coordinating center of the Asthma Clinical Research Network. A combination of manual and electronic processes has been designed to process clinical trial data from the point of collection to statistical analysis. A distributed database management system consisting of modular applications for separate data processing activities was developed to enter, track, verify, validate, and edit collected data. In addition, processes for monitoring and reporting data quality are discussed.

Asthma↗
PubMed2001

Attrition and retention of ethnically diverse subjects in a multicenter randomized controlled research trial.

Recruitment and retention of subjects is critically important for the conduct of randomized clinical trials. When significant effort is given toward recruiting members of ethnic minorities in a sample, a similar rate of retention for all subgroups of subjects is essential. Little is known about why research subjects withdraw consent to participate in research and whether attrition is influenced by ethnicity or other factors. The purpose of this study was to determine the reasons for withdrawal from a large, multicenter randomized trial and whether these reasons differed among ethnic and gender subgroups. Additionally, we were interested in comparing withdrawn subjects to matched subjects who stayed in the trial to determine what factors encouraged full study completion. Using a cohort survey design, adult subjects (n = 35) who withdrew from a large, multicenter randomized trial and matched subjects who completed the study (n = 35) were interviewed by telephone after study completion. Subjects who withdrew consent tended to be female and members of ethnic minorities. The most frequent problems-reported significantly more often by subjects who withdrew consent compared to matched retained subjects-were interference with work, lack of time, complicated and cumbersome record-keeping requirements, difficult study medicine regimens, and difficulty rescheduling appointments due to lack of flexibility on the part of study personnel. Only 17% of withdrawn subjects were satisfied with the overall research experience compared to 52% of matched retained subjects. Matched subjects who completed all required visits in the randomized controlled trial reported three reasons that promoted completion: remuneration, commitment to finish, and belief that the study was important.

Adult↗
PubMed2001

Recruitment strategies in the Asthma Clinical Research Network.

In any clinical trial, recruitment of trial participants usually requires an intense effort to reach the target sample size. The Asthma Clinical Research Network (ACRN) was keenly aware of this issue at its inception and therefore initiated and emphasized recruitment strategies for each of its clinical trials. This article describes the recruitment strategies for the ACRN's first four major clinical trials. Particular attention is given to the strategies for the recruitment of women and minorities. Finally, the specific strategies of each of the six ACRN clinical centers are presented.

Adolescent↗
PubMed2001

Development and deployment of an internet-based data management system for use by the Asthma Clinical Research Network.

Data management system development for the first Asthma Clinical Research Network (ACRN) study began at the data coordinating center (DCC) in May 1995 with the requirement for delivery of a production system by November 1995. Special methods had to be used to establish an internet local area network (LAN), place clinical client systems, and achieve an accelerated software development cycle. The development of a fully integrated data management system prior to the start of the study was not possible. Therefore an early analysis focused on identifying discrete groupings of data management functions that would allow development of distinct database modules to provide specific functionality such as subject randomization, subject registration, and data entry. The modules were categorized as either being associated with clinical centers or the DCC so that the clinical center modules could be developed and delivered to meet the start date of the study. In the second phase of development during the relatively slow patient-enrollment period, the DCC functional modules were delivered discretely over time. While at the time this development model was a necessity due to limited DCC resources, it continues to be used today as it permits the DCC to implement studies more rapidly and efficiently for the ACRN. This paper describes the methodologies used to develop an internet-based LAN, establish clinical center client systems, establish DCC client and server operations, and develop a data management system. It describes the circumstances that contributed to the development of these systems and the special methodologies developed. The technical aspects of the data management system and LAN are presented as well as a description of the requirements and constraints analysis used to develop the hardware and software systems.

Asthma↗