In patients with COPD and a history of exacerbations, a once-daily treatment regimen of combined fluticasone furoate and vilanterol was associated with a lower rate of exacerbations than usual care, without a greater risk of serious adverse events. (Funded by GlaxoSmithKline; Salford Lung Study ClinicalTrials.gov number, NCT01551758 .).
This paper addresses challenges of identifying, enrolling, and retaining participants in a trial conducted within a routine care setting. All patients who are potential candidates for the treatments in routine clinical practice should be considered eligible for a pragmatic trial. To ensure generalizability, the recruited sample should have a similar distribution of the treatment effect modifiers as the target population. In practice, this can be best achieved by including-within the selected sites-all patients without further selection. If relevant heterogeneity between subgroups is expected, increasing the relative proportion of the subgroup of patients in the heterogeneous trial could be considered (oversampling) or a separate trial in this subgroup can be planned. Selection will nevertheless occur. Low enrollment and loss to follow-up can introduce selection and can jeopardize validity as well as generalizability. Pragmatic trials are conducted in clinical practice rather than in a dedicated research setting, which could reduce recruitment rates. However, if a trial poses a minimal burden to the physician and the patient and routine clinical practice is maximally adhered to, the participation rate may be high and loss to follow-up will not be a specific problem for pragmatic trials.
Guidelines for chronic obstructive pulmonary disease (COPD) management are based largely on results from double-blind randomised controlled trials (RCTs) of efficacy. These trials have high internal validity and test whether a drug is efficacious, but they are conducted in highly selected populations that may differ significantly from patients with COPD seen in routine practice.We compared the baseline characteristics, healthcare use and outcomes between the Salford Lung Study (SLS), an open-label effectiveness RCT, with six recent large-scale efficacy RCTs. We also calculated the proportion of SLS patients who would have been eligible for inclusion in an efficacy RCT by applying the inclusion criteria used in efficacy trials of combination treatments.SLS patients were older, included more females and more current smokers, had more comorbidities (including asthma), and had more often experienced exacerbations prior to inclusion. In the SLS, rates of moderate or severe exacerbations, incidence of overall serious adverse events (SAEs), and SAEs of pneumonia were more frequent. A maximum of 30% of patients enrolled in the SLS would have been eligible for a phase IIIa regulatory exacerbation study.Patients in large COPD efficacy RCTs have limited representativeness compared with an effectiveness trial. This should be considered when interpreting efficacy RCT outcomes and their inclusion into guidelines.
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