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Analyzing symptom management trials: the value of both intention-to-treat and per-protocol approaches
Barbara Given1, Charles W Given, Alla Sikorskii
1College of Nursing, Michigan State University in East Lansing, USA.
Purpose/Objectives:
Two analytical approaches are described for a randomized trial testing interventions for symptom management.
Design:
To compare an intention-to-treat with a perprotocol approach.
Setting:
Patients were accrued from six cancer centers.
Sample:
94 men and 140 women with solid tumors were accrued.
Methods:
An intention-to-treat approach (as randomized) and per-protocol analyses (at least one symptom reaching threshold and one follow-up intervention) were compared. The analysis determines how each approach affects results. A two-arm, six-contact, eight-week trial was implemented. In one arm, nurses followed a cognitive behavioral protocol. In the second arm, a non-nurse coach referred patients to a symptom management guide.
Main Research Variables:
Trial arm; summed severity scores; interference-based severity categories at intake, 10 weeks, and 16 weeks; site; and stage of cancer.
Findings:
Each arm produced a reduction in severity at 10 and 16 weeks with no differences between arms. In the per-protocol analyses, symptoms reported at the first contact required more time to resolve. Older patients exposed to the nurse arm resolved in fewer contacts.
Conclusions:
The intention-to-treat analyses indicated that both arms were successful but offered few insights into how symptoms or patients influenced severity. Per-protocol analyses (intervention and dose), when, and which strategies affected symptoms.
Implications For Nursing:
Each analytical strategy serves a purpose. Intention-to-treat defines the success of a trial. Per-protocol analyses allow nurses to pose clinical questions about response and dose of the intervention. Nurses should participate in analyses of interventions to understand the conditions where interventions are successful.
