Observational and interventional studies

One of the editorials in this week's NEJM gives a great example of the relative roles of observational and interventional studies in clinical research. The editorial, "The healing power of listening in the ICU," discusses a randomized trial in the same issue that compares two different communication strategies for working with families who had a patient dying in the ICU.

The editorial by Lilly and Daly notes:

Recommendations to improve care for patients dying in ICUs are rooted in both observational and interventional studies. Observational studies confirm our own practical experience that nearly every American family will be affected by the loss of a loved one in an ICU and that the effect of this loss can be mitigated by high-quality care. The field has been advanced by interventional studies showing that proactive communication processes, including intensive communication as well as ethics and palliative care consultations, improve outcomes. Evidence that proactive multidisciplinary conferences in which care providers and family members address bereavement, with the provision of printed materials, is another important advance in the field of end-of-life care in the ICU. All providers of critical care should receive training that will allow them to offer the kind of support that they would want if they had a family member who was facing death in an ICU.

Observational studies begin to confirm that something that we believe to be true actually has some objective data to indicate that it really might be true. In this case, the observational data confirms that the question of communication with families during end-of-life care is an important part of the process. Observational studies provide data that aid investigators in developing hypotheses and ideas for feasible interventions, that can then be explored in future research.

Interventional studies then build on this experience - now that we have confirmed that the question is an important one, we can design interventions that attempt to address the issue. The trial in this NEJM looks at strategies for improving the communication experience of families with patients at the end of life in the ICU. These studies further explore the studies initiated and inspired by observational data, and move more toward the hypothesis-proving end of the clinical research spectrum.

While sometimes it can be easy to focus on looking for the randomized clinical trial that "answers" a clinical question, a trial on its own doesn't provide an adequate picture of the scope of a given clinical problem. Both kinds of studies provide essential pieces of the puzzle for understanding clinical issues, and the editorial commentary above highlights how the two kinds of evidence come together and provide actionable solutions for a real-world clinical challenge.

The full citation for the editorial: Lilly CM, Daly BJ. The healing power of listening in the ICU. New Engl J Med 2007;356:513-5. (full-text)

The study they're commenting on: Lautrette A, Darmon M, Megarbane B, et al. A communication strategy and brochure for relatives of patients dying in the ICU. N Engl J Med 2007;356:469-478. (full-text)