To the Editor.
—Clinical intuition suggests that the availability of better physiological information should lead to better outcomes by enabling physicians to manage patients in a more sophisticated manner. The article by Dr Connors and colleagues1 is a provocative study that questions the validity of that concept and illustrates the importance of evidencebased clinical decision making.The authors are careful to point out many of their study's limitations, principally its observational design, and offer several plausible explanations for their findings. They do not, however, mention an important limitation: the composition of the patient population. Most of the patients in the study appear to have had noncardiac illnesses (respiratory failure and multiorgan system failure). Patients with acute myocardial infarction (MI) are conspicuously absent from the study population. Thus, the study's patient population may be a subset of critically ill patients who are least likely to benefit from application of the information available from
Lewis RP. Effectiveness of Right Heart Catheterization: Time for a Randomized Trial. JAMA. 1997;277(2):109. doi:10.1001/jama.1997.03540260023014