The empirical basis for determinations of medical futility

Abstract

Background: Decisions to limit treatment in critically ill patients often rely on publications that make claims of futility based on outcome data. Our objective was to systematically review the criteria for futility and the strength of empirical evidence across clinical studies that purport to support or refute claims of futility.

Methods: The MEDLINE database was searched for relevant articles published between 1980 and 2008. Selected studies reported original outcome data in critically ill or cardiac arrest patients and claimed that these data can support or refute decisions to limit treatment in comparable patients. Two authors independently abstracted data on patient characteristics, intervention, outcomes, cost, and design.

Results: Forty seven studies supporting a claim of futility and 45 refuting it were reviewed. Median point estimate for adverse outcome in studies supporting claims of futility was 100% (range 75% to 100%); median lower 95% confidence limit was 91% (range 48% to 99%). Explicit thresholds for futility were missing in 88% of articles. The original criteria for quantitative futility were fulfilled by only 28% of data, and almost exclusively in studies of cardiopulmonary resuscitation (CPR) for cardiac arrest. Substantial statistical overlap was observed between data brought in support of futility claims and data brought to refute them.

Conclusions: Most studies that purport to guide determinations of futility are based on insufficient data to provide statistical confidence for clinical decision-making. They usually lack explicit a priori thresholds for determination of futility. Many studies draw disparate conclusions based on statistically similar data. In most circumstances these problems preclude confident determinations of futility.

Figure 1

Study selection flow diagram. The principal reason for rejection of articles in the full articles review phase fell into one of the following six categories: 1) Article does not directly address the issue of futility of intensive care or resuscitation; 2) Data presentation and/or methodology of the article render the data presented therein not amenable to the analysis specific to this review (e.g. the article does not explicitly mention the absolute number of adverse outcomes and/or the total number of patients in the group upon which the conclusion is based); 3) Article lacks a clear conclusion as to whether treatment should be withheld or withdrawn based on the data presented; 4) Article examines the decision to give or withdraw care as the primary outcome; 5) Article primarily examines the efficacy of specific diagnostic or therapeutic interventions (e.g. steroids, pulmonary artery catheters, antibiotics), rather than the futility of the overall life-saving effort; 6) Article is not strictly a clinical study of patient outcomes. These categories were not necessarily mutually exclusive. However, in the interest of simplicity, the articles are presented by the primary category for exclusion.

Figure 2

Data point estimates in studies supporting claims of futility (black diamond) and those refuting such claims (blue square), with 95% confidence interval (CI). Data supporting claims of futility were arranged in descending order of lower 95% confidence limit, data refuting such claims were arranged in ascending order of upper 95% confidence limit.