To the Editor:
I read with interest the recent article by Bircher et al. regarding survival after in-hospital cardiac arrest.1 The article, like others from the Get With The Guidelines–Resuscitation Investigators, continues to disseminate inaccurate time-interval data from in-hospital resuscitation attempts. To their credit, the authors do acknowledge (more clearly than in some other Get With The Guidelines–Resuscitation articles) the limitations of their data, most importantly “the lack of independent verification of the times recorded.” But taking inaccurate time-interval data from Get With The Guidelines–Resuscitation or other sources at face value hides serious delays in response to in-hospital cardiac arrests. It can also lead to flawed studies and questionable conclusions.
In the case of the present article, the conclusion that survival rates after both cardiopulmonary resuscitation (CPR) and defibrillation or epinephrine are time-dependent is hardly surprising; indeed, it would be astonishing if this were not the case, in view of the overwhelming evidence of the relationship (at least for starting CPR and first defibrillation) from out-of-hospital and animal studies.2 The inaccuracy of the underlying data from this study limits the yield of useful information, leading to the limited and unsurprising conclusion that longer times to emergency interventions are worse for survival.
The time data reported here and in other Get With The Guidelines–Resuscitation studies only loosely represent reality. Current Get With The Guidelines–Resuscitation data include a figure from all hospitals for times to first defibrillation of 1 minute median and 0 minutes first interquartile. Such numbers are typical, when they are tracked at all—but they strain credulity.3 The time intervals are imprecise—typically based on a handwritten record marking only the nearest whole minute—and the reported time intervals are often so short as to be simply impossible. Data-acquisition methods are not standardized across hospitals and wide variation is unavoidable, as evidenced by the 5,036 instances of negative times to start of CPR. Although there is no direct statistical evidence to show the inaccuracy—no one is reporting better data for comparison—some clinicians will no doubt recognize simply by reflecting on their own clinical experience that the reported intervals are impossible. Additional prima facie evidence is available at most clinical simulation centers simply by timing simulated defibrillation attempts under realistic conditions, as in “mock codes.”4,5
Inaccurate time data is a major impediment to resuscitation research, offering only a blurred image of clinical reality. The authors state that “causal factors for delays and…other unknown factors that may influence timeliness of CPR or defibrillation and epinephrine treatment…remain areas of active investigation within Get With The Guidelines–Resuscitation.” Those efforts are welcome, but such factors are not going to be revealed by the current numbers—far better data quality is required. Equally important is that the poor time data obscure the problem of serious delays in cardiac arrest response.
The flawed data can also lead to dubious conclusions. A recent study of Get With The Guidelines–Resuscitation’s pediatric data found no evidence that defibrillation success decreases with time. This astonishing finding must be questioned in light of the limitations of the underlying data.6
In 2000, the American Heart Association (Dallas, Texas) and International Liaison Committee on Resuscitation called for better time-interval data from in-hospital resuscitation attempts. The 2000 Emergency Cardiac Care Guidelines stated:
Documentation of in-hospital resuscitation events is often inaccurate and therefore unreliable in making quantitative assessments of such critical components as time to defibrillation and other interventions during resuscitation. This must be corrected [in order]… to provide accurate assessment of resuscitation practices…. Accurate time-interval data must be obtained because it is the key to future high-quality research.7
Unfortunately, nothing meaningful has been done to address the problem in the years since the 2000 statement. This is a serious impediment to hospital quality improvement and resuscitation research—even more so because fixing the problem can be relatively simple.8 In addition to conducting studies based on their current data, Get With The Guidelines–Resuscitation researchers should endeavor to improve the quality of their future time data. In so doing, they can increase the probability of finding new clinical approaches that will increase survival.
The author declares no competing interests.