After implementing 24 hour intensivist staffing, there was a significant decline in adjusted total hospital cost estimates among the sickest patients admitted at night with no significant changes among less-ill patients admitted at night or among patients admitted during the day. There were also increased numbers of total ICU admissions. Although this increase might have been effected by shorter ICU stays and hence, more available beds, the increase in ICU admissions is part of an overall trend. The demand for medical ICU care has been steadily increasing at our institution from 1200 admissions in 1997 to 2600 admissions in 2009. These findings could be related to the implementation of the new staffing model. We previously reported that adherence to evidence-based processes of care and ICU complications both improved with a greater intensivist presence.(7
) Together, these findings are consistent with the hypothesis that sicker patients may benefit from the 24-hour presence of experienced clinicians. These results are neither sensitive to changes in sets of explanatory variables (e.g. using different combinations of clinical variables) nor to a specification that uses the full sample and includes multiple interaction terms including one for each treatment-quartile-day/night combination (these results are available from the authors upon request). Our results are consistent with previous studies that suggest that preventable adverse events are more likely during nighttime hours when house officers are less likely to be supervised.(14
). The observed findings are likely to be even more pronounced in teaching hospitals where night time medical ICU coverage is provided by internal medicine residents only without full time presence of at least a critical care fellow.
Although we have incorporated adjustments for overall trends and possible differences in ICU cohorts before and after the staffing change, this study remains an uncontrolled retrospective analysis that may not have accommodated important factors. To the best of our knowledge, there were no other projects undertaken at the ICU that may have influenced the costs of care of the sickest patients admitted at night.
Recent articles have identified the scarcity of evidence for appropriate ICU staffing models.(1
) In combination with our earlier study (7
) that showed improvements in quality, we provide evidence that 24-hour in-house intensivist staffing also reduces costs among the sickest patients admitted at night. Our finding of reduced cost is consistent with our earlier findings of decreased ICU and total length of stay for patients treated by 24-hour intensivists. Indeed, parallel analyses examining ICU and total length of stay show that reductions in these were also focused on the sickest patients admitted at night. The magnitude of these reductions in length of stay corresponds to estimated reductions in costs for the sickest night patients of $5000 and $5500 per day for total and ICU costs, respectively. Changes in types of ancillary services (e.g., laboratory, pharmacy, radiology) were not significant. We suspect these results are due to more rapid introduction of effective intervention and might explain the decreased cost estimates associated with 24-hour coverage. Future studies examining the timing of critical processes of care might be especially useful in understanding the mechanism by which 24-hour staffing has its effects. Similar insights may be generated by examining changes in diagnostic and therapeutic plans instituted when attending physicians who are not in-house overnight first see patients in the morning. It is difficult to predict precisely which specific clinical decisions most likely explain these patterns given the diversity of such decisions made by intensivists. However, the possibility that errors may be avoided must also be considered.
Regardless of the mechanisms explaining our observed findings, the fact that the benefits seem to be greatest among the sickest patients suggests there may be opportunities to focus efforts to improve costs and outcomes through 24-hour staffing in institutions that see the sickest patients. Alternatively, one could imagine having on-call intensivists come in to see all patients who exceed some level of severity rather than making decisions from home though staff satisfaction surveys at our institution suggest attending intensivists prefer the 24-hour staffing model to the on-demand model.(7
The cost savings we observe in this paper of somewhat more than $10,000 per patient among the sickest patients admitted at night suggest the potential for large savings for specific patients that are big enough to make this economically attractive even for quite small ICUs. For example, assume that overnight presence of an ICU physician cost $2,500 per night, a hospital would then have to admit only one patient to the ICU each night on average to justify the expense from an economic perspective. This is because the savings of $10,000 are realized on 4th quartile patients (who average one in four) and the assumed cost of hiring an intensivist for four nights in this example is also $10,000. Of course, savings could be far less if much of the cost savings come from reductions in ICU and hospital length of stay that are effectively fixed costs. Furthermore, the overall distribution of patients in such ICUs would need to be similar in terms of APACHE III scores to the patient population in our ICU in order to see similar savings with nighttime intensivists.
Our study only focuses on costs incurred within the hospital stay. Downstream costs associated with follow-up care are relevant from a societal perspective, as are indirect costs associated with work loss and long term care. However, such data were not available. This paper is an uncontrolled observational study based on an analysis of administrative billing data combined with information from the APACHE database and so is subject to the limitations of such a study design. In addition, the continuous staff intensivist presence may have facilitated faster ICU transfer of critically ill patients and more rapid resuscitation measures. This in turn could explain not only a shorter length of stay but also higher APACHE III scores calculated in the ICU. Although DNR status on admission did not differ between the two periods (p=0.758), it is possible that the continuous presence of attending physicians facilitated end of life discussions. Detailed accounts of end of life care were not available at the time of this cost analysis. Furthermore, this was a single center study within one intensive care unit in a large tertiary referral center. Results may not be generalizable to all ICUs.
Despite these limitations, our study suggests that 24-hour intensivist staffing is particularly beneficial for the sickest patients and seems to manifest itself in terms of reduced length of stay that in turn translates into reduced total cost estimates. Further investigation into the various components of such reductions in costs, including whether the difference stems from changes in practice patterns for night patients, and whether the fixed costs of hiring additional intensivist staff are outweighed by savings from reduced lengths of stay and other components, especially in smaller ICUs that may not see the sickest patients on a regular basis, is warranted.