There exists wide variation in the use of intensive care for patients with a primary diagnosis of DKA across New York State hospitals. Much of the variation in practice was due to identifiable patient and institutional factors. However, there was also persistent variation between hospitals that could not be explained by observed patient or hospital characteristics.
Some of the independent explanatory factors were consistent with the use of intensive care for patients with a higher severity of illness, for example for patients with a greater number of comorbidities. The volume of patients treated with DKA was also inversely correlated with the use of intensive care, consistent with the idea that care for DKA patients could be provided in other areas in hospitals where DKA may represent a more routine admission diagnosis. Other factors, however, such as greater use of intensive care for patients with higher socio-economic status or admitted to hospitals that use intensive care more frequently for non-DKA in-patient admissions, are not as clearly linked to quality of care decisions and may represent potential targets for decreasing potentially unnecessary intensive care use.
Much of the inter-hospital variability in ICU admission practices for patients with DKA could not be explained by available patient factors. This observation coupled with the finding that the overall frequency of admission of non-DKA in-patients to the ICU was one of the largest predictors of ICU utilization for DKA suggests that there are unmeasured institutional factors that impact decisions to admit patients to ICU. For example, hospitals that admit DKA patients to the ICU more frequently may have lower nurse-to-patient ratios on general medical floors or may have busier emergency departments with priority placed on fast transfer out of the emergency room prior to resolution of acidosis and stabilization. Hospitals with lower ICU admission rates for DKA may have intermediate care units or step-down units to which DKA patients can be triaged.
We find it useful to stratify these potentially influential factors into those that are “structural” and those which are more about “culture”. Structural factors may include staffing patterns (nurse and physician) throughout the hospital or the presence of protocols to allow for continuous insulin infusions on general medical wards. Cultural factors may include prevailing attitudes such as “DKA should be cared for in an ICU because that’s the way it’s always been done at this hospital.” Enacting change in either type of factor is possible, yet each is fraught with its own challenges. Changing structural factors is theoretically easy to accomplish, but is often hampered by limited resources; for example, hiring more healthcare providers is expensive and approving new policies is time-consuming and labor-intensive. Altering culture requires buy-in from participants and is inherently challenging to foster.
Non-uniformity in practice has been shown to be undesirable in domains of healthcare other than the use of intensive care (20
). In civilian trauma care, triage protocols designed to appropriately utilize resources have been shown to be effective in decreasing “over-triage” without negatively impacting outcomes when applied both in pre-hospital (21
) and in-hospital (22
) settings. Within hospital-based critical care, standardizing care to consistently implement optimal management strategies in the ICU can improve outcomes (23
We found no association between ICU utilization and either hospital length of stay or mortality. Studies of ICU triage decisions examining heterogeneous patient cohorts show overall worse hospital mortality for patients who did not receive intensive care (25
). A recent observational study examined the impact of ICU triage decisions on medical and surgical patients and found that patients triaged to the ICU had lower 28-day and 3-month mortality than those patients denied admission (26
). However, patients estimated to have a risk of hospital death of less than 5%—most DKA patients—did not have any survival benefit from admission to the ICU, consistent with our findings. We recommend caution when interpreting the present lack of association between ICU utilization and short-term patient outcomes for DKA. Our results are potentially consistent with two quite divergent interpretations: (1) that ICU admission is not beneficial for DKA patients or (2) that hospitals are appropriately triaging higher-risk patients into effective ICU therapy which is reducing any excess mortality they might otherwise have. In either case, use of intensive care would appear to have no association with outcome in an observational study such as our own.
Our study has several limitations. Our data are from New York State. While the population of New York represents 6.3% of the U.S. population (27
) and we analyzed data from 159 hospitals, we cannot be sure that these findings extrapolate to other parts of the country (28
). Patient information also came from an administrative dataset with the potential for misclassification of patients (29
). However, other studies have used billing data to study DKA (10
) and the demographics of our cohort (specifically, the mean age and the percentage of patients with diabetes who had DKA) are consistent with other more detailed clinical cohorts (11
). Additionally, severity of acute illness was not captured in our dataset; thus, it is possible that DKA patients at some institutions were more critically ill than at others and may account for some of the variation in triage practice. We did not have access to information on the bed occupancy (either hospital or ICU) on the day of admission for each patient. Daily occupancy has been shown to impact the decision to admit an individual patient to the ICU (33
). Moreover, there may be other factors (i.e., nurse-to-patient staffing ratios, the ability of non-ICU settings to provide close monitoring, or the availability of step-down units) that could be large drivers of hospital-level practice. Finally, we were unable to confirm whether patients with a diagnosis of DKA who spent time in the ICU during their admission were admitted to the ICU directly from the emergency department. It is possible that some patients were initially triaged to the floor and subsequently required transfer to the ICU. Given the relative paucity of poor outcomes for DKA, however, we believe this need to “step-up” care and, hence, erroneous categorization is likely rare.