Variation in use of intensive care for adults with diabetic ketoacidosis*

Abstract

Objective: Intensive care unit beds are limited, yet few guidelines exist for triage of patients to the intensive care unit, especially patients at low risk for mortality. The frequency with which low-risk patients are admitted to intensive care units in different hospitals is unknown. Our objective was to assess variation in the use of intensive care for patients with diabetic ketoacidosis, a common condition with a low risk of mortality.

Design: Observational study using the New York State In-patient Database (2005-2007).

Setting: One hundred fifty-nine New York State acute care hospitals.

Patients: Fifteen thousand nine hundred ninety-four adult (≥ 18) hospital admissions with a primary diagnosis of diabetic ketoacidosis (International Classification of Diseases, Ninth Revision, Clinical Modification 250.1x).

Interventions: None.

Measurements and main results: We calculated reliability- and risk-adjusted intensive care unit utilization, hospital length of stay, and mortality. We identified hospital-level factors associated with increased likelihood of intensive care unit admission after controlling patient characteristics using multilevel, mixed-effects logistic regression analyses; we assessed the amount of residual variation in intensive care unit utilization using the intraclass correlation coefficient. Use of intensive care for diabetic ketoacidosis patients varied widely across hospitals (adjusted range: 2.1% to 87.7%), but was not associated with hospital length of stay or mortality. After multilevel adjustment, hospitals with a high volume of diabetic ketoacidosis admissions admitted diabetic ketoacidosis patients to the intensive care unit less often (odds ratio 0.40, p = .002, highest quintile compared to lowest), whereas hospitals with higher rates of intensive care unit utilization for all nondiabetic ketoacidosis in-patients admitted diabetic ketoacidosis patients to the intensive care unit more frequently (odds ratio 1.31, p = .001, for each additional 10% increase). In the multilevel model, more than half (58%) of the variation in the intensive care unit admission practice attributable to hospitals remained unexplained.

Conclusions: We observed variations across hospitals in the use of intensive care for diabetic ketoacidosis patients that was not associated with differences in-hospital length of stay or mortality. Institutional practice patterns appear to impact admission decisions and represent a potential target for reduction of resource utilization in higher use institutions.

Figure 1

Distribution of use of intensive care for patients with DKA across acute care hospitals in New York State (reliability- and risk-adjusted*). * For reliability- and risk-adjusted rates of the use of intensive care, the expected value is the actual cohort ICU utilization rate

Figure 2A

Median hospital length of stay for DKA patients in acute care hospitals in New York State, stratified by proportion of patients admitted to ICU with DKA in each hospital.* * ■ = median hospital length of stay; bars show the 25^th-75^th percentile for all patients in each group † For reliability- and risk-adjusted rates of the use of intensive care, the expected value is the actual cohort ICU utilization rate

Figure 2B

Hospital mortality* for DKA patients admitted to acute care hospitals in New York State stratified by proportion of patients admitted to ICU with DKA in each hospital. * Mortality for patients admitted to the hospital with DKA stratified by the hospital-level frequency of admission to ICU. For example, 13 DKA patients out of 1,772 patients in the 11 hospitals with intensive care use for DKA between 10-19% died resulting in a 13/1,772 = 0.73% unadjusted mortality rate. † For reliability- and risk-adjusted rates (mortality and use of ICU), the expected value is the actual cohort rate (mortality and ICU use respectively).