For the 39,107 patients with NSTEMI in our analysis cohort, the median age overall was 64 (54, 75) years. Women made up 37.0% of the population and 82.1% of patients were Caucasian. The median LOS (25th, 75th) for the overall cohort in our study population was 3 (2, 5) days and the distribution of LOS is displayed in . There were 13,047 (33.4%) patients with LOS ≤2 days; 15,870 (40.6%) with LOS 3–4 days; 6,325 (16.1%) with LOS 5–7 days; and 3,865 (9.9%) with LOS ≥8 days. Twenty-six percent of patients had a LOS >4 days.
The patient baseline and hospital characteristics of our population categorized by LOS are displayed in . As LOS increased, patients were older, more often female, and less frequently Caucasian. In addition, as LOS increased, patients more frequently presented with heart failure symptoms and ST-segment depression on the initial ECG. They also had an increased number of co-morbidities, including a history of prior MI, heart failure, hypertension, atrial fibrillation, CABG, stroke, or peripheral arterial disease. Patients with longer hospital LOS presented with higher serum creatinine levels, had higher peak serum creatinine levels, and were more likely to be on hemodialysis. These patients were also less likely to be current smokers.
Patient Baseline and Hospital Characteristics by LOS Category
Patients with higher LOS were more likely to be treated at an academic medical center, and at centers with larger bed volumes. Urban versus rural setting of the hospital did not seem to be associated with LOS ().
Medication Use by LOS
In the absence of documented contraindications, the administration of medications to treat acute coronary syndromes within 24 hours is shown in for each category of LOS, as well as the use of anticoagulants at any time during the hospitalization. shows discharge medications by LOS category. In general, patients with longer LOS were less likely to be treated with evidence-based medications during the hospitalization and at the time of discharge.
Medications within 24 Hours or Anytime* by LOS Category
Discharge Medications by LOS Category
Clopidogrel use in the first 24 hours after presentation was 77.1% in the ≤2 days group, 66.6% in the 3–4 days group, 56.7% in the 5–7 days group, and 51.8% in the ≥8 days group (p<0.0001 for all comparisons). This pattern was also generally true for aspirin, beta-blockers, angiotensin converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARBs), and statins. The use of anticoagulants such as unfractionated heparin, low molecular weight heparin, bivalirudin, or fondaparinux differed to a lesser degree ().
Patients who had longer LOS were also less likely to be discharged home on evidence-based medications. Those with the longest LOS (≥8 days) were the least likely to be discharged home on aspirin (95.8%), clopidogrel (76.0%), or a statin (83.0%); p<0.0001 for all comparisons among LOS groups for each medication ().
In-hospital Procedures, Complications, and Delays to Cardiac Catheterization
Longer LOS was associated with higher rates of clinical complications, less use of PCI, and longer delays to cardiac catheterization and PCI when they were performed (). Patients with LOS ≥8 days had the highest rates of MI (2.5%), shock (7.6%), heart failure (18.3%), stroke (2.1%), or major bleeding (38.8%) compared with all other groups; p<0.0001. Nevertheless, patients with LOS ≥8 days were the least likely to receive early cardiac catheterization or PCI (53.7%), and were most likely to receive a noninvasive stress test; p<0.0001 for all comparisons. Furthermore, if they did receive cardiac catheterization or PCI, they had the longest delays in time from presentation to cardiac catheterization (49.3 hours, interquartile range [IQR] 19.2, 110.0) or PCI (55.0 hours, IQR 18.4, 131.6) ().
In-hospital Procedures and Complications by LOS Category
Delays to cardiac catheterization and the presence of complications were both associated with longer LOS (). Almost 85% of patients (n=33,010) had no complications. Less than 2% had three or more complications. Moreover, approximately 90% of patients (n=35,037) went to the catheterization lab within three days. The shortest LOS was among those patients with no complications who went to the catheterization lab within three days. The longest LOS was in those patients with at least one complication who went to the catheterization lab after three days. Irrespective of complications, LOS was longer in the cohort who got catheterized after three days, as compared to those who got catheterized within three days (6.66 vs. 2.89, respectively).
Length of Stay based on Time to Catheterization and Occurrence of Complications
The risk of mortality calculated by the ACTION Registry-GWTG mortality risk score was also positively associated with hospital LOS.12
demonstrates that as the risk increases, there is a consistent increase in LOS.
Length of Stay based on ACTION Registry-GWTG Mortality Risk Score
Day of Week Admitted to the Hospital and LOS
Depicted in is the time to cardiac catheterization and hospital LOS based on the day of the week admitted to the hospital. Admission to the hospital on a Friday afternoon or evening was studied for its association with prolonged LOS as a way to describe possible delays in care from the upcoming weekend. Those admitted on a Friday afternoon or evening had the longest delays to catheterization (58.5 [13.8–67.1] hours) and longest LOS (3.8 [2.8–4.9] days). While those admitted on Friday morning had a very short time to catheterization (10.6 [4.5–72.0] hours), but this did not translate to earlier discharge (3.5 [2.2–5.1] days).
Arrival to Catheterization Lab and LOS Based on Day and Time of Hospital Admission
Factors Associated with Prolonged Length of Stay
Baseline demographic, clinical factors, and hospital features associated with prolonged LOS (>4 days vs. ≤4 days) are displayed in . The factors most strongly associated with LOS >4 days in the adjusted model were undergoing cardiac catheterization >48 hours after presentation (odds ratio [OR] 4.87; 95% confidence interval [CI]: 4.54–5.22), shock at presentation (OR 7.82; 95% CI: 6.01–10.17), or heart failure without shock (OR 2.09; 95% CI: 1.93–2.26). Older age was also strongly associated with LOS >4 days with an OR of 1.14 (95% CI: 1.13–1.16) per every 5-year increase in age.
Factors Associated with Prolonged LOS (>4 days vs. ≤4 days)*
As compared to admission to the hospital on a Monday–Wednesday, admission on a Friday afternoon or evening (OR 1.13; 95% CI: 1.02–1.25) or on a Thursday (OR 1.50; 95% CI: 1.40–1.61) was associated with LOS >4 days. Those patients admitted to the hospital on a Saturday were less likely to have a prolonged LOS (OR 0.88; 95% CI: 0.81–0.96) when compared to those admitted to the hospital Monday–Wednesday.
Other comorbidities such as anemia, prior MI, diabetes, heart failure, stroke, peripheral arterial disease, and hypertension all were linked to LOS >4 days. Patients with a history of prior PCI were less likely to have prolonged LOS (OR 0.82; 95% CI: 0.77–0.88). Additionally, patients with private/HMO insurance were also less likely to have a prolonged LOS as compared to patients with all other types of insurance (Medicare, Medicaid), or no insurance at all (none/self-pay). Treatment at an academic medical center versus a non-academic center, a rural hospital versus an urban setting hospital, race of the patient, smoking status, and a history of CABG were variables tested and not associated with a prolonged LOS >4 days ().
Geographical Variations in Hospital Length of Stay
Shown in are the differences in hospital LOS among four regions in the U.S. The Northeast appears to have the highest percentage of patients with an LOS of at least five days. On the other hand, the West appears to have the lowest percentage of those with LOS ≥5 days and the highest percentage of those with the shortest LOS ≤2 days. The median (25th, 75th) LOS were significantly different among the regions, although only to a mild degree. The shortest LOS was in the West region at 2.77 days (1.98–4.14), while the longest LOS was in the Northeast at 3.34 (2.52–5.14). The South had a median LOS of 3.10 days (2.22–4.63) and the Midwest had a median LOS of 2.97 (2.08–4.56); p<0.0001 for all comparisons.
Geographical Variation in Hospital Length of Stay