Unstable angina: trends and characteristics associated with length of hospitalization in the face of diminishing frequency—an evidence of a paradigm shift

Abstract

Background Unstable angina (UA) has been one of the most common presentations of acute coronary syndrome. The numbers of admitted UA patients have been diminishing in the recent past. However, we are seeing higher costs and higher length of inpatient stay. We attempt to identify the trends and characteristics of length of hospitalization in patients admitted with UA using a nationally representative dataset. Methods We used the nationwide inpatient sample (NIS) from 2002-2014 to assess the factors associated with length of stay in patients admitted with unstable angina using ICD-9-CM primary diagnosis codes (411.1, 411.81, and 411.89). All variables pertaining to hospitalization were compared across the 3 groups based on varied length of hospital stay. Results A total of 131,601 patients were admitted with the diagnosis of UA. The length of inpatient stay was ≤1 day, 2-6 days, and ≥7 days in 60,309 (45.83%), 67,291 (51.13%), and 4,001 (3.05%) patients, respectively. In a multivariate adjusted model, the percentage increased odds of ≥2 days of inpatient stay was noted as follows: age ≥65 years (29%), female gender(24%), African-American race (28%), obesity (14%), diabetes mellitus (15%), chronic lung disease (33%), congestive heart failure (529%), renal failure (26%), coagulopathy (68%), alcohol abuse (21%), peripheral vascular disease (22%), myocardial infarction (17%), deep vein thrombosis (119%), sepsis (105%), pneumonia (171%), stroke (164%), urinary tract infection (112%), blood loss (95%), cardiac catheterization (86%), percutaneous transluminal coronary angioplasty (24%), and blood transfusion (206%). The percentage of UA patients with ≥2 days of hospital stay has decreased from 15% to 3.7%, whereas the average costs of managing a UA patient in the hospital have increased by 175%. Conclusions More than half of patients admitted with UA stay in the hospital for ≥2 days, with the most important determinants being pre-existing medical comorbidities and inpatient complications.