A Nationwide Analysis of Trends in in-Hospital Mortality in Patients with Sickle Cell Disease from 2000 to 2014

Background:

Patients with Sickle cell disease (SCD) have high rates of hospitalizations in the US annually and carry a higher rate of in-hospital mortality compared to the general population. There have been very few therapeutic innovations for the treatment of SCD in the past few decades. Changes in mortality in these patients reflect the availability of healthcare delivery and improvements in management of long term complications of SCD. A nationwide analysis was conducted to study the mortality of patients in SCD over a period of 15 years (2000 to 2014). The national inpatient sample is a database supported by the Agency of Healthcare Research and Quality.

Methods:

In this study, all patients who were hospitalized between the years 2000 to 2015 were analyzed and mortality was studied in SCD patients. Mortality during hospital stay was studied with respect to hospital size, rural vs. urban location and the most common medical comorbidities. Data pertaining to demographic factors of gender, geographic location and hospital size (measure of expertise and facilities available) were extracted. Access to healthcare was assessed using insurance coverage as a surrogate and its effect on mortality was evaluated. The effect of common medical comorbid conditions such as atrial fibrillation (Afib), hypertension (HTN), hyperlipidemia (HLP), diabetes mellitus (DM), chronic kidney disease (CKD) and tobacco smoking was assessed. Chi-square test analysis was used to validate the statistical significance of difference seen between the groups with a significance identified with a p value< 0.05. Multivariate analysis was used to determine independent predictors of mortality.

Results:

Out of a total of 1280693 hospitalizations over 15 years there were 9230 deaths of which 4230 were males and 5000 were females. There was no difference in the rate of mortality between hospitals of different sizes (small vs. medium vs. large) teaching and non-teaching hospitals. The mortality/hospitalization ratio was statistically different between Northeast, Midwest, South and West regions (0.63%, 0.65%, 0.76% and 0.89 respectively; p = 0.008). A statistically significant difference was noted between the insurance status (Medicaid vs. Medicare vs. private vs. self) amongst sickle cell patients who died during hospitalization. The odds of dying during hospitalization has gradually decreased from 2000 to 2014 (p = 0.007). The average age of death was 43.8 years and the age group of 35-49 years accounted for the highest amount of mortality (33%). Univariate analysis showed a significant difference in the common medical comorbidities of HTN, HLP, DM, CKD and smoking status in SCD patients who died during hospitalization. Multiple regression analysis revealed females are less likely to suffer from in-hospital mortality than males (OR 0.80; P < 0.04), medical comorbidities of Afib, DM, HTN and CKD are significant risk factors (ORS: 4.3, 1.4, 1.8 and 1.3).

Conclusions:

In-hospital mortality in SCD patients has improved significantly over the past 2 decades which may reflect some improvements in health care delivery and possibly the usage of hydroxyurea. However, common medical comorbidities such as Afib, HTN, DM and CKD continue to remain significant risk factors for mortality in these patients. Aggressive management of these medical comorbidities may further decrease morbidity and mortality in SCD patients in the future.