Current Epidemiology and Hospitalization Characteristics for Acute Chest Syndrome: A Nationally Representative Survey.

Acute chest syndrome (ACS) is a major cause of morbidity and the leading cause of mortality in patients with sickle cell disease (SCD). While the causes, outcome, and response to therapy in ACS has been described before, there is scant literature on current nationally representative estimates of burden, characteristics and cost of hospitalizations for SCD patients with ACS.

The Nationwide Inpatient Sample (NIS) database, sponsored by the Agency for Health Care Quality and Research, is a stratified probability sample of 20% of all hospital discharges among U.S. community hospitals (n=1,044, sampling universe = 90% of all such discharges). Sampling weights were applied to represent all community hospital discharges in the US for the year 2007.

Presence of following ICD-9-CM diagnosis codes were used to define SCD related hospitalizations: 28241, 28242, 2825, 28260, 28261, 28262, 28263, 28264, 28268, and 28269. ICD-9-CM 517.3 was used to identify ACS as a diagnosis during hospitalization for SCD. Only data on SCD related hospitalizations were analyzed.

In 2007, there were 86,318 discharges nationwide with a primary diagnosis and 79,766 with a secondary diagnosis of SCD (total=166,084). Of these, 7039 (4.2%) had ACS as a complication. Though, males represented 37.5% of SCD related hospitalizations but accounted for 52.1% of ACS episodes. ACS was more common complication in those with age <18 yrs than 18-44 age group (8.1% vs. 3.5%)

Pulmonary hypertension as one of the discharge diagnosis was reported in 4.7% of the patients with ACS as compared to 2.2% of the patients without ACS (p <0.001). At least one simple transfusion was seen in 43.0% of SCD patients admitted with a ACS compared to 21.7% without ACS (p-value <0.001). Exchange transfusion (3.6% vs. 0.4%; p <0.001) and mechanical ventilation (2.2% vs. 0.7%; p<0.001) were more frequently among hospitalizations with ACS than without it.. The mean (SD) length of hospitalization in SCD patients with ACS was higher (6.9±0.3 vs. 5.2±0.1; p<0.001) than those without ACS. The mean length of stay by various age categories is depicted in Table 1. Presence of ACS was associated with significantly higher mean charges per hospitalization (USD 35145 vs. USD 22836; p<0.001) Higher in-hospital mortality (1.3% vs. 0.5%, p<0.001) was seen among SCD hospitalizations with ACS as complications than without. The majority of deaths were in the 18-44 years age group (69.9%) followed by 18.2% deaths in <18 years group.

ACS is a major and common complication in hospitalizations with SCD as a discharge diagnosis. Among SCD patients, presence of ACS is associated with an increased risk of receiving a simple or exchange transfusion, mechanical ventilation, increased length of hospital stay, higher hospital charges and in-hospital mortality.

No relevant conflicts of interest to declare.