Are We Missing the Mark? Respiratory Symptoms, Cxr's and Acute Chest Syndrome (ACS) in Sickle Cell Disease (SCD)

Background: Acute chest syndrome (ACS) is a common complication of SCD detected by chest radiography (CXR) with significant morbidity and mortality. Previous studies show that clinical assessment alone grossly underestimates the presence of ACS. We evaluate whether abnormal respiratory signs and symptoms are predictive of ACS.

Methods: Data was obtained by electronic medical record using ICD-9 codes linked to fever and SCD in the year 2013 in children 2 months to 18 years at two Children's Healthcare of Atlanta campuses (Egleston and Scottish Rite). Information on demographics, vital signs, respiratory symptoms on review of systems (ROS), physical exam (PE) findings and ACS diagnosis were obtained by direct chart review.

Results: 610 visits of 356 patients with SCD/fever were included. 95 patients were excluded prior to analysis due to lack of measured fever, inaccurate sickle cell diagnosis, age, or CXR already completed by another institution. Mean age was 5.7±5 years & 178 (50%) were female. 67% had Hb-SS, 23% had Hb-SC, & 10% had other genotype. 379 CXR's (62%) were ordered, of which 66 (17%) were positive (Table 1). Of the patients who were admitted for ACS (n=64), the average length of stay was 4.4±3 days, 15 (23%) required oxygen, 3 required BIPAP (5 %) and 8 (12%) required transfusions. None required ICU level care. Five patients who were admitted with negative CXRs from the ED developed ACS on the ward (5%). One discharged patient was called back for a radiology diagnosis of ACS not noted by the ED physician. 63 (16%) additional patients discharged from the ED returned within 72 hours. 33/63 (52%) received CXRs on repeat visit and 7/63 (11%) had developed ACS. 6 of these patients had a negative CXR at their initial ED encounter. One patient who was discharged without a CXR returned within 24 hours with ACS. History of ACS (odds ratio=2.5, 95% CI: 1.4-4.4, p<0.01), tachypnea (OR=2.0, 95% CI: 1.1-3.4, p=0.03), and abnormal physical exam findings (OR=2.8, 95% CI: 1.5-5, p<0.01) were all associated with positive CXR finding and ACS.

Conclusions: CXRs were ordered in only 62% of encounters of febrile children with SCD. The prevalence of ACS among patients evaluated by CXR at the initial ED encounter was 17%. Patients with a past history of ACS were more likely to receive CXR's & more likely to have ACS. Tachypneic patients were not more likely to receive CXR's, but were more likely to have ACS. Respiratory signs/symptoms & abnormal lung PE findings made physicians more likely to order CXR's, & also were predictive of ACS. Tachypnea & history of ACS are high risk factors for ACS in febrile children with SCD, in addition to abnormal ROS and PE. However, 62% of children with ACS had a normal lung exam. Clinical assessment alone is a poor predictor for ACS.