Results
We identified 424 SCD subjects who presented to our PED meeting inclusion and exclusion criteria, with 25% (n=108) presenting with fever. Within the febrile group, 69% (n=74) of subjects received a CXR on presentation compared to 42% (n=133) of afebrile group (p<0.0001). Of the febrile subjects, 21% (n=23) had more than 2 febrile episodes of whom 100% received CXRs. Of the subjects who were ultimately hospitalized, 46% (n=50) within the febrile group received at least one inpatient CXR compared to 26% (n=82) of the afebrile group (p<0.001). Additional radiation exposure via x-ray imaging and CT scans during their hospitalization occurred in 26% (n=28) of the febrile group compared to 28% (n=90) in the afebrile group.
There were no significant differences between the febrile and afebrile subjects when it came to sex, asthma diagnosis/comorbidity, hydroxyurea use, folic acid supplementation, or pneumococcal prophylaxis (Tables 1 & 2). Overall, 10% of patients presenting to the PED were diagnosed with ACS (n=42), 13% (n=14) of those presenting with fever compared to 9% (n=28) of those presenting without fever. Those subjects diagnosed with ACS were significantly more likely to present with chest pain (p=0.003), tachypnea (p=0.001), and hypoxia (p<0.0001), and were more likely to have a history of asthma (p=0.0085). Sickle cell genotype, home medications, and history of splenectomy were not significantly associated with ACS diagnosis.
Upon multivariable modeling, when adjusting for known significant predictors of fever and pre-existing asthma diagnosis, the only significant predictors of ACS diagnosis were chest pain and hypoxia. Patients without chest pain had an odds ratio (OR) =0.3 of ACS diagnosis [95% Confidence Interval, CI 0.14-0.67], indicating they had 70% lower odds of ACS compared to patients with chest pain (Table 3). Patients without hypoxia had OR=0.12 of ACS compared to those with hypoxia [CI 0.06-0.25], indicating 88% reduced odds of ACS diagnosis (Table 3). Conversely, those with chest pain had 3.3-fold increased odds of ACS diagnosis [CI 1.5-7.4] and those with hypoxia had 8.4 times the odds of ACS diagnosis [CI 4-17.9] compared to those without these symptoms.