Spirometry use in patients with sickle cell disease with and without asthma and acute chest syndrome: A multicenter study

Abstract A de‐identified data repository of electronic medical record data, i2b2 (Informatics for Integrating Biology and the Bedside), including four geographically diverse academic medical centers, was queried to determine the use of diagnostic spirometry testing in African American children and young adults 5‐34 years of age with sickle cell disease (SCD) with or without a documented history of asthma and/or acute chest syndrome (ACS). A total of 2749 patients were identified with SCD, of these 577 had asthma and 409 had ACS. Cross‐referencing the CPT code for diagnostic spirometry showed that for patients identified as having SCD, a history of ACS, and a diagnosis of asthma, only 31% across all four centers had spirometry. Having an asthma diagnosis was associated with ACS. Among SCD patients with asthma, the proportion with ACS for the four centers was 47%, 75%, 38%, and 36% respectively. The bivariate association between asthma and ACS for each Center was significant for each (P < .001). To summarize, only one third of patients with co‐morbid SCD, ACS, and asthma received the spirometry procedure as recommended in evidence‐based guidelines, suggesting limited testing for changes in pulmonary function. Future studies to determine barriers and facilitators to implementation of pulmonary testing in SCD are warranted.


INTRODUCTION
The prevalence of diagnostic spirometry testing, an accepted method for asthma screening and monitoring, for children with sickle cell dis- ease (SCD) is unknown. Children with SCD and asthma have a fivefold increased risk for acute chest syndrome (ACS) compared to children with SCD without asthma [1,2]. Although ACS is a leading cause of mortality in the SCD population and there seems to be increasing recognition of the importance of comorbid asthma and SCD, asthma continues to be underdiagnosed and undertreated in those with SCD eJHaem. 2020;1:239-242. wileyonlinelibrary.com/journal/jha2 239 F I G U R E 1 Distributions across four academic health centers: Sickle cell disease, asthma diagnosis, acute chest syndrome diagnosis, and spirometry [3]. The purpose of this study was to determine the percentage of African American children and young adults of age 5-34 years with SCD who had spirometry testing done and the correlation with spirometry testing and a diagnosis of asthma and/or ACS.
SCD is a common genetic disorder affecting approximately 100 000 individuals in the United States [4]. According to the Centers for Disease Control and Prevention, approximately 25 million persons in the United States have asthma, a condition influenced by both genetic and environmental factors [5]. A common complication for SCD patients is ACS, characterized by chest pain, tachypnea, fever, respiratory distress, and lung infiltrates [6]. ACS is the leading cause of premature death [7] and the second most common reason for hospitalization in children [8] with SCD. A relationship has been identified among patients comorbid with asthma and SCD, with pediatric patients being five times more likely to experience respiratory symptoms during a vaso-occlusive episode if asthma is present [9].

METHODS
We queried four AMC EMRs using i2b2 for the count of African  We utilized the i2b2 data to produce descriptive statistics including frequencies and percentages. Bivariate associations were analyzed using either chi-square or Fisher's test.

RESULTS AND DISCUSSION
As displayed in Figure 1, a total of 2749 African American patients were identified with SCD, of these 577 had asthma and 409 had a history of ACS. Two hundred forty-nine had SCD, ACS, and asthma, out of which 77 had spirometry performed within the study period. Academic Center C had the highest proportion of SCD patients with asthma at 31%, with A, B, and D having 18%, 15%, and 9% of SCD patients diagnosed with asthma, respectively. The difference in proportions across centers was statistically significant (P < .001). On the other hand, the percentage of SCD patients with ACS at the four centers was 17%, 21%, 12%, and 16%, respectively. The between-center difference was again significant (P < .001).
A closer look revealed that an asthma diagnosis was associated with ACS ( Figure 2). Among SCD patients without asthma, 10-14% had ACS for Center A, B, and D, whereas 0% had ACS at Center C. On the other hand, among SCD patients with asthma, the proportions with ACS were similar for Centers A, C, and D (47%, 38%, and 36%, respectively) but higher for Center B (75%). Separate analysis of the bivariate association between asthma and ACS for each Center showed that the association was significant for each (P < .001). The meaning of these findings is unclear and warrants further study, especially the practices at Center B where those with SCD and asthma had unusually high ACS rate and Center C where those with SCD and no asthma did not have ACS. With regard to odds ratio, the interpretation of which is the outcome and which is the risk factor is based on clinical knowledge. We believe the evidence in the literature shows that asthma is a risk factor for developing ACS.
Notably, for patients identified as having SCD, a history of ACS, and a diagnosis of asthma, only 31% across all four Centers had spirometry ( Figure 1). For the same group, Centers B and C had spirometry performed in 42% and 36%, respectively. For unknown reasons, these