Establishing a Role for Asthma Management As Adjuvant Therapy for Vaso-Occlusive Crisis: Pulmonary Risk Stratification and Proposed Interventions

Background: Asthma is a common comorbid condition in patients with sickle cell disease. It has been well reported that patients with sickle cell and asthma have increased risk of morbidity and mortality, especially in regards to acute chest syndrome. Limited research, however, has been done to establish the role of asthma in vaso-occlusive crisis. Prior work by this group assessed the hypothesis that patients with sickle cell disease and comorbid asthma have increased severity and frequency of vaso-occlusive crisis secondary to increased impairment in oxygen exchange and associated sickling. A positive association was identified, providing groundwork for additional study.

Objectives: This study was designed to further identify and risk-stratify patients at increased likelihood of vaso-occlusive complications that would benefit from respiratory-driven interventions. This was proposed through more extensive evaluation of the association between a diagnosis of comorbid asthma and frequency and severity of sickle cell vaso-occlusive crisis in addition to other potential indicators of risk, including passive smoke exposure and pulmonary function testing results.

Design/Method: Following development and updating of a comprehensive institutional database, patients were identified with sickle cell disease and comorbid asthma ages 6 to 12 years of age. An additional subset of patients was identified as phenotypic and age-matched controls. Rates of emergency department visits and hospitalizations, frequency of vaso-occlusive crises, association with respiratory symptoms, smoke exposure status, pulmonary function test results, and use of asthma controller medications were retrospectively analyzed over a 5-year period. Data collection and interpretation were accompanied by review of existing literature.

Results: Patients with sickle cell disease and comorbid asthma had a statistically significant greater number of presentations for pain over the study period in addition to presentations for acute chest and respiratory symptoms. Analysis of symptom chronology did not show a definitive relationship between onset of respiratory symptoms and subsequent development of pain symptoms. Smoke exposure status was evaluated as a possible compounding factor. A statistically significant association between use of asthma controller medication and patients presenting with pain was identified (p <0.01), although pulmonary function test results indicated that not all patients with a clinical diagnosis of asthma met objective criteria.

Conclusion: Asthma management may have a role in the treatment of sickle cell vaso-occlusive crisis as evidenced by more frequent pain presentations in patients with asthma as well as a correlation in those patients on controller therapy. Results of pulmonary function testing indicated that not all patients met criteria for an objective diagnosis of asthma, suggesting that there may be a different etiology for these patients' lung impairment. Despite this, pulmonary function testing may still provide insight into disease progression. Further study of the use of asthma management as adjuvant therapy for sickle cell patients is in progress with the intent to improve pain management and decrease hospital encounters and hospital length of stay.