Predicting frequent emergency department visits among children with asthma using EHR data.

OBJECTIVE: For children with asthma, emergency department (ED) visits are common, expensive, and often avoidable. Though several factors are associated with ED use (demographics, comorbidities, insurance, medications), its predictability using electronic health record (EHR) data is understudied. METHODS: We used a retrospective cohort study design and EHR data from one center to examine the relationship of patient factors in 1 year (2013) and the likelihood of frequent ED use (≥2 visits) in the following year (2014), using bivariate and multivariable statistics. We applied and compared several machine-learning algorithms to predict frequent ED use, then selected a model based on accuracy, parsimony, and interpretability. RESULTS: We identified 2691 children. In bivariate analyses, future frequent ED use was associated with demographics, co-morbidities, insurance status, medication history, and use of healthcare resources. Machine learning algorithms had very good AUC (area under the curve) values [0.66-0.87], though fair PPV (positive predictive value) [48-70%] and poor sensitivity [16-27%]. Our final multivariable logistic regression model contained two variables: insurance status and prior ED use. For publicly insured patients, the odds of frequent ED use were 3.1 [2.2-4.5] times that of privately insured patients. Publicly insured patients with 4+ ED visits and privately insured patients with 6+ ED visits in a year had ≥50% probability of frequent ED use the following year. The model had an AUC of 0.86, PPV of 56%, and sensitivity of 23%. CONCLUSION: Among children with asthma, prior frequent ED use and insurance status strongly predict future ED use.

Nitric oxide in the human respiratory cycle.

Interactions of nitric oxide (NO) with hemoglobin (Hb) could regulate the uptake and delivery of oxygen (O(2)) by subserving the classical physiological responses of hypoxic vasodilation and hyperoxic vasconstriction in the human respiratory cycle. Here we show that in in vitro and ex vivo systems as well as healthy adults alternately exposed to hypoxia or hyperoxia (to dilate or constrict pulmonary and systemic arteries in vivo), binding of NO to hemes (FeNO) and thiols (SNO) of Hb varies as a function of HbO(2) saturation (FeO(2)). Moreover, we show that red blood cell (RBC)/SNO-mediated vasodilator activity is inversely proportional to FeO(2) over a wide range, whereas RBC-induced vasoconstriction correlates directly with FeO(2). Thus, native RBCs respond to changes in oxygen tension (pO2) with graded vasodilator and vasoconstrictor activity, which emulates the human physiological response subserving O(2) uptake and delivery. The ability to monitor and manipulate blood levels of NO, in conjunction with O(2) and carbon dioxide, may therefore prove useful in the diagnosis and treatment of many human conditions and in the development of new therapies. Our results also help elucidate the link between RBC dyscrasias and cardiovascular morbidity.