Table 4.

Five sample association rules.

Item on the left-hand side of the rule		Implication of the item	Intervention compiled for the item
Rule 1: The patient had ≥12 EDa visits in the past year AND the patient had ≥21 distinct medications in all of the asthma medication orders in the past year → the patient will incur one or more asthma hospital visits in the subsequent year.
	The patient had ≥12 ED visits in the past year	Having many ED visits reflects poor asthma control	Implement control strategies to avoid the need for emergency care
	The patient had ≥21 distinct medications in all of the asthma medication orders in the past year	Using many asthma medications reflects poor asthma control	Tailor prescribed asthma medications and help the patient maximize asthma control medication adherence
Rule 2: The patient had ≥9 distinct asthma medication prescribers in the past year AND the block group where the patient lives has a national health literacy score [42] ≤244 AND the patient had ≥21 distinct medications in all of the asthma medication orders in the past year → the patient will incur one or more asthma hospital visits in the subsequent year.
	The patient had ≥9 distinct asthma medication prescribers in the past year	Having many asthma medication prescribers reflects poor care continuity, which often leads to poor outcomes	Provide the patient with social resources to address social chaos that leads to ineffective access to health care
	The block group where the patient lives has a national health literacy score ≤244	Having low health literacy is correlated with poor outcomes	Improve education access in the area where the patient lives to help increase health literacy
Rule 3: The patient had a total of ≥25 units of systemic corticosteroids ordered in the past year AND the patient had ≥12 ED visits in the past year AND the patient is Hispanic → the patient will incur one or more asthma hospital visits in the subsequent year.
	The patient had a total of ≥25 units of systemic corticosteroids ordered in the past year	Systemic corticosteroids are one type of asthma medication intended for short-term use to relieve acute asthma exacerbations. Using a lot of systemic corticosteroids reflects poor asthma control	Tailor prescribed asthma medications and help the patient maximize asthma control medication adherence
	The patient is Hispanic	In the US, Hispanic people have a disproportionately high rate of poor asthma outcomes	—b
Rule 4: The patient had ≥4 major visits for asthma in the past year AND the patient is between 11 and 35 years old AND the patient had no outpatient visit in the past year AND the average length of an inpatient stay of the patient in the past year is >1.75 and ≤2.95 days → the patient will incur one or more asthma hospital visits in the subsequent year.
	The patient had ≥4 major visits for asthma in the past year	As defined in our paper [23], a major visit for asthma is an inpatient stay or ED visit having an asthma diagnosis code, or an outpatient visit having a primary diagnosis of asthma. Intuitively, all else being equal, a patient having major visits for asthma has a higher likelihood of incurring future asthma hospital visits than a patient having only outpatient visits with asthma as a secondary diagnosis	Implement control strategies to avoid the need for emergency care
	The average length of an inpatient stay of the patient in the past year is >1.75 and ≤2.95 days	Having inpatient stays reflects poor asthma control	Implement control strategies to avoid the need for emergency care
	The patient had no outpatient visit in the past year	For good asthma management, a patient with asthma is supposed to see the primary care provider regularly. Having no outpatient visit often implies that the patient has no primary care provider	Help the patient obtain a primary care provider if the patient does not already have one
Rule 5: The patient had ≥4 major visits for asthma in the past year AND the patient's last ED visit is within the last 49 days AND the patient had between 6 and 8 distinct asthma medication prescribers in the past year AND the patient had a total of ≥36 units of asthma medications ordered in the past year AND >23.7% and ≤33.3% of families in the block group where the patient lives are below 150% of the federal poverty level → the patient will incur one or more asthma hospital visits in the subsequent year.
	The patient’s last ED visit is within the last 49 days	Having a recent ED visit reflects poor asthma control	Implement control strategies to avoid the need for emergency care
	The patient had a total of ≥36 units of asthma medications ordered in the past year	Taking many asthma medications reflects poor asthma control	Tailor prescribed asthma medications and help the patient maximize asthma control medication adherence
	>23.7% and ≤33.3% of families in the block group where the patient lives are below 150% of the federal poverty level	Poverty correlates with poor outcomes	Provide living wage programs in the area where the patient lives to increase resources for health care

^aED: emergency department.

^bNot applicable.