TABLE 4.

Unadjusted trends and regression‐adjusted changes in the percent of patients outpatient visits, quality measures, and health care utilization events, for plan switchers vs stayers before and after January 2015, 2014—2016 (N = 28 537)

Outcomes	Percent of patients per quarter, before Jan. 2015	Percent of patients per quarter, after Jan. 2015	Adjusted percentage‐point difference‐in‐difference	95% CI
Outpatient visits
Plan stayer	74	71
Plan switcher	71	66	−2.06***	−2.82, −1.3
Asthma outpatient visits
Plan stayer	9.8	8.3
Plan switcher	10	8.4	−0.4	−0.89, 0.08
Rx adherence
Plan stayer	32	26
Plan switcher	27	22	0.56	−0.57, 1.7
Asthma Med ratio
Plan stayer	62	49
Plan switcher	58	45	0.35	−1, 1.7
ED visits
Plan stayer	15	14
Plan switcher	16	15	−0.12	−0.72, 0.49
Asthma ED visits
Plan stayer	1.7	1.4
Plan switcher	2.3	1.9	−0.06	−0.3, 0.18
Hospitalization rate
Plan stayer	<1%	1
Plan switcher	<1%	<1%	−0.08	−0.23, 0.08
IP asthma
Plan stayer	<1%	<1%
Plan switcher	<1%	<1%	0.03	−0.05, 0.11

The second and third columns represent the unadjusted percent of patients who ever have an outpatient visit, hospitalization, or ED visit in a given quarter, and the percent of patients who were adherent to asthma medication in a given year. The fourth column shows the adjusted difference‐in‐difference in outcomes, which is given as the percentage‐point change in the percent of patients with an outcome from the preswitch period to the postswitch period. The 95% confidence interval is the range of likely values associated with the treatment effect. Primary care provider is abbreviated as PCP. Asthma medication adherence is abbreviated as Rx adherence. The asthma medication ratio is abbreviated as Asthma Med Ratio. Hospitalizations for asthma are abbreviated as IP Asthma. Emergency department is abbreviated as ED.

^* P < .05; **P < .01; ***P < .001.