Table 2

Changes in Office Visits Associated With Proportional Increases in Secure Message Threads and Telephone Encounters

Model and Variable	Change With 10% Increase in Secure Messaging Threads % (95% CI)	Change With 10% Increase in Telephone Encounters % (95% CI)
Adjusted model^a
Full study population	1.25 (1.21–1.29)	2.74 (2.70–2.77)
Interaction model^a
Study period
Baseline	1.13 (0.89–1.38)	2.93 (2.70–3.15)^b
PCMH implementation (Ref)	1.14 (0.93–1.35)	2.74 (2.55–2.93)
Postimplementation	1.20 (0.98–1.41)	2.57 (2.38–2.77)^c
Age-group, y
18–44	1.28 (1.03–1.53)	2.93 (2.70–3.17)^b
45–54	1.21 (0.99–1.43)	2.94 (2.74–3.14)^b
55–64 (Ref)	1.14 (0.93–1.35)	2.74 (2.55–2.93)
65–75	1.22 (0.93–1.50)	2.81 (2.56–3.06)
Sex
Female (Ref)	1.14 (0.93–1.35)	2.74 (2.55–2.93)
Male	1.18 (0.97–1.39)	2.62 (2.43–2.81)^c
Morbidity burden (ACG RUB)
Moderate (Ref)	1.14 (0.93–1.35)	2.74 (2.55–2.93)
High	0.84 (0.62–1.06)^c	2.66 (2.46–2.86)^c
Very high	0.69 (0.45–0.93)^c	2.72 (2.51–2.93)
Insurance type
Commercial (Ref)	1.14 (0.93–1.35)	2.74 (2.55–2.93)
Medicaid/state-subsidized	1.00 (0.63–1.38)	3.16 (2.83–3.48)^b
Medicare	0.96 (0.68–1.23)	2.78 (2.53–3.03)

ACG = adjusted clinical group; PCMH = patient-centered medical home; Ref = referent category; RUB=resource utilization band.
Note: Results are from log-linear regression models.
↵a Adjusted for age, sex, morbidity burden, insurance type, clinician network, well-care waiver, pharmaceutical coverage, education, income, baseline secure messaging use, hemoglobin A_1c level, blood pressure, low-density lipoprotein cholesterol level, study period, calendar quarter, physician secure messaging, and physician telephone encounter use.
↵b Positive effect modification at P ≤.05, compared with referent category.
↵c Negative effect modification at P ≤.05, compared with referent category.