Table 3. Bivariate Probit Equations for the Probability of Regular Primary Care and the Probability of Glycemic Control (Year and quarter fixed effects are not shown).

Variables	Probability of Regular Primary Care			Probability of Glycemic Control
Variables	Coefficient (Δz)	P Value	95% CI	Coefficient (Δz)	P Value	95% CI
Demographics
Age	0.026	0.000^***	0.020–0.033	−0.016	0.000^***	−0.022 to −0.010
Female sex	0.077	0.000^***	0.044–0.109	0.031	0.040^*	0.001–0.060
Diabetes mellitus
Identified from registry	0.025	0.393	−0.032 to 0.081	0.206	0.000^***	0.154–0.258
Duration	−0.008	0.259	−0.023 to 0.006	−0.043	0.000^***	−0.057 to −0.030
Duration × age	−0.0003	0.003^**	−0.0005 to −0.0001	0.0005	0.000^***	0.0003–0.0007
Duration × registry	0.029	0.000^***	0.021–0.037	−0.017	0.000^***	−0.024 to −0.010
Risk factors
Insulin prescribed	0.226	0.000^***	0.190–0.262	−0.438	0.000^***	−0.469 to −0.406
High LDL diagnosis	0.281	0.000^***	0.231–0.331	−0.100	0.000^***	−0.154 to −0.047
BMI	−0.090	0.000^***	−0.120 to −0.061	−0.030	0.009^***	−0.052 to −0.007
Excess BMI	0.124	0.000^***	0.094–0.154	−0.003	0.804	−0.026 to 0.020
BMI × age	−0.0005	0.000^***	−0.0006 to −0.0003	0.0006	0.000^***	0.0005–0.0008
Blood pressure index	−0.023	0.000^***	−0.031 to −0.015	−0.018	0.000^***	−0.025 to −0.011
Tobacco smoker	−0.154	0.000^***	−0.187 to −0.120	0.018	0.286^***	−0.015 to 0.050
Smokeless tobacco user	0.211	0.000^***	0.159–0.264	0.004	0.869	−0.043 to 0.050
Access
Matanuska-Susitna borough resident	−0.078	0.011^*	−0.138 to −0.018	0.177	0.000^***	0.130–0.224
Outside service area	−0.644	0.000^***	−0.698 to −0.590	−0.258	0.000^***	−0.353 to −0.164
Miles to primary care	−0.010	0.000^***	−0.012 to −0.008	—	—	—
Primary care
Regular primary care	—	—	—	1.163	0.000^***	0.813–1.513
Constant	2.404	0.000^***	1.627–3.180	−0.297	0.393	−0.978 to 0.384
Summary statistics
ρ	−0.338	0.004^**	—	—	—	—
Log likelihood	−36,102		—	—	—	—
Wald χ² (70)	5,041	0.000^***	—	—	—	—
Observations	38,889		—	—	—	—

↵* P < .05;
↵** P < .01;
↵*** P < .001
^†Blood pressure index, derived from blood pressure measured during the initial encounter: (systolic pressure − 100)/20 + (diastolic pressure − 70)/10.
BMI, body mass index; CI, confidence interval; LDL, low-density lipoprotein.