Physician-Level Continuity of Care and Patient Outcomes in All-Payer Claims Database

Mingliang Dai; Zachary J. Morgan; Kyle Russel; Beth A. Bortz; Lars E. Peterson; Andrew W. Bazemore

doi:10.3122/jabfm.2023.230119R1

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Figure 1.
Contextualizing the associations between physician-level continuity of care and total cost with patient age and comorbidity.

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Table 1.

Patient Characteristics by Physician-Level Continuity of Care Quintile, 2019

	Attributed to physicians with bottom (1) to top (5) quintiles of Physician-Level Continuity of Care
Patient Sample (n = 1,612,377)	Quintile 1 n = 323,115	Quintile 2 n = 319,010	Quintile 3 n = 350,216	Quintile 4 n = 335,228	Quintile 5 n = 284,808
Range of Phy-CoC scores	<0.39	0.39-0.55	0.55-0.64	0.64-0.73	>=0.73
Age, mean (SD)	28 (26)	48 (25)	56 (22)	58 (22)	58 (23)
Gender
Woman	18.8%	20.0%	22.1%	21.7%	17.3%
Man	21.6%	19.5%	21.2%	19.6%	18.1%
Geography of residence
Isolated small rural town	8.6%	15.6%	14.9%	24.6%	36.4%
Small rural town	9.7%	12.4%	19.0%	22.2%	36.7%
Large rural city/town	15.7%	12.7%	16.3%	24.6%	30.6%
Urban	21.3%	20.8%	22.4%	20.4%	15.1%
SDI score	29 (29)	26 (26)	30 (29)	33 (30)	36 (30)
CCI score	0.7 (1.8)	1.2 (2.3)	1.4 (2.4)	1.6 (2.5)	1.7 (2.6)
MARA score	0.6 (1.4)	0.9 (1.7)	1.1 (1.8)	1.2 (1.9)	1.2 (2.0)
Utilization outcomes in 2019
Total cost, mean (SD)	$5,496 (22,426)	$8,428 (23,980)	$9,551 (25,197)	$10,441 (25,183)	$10,777 (25,672)
Any preventable hospitalization	0.3%	0.6%	0.8%	0.9%	1.1%
Primary insurance payer
Medicare	8.3%	16.7%	24.1%	26.7%	24.2%
Medicaid	34.7%	19.9%	14.7%	15.4%	15.2%
Commercial	26.9%	22.4%	21.2%	16.9%	12.6%
Specialty of attributed physician
Family medicine	14.7%	21.2%	26.3%	21.2%	16.5%
Internal medicine	7.2%	18.3%	22.1%	27.2%	25.1%
Pediatric medicine	61.9%	17.7%	5.7%	7.2%	7.4%

Abbreviations: SDI, Social deprivation Index; CCI, Charlson’s comorbidity Index; MARA, Milliman Advanced Risk Adjusters; SD, standard deviation.

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Table 2.

Adjusted Associations Between Physician-Level Continuity of Care Quintile, Total Cost, and Preventable Hospitalization

Variable	Total Cost% Change (95% CI)	Any Preventable HospitalizationOdds Ratio (95% CI)
Physician-Level Continuity of Care Quintile
Quintile 5 (highest scores)	10.8% (8.1%, 13.7%)^*	1.08 (1.01, 1.15)
Quintile 4	11.8% (9.1%, 14.6%)^*	0.97 (0.91, 1.03)
Quintile 3	7.0% (4.4%, 9.6%)^*	0.98 (0.92, 1.04)
Quintiles 1&2 (lowest scores)	–	–
Age^{^†}	−0.4% (−0.5%, −0.3%)^*	1.16 (1.14, 1.18)^*
Gender
Female	10.5% (10.2%, 10.8%)^*	1.22 (1.17, 1.27)^*
Male	–	–
Geography of residence
Isolated small rural town	1.6% (0.5%, 2.7%)^*	1.01 (0.90, 1.14)
Small rural town	0.8% (−0.3%, 1.9%)	1.25 (1.14, 1.37)^*
Large rural city/town	1.9% (0.9%, 2.8%)^*	1.20 (1.09, 1.31)^*
Urban	–	–
Primary insurance payer
Medicare	−34.9% (−35.2%, −34.6%)^*	1.56 (1.44, 1.70)^*
Medicaid	−25.0% (−25.5%, −24.6%)^*	1.62 (1.43, 1.84)^*
Commercial	–	–
SDI
75+	0.3% (−0.2%, 0.8%)	1.08 (1.03, 1.14)
1 to 74	–	–
CCI (log)^{^†}	8.7% (8.6%, 8.7%)^*	1.23 (1.22, 1.24)^*
MARA (log)^{^†}	28.8% (28.8%, 28.9%)^*	1.49 (1.48, 1.50)^*
Physician specialty
Internal medicine	0.7% (−1.3%, 2.7%)	0.96 (0.92, 1.00)
Pediatric medicine	−10.4% (−12.4%, −8.3%)^*	–^**
Family medicine	–	–

Abbreviations: SDI, Social deprivation Index; CCI, Charlson’s comorbidity Index; MARA, Milliman Advanced Risk Adjusters; CI, confidence interval.
↵Notes: *P < .05.
↵**The specification of preventable hospitalization targets patients aged 18 and older. As a result, patients of pediatricians were excluded from this regression.
^†Age centered at 53, estimate of 10-year increase. CCI centered at 0, estimate of 1 point increase. MARA centered at 1, estimate of 1 point increase.

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Table 3.

Adjusted Associations Between Physician-Level Continuity of Care Quintile and Total Cost with Interactions with Patient Characteristics

CoC Interacting with	Physician-Level Continuity of Care Quintile^{^†}
CoC Interacting with	Quintile 3	Quintile 4	Quintile 5
Physician specialty
Internal medicine	−4.8% (−9.8%, 0.4%)	2.4% (−2.9%, 8.0%)	1.8% (−3.6%, 7.5%)
Pediatric medicine	−12.6% (−19.6%, −4.9%)^*	−17.0% (−23.8%, −9.6%)^*	−26.0% (−31.9%, −19.6%)^*
Family medicine	–	–	–
Primary payer
Medicare	1.6% (0.4%, 2.9%)^*	−1.0% (−2.3%, 0.2%)	2.8% (1.4%, 4.1%)^*
Medicaid	2.1% (0.4%, 3.8%)^*	8.7% (6.9%, 10.5%)^*	1.1% (−0.5%, 2.8%)
Commercial	–	–	–
Patient age^†
10 years older	−2.7% (−3.0%, −2.4%)^*	−2.8% (−3.1%, −2.5%)^*	−3.8% (−4.2%, −3.5%)^*
CCI (log)^†
1 point higher	−1.7% (−1.9%, −1.5%)^*	−2.4% (−2.6%, −2.1%)^*	−1.7% (−1.9%, −1.4%)^*
MARA (log)^†
1 point higher	1.8% (1.6%, 1.9%)^*	1.9% (1.8%, 2.0%)^*	1.6% (1.5%, 1.8%)^*

Abbreviations: CoC, continuity of care; CCI, Charlson’s comorbidity index; MARA, Milliman advanced risk adjusters.
Notes: Estimates of two-way interactions are shown, with all main effects (as in Table 2) included in the model.
↵*P < .05.
↵^†Quintiles 1&2 are reference category for CoC. Age centered at 53, estimate of 10-year increase. CCI centered at 0, estimate of 1 point increase. MARA centered at 1, estimate of 1 point increase.

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Appendix A.

Adjusted Associations Between Physician CoC, Total Cost and Preventable Hospitalization: A Sensitivity Analysis of Patients with 2 or More visits in 2019

Variable	Total Cost% Change (95% CI)	Any Preventable HospitalizationOdds Ratio (95% CI)
CoC
Quintile 3	5.9% (3.4%, 8.5%)^*	1.00 (0.94, 1.07)
Quintile 4	10.1% (7.5%, 12.8%)^*	0.98 (0.92, 1.05)
Quintile 5	8.8% (6.1%, 11.5%)^*	1.08 (1.01, 1.15)
Quintiles 1&2	–	–
Age^{^†}	−1.4% (−1.5%, −1.2%)^*	1.16 (1.13, 1.18)^*
Gender
Woman	8.4% (8.0%, 8.7%)^*	1.22 (1.17, 1.27)^*
Man	–	–
Geography of residence
Isolated small rural town	1.4% (0.2%, 2.6%)^*	1.03 (0.91, 1.16)
Small rural town	1.0% (−0.2%, 2.2%)	1.25 (1.14, 1.37)^*
Large rural city/town	1.8% (0.8%, 2.9%)^*	1.17 (1.07, 1.28)^*
Urban	–	–
Primary insurance payer
Medicare	−33.7% (−34.1%, −33.4%)^*	1.53 (1.40, 1.70)^*
Medicaid	−23.5% (−24.0%, −23.0%)^*	1.54 (1.34, 1.78)^*
Commercial	–	–
SDI
75+	0.3% (−0.2%, 0.9%)	1.08 (1.02, 1.14)
1 to 74	–	–
CCI (log)^†	7.2% (7.1%, 7.3%)^*	1.24 (1.22, 1.25)^*
MARA (log)^†	29.0% (29.0%, 29.1%)^*	1.49 (1.48, 1.51)^*
Physician specialty
Internal medicine	0.7% (−1.3%, 2.7%)	0.96 (0.94, 1.07)
Pediatric medicine	−13.8% (−15.8%, −11.9%)^*	0.26 (0.18, 0.39)^*
Family medicine	–	–

Notes: Estimates of two-way interactions are shown, with all main effects (as in Table 3) included in the model.
↵*P < .05.
↵^†Quintiles 1&2 are reference category for CoC. Age centered at 53, estimate of 10-year increase. CCI centered at 0, estimate of 1 point increase. MARA centered at 1, estimate of 1 point increase.
Abbreviations: SDI, social deprivation index; CCI, Charlson’s comorbidity index; MARA, Milliman advanced risk adjusters; CI, confidence interval.

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Appendix B.

Regression Model of 2019 Total Allowed Patient Costs with 3-way Interactions

Variable			Modeled Coefficients	Implied Percent Change
Intercept			8.5760 (8.5572, 8.5949)	$5303.11 ($5204.00, $5404.11)
Age
Centered at 53, Unit Increase of 10			0.0039 (0.0018, 0.0061)	0.4% (0.2%, 0.6%)
Gender
Woman			0.0968 (0.0939, 0.0996)	10.2% (9.8%, 10.5%)
Man			REFERENCE	REFERENCE
SDI
75+			0.0035 (−0.0015, 0.0085)	0.3% (−0.1%, 0.8%)
1 to 74			REFERENCE	REFERENCE
Rurality (From RUCA)
Isolated small rural town			0.0155 (0.0047, 0.0264)	1.6% (0.5%, 2.7%)
Large rural city/town			0.0053 (−0.0056, 0.0162)	0.5% (−0.6%, 1.6%)
Small rural town			0.0179 (0.0083, 0.0276)	1.8% (0.8%, 2.8%)
Urban			REFERENCE	REFERENCE
Payer
Medicare			−0.4286 (−0.4368, −0.4203)	−34.9% (−35.4%, −34.3%)
Medicaid			−0.2960 (−0.3038, −0.2881)	−25.6% (−26.2%, −25.0%)
Commercial			REFERENCE	REFERENCE
CCI (log)
Centered at 0, Unit Increase of 1			0.0887 (0.0869, 0.0905)	9.3% (9.1%, 9.5%)
MARA (log)
Centered at 1, Unit Increase of 1			0.2525 (0.2517, 0.2533)	28.7% (28.6%, 28.8%)
PCP Specialty
Internal medicine			0.0270 (−0.0058, 0.0598)	2.7% (−0.6%, 6.2%)
Pediatric medicine			0.1505 (0.1133, 0.1876)	16.2% (12.0%, 20.6%)
Family medicine			REFERENCE	REFERENCE
BB-COC-PC of attributed PCP
Percentile 40 to 60			0.1293 (0.0966, 0.1620)	13.8% (10.1%, 17.6%)
Percentile 60 to 80			0.1642 (0.1296, 0.1989)	17.9% (13.8%, 22.0%)
Percentile 80 to 100			0.1612 (0.1234, 0.1991)	17.5% (13.1%, 22.0%)
Percentile 0 to 40			REFERENCE	REFERENCE
Specialty * Age
Internal medicine	Age Centered at 53, Unit Increase of 10		−0.0205 (−0.0242, −0.0167)	−2.0% (−2.4%, −1.7%)
Pediatric medicine	Age Centered at 53, Unit Increase of 10		0.0858 (0.0799, 0.0916)	9.0% (8.3%, 9.6%)
Family medicine	Age Centered at 53, Unit Increase of 10		REFERENCE	REFERENCE
MARA * Speciality
Internal medicine	MARA Centered at 1, Unit Increase of 1		0.0098 (0.0082, 0.0115)	1.0% (0.8%, 1.2%)
Pediatric medicine	MARA Centered at 1, Unit Increase of 1		−0.0300 (−0.0313, −0.0287)	−3.0% (−3.1%, −2.8%)
Family medicine	MARA Centered at 1, Unit Increase of 1		REFERENCE	REFERENCE
CCI * Speciality
Internal medicine	CCI Centered at 0, Unit Increase of 1		0.0020 (−0.0012, 0.0052)	0.2% (−0.1%, 0.5%)
Pediatric medicine	CCI Centered at 0, Unit Increase of 1		0.0003 (−0.0032, 0.0037)	0.0% (−0.3%, 0.4%)
Family medicine	CCI Centered at 0, Unit Increase of 1		REFERENCE	REFERENCE
BB-COC-PC * Specialty
Internal medicine	Percentile 40 to 60		−0.0468 (−0.1020, 0.0085)	−4.6% (−9.7%, 0.9%)
Internal medicine	Percentile 60 to 80		0.0640 (0.0094, 0.1186)	6.6% (0.9%, 12.6%)
Internal medicine	Percentile 80 to 100		0.0174 (−0.0388, 0.0736)	1.8% (−3.8%, 7.6%)
Internal medicine	Percentile 0 to 40		REFERENCE	REFERENCE
Pediatric medicine	Percentile 40 to 60		−0.1665 (−0.2876, −0.0455)	−15.3% (−25.0%, −4.4%)
Pediatric medicine	Percentile 60 to 80		−0.1453 (−0.2626, −0.0281)	−13.5% (−23.1%, −2.8%)
Pediatric medicine	Percentile 80 to 100		−0.0963 (−0.2272, 0.0346)	−9.2% (−20.3%, 3.5%)
Pediatric medicine	Percentile 0 to 40		REFERENCE	REFERENCE
Family medicine	Percentile 40 to 60		REFERENCE	REFERENCE
Family medicine	Percentile 60 to 80		REFERENCE	REFERENCE
Family medicine	Percentile 80 to 100		REFERENCE	REFERENCE
Family medicine	Percentile 0 to 40		REFERENCE	REFERENCE
BB-COC-PC * Payer
Medicare	Percentile 40 to 60		0.0126 (0.0001, 0.0250)	1.3% (0.0%, 2.5%)
Medicare	Percentile 60 to 80		−0.0102 (−0.0229, 0.0026)	−1.0% (−2.3%, 0.3%)
Medicare	Percentile 80 to 100		0.0279 (0.0145, 0.0413)	2.8% (1.5%, 4.2%)
Medicare	Percentile 0 to 40		REFERENCE	REFERENCE
Medicaid	Percentile 40 to 60		0.0149 (−0.0013, 0.0312)	1.5% (−0.1%, 3.2%)
Medicaid	Percentile 60 to 80		0.0850 (0.0686, 0.1013)	8.9% (7.1%, 10.7%)
Medicaid	Percentile 80 to 100		0.0169 (0.0003, 0.0335)	1.7% (0.0%, 3.4%)
Medicaid	Percentile 0 to 40		REFERENCE	REFERENCE
Commercial	Percentile 40 to 60		REFERENCE	REFERENCE
Commercial	Percentile 60 to 80		REFERENCE	REFERENCE
Commercial	Percentile 80 to 100		REFERENCE	REFERENCE
Commercial	Percentile 0 to 40		REFERENCE	REFERENCE
BB-COC-PC * Age
Percentile 40 to 60	Age Centered at 53, Unit Increase of 10		−0.0173 (−0.0207, −0.0139)	−1.7% (−2.1%, −1.4%)
Percentile 60 to 80	Age Centered at 53, Unit Increase of 10		−0.0142 (−0.0178, −0.0105)	−1.4% (−1.8%, −1.0%)
Percentile 80 to 100	Age Centered at 53, Unit Increase of 10		−0.0285 (−0.0324, −0.0245)	−2.8% (−3.2%, −2.4%)
Percentile 0 to 40	Age Centered at 53, Unit Increase of 10		REFERENCE	REFERENCE
BB-COC-PC * MARA
Percentile 40 to 60	MARA Centered at 1, Unit Increase of 1		0.0080 (0.0067, 0.0094)	0.8% (0.7%, 0.9%)
Percentile 60 to 80	MARA Centered at 1, Unit Increase of 1		0.0087 (0.0073, 0.0102)	0.9% (0.7%, 1.0%)
Percentile 80 to 100	MARA Centered at 1, Unit Increase of 1		0.0102 (0.0087, 0.0118)	1.0% (0.9%, 1.2%)
Percentile 0 to 40	MARA Centered at 1, Unit Increase of 1		REFERENCE	REFERENCE
BB-COC-PC * CCI
Percentile 40 to 60	CCI Centered at 0, Unit Increase of 1		−0.0116 (−0.0142, −0.0090)	−1.2% (−1.4%, −0.9%)
Percentile 60 to 80	CCI Centered at 0, Unit Increase of 1		−0.0145 (−0.0173, −0.0117)	−1.4% (−1.7%, −1.2%)
Percentile 80 to 100	CCI Centered at 0, UnitIncrease of 1		−0.0132 (−0.0162, −0.0101)	−1.3% (−1.6%, −1.0%)
Percentile 0 to 40	CCI Centered at 0, Unit Increase of 1		REFERENCE	REFERENCE
BB-COC-PC * Speciality * Age
Internal medicine	Percentile 40 to 60	Age Centered at 53, Unit Increase of 10	0.0159 (0.0102, 0.0215)	1.6% (1.0%, 2.2%)
Internal medicine	Percentile 60 to 80	Age Centered at 53, Unit Increase of 10	−0.0009 (−0.0066, 0.0048)	−0.1% (−0.7%, 0.5%)
Internal medicine	Percentile 80 to 100	Age Centered at 53, Unit Increase of 10	0.0077 (0.0018, 0.0136)	0.8% (0.2%, 1.4%)
Internal medicine	Percentile 0 to 40	Age Centered at 53, Unit Increase of 10	REFERENCE	REFERENCE
Pediatric medicine	Percentile 40 to 60	Age Centered at 53, Unit Increase of 10	−0.0120 (−0.0316, 0.0076)	−1.2% (−3.1%, 0.8%)
Pediatric medicine	Percentile 60 to 80	Age Centered at 53, Unit Increase of 10	0.0028 (−0.0148, 0.0204)	0.3% (−1.5%, 2.1%)
Pediatric medicine	Percentile 80 to 100	Age Centered at 53, Unit Increase of 10	0.0576 (0.0362, 0.0790)	5.9% (3.7%, 8.2%)
Pediatric medicine	Percentile 0 to 40	Age Centered at 53, Unit Increase of 10	REFERENCE	REFERENCE
Family medicine	Percentile 40 to 60	Age Centered at 53, Unit Increase of 10	REFERENCE	REFERENCE
Family medicine	Percentile 60 to 80	Age Centered at 53, Unit Increase of 10	REFERENCE	REFERENCE
Family medicine	Percentile 80 to 100	Age Centered at 53, Unit Increase of 10	REFERENCE	REFERENCE
Family medicine	Percentile 0 to 40	Age Centered at 53, Unit Increase of 10	REFERENCE	REFERENCE
BB-COC-PC * MARA * Speciality
Internal medicine	Percentile 40 to 60	MARA Centered at 1, Unit Increase of 1	−0.0039 (−0.0064, −0.0014)	−0.4% (−0.6%, −0.1%)
Internal medicine	Percentile 60 to 80	MARA Centered at 1, Unit Increase of 1	−0.0019 (−0.0043, 0.0006)	−0.2% (−0.4%, 0.1%)
Internal medicine	Percentile 80 to 100	MARA Centered at 1, Unit Increase of 1	−0.0075 (−0.0100, −0.0049)	−0.7% (−1.0%, −0.5%)
Internal medicine	Percentile 0 to 40	MARA Centered at 1, Unit Increase of 1	REFERENCE	REFERENCE
Pediatric medicine	Percentile 40 to 60	MARA Centered at 1, Unit Increase of 1	−0.0002 (−0.0044, 0.0040)	−0.0% (−0.4%, 0.4%)
Pediatric medicine	Percentile 60 to 80	MARA Centered at 1, Unit Increase of 1	−0.0010 (−0.0047, 0.0027)	−0.1% (−0.5%, 0.3%)
Pediatric medicine	Percentile 80 to 100	MARA Centered at 1, Unit Increase of 1	−0.0144 (−0.0182, −0.0106)	−1.4% (−1.8%, −1.1%)
Pediatric medicine	Percentile 0 to 40	MARA Centered at 1, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 40 to 60	MARA Centered at 1, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 60 to 80	MARA Centered at 1, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 80 to 100	MARA Centered at 1, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 0 to 40	MARA Centered at 1, Unit Increase of 1	REFERENCE	REFERENCE
BB-COC-PC * CCI * Speciality
Internal medicine	Percentile 40 to 60	CCI Centered at 0, Unit Increase of 1	−0.0058 (−0.0105, −0.0011)	−0.6% (−1.0%, −0.1%)
Internal medicine	Percentile 60 to 80	CCI Centered at 0, Unit Increase of 1	−0.0136 (−0.0182, −0.0091)	−1.4% (−1.8%, −0.9%)
Internal medicine	Percentile 80 to 100	CCI Centered at 0, Unit Increase of 1	−0.0032 (−0.0080, 0.0016)	−0.3% (−0.8%, 0.2%)
Internal medicine	Percentile 0 to 40	CCI Centered at 0, Unit Increase of 1	REFERENCE	REFERENCE
Pediatric medicine	Percentile 40 to 60	CCI Centered at 0, Unit Increase of 1	0.0110 (0.0002, 0.0217)	1.1% (0.0%, 2.2%)
Pediatric medicine	Percentile 60 to 80	CCI Centered at 0, Unit Increase of 1	0.0053 (−0.0048, 0.0154)	0.5% (−0.5%, 1.6%)
Pediatric medicine	Percentile 80 to 100	CCI Centered at 0, Unit Increase of 1	0.0113 (0.0008, 0.0217)	1.1% (0.1%, 2.2%)
Pediatric medicine	Percentile 0 to 40	CCI Centered at 0, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 40 to 60	CCI Centered at 0, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 60 to 80	CCI Centered at 0, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 80 to 100	CCI Centered at 0, Unit Increase of 1	REFERENCE	REFERENCE
Family medicine	Percentile 0 to 40	CCI Centered at 0, Unit Increase of 1	REFERENCE	REFERENCE