Reduced Access to Biologic Medications in Socially Vulnerable Patients with IBD

Abstract

Introduction: Novel but expensive biologics are more effective in producing sustained clinical remission in IBD than low-cost alternatives including immunomodulators and corticosteroids. However, social determinants of health (SDOH) can affect access to effective treatments. We hypothesized that SDOH, measured using the Centers for Disease Control’s social vulnerability index (SVI) on a 0-1 scale (higher scores indicated greater social vulnerability) influenced access to biologic medications for IBD patients in the United States.

Methods: We identified individuals with IBD from a longitudinal cohort of patients managed in a single academic center from 2015 and 2022. We linked patients with their SVI and 4 subscales (Socioeconomic Status, Household Composition, Minority and Language, Housing and Transportation) based on their current address geocoded to individual Census tracts. Separately, we examined the relationship between both biologic prescription (defined by at least one prescription) and sustained biologic access (defined by at least three prescriptions) and SVI using multivariable logistic regression and adjusting a priori for IBD type, age, sex, race, ethnicity, language, comorbidities, tobacco use, and insurance type.

Results: We identified 8,963 patients with IBD; 48% were prescribed 5-aminosalicylates (5-ASA), 38% immunomodulators, 52% biologics, and 75% corticosteroids. When accounting for all biologic types, (intravenous and subcutaneous) higher SVI was not associated with decreased prescriptions or sustained access. However, when sub-grouped by route of administration, patients with a higher SVI were less likely to be sustained on intravenous biologics (OR 0.58, 95% CI 0.46-0.71, p < 0.001). Additionally, patients with higher SVI were more likely to be prescribed (OR 1.39, 95% CI 1.14-1.69, p < 0.001) and sustained on (OR 1.24 95% CI 1.00-1.54, p = 0.048) subcutaneous biologics. When examining individual subthemes, socioeconomically vulnerable patients were more likely to be prescribed (OR 1.55, 95% CI 1.17-2.05, p = 0.002) and sustained on (OR 1.37, 95% CI 1.01-1.85, p = 0.042) subcutaneous biologics while those with poor access to housing and transportation were less likely to be prescribed (OR 0.70, 95% CI 0.57, 0.85, p < 0.001) and sustained on (OR 0.55, 95% CI 0.44, 0.68, p < 0.001) intravenous biologics. Minority Status and Language was associated with sustained biologic access (OR 1.24, 95% CI 1.05-1.48, p = 0.012) while Household Composition was not associated with any differences in biologic prescribing practices.

Conclusions: Clear differences in biologic prescribing practices for socially vulnerable patients exist. Highly vulnerable patients are less likely to be sustained on intravenous biologics, such as infliximab and vedolizumab. Socioeconomic status and housing and transportation seem to play an important role, with socioeconomically disadvantaged patients being more likely to be sustained on subcutaneous therapies while those with poor access to housing and transportation were less likely to be sustained on intravenous biologics. Decreasing the cost of intravenous biologics and increasing the number of available subcutaneous biologic therapies may be two strategies for improving equitable access to effective IBD treatments for all patients.

The Social Vulnerability Index

For more information on the CDC’s social vulnerability index, please click the link below.

CDC SVI

Baseline Patient Characteristics

Characteristic	N = 8,9631
IBD Diagnosis
CD	4,536 (51%)
UC	4,386 (49%)
IC	2 (<0.1%)
Unknown	39 (0.4%)
Age	48 (19)
Sex
Male	4,064 (45%)
Female	4,899 (55%)
Race
White	7,811 (87%)
Black	607 (6.8%)
Asian or Pacific Islander	222 (2.5%)
American Indian or Alaska Native	35 (0.4%)
Other	288 (3.2%)
Ethnicity
Hispanic	184 (2.1%)
Non-Hispanic	8,779 (98%)
Preferred Language
English	8,881 (99%)
Other	82 (0.9%)
Charlson Comorbidity Index	3.6 (5.2)
Active Tobacco Use	1,052 (12%)
Insurance Type
Private Insurance	5,791 (65%)
Medicaid	1,403 (16%)
Medicare	1,665 (19%)
Other Governmental	62 (0.7%)
Other	42 (0.5%)
5-aminosalicylic acid	4,268 (48%)
Immunomodulator	3,428 (38%)
Biologic	4,622 (52%)
Small Molecule	275 (3.1%)
Steroids	6,740 (75%)
Social Vulnerability Index	0.36 (0.26)
1 n (%); Mean (SD)

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Geographic Distribution of Patients

This map represents the geographic distribution of 14,262 patients with IBD seen at the University of Michigan subdivided by Census tract. Darker areas represent less vulnerable Census tracts and lighter areas represent more vulnerable Census tracts.

Hover over individual Census tracts to show the SVI value for that area.

Total SVI Multivariable Logistic Regression Tables

The relationship between high social vulnerability and biologic prescribing practices, including all covariates

All Biologics

Characteristic	Biologic Prescribed			Sustained Biologic Access
	OR1	95% CI1	p-value	OR1	95% CI1	p-value
IBD Diagnosis
CD	—	—		—	—
UC	0.24	0.22, 0.27	<0.001	0.29	0.27, 0.32	<0.001
IC	0.00		>0.9	0.00		>0.9
Unknown	0.15	0.07, 0.32	<0.001	0.13	0.04, 0.32	<0.001
Age	0.97	0.97, 0.97	<0.001	0.97	0.97, 0.97	<0.001
Sex
Male	—	—		—	—
Female	0.81	0.74, 0.89	<0.001	0.81	0.74, 0.89	<0.001
Race
White	—	—		—	—
Black	1.08	0.90, 1.31	0.4	1.25	1.03, 1.50	0.021
Asian or Pacific Islander	0.73	0.54, 0.99	0.040	0.91	0.67, 1.23	0.5
American Indian or Alaska Native	0.62	0.30, 1.28	0.2	0.82	0.38, 1.69	0.6
Other	1.09	0.82, 1.44	0.6	0.98	0.74, 1.29	0.9
Ethnicity
Hispanic	—	—		—	—
Non-Hispanic	0.98	0.69, 1.39	>0.9	0.83	0.59, 1.17	0.3
Preferred Language
English	—	—		—	—
Other	0.65	0.39, 1.09	0.11	0.99	0.58, 1.65	>0.9
Charlson Comorbidity Index	0.97	0.96, 0.98	<0.001	0.99	0.97, 1.00	0.010
Active Tobacco Use
No	—	—		—	—
Yes	0.92	0.79, 1.06	0.2	0.98	0.85, 1.13	0.8
Insurance Type
Private Insurance	—	—		—	—
Medicaid	0.80	0.70, 0.92	0.002	0.85	0.74, 0.97	0.018
Medicare	0.83	0.72, 0.96	0.012	0.81	0.69, 0.94	0.006
Other Governmental	0.61	0.34, 1.08	0.090	0.38	0.20, 0.71	0.003
Other	0.86	0.43, 1.69	0.7	0.93	0.47, 1.83	0.8
Social Vulnerability Index	1.11	0.91, 1.34	0.3	0.86	0.70, 1.04	0.11
1 OR = Odds Ratio, CI = Confidence Interval

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Intravenous Biologics

Characteristic	IV Biologic Prescribed			Sustained IV Biologic Access
	OR1	95% CI1	p-value	OR1	95% CI1	p-value
IBD Diagnosis
CD	—	—		—	—
UC	0.49	0.45, 0.54	<0.001	0.52	0.47, 0.58	<0.001
IC	0.00		>0.9	0.00		>0.9
Unknown	0.17	0.05, 0.45	0.001	0.07	0.00, 0.32	0.008
Age	0.97	0.97, 0.97	<0.001	0.96	0.96, 0.97	<0.001
Sex
Male	—	—		—	—
Female	0.84	0.76, 0.92	<0.001	0.79	0.71, 0.88	<0.001
Race
White	—	—		—	—
Black	1.13	0.94, 1.36	0.2	1.45	1.19, 1.77	<0.001
Asian or Pacific Islander	0.77	0.56, 1.05	0.10	0.89	0.63, 1.23	0.5
American Indian or Alaska Native	0.69	0.30, 1.45	0.3	0.85	0.33, 1.91	0.7
Other	1.11	0.84, 1.45	0.5	1.19	0.89, 1.60	0.2
Ethnicity
Hispanic	—	—		—	—
Non-Hispanic	0.84	0.60, 1.18	0.3	0.82	0.57, 1.17	0.3
Preferred Language
English	—	—		—	—
Other	0.78	0.44, 1.32	0.4	1.14	0.63, 1.98	0.7
Active Tobacco Use
No	—	—		—	—
Yes	0.96	0.83, 1.10	0.5	0.97	0.83, 1.14	0.7
Charlson Comorbidity Index	1.00	0.99, 1.01	0.5	1.02	1.01, 1.03	0.004
Insurance Type
Private Insurance	—	—		—	—
Medicaid	0.95	0.83, 1.09	0.5	1.05	0.91, 1.21	0.5
Medicare	1.07	0.91, 1.25	0.4	1.04	0.87, 1.26	0.6
Other Governmental	0.60	0.31, 1.09	0.11	0.36	0.15, 0.78	0.016
Other	0.93	0.46, 1.82	0.8	0.93	0.42, 1.94	0.9
Social Vulnerability Index	0.88	0.72, 1.06	0.2	0.58	0.46, 0.71	<0.001
1 OR = Odds Ratio, CI = Confidence Interval

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Subcutaneous Biologics

Characteristic	SubQ Biologic Prescribed			Sustained SubQ Biologic Access
	OR1	95% CI1	p-value	OR1	95% CI1	p-value
IBD Diagnosis
CD	—	—		—	—
UC	0.28	0.25, 0.30	<0.001	0.28	0.25, 0.31	<0.001
IC	0.00		>0.9	0.00		>0.9
Unknown	0.26	0.10, 0.59	0.003	0.25	0.08, 0.64	0.010
Age	1.00	0.99, 1.00	0.021	0.99	0.99, 1.00	<0.001
Sex
Male	—	—		—	—
Female	1.05	0.95, 1.15	0.3	1.02	0.92, 1.13	0.8
Race
White	—	—		—	—
Black	0.95	0.78, 1.15	0.6	1.08	0.88, 1.31	0.5
Asian or Pacific Islander	0.79	0.56, 1.09	0.2	0.89	0.62, 1.26	0.5
American Indian or Alaska Native	0.49	0.18, 1.14	0.12	0.77	0.28, 1.77	0.6
Other	1.02	0.76, 1.36	0.9	0.89	0.63, 1.22	0.5
Ethnicity
Hispanic	—	—		—	—
Non-Hispanic	1.22	0.85, 1.78	0.3	1.07	0.73, 1.62	0.7
Preferred Language
English	—	—		—	—
Other	0.72	0.39, 1.25	0.3	1.05	0.57, 1.86	0.9
Active Tobacco Use
No	—	—		—	—
Yes	1.07	0.92, 1.23	0.4	1.08	0.93, 1.27	0.3
Charlson Comorbidity Index	0.96	0.95, 0.98	<0.001	0.97	0.96, 0.98	<0.001
Insurance Type
Private Insurance	—	—		—	—
Medicaid	0.91	0.80, 1.05	0.2	0.88	0.75, 1.01	0.079
Medicare	0.67	0.57, 0.78	<0.001	0.64	0.54, 0.77	<0.001
Other Governmental	0.80	0.43, 1.42	0.5	0.58	0.27, 1.12	0.12
Other	0.79	0.37, 1.58	0.5	0.90	0.40, 1.88	0.8
Social Vulnerability Index	1.39	1.14, 1.69	0.001	1.24	1.00, 1.53	0.048
1 OR = Odds Ratio, CI = Confidence Interval

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SVI Subtheme Multivariable Logistic Regression Tables

The relationship between themes of high social vulnerability and biologic prescribing practices, adjusted for IBD type, age, sex, race, ethnicity, language, comorbidities, tobacco use, and insurance type.

All Biologics

Characteristic	Biologic Prescribed			Sustained Biologic Access
	OR1	95% CI1	p-value	OR1	95% CI1	p-value
Socioeconomic Status	1.33	1.01, 1.75	0.042	1.20	0.92, 1.59	0.2
Household Composition & Disability	1.14	0.90, 1.45	0.3	0.97	0.76, 1.22	0.8
Minority Status & Language	1.02	0.86, 1.21	0.8	1.24	1.05, 1.48	0.012
Housing Type & Transportation	0.73	0.60, 0.89	0.002	0.66	0.54, 0.80	<0.001
1 OR = Odds Ratio, CI = Confidence Interval

NULL

IV Biologics

Characteristic	IV Biologic Prescribed			IV Sustained Biologic Access
	OR1	95% CI1	p-value	OR1	95% CI1	p-value
Socioeconomic Status	1.11	0.85, 1.46	0.4	0.98	0.73, 1.33	>0.9
Household Composition & Disability	1.06	0.84, 1.34	0.6	0.88	0.68, 1.14	0.3
Minority Status & Language	1.07	0.90, 1.27	0.4	1.29	1.07, 1.56	0.007
Housing Type & Transportation	0.70	0.57, 0.85	<0.001	0.55	0.44, 0.68	<0.001
1 OR = Odds Ratio, CI = Confidence Interval

NULL

SubQ Biologics

Characteristic	SubQ Biologic Prescribed			Sustained SubQ Biologic Access
	OR1	95% CI1	p-value	OR1	95% CI1	p-value
Socioeconomic Status	1.55	1.17, 2.05	0.002	1.37	1.01, 1.85	0.042
Household Composition & Disability	1.20	0.95, 1.53	0.13	1.03	0.80, 1.34	0.8
Minority Status & Language	1.00	0.84, 1.19	>0.9	1.16	0.96, 1.41	0.12
Housing Type & Transportation	0.80	0.66, 0.98	0.034	0.85	0.68, 1.06	0.15
1 OR = Odds Ratio, CI = Confidence Interval

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