Patterns and predictors of long-term retention of inflammatory bowel or rheumatoid disease patients on innovator infliximab: an analysis of a Canadian prescriptions claims database

Figures & data

Table 1 Patient baseline characteristics in the overall IBD cohort (n=7,806) and RD cohort (n=2,935)

Variable	IBD	RD
	n (%)	n (%)
Age, years
0–18	799 (10)	146 (5)
19–64	6,383 (82)	2,284 (78)
65+	624 (8)	505 (17)
Sex
Female	4,121 (53)	1,766 (60)
Male	3,661 (47)	1,157 (39)
Not reported	24 (<1)	121 (4)
Biologic status
Naïve	7,366 (94)	1,910 (65)
Experienced	440 (6)	1,025 (35)
Insurance type
Private	5,786 (74)	1,679 (57)
Public	2,020 (26)	1,256 (43)
Geographic region
Eastern Canada	744 (10)	217 (7)
Ontario	3,855 (49)	1,547 (53)
Quebec	1,953 (25)	817 (28)
Western Canada	1,254 (16)	354 (12)
Concomitant medication(s)a
Yes	4,273 (55)	2,418 (82)
No	3,533 (45)	517 (18)

Note:

a Includes methotrexate, azathioprine, and 6-mercaptopurine for IBD cohort and methotrexate, azathioprine, cyclosporine, leflunomide, sulfasalazine, hydroxychloroquine, and prednisone for RD cohort.

Abbreviations: IBD, inflammatory bowel disease; RD, rheumatologic disease.

Figure 1 Overall 5-year retention of IBD and RD patients on IFX.

Note: Overall retention in the total cohort of IBD patients (n=7,806) and RD patients (n=2,935) on IFX reported at 12-month intervals over a 5-year period.
Abbreviations: IBD, inflammatory bowel disease; IFX, infliximab; RD, rheumatologic disease.

Table 2 Unadjusted OR of being retained based on cumulative IFX exposure in the overall IBD and RD cohorts

Years on IFX	IBD cohort			RD cohort
	Subsequent 12-month retention	OR (vs 1 year on IFX)	95% CI	Subsequent 12-month retention	OR (vs 1 year on IFX)	95% CI
1	80.3%	Ref.	Ref.	74.3%	Ref.	Ref.
2	84.7%	1.36	1.19–1.54	81.1%	1.48	1.22–1.80
3	86.3%	1.54	1.32–1.81	85.8%	2.08	1.63–2.67
4	88.2%	1.83	1.48–2.25	86.0%	2.13	1.58–2.87
5	91.9%	2.77	1.96–3.91	86.9%	2.29	1.53–3.44

Notes: Data are for stable IFX patients. All patients had 1 year of prior IFX experience (ie, patients in the 1-year cohort had been on IFX for 1 year before).

Abbreviations: IBD, inflammatory bowel disease; IFX, infliximab; RD, rheumatologic disease; OR, odds ratio; Ref., referent.

Figure 2 Relative risk of being retained on IFX at 5 years after controlling for variables of interest in (A) the overall IBD and RD cohort and (B) RD vs IBD patients.

Abbreviations: AS, ankylosing spondylitis; IBD, inflammatory bowel disease; IFX, infliximab; RA, rheumatoid arthritis; RD, rheumatologic disease; PsA, psoriatic arthritis.

Figure S1 Derivation of pair-wise comparisons.

Notes: The equations used to conduct the pair-wise comparisons. Equation 1 was used to calculate the OR. Equation 2 was used to calculate SE which was used in Equation 3 to calculate the 95% CI of the estimated OR. “a” is the number of patients who were retained in the subsequent 12 months, “c” is the number of patients who were retained in the reference year, “b” the number of patients who were not retained in the subsequent 12 months, and “d” is the number of patients who were not retained in the reference year.

Abbreviations: OR, odds ratio; SE, standard error.

Table S1 Unadjusted OR of being retained based on cumulative IFX exposure in subpopulations of IBD patients (OR [95% CI])

Subgroup	Retention (year vs year)
	2 vs 1	3 vs 1	4 vs 1	5 vs 1
Female (n=2,248)	1.41 (1.18–1.68)	1.68 (1.36–2.09)	1.69 (1.28–2.22)	3.08 (1.89–5.05)
Male (n=2,020)	1.29 (1.06–1.57)	1.40 (1.11–1.77)	2.01 (1.45–2.78)	2.57 (1.56–4.21)
Age 0–18 (n=432)	1.71 (1.09–2.69)	1.52 (0.90–2.58)*	1.38 (0.68–2.81)*	0.75 (0.29–1.94)*
Age 19–64 (n=3,490)	1.31 (1.14–1.51)	1.50 (1.26–1.78)	1.84 (1.47–2.31)	3.58 (2.36–5.41)
Age 65+ (n=359)	1.58 (0.96–2.58)*	2.29 (1.22–4.29)	2.22 (1.02–4.82)	1.45 (0.59–3.56)*
Privately insured (n=2,995)	1.33 (1.14–1.55)	1.57 (1.30–1.90)	1.83 (1.42–2.35)	2.75 (1.77–4.25)
Publicly insured (n=1,286)	1.38 (1.07–1.79)	1.40 (1.05–1.88)	1.69 (1.16–2.46)	2.48 (1.41–4.35)
East (n=415)	1.77 (1.11–2.82)	1.40 (0.84–2.34)*	1.78 (0.88–3.59)*	NA
Ontario (n=2,230)	1.42 (1.18–1.71)	1.59 (1.28–1.98)	2.06 (1.53–2.78)	2.18 (1.43–3.34)
Quebec (n=1,043)	1.16 (0.90–1.50)*	1.42 (1.03–1.96)	1.33 (0.90–1.98)*	4.10 (1.78–9.48)
West (n=593)	1.26 (0.92–1.73)*	1.58 (1.04–2.39)	1.94 (1.11–3.41)	2.28 (0.95–5.48)*
Bio-naïve (n=4,072)	1.32 (1.16–1.51)	1.54 (1.31–1.81)	1.84 (1.49–2.28)	2.69 (1.90–3.80)
Bio-experienced (n=209)	2.45 (1.24–4.84)	1.53 (0.70–3.35)*	1.16 (0.41–3.28)*	NA
Concomitant immunomodulator (n=2,520)	1.31 (1.07–1.61)	1.35 (1.05–1.73)	1.88 (1.31–2.70)	2.33 (1.28–4.25)
No concomitant immunomodulator (n=1,761)	1.43 (1.20–1.69)	1.75 (1.42–2.14)	1.90 (1.47–2.45)	3.18 (2.09–4.85)

Notes:

* P-value >0.05; all other values are statistically significant with P<0.05.

Abbreviations: IBD, inflammatory bowel disease; IFX, infliximab; NA, not available (due to small number of patients in subgroup, statistical analysis could not be done); OR, odds ratio.

Table S2 Unadjusted OR of being retained based on cumulative IFX exposure in subpopulations of RD patients (OR [95% CI])

Subgroup	Retention (year vs year)
	2 vs 1	3 vs 1	4 vs 1	5 vs 1
Male (n=646)	1.40 (1.02–1.91)	1.83 (1.24–2.70)	2.60 (1.54–4.38)	2.46 (1.24–4.87)
Female (n=971)	1.55 (1.20–1.98)	2.26 (1.64–3.11)	1.89 (1.31–2.72)	2.33 (1.39–3.90)
Age 0–18 (n=85)	1.76 (0.72–4.34)*	4.59 (1.01–20.94)	1.64 (0.43–6.23)*	0.33 (0.06–1.75)*
Age 19–64 (n=1,228)	1.53 (1.22–1.91)	2.11 (1.59–2.81)	2.28 (1.62–3.23)	2.68 (1.65–4.35)
Age 65+ (n=312)	1.26 (0.81–1.95)*	1.72 (1.00–2.97)	1.72 (0.88–3.36)*	2.00 (0.82–4.91)*
Privately insured (n=851)	1.61 (1.24–2.01)	2.36 (1.67–3.32)	2.40 (1.57–3.66)	2.81 (1.57–5.03)
Publicly insured (n=774)	1.29 (0.96–1.72)*	1.73 (1.21–2.48)	1.76 (1.15–2.70)	1.76 (0.99–3.11)*
East (n=119)	1.26 (0.59–2.66)*	1.85 (0.74–4.59)*	1.47 (0.56–3.91)*	5.90 (0.76–45.82)*
Ontario (n=877)	1.43 (1.09–1.88)	1.78 (1.28–2.50)	2.30 (1.49–3.57)	3.25 (1.67–6.34)
Quebec (n=458)	1.56 (1.09–2.21)	2.45 (1.54–3.88)	2.88 (1.61–5.13)	1.43 (0.76–2.69)*
West (n=171)	1.55 (0.87–2.76)*	2.83 (1.25–6.38)	0.84 (0.38–1.87)*	1.38 (0.43–4.49)*
Bio-naïve (n=1,153)	1.40 (1.11–1.76)	2.01 (1.50–2.69)	1.73 (1.24–2.42)	1.88 (1.19–2.95)
Bio-experienced (n=472)	1.62 (1.13–2.31)	2.11 (1.32–3.37)	4.0 (1.95–8.19)	4.06 (1.58–10.45)
Concomitant DMARD (n=1,366)	1.39 (1.11–1.74)	2.11 (1.57–2.83)	1.89 (1.33–2.70)	2.54 (1.56–4.12)
No concomitant DMARD (n=259)	1.76 (1.20–2.59)	2.05 (1.31–3.23)	2.79 (1.58–4.91)	1.74 (0.82–3.70)*
RA (n=1,345)	1.41 (1.14–1.74)	1.93 (1.48–2.51)	1.94 (1.41–2.68)	2.18 (1.40–3.38)
AS (n=143)	2.85 (1.34–6.06)	3.11 (1.31–7.39)	7.69 (1.77–33.31)	2.38 (0.67–8.47)*
PsA (n=137)	1.37 (0.66–2.83)*	4.06 (1.18–14.02)	1.87 (0.61–5.76)*	4.68 (0.60–36.51)*

Notes:

* P-value >0.05; all other values are statistically significant with P<0.05.

Abbreviations: AS, ankylosing spondylitis; DMARD, disease-modifying anti-rheumatic drug; IFX, infliximab; OR, odds ratio; PsA, psoriatic arthritis; RA, rheumatoid arthritis; RD, rheumatologic disease.