Rates, factors, reasons, and economic impact associated with switching in rheumatoid arthritis patients newly initiated on biologic disease modifying anti-rheumatic drugs in an integrated healthcare system

Figures & data

Figure 1. Study flow diagram.

Figure 2. Reasons for switching. *AE, adverse events; LoE, loss of efficacy; LaE, lack of efficacy.

Table 1. Baseline patient characteristics for newly-initiated bDMARD users (non-experienced population).

Patient characteristics	Total patients	Switchers	Non-switchers	p-value*
	(n = 2171) (100%)	(n = 251) (12%)	(n = 1920) (88%)
Female, (n, %)	1762 (81.2%)	212 (84.5%)	1550 (80.7%)	0.1549
Age, years (mean, SD)	50 ± 12.6	50 ± 12.1	50 ± 12.7	0.5169
≥65 years of age	244 (11.2%)	22 (8.8%)	222 (11.6%)	0.1869
<65 years of age	1927 (88.8%)	229 (91.2%)	1698 (88.4%)	0.1562
Body Mass Index (BMI) Information
BMI kg/m^2 (mean, SD)	29.33 ± 6.72	29.76 ± 6.30	29.27 ± 6.77	0.3012
Normal BMI, 18.50–24.99 kg/m^2 (n, %)	575 (26.5%)	54 (21.5%)	521 (27.1%)	0.1497
Overweight BMI, ≥ 25–< 30 kg/m^2 (n, %)	622 (28.7%)	70 (27.9%)	552 (28.8%)
Obese BMI, ≥ 30 kg/m^2 (n, %)	799 (36.8%)	107 (42.6%)	692 (36.0%)
Unknown	175 (8.1%)	20 (8.0%)	155 (8.1%)
Race (n, %)
Caucasian	874 (40.3%)	117 (46.6%)	757 (39.4%)	0.1531
African American	233 (10.7%)	25 (10.0%)	208 (10.8%)
Hispanic	855 (39.4%)	82 (32.7%)	773 (40.3%)
Asian/Pacific Islander	191 (8.8%)	25 (10.0%)	166 (8.6%)
Other	18 (0.8%)	2 (0.8%)	16 (0.8%)
Insurance type (n, %)
Commercial	2119 (97.6%)	247 (98.4%)	1872 (97.5%)	0.3771
Medcaid	334 (15.4%)	34 (13.5%)	300 (15.6%)	0.3906
Medicare	35 (1.6%)	3 (1.2%)	32 (1.7%)	0.5771
Charlson Comorbidity Index (CCI) Score, mean, SD	1.80 (± 2.2)	1.80 (± 2.2)	2.19 (±2.4)	0.0065
Comorbidities (n, %)
Cerebrovascular disease	20 (0.9%)	1 (0.4%)	19 (1.0%)	0.3566
Chronic pulmonary disease	233 (10.7%)	30 (12.0%)	203 (10.6%)	0.5067
Diabetes	225 (10.4%)	22 (8.8%)	203 (10.6%)	0.3768
Dyslipidemia	96 (4.4%)	10 (4.0%)	86 (4.5%)	0.7197
Hypertension	683 (31.5%)	84 (33.5%)	599 (31.2%)	0.4668
Myocardial infarction	30 (1.4%)	1 (0.4%)	29 (1.5%)	0.1558
Renal disease	104 (4.8%)	10 (4.0%)	94 (4.9%)	0.5247
Rheumatic disease	1983 (91.3%)	222 (88.4%)	1761 (91.7%)	0.0831
Any malignancy	20 (0.9%)	3 (1.2%)	17 (0.9%)	0.6294
Concomitant medication use with initial bDMARD therapy (n, %)
Non-steriodal anti-inflammatory drugs (NSAIDs)	2171 (100.0%)	251 (100.0%)	1920 (100.0%)	—
Corticosteroid	1352 (62.3%)	185 (73.7%)	1167 (60.8%)	<0.0001*
Narcotics	1029 (47.4%)	138 (55.0%)	891 (46.4%)	0.0105*
Anti-hypertensives	807 (37.2%)	101 (40.2%)	706 (36.8%)	0.285
Anti-diabetes	204 (9.4%)	21 (8.4%)	183 (9.5%)	0.552
Anti-hyperlipidemia	439 (20.2%)	56 (22.3%)	383 (19.9%)	0.3808
All cause healthcare resource utilization during 6 months prior
Emergency Room Visits (n, %)	379 (17.5%)	55 (22.0%)	326 (17.0%)	0.0331*
Number of Emergency Room Visits (mean, SD)	2 ± 1.2	3 ± 1.4	2 ± 1.2	0.3941
Hospital visits (n, %)	204 (9.4%)	22 (9.0%)	243 (12.7%)	0.0251*
Number of Hospital visits (mean, SD)	1 ± 0.8	1 ± 0.5	1 ± 0.8	0.4101
Hospital days (mean, SD)	4 ± 9.7	4 ± 8.2	6 ± 6.8	0.0214*
Outpatient Visits (n, %)	2171 (100%)	251 (100%)	1929 (100%)	—
Number of Outpatient Visits (mean, SD)	8 ± 6.1	11 ± 6.6	8 ± 6.0	0.0004*
AIDS/HIV	1 (0.05%)	0	1 (0.05%)	0.7176
Peripheral vascular disease	13 (0.6%)	0	13 (0.7%)	0.191
Congestive heart failure	18 (0.8%)	0	18 (0.9%)	0.1235
Hemiplegia or paraplegia	2 (0.1%)	0	2 (0.1%)	0.609
Liver disease	6 (0.3%)	0	6 (0.3%)	0.3751
Metastatic solid tumor	1 (0.05%)	1 (0.4%)	0	0.0057
Peptic ulcer disease	13 (0.6%)	4 (1.6%)	9 (0.5%)	0.0298

*p-value set at <0.05 for statistical significance.

Table 2. Factors associated with bDMARD switchers vs non-switchers.

Patient and clinical characterisitics	OR (95% CI)
Patient gender
Female	1.48 (1.02–1.86)*
Patient age groups, years
<65 years (reference)	1.00
≥65 years	0.71 (0.36–1.38)
Race
Caucasian (reference)	1.00
African American	0.73 (0.45–1.17)
Asian/Pacific Islander	1.12 (0.69–1.82)
Hispanic	0.68 (0.49–0.92)
Insurance type
Commercial	1.90 (0.64–2.69)
Medicaid and Medicare	0.89 (0.58–1.71)
BMI
Normal BMI, 18.50–24.99 kg/m^2 (n, %)	1.00
Overweight BMI, ≥25–<30 kg/m^2 (n, %)	1.20 (0.81–1.77)
Obese BMI, ≥30 kg/m^2 (n, %)	1.51 (1.04–2.19)*
CCI score
Score ≤2	1.22 (0.87–1.74)
Score ≥3	0.58 (0.33–0.98)*
Concomitant medication use with initial bDMARD therapy
Corticosteroid	1.64 (1.21–2.24)*
Narcotics	1.19 (0.89–1.59)
Anti-hypertensives	1.05 (0.74–1.48)
Anti-diabetes	0.99 (0.56–1.75)
Anti-hyperlipidemia	1.33 (0.91–1.94)
Prior healthcare resource use
Emergency room visits	1.12 (1.02–1.54)*
Hospital length of stay	1.29 (0.90–1.84)
Hospitalization visits	1.22 (0.76–1.95)
Any prior medical visits	1.35 (1.06 -2.01)*
Initial bDMARD therapy
Adalimumab	1.66 (0.83–1.85)
Etanercept	1.71 (1.07–1.98)*
Prior use of conventional DMARDS
Hydroxychloroquine	1.15 (0.86–1.53)
Leflunomide	1.32 (0.92–1.89)
Methotrexate	0.82 (0.65–1.07)
Other conventional DMARDs	1.29 (1.04–2.25)*

*p-value of <0.05 indicates statistically significant.

Table 3. Gamma regression model of mean total RA-related 12 month costs.

Parameter	Estimate	Standard Error	Likelihood ratio (95% CI)		p-value
Intercept	7.2762	0.6213	6.0168	8.4762	<0.0001
Switch vs no switch	1.2463	1.1485	1.0192	1.3734	0.0458
Female vs Male	1.3321	1.1865	1.2803	1.5839	0.0327
Age <65	1.0579	1.3868	0.8953	1.289	0.8811
Baseline CCI score	0.9131	0.8545	0.4135	1.196	0.4643
Corticosteroid use	1.2952	1.1418	1.1595	1.6089	0.0319
Narcotic use	1.2542	1.1991	1.1461	1.8362	0.0488
Commercial Insurance	1.0219	1.4845	0.9012	1.0775	0.9641
Prior ER visits	1.1909	1.2211	0.8263	1.6437	0.3857
Prior hospitalizations	1.2061	1.2544	0.8108	1.7236	0.4327

p-value of <0.05 indicates statistically significant.