Persistence, switch rates, drug consumption and costs of biological treatment of rheumatoid arthritis: an observational study in Italy

Figures & data

Figure 1 Patient distribution by biologic drug at baseline.

Table 1 Baseline demographic, therapeutic and clinical characteristics of patients enrolled in the study

	Infliximab (n=94)	Adalimumab (n=144)	Etanercept (n=236)
Age (years), mean ± SD	53.4 ± 13.0	56.5 ± 13.0	52.6 ± 14.1
Male, n (%)	29 (30.9)	28 (19.4)	51 (21.6)
Female/male ratio	2/2	4/1	3/6
CCI, mean ± SD	2.9 ± 1.3	3.0 ± 1.9	2.7 ± 1.4
Established*, n (%)	57 (60.6)	63 (43.8)	105 (44.5)
Pre-index DMARD use, n (%)	83 (88.3)	117 (81.3)	180 (76.3)

Notes:

* Patients were already in treatment with biologic agents before the index date.

Abbreviations: SD, standard deviation; CCI, Charlson Comorbidity Index; DMARDs, disease-modifying anti-rheumatic drugs.

Figure 2 Persistence with biologic therapy: adalimumab, etanercept and infliximab.

Notes: First year: Eta vs. Ada p=0.69; Eta vs. Inf p=0.007; Ada vs. Inf p=0.32. Second year: Eta vs. Ada p<0.001; Eta vs. Inf p=0.002; Ada vs. Inf p=0.54. Third year: Eta vs. Ada p=0.008; Eta vs. Inf p=0.014; Ada vs. Inf p=0.88. Fourth year: Eta vs. Ada p=0.002; Eta vs. Inf p=0.031; Ada vs. Inf p=0.62.
Abbreviations: Eta, etanercept; Ada, adalimumab; Inf, infliximab.

Figure 3 Percentage of patients switching from initial therapy.

Notes: First year: Eta vs. Ada p=0.05; Eta vs. Inf p=0.25; Ada vs. Inf p=0.55. Second year: Eta vs. Ada p=0.18; Eta vs. Inf p=0.05; Ada vs. Inf p=0.64.
Abbreviations: Eta, etanercept; Ada, adalimumab; Inf, infliximab.

Figure 4 Percentage of patients with drug consumption escalation.

Abbreviations: Eta, etanercept; Ada, adalimumab; Inf, infliximab.

Figure 5 Percentage of patients with drug consumption reduction.

Abbreviations: Eta, etanercept; Ada, adalimumab; Inf, infliximab.

Table 2 Multivariable logistic regression model of persistence to therapy and switching among biologic agents

	Persistence			Switch
	OR	95% CI	p-Value	OR	95% CI	p-Value
Male	1.073	0.653–1.761	0.782	1.268	0.692–2.323	0.441
Age	1.000	0.985–1.016	0.970	0.990	0.971–1.010	0.335
CCI	0.934	0.824–1.060	0.291	1.110	0.951–1.296	0.185
Drug dose escalation	0.848	0.452–1.591	0.608	2.751	1.404–5.389	0.003
Drug dose reduction	0.855	0.469–1.558	0.609	1.631	0.780–3.409	0.194
Etanercept	ref.			ref.
Adalimumab	0.511	0.317–0.822	0.006	2.066	1.103–3.867	0.023
Infliximab	0.759	0.428–1.348	0.347	1.714	0.823–3.572	0.150

Abbreviations: OR, odds ratio; 95% CI, 95% confidence interval; CCI, Charlson Comorbidity Index.

Figure 6 Costs for the three biologics investigated*.

Notes: *Excluding infusion costs for infliximab.

Figure 7 Costs for other health care consumption (excluding drugs).

Table 3 Mean annual costs of treatment per indicator of pharmacological consumption.

	Biologics	Other health care consumption	Total	Difference	p-Value
No switch	€10,753	€579	€11,332	−€1,378	0.007
Switch	€12,163	€547	€12,710
No drug consumption increase	€10,732	€620	€11,352	−€1,597	0.005
Drug consumption increase	€12,744	€205	€12,949
No drug consumption reduction	€11,079	€601	€11,680	€1,177	0.027
Drug consumption reduction	€10,106	€397	€10,503

Table 4 Cost of illness, generalized linear model

	β	95% CI	p-Value
Male	23.32	−1,189.11 to 1,235.76	0.970
Age	−67.30	−111.17 to −23.43	0.003
CCI	386.77	−79.27 to 852.82	0.104
Dose escalation	1,738.17	−75.58 to 3,551.92	0.060
Dose reduction	−2,523.31	−4,803.22 to −243.39	0.030
Switch	627.09	−716.88 to 1,971.07	0.360
Adalimumab vs. etanercept	1,606.45	316.88 to 2,896.01	0.015
Infliximab vs. etanercept	−2,459.27	−3,871.93 to −1,046.60	0.001
Baseline cost	15,543.45

Note: β, beta coefficients.

Abbreviations: 95% CI, 95% confidence interval; CCI, Charlson Comorbidity Index.