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Rheumatology Advance Access originally published online on May 3, 2007
Rheumatology 2007 46(7):1148-1152; doi:10.1093/rheumatology/kem074
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© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Common Attribution Non-Commercial License (http://creativecommons/org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Quality of life and economic impact of switching from established infliximab therapy to adalimumab in patients with rheumatoid arthritis

C. A. E. Walsh1, P. Minnock2, C. Slattery1, N. Kennedy2, F. Pang3, D. J. Veale1,2, B. Bresnihan1,2 and O. FitzGerald1,2

1Department of Rheumatology, St Vincent's University Hospital, Elm Park, Dublin, Ireland, 2Rheumatology Rehabilitation Unit, Harold's Cross, Dublin, Ireland and 3Formerly of Health Economics and Outcome Research, Abbott Laboratories Ltd., Maidenhead, United Kingdom.

Correspondence to: Dr Ceara Walsh, Department of Rheumatology, St. Vincent's University Hospital, Elm Park, Dublin 4, Ireland. E-mail: cearawalsh{at}eircom.net


   Abstract
Top
 Abstract
Introduction
 Methods
 Results
 Discussion
 Acknowledgements
 References
 
Objective. To evaluate the quality of life and economic impact of switching therapy from infliximab to adalimumab in patients with rheumatoid arthritis (RA).

Methods. In this open-label study, patients demonstrating a clinical response to infliximab were switched to treatment with adalimumab and followed for 16 weeks. Both generic (Health Assessment Questionnaire and Short Form 36 Physical Component Summary and Mental Component Summary) and specific (Rheumatoid Arthritis Quality of Life questionnaire) assessment instruments of physical function and of quality of life were employed. An economic analysis of treatment-related costs was also performed. Disease activity was assessed by the composite 28-joint count Disease Activity Score (DAS28). C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured as acute phase markers.

Results. Nineteen patients were enrolled and completed the study. No changes in functional and quality-of-life measures were observed. One-year extrapolation data showed potential reductions in costs following switching to adalimumab that could be attributed primarily to reductions in patient- and staff-related costs. Safety and tolerability were similar for both treatments. Although there was a significant reduction in DAS28 (P < 0.005) and CRP (P < 0.001) after switching to adalimumab, there were no significant changes in individual DAS28 components, including swollen and tender joint counts and ESR.

Conclusions. A switch from infliximab to adalimumab in patients with RA who have responded to infliximab is a feasible, well-tolerated treatment option, with the potential for direct and indirect economic advantages.

KEY WORDS: Adalimumab, Infliximab, Therapeutic switch, Quality of life, Economic analysis


   Introduction
Top
 Abstract
 Introduction
Methods
 Results
 Discussion
 Acknowledgements
 References
 
Rheumatoid arthritis (RA) is the most common form of inflammatory arthritis and is now widely treated with tumour necrosis factor (TNF) antagonists, particularly in patients with moderate to severe RA [1]. Although direct clinical trials comparing etanercept, infliximab and adalimumab have not been conducted, existing data suggest that TNF antagonists have similar safety profiles as well as clinical and radiographic efficacy in RA, whether used alone or in combination with methotrexate (MTX) [2–5]. However, some patients may experience treatment failure with their initial agent owing to primary or secondary loss of efficacy or intolerance and may benefit from a therapeutic switch from one TNF antagonist to another [4, 6–11]. Early TNF antagonist switch studies have found that it is reasonable and, in most cases, clinically beneficial to switch to another TNF antagonist before trying other therapeutic approaches [4, 6, 9].

Prescribing a particular TNF antagonist is an important decision that can greatly impact a patient's quality of life and can be associated with varying medical costs owing to differences in routes of administration with each agent. Etanercept and adalimumab are TNF antagonists that are administered subcutaneously. Both can be self-administered at home, provided that the patient has no functional limitations. Currently available subcutaneous therapies have disadvantages, including requiring more frequent administration, the patient having to learn proper handling and storage of medication and the risk of pain and irritation at the injection sites. Infliximab is a monoclonal antibody administered intravenously. Its use can be inconvenient for patients with respect to travelling and taking time off work for infusions and also for patients with difficulties regarding intravenous access. Infliximab administration may use more health care resources with requirements for infusion suites and equipment as well as medical and nursing supervision [12]. All of these factors can lead to dissatisfaction with treatment and can negatively affect a patient's quality of life, lead to non-compliance with therapy, and ultimately affect long-term therapeutic outcomes [13].

Our primary hypothesis was that switching from infliximab to adalimumab would prove more convenient to patients, resulting in improved quality-of-life measures, and that the switch from hospital-administered infliximab to home-administered adalimumab would result in economic advantages for both patients and the health system. We also recorded the clinical response, safety and tolerability of this therapeutic switch.


   Methods
Top
 Abstract
 Introduction
 Methods
Results
 Discussion
 Acknowledgements
 References
 
This 32-week, open-label study was conducted at a single centre in Dublin, Ireland.

The study was designed primarily to evaluate the impact on quality of life and economic aspects of switching patients with RA who were established (at least 12 weeks of therapy) on infliximab treatment to adalimumab treatment. As secondary outcomes, clinical responses, safety and tolerability were also evaluated.

Study design
After enrollment, patients continued infliximab therapy at the previously prescribed dosage for two infliximab infusion cycles. Patients were then switched to treatment with adalimumab 40 mg subcutaneously every other week (eow) for 16 weeks. Adalimumab was provided as a subcutaneous injection solution in pre-filled syringes containing 40 mg/0.8 ml (Abbott Laboratories, Abbott Park, IL, USA). Patients were allowed to continue other antirheumatic therapies, including disease-modifying antirheumatic drugs (DMARDs), non-steroidal anti-inflammatory drugs (NSAIDs), and corticosteroids. Clinic visits occurred at baseline (week 0, penultimate infliximab infusion), Week 8 (final infliximab infusion before the switch), week 16 (switch to adalimumab 40 mg eow), week 20, week 24 and week 32 (final follow-up visit).

Inclusion criteria
Patients were eligible if they had RA and, after a minimum of 12 weeks of infliximab treatment, were considered infliximab responders [improvement in 28-joint count Disease Activity Score (DAS28) > 1.2 3 months after treatment] but had ongoing, varying levels of disease activity despite this response. Patients must have been willing to self-administer subcutaneous adalimumab injections. All patients provided written, informed consent. Ethical approval was obtained from the Medical Research and Ethics Committee at St Vincent's University Hospital.

Functional and quality of life assessments
Physical function was assessed using the Health Assessment Questionnaire Disability Index (HAQ DI). Both disease-specific [Rheumatoid Arthritis Quality of Life questionnaire (RAQoL)] and generic [Physical Component Summary (PCS) and Mental Component Summary (MCS) of the Short Form 36 (SF-36)] quality-of-life measures were employed. HAQ DI, RAQoL and SF-36 were assessed at baseline, at the time of the switch (week 16), and at the final visit.

Economic analysis
An economic analysis was performed at each visit. A description of the unit costs used in the economic analysis is provided in Table 1. Staff salaries and the time patients spent with the various professionals at each visit were recorded so the cost of consultations could be estimated. Patient-related loss of earnings was estimated using the average industrial wage in addition to the time spent at the visit and travelling to and from treatment. Travel costs were estimated by calculating the distance between each patient's home address in kilometers and determining the expense using the civil service mileage allowance. In Ireland, non-hospital-administered, high-cost treatments are reimbursed by a national Health Service Executive funding scheme known as the ‘high-tech’ scheme. The source for the individual drug treatment costs are also described in Table 1.


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  		TABLE 1. Description of unit costs used in economic analysis

 
Clinical assessments
Disease activity was assessed with the DAS28 [14], and was measured prior to the infliximab infusion at baseline, before the switch (week 8) and at each visit following switching to adalimumab therapy.

Laboratory measurements, including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), and safety evaluations, including physical examinations, vital sign measurements and adverse events reports were assessed at each visit.

Statistical analysis
Statistical analysis was performed using SPSS version 11.0. Differences were assessed using the Student's paired t-test, where P < 0.05 was deemed significant.


   Results
Top
 Abstract
 Introduction
 Methods
 Results
Discussion
 Acknowledgements
 References
 
Patient disposition
A total of 19 patients were enrolled in the study. Baseline demographics and clinical characteristics of patients who switched from infliximab to adalimumab are included in Table 2. The doses and/or frequency of administration of infliximab had previously been increased from the original prescribing dose of 3 mg/kg every 8 weeks by the attending physician because of ongoing disease activity. No patients discontinued adalimumab therapy during the study period following the switch from infliximab.


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  		TABLE 2. Baseline demographic and disease severity characteristics

 
Concomitant antirheumatic therapy at baseline, at the time of the switch, and 16 weeks following the switch is summarized in Table 3. DMARDs included hydroxychloroquine, leflunomide, MTX and azathioprine. The mean dose and number of patients receiving DMARDs, corticosteroids and NSAIDs remained stable throughout the study. The slight increase in mean MTX dose can be attributed to one patient who required an increase in dose from 10 mg to 15 mg 3 months after the switch to adalimumab. The increase in steroid dose was the result of two patients who began receiving steroids and one patient who discontinued steroids at the time of the switch, as well as two patients who increased steroid doses and one patient who decreased steroid dose following the switch. One patient discontinued NSAID therapy at the time of switch. Finally, one patient required one intra-articular injection of a knee prior to switching therapy and two intra-articular injections of a knee after switching therapy. A second patient had an intra-articular injection of a knee prior to switching therapy.


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  		TABLE 3. Concomitant medications at baseline, time of switch, and 16 weeks after switching from infliximab to adalimumab

 
Functional and quality-of-life assessments
No significant changes in functional or quality-of-life assessments were observed either before or after the switch from infliximab to adalimumab. Table 4 summarizes HAQ DI, RAQoL and SF-36 PCS and SF-36 MCS scores throughout the study.


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  		TABLE 4. Quality-of-life and functional assessments before, during, and after a switch from infliximab to adalimumab

 
Economic impact
Direct and indirect costs were evaluated both before the switch, when patients received two cycles of infliximab, and following the switch, when patients received adalimumab 40 mg eow for 16 weeks. Total costs were {euro}114 980 prior to switching therapy and {euro}131 550 after switching therapy, resulting in an overall cost of {euro}16 570 to switch 19 patients from infliximab to adalimumab during the study period (Table 5).


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  		TABLE 5. Total and estimated yearly costs based on 19 patients for infliximab administration and adalimumab administrationa and potential savings following a switch from infliximab to adalimumab

 
In a post hoc analysis, we extrapolated the results to show the estimated costs of each treatment over a 54-week period (Table 5) to reflect a more ‘real-life’ economic evaluation. Based on the 1-yr data extrapolation, total annual costs for 19 patients receiving infliximab therapy are estimated at {euro}483 684 and an estimated {euro}410 102 for adalimumab therapy. This analysis showed a potential reduction of {euro}7479 per year in salary costs after switching to adalimumab based on the time spent by different health professionals with 19 patients. Moreover, patient-related costs could potentially be reduced by {euro}22 234 per year in patients receiving adalimumab therapy. Estimated total savings following a switch from infliximab to adalimumab in 19 patients is {euro}73 582 and estimated health care–related savings is {euro}51 348.

Clinical assessments
Following the switch from infliximab to adalimumab, a significant improvement was seen in DAS28 for the entire study population (N = 19). Mean (±S.E.M.) DAS28 was 4.05 (±0.267) at baseline, 3.94 (±0.328) at time of the switch and 3.01 (±0.266) at the final visit (P < 0.005 vs both baseline and time of the switch) (Fig. 1A). There were no statistically significant changes in mean tender joint counts (Fig. 1B) or swollen joint counts (Fig. 1C) from baseline through the final adalimumab treatment. CRP levels increased slightly from baseline to the time of the switch; however, CRP levels decreased significantly from a mean (±S.E.M.) baseline level of 13.47 (±2.36) to 8.05 (±1.94) at the final visit (P < 0.05) (Fig. 1D). No significant changes in ESR levels occurred from baseline through the final visit (Fig. 1D). At the final visit, patients’ general health assessment ratings had decreased from baseline and the time of the switch; however, these changes were not statistically significant.


Figure 1
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  		FIG. 1. Clinical assessments before, during, and after the switch from infliximab to adalimumab. (A) Disease Activity Scores (DAS28, mean ± S.E.M.), *P < 0.005 vs baseline and P < 0.005 vs time of switch. (B) Tender joint counts (mean ± S.E.M.). (C) Swollen joint counts (mean ± S.E.M.). (D) C-Reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels (mean ± S.E.M.). *P = 0.001 vs baseline; {dagger}P < 0.05 vs time of switch.

 
Safety
Safety and tolerability were maintained when patients switched from infliximab to adalimumab. No adverse events were reported during infliximab therapy prior to switching to adalimumab. One patient developed a lower respiratory tract infection after the switch to adalimumab. Two patients suffered transient nausea and vomiting after switching from infliximab to adalimumab.


   Discussion
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
Acknowledgements
 References
 
This study primarily evaluated quality of life and economic effects of switching TNF antagonists. In addition, the feasibility of switching patients who had demonstrated a response to infliximab infusions to adalimumab injections and whether the change in therapy could maintain clinical efficacy and tolerability were also assessed.

Based on the results of the HAQ DI, the RAQoL and the SF-36 PCS or SF-36 MCS, no significant changes in physical function or in quality of life were seen either before or after the switch to adalimumab. It is important to note that there was no worsening in these measures. In addition, although there were no changes in these assessments over this short-term study period, switching from infliximab to adalimumab may be more convenient for some patients over the long term, primarily owing to the fewer number of hospital visits that will be required of them with adalimumab therapy compared with infliximab therapy. This may be particularly important for patients who have to take time off from work or have transportation issues for their visits.

The economic impact of switching from infliximab to adalimumab is a practical issue to address owing to the larger direct and indirect costs to patients with RA and to society [15, 16]. Although drug treatment only constitutes a portion of the total costs of treating RA, the recent increase in the use of these more expensive TNF antagonists over less expensive DMARDs has caused an increase in the percentage of drug costs for treating RA [17]. Therefore, the cost effectiveness of these agents is an important issue debated by both clinicians and health care policy makers [18].

In this study analysis, switching from infliximab to adalimumab was associated with overall increases in costs of {euro}16 570, likely because of the requirements for additional monitoring during the 32-week study period, with patients attending every 4 weeks for review after the switch to adalimumab. However, in a true clinical setting, patients receiving adalimumab are generally reviewed in outpatient clinics 3 times per year. In the intervening period, they generally visit their general practitioner for blood tests (complete blood counts and liver function tests) every 2 months, primarily to monitor the potential effects of concomitant medications. Because this study does not give a realistic picture of patient follow-up while receiving adalimumab, a post hoc analysis was performed to estimate costs for 19 patients over a 54-week period. Based on this cost extrapolation, overall costs of treatment with adalimumab are potentially reduced owing to reductions in patient- and staff-related costs and a potential reduction in TNF antagonist costs. Total savings, based on 19 patients, following a switch from infliximab to adalimumab would be {euro}73 582, and the estimated health care–related savings would be {euro}51 348. Overall, the study proposes that a therapeutic intervention to decrease costs, such as switching from infliximab to adalimumab, may have the potential for significant economic benefit to the individual and society, especially in patients in whom ongoing disease activity has necessitated an increase in dosage or frequency of administration of their original anti-TNF therapy.

The primary outcome of this study was the functional and economic impact of switching therapy. However, the study also showed that switching from infliximab to adalimumab is safe and well tolerated with a significant improvement in disease activity based on improvement in DAS28 scores. All patients who switched to adalimumab continued on treatment throughout the study, without significant changes in concomitant medications. In contrast to the UK where National Institute for Health and Clinical Excellence (NICE) guidelines require that patients have a baseline DAS28 score of 5.2 prior to the commencement of a biologic agent, in Ireland, the decision to prescribe TNF antagonist therapy is at the discretion of the primary physician. It is of interest to note the further significant improvement in DAS28 scores in this patient cohort even though the patients would not have fulfilled the NICE guidelines.

Results of studies have yielded good clinical responses when patients were switched to adalimumab because of lack of response or intolerance to infliximab or etanercept [9, 11, 19–23]. In contrast, until recently, little was known about the clinical benefit of switching from one TNF antagonist to another when a patient has responded to and is tolerating his or her first treatment. Preliminary data from a small open-label study of 14 RA patients in the UK suggest that switching patients who are stable on infliximab to adalimumab yields a good clinical response and is safe [24]. To our knowledge, this is only the second study with adalimumab to investigate a switch in patients who have demonstrated a response to infliximab. In this study, 31.6% of patients had low disease activity (DAS28 < 3.2) and 21.1% of patients had high disease activity (DAS28 > 5.1) during infliximab therapy [25]. Although this study and the study from the UK were conducted in a small number of patients, they provide additional data to support the concept of switching patients from infliximab to adalimumab without risking clinical response or safety.

There are several limitations that should be considered in the overall analysis of the study. Improvements in disease activity parameters following the switch to adalimumab may reflect timing of data collection more than increased efficacy with adalimumab. DAS28 was calculated for patients receiving infliximab immediately prior to their next treatment, potentially the worst day of their infusion cycle. Also, alterations were permitted in concomitant medications as per standard care, which may have affected disease activity. This economic analysis also has several limitations. A true economic evaluation of these agents is difficult in this analysis because this study was not a direct head-to-head comparison. Development of a complete cost-effectiveness model of TNF antagonist therapy would require evaluation of long-term disease outcomes. Also, infliximab costs were calculated using patient weight; therefore, costs would increase in treatment facilities where the unused infliximab is discarded. Finally, this study evaluated 19 patients over a short treatment period; extrapolation of the data to a larger population of patients should be undertaken with caution.

In conclusion, in this open-label study of 19 patients with RA, switching from infliximab to adalimumab was safe and well tolerated. Although there were no changes in functional assessments or in quality-of-life measures, the study did show that there may be direct and indirect cost savings after switching patients from infliximab to adalimumab. In addition, there was a significant reduction in disease activity following the switch from infliximab to adalimumab. Therefore, a therapeutic switch from infliximab to adalimumab in patients with RA who have demonstrated a response to infliximab is a feasible treatment option that may improve clinical response and may have both direct and indirect economic advantages.

This study supports the soon-to-be published, updated NICE guidelines, which recommend that when selecting a TNF antagonist, rheumatologists should consider clinical evidence and experience, the impact of therapy on the patient's quality of life, and medication costs to determine which agent is best suited for an individual patient.

Formula


   Acknowledgements
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Acknowledgements
References
 
This study was an investigator-originated study sponsored by Abbott Laboratories, Ltd. Dr Ceara Walsh receives a Clinical Research Training Fellowship from the Health Research Board of Ireland. We thank Michelle L. Metelo, PharmD, of JK Associates, Inc., for her writing and editorial assistance in the development of this manuscript.

F.P. is a former employee of Abbott Laboratories, Ltd. O.F. has given occasional lectures for Abbott and has received grant support for investigator-led studies. The other authors have no conflict of interest to declare.


   References
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Acknowledgements
 References
 

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Submitted 20 December 2006; revised version accepted 2 March 2007.
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