Psoriasis is a chronic inflammatory skin disease of unknown etiology characterized by recurrent outbreaks. It is a prevalent disorder that affects between 1% and 2% of the population,1,2 and 5% to 10% of those affected have moderate to severe forms of the disease.3 While no definition of moderate to severe psoriasis has been universally accepted, a recent Spanish consensus document defined it as psoriasis that requires (or has previously required) systemic therapy with conventional drugs, a biologic agent, phototherapy, or photochemotherapy.1 The same consensus document specified that systemic treatment is indicated in patients who meet the following criteria: disease not controlled with topical treatment; extensive disease (body surface area affected≥5%–10%); Psoriasis Area Severity Index PASI≥10; rapid worsening; involvement of visible areas; functional impairment (palmoplantar or genital involvement); subjective perception of severity (Dermatology Life Quality Index>10); extensive erythroderma or pustular psoriasis; or disease associated with psoriatic joint disease.

The therapeutic arsenal available to treat psoriasis includes phototherapy, various topical treatments, the classic systemic treatments (acitretin, methotrexate, and ciclosporin), and the modern biologic agents (etanercept, adalimumab, infliximab, and ustekinumab). Given the high prevalence of the disorder and the development of new therapies, such as the biologic agents, the cost associated with the treatment of patients with moderate to severe psoriasis has increased dramatically in recent years.4,5

At the same time, there has been a decline in the prescription of phototherapy, despite the fact that this therapeutic option has been shown to be both safe and cost-effective.6–9 One of the main reasons for this decline appears to be that patients find it difficult to attend the outpatient clinic for phototherapy sessions 3 or 4 days a week because of the loss of work time, and consequently of income, involved. Most of these logistic drawbacks can be overcome by home-based phototherapy, that is, by the patients carrying out the phototherapy sessions in a controlled manner in their own home. Several studies have shown home phototherapy to be an inexpensive, safe, and effective treatment for psoriasis.4,10–13 However, this treatment modality has not yet been used in the Spanish public health care system.

The aim of this study was to assess the efficiency of narrowband UV-B phototherapy administered in the home to treat moderate to severe psoriasis under normal practice conditions in our setting, and to compare it with that of biologic drug therapy.

We designed a cost-effectiveness study to analyze the efficiency of home narrowband UV-B phototherapy and biologic agents (etanercept, adalimumab, and infliximab) for the treatment of moderate to severe psoriasis. Using hospital funding, our dermatology department acquired 3 home phototherapy units; the patients bore no part of the cost of this acquisition.

Study Type and General Information

This was a retrospective cost-effectiveness study carried out in the psoriasis unit of a tertiary hospital between September 2009 and September 2010 to compare home narrowband UV-B phototherapy with biologic therapy. Decision trees were constructed (Fig. 1) to calculate the direct costs, effectiveness, and efficiency (cost/effectiveness) of the 2 types of treatment studied (home phototherapy and biologic therapy with etanercept, adalimumab and infliximab). As the analysis was carried out from the payer's perspective, it only took into account direct costs. Consequently, we calculated the cost to the Spanish National Health Service of providing home phototherapy or biologic therapy to these patients. The treatment period stipulated for both therapeutic options was 4 months. It was not necessary to apply a discount rate for future costs and results because both the cost and the effective outcomes occurred within a maximum of 4 months.

Figure 1.

Simplified model of the decision tree used. Cb indicates cost of biologic therapy; Cph, cost of phototherapy; Eb, probability of PASI-75 response with biologic therapy; Eph, probability of PASI-75 response with phototherapy; 1-Eb, probability of no PASI-75 response to biologic therapy; 1-Eph, probability of no PASI-75 response to phototherapy. Incremental cost-effectiveness of the biologic therapy=(Cb−Cph)/ (Eb−Eph).

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Home Phototherapy

The phototherapy device used was a Waldmann UV 100 T-L home phototherapy unit (Fig. 2). The lamp was delivered to the patient's home by a delivery service company, remained there for the duration of treatment, and was collected at the end of treatment by the same company. No additional tests were performed before or during phototherapy. Each patient received 30minutes of training. This comprised a 10-minute session given by the physician in the dermatology office and 20minutes instruction on how to use the phototherapy unit given by the nurse, who also explained the need to protect the eyes and genitals. During the treatment sessions, patients protected their eyes with dark glasses and shielded their genitals with dark-colored underwear. The number of sessions prescribed depended on the patient's initial PASI score: patients with a PASI under 15 were prescribed a continuous regimen of 2 days of treatment followed by 1 day off, and patients with a PASI score above 15 followed a regimen of 3 days of treatment followed by 1 day off. Phototherapy sessions were continued for 16 weeks or until the patient achieved a 90% improvement in their PASI score (PASI-90); no maintenance regimen was used. All patients receiving phototherapy attended the hospital for assessment 5 times during the 4-month study period (an initial consultation and 4 follow-up visits).

Figure 2.

Waldmann UV 100 T-L phototherapy units used in the pilot study.

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The phototherapy dose was calculated for each patient on the basis of their Fitzpatrick skin phototype (the so-called American protocol)7,15: an initial dose of 0.20J/cm2 for phototype II and an initial dose of 0.25J/cm2 for phototype III. The dose was increased by 20% in each of the first 3 sessions and by 10% thereafter.

Biologic drugs have revolutionized the treatment of psoriasis,1 achieving success rates at week 16 as high as 60% to 80% PASI-75.2,16 However, since these treatments are expensive and not without adverse effects,5,17 they are not generally considered to be a first-line option. The results of a safety study in 988 patients with psoriasis treated with biologic agents showed that these drugs were associated with various adverse events, including reactions to infliximab infusion (34%), abnormal laboratory test results (13%), and infections (12%).18 Efficiency studies report a cost per PASI-75 of €8013 for adalimumab and between €9370 and €17112 for the other biologic agents.19

Recent studies indicate an increase among Spanish dermatologists in the prescription of biologic agents for the treatment of psoriasis, with up to 23% of patients with moderate to severe psoriasis being prescribed a biologic agent.3 The resulting increase in medication costs in dermatology has raised questions about the cost-effectiveness of biologic therapies. For example, according to data from the health service for the Community of Madrid (SERMAS), the increase in the number of patients in the Madrid area receiving biologic agents for psoriasis has doubled the cost of treatment in this setting between 2007 and 2009 (299 patients at a cost of €5306951 in 2007, 504 patients at €8210160 in 2008, and 674 patients at €10801524 in 2009). This upward trend continued throughout 2010 (909 patients at a cost of €12204234).

While our study analyzed only a small number of patients, our findings with respect to the cost of achieving a PASI-75 with biologic therapy are in line with those reported in the literature.19

Phototherapy with narrowband UV-B at 311nm is a safe and effective treatment for patients with psoriasis.8,9 It is estimated that between 50% and 80% of patients achieve a PASI-75,6,7 and the remission rate of psoriasis 1 year after treatment has been reported to be around 38%.10 One variable that can improve the effectiveness of phototherapy is the frequency of sessions, and a regimen based on 5 sessions a week has been shown to be more effective than a regimen of 3 sessions a week, as long as the dose is increased gradually to avoid adverse effects.7,15

With respect to cost, Langan et al.20 determined the cost of narrowband UV-B phototherapy to be €325 for 2 years’ treatment with phototherapy, of which 70% was the cost of personnel. A more recent study estimated the annual cost of narrowband UV-B phototherapy, at $1734, to be lower than that of most other therapeutic options ($4235 for PUVA, $7768 for ciclosporin, $9163 for acitretin, $23538 for adalimumab, $23639 for infliximab, and $24439 for etanercept) except methotrexate, at $1197.5 Given that the average annual cost of biologic treatment for a patient with psoriasis is between €14000 and €18000,2,5,21 the much lower cost of phototherapy would appear to be a key consideration if we wish to optimize the efficiency of treatment in this very prevalent disease. In view of the striking difference in cost, it is remarkable that the number of patients being treated with biologic agents is growing steadily, while the number of patients being treated with UV-B is declining. One possible explanation for this phenomenon is that the chief barrier to phototherapy treatment for patients is the inconvenience and time involved in traveling to the hospital 3 to 4 days a week for treatment.22 Another factor may be that not all hospitals are equipped to offer phototherapy. Furthermore, the patient must bear the indirect costs associated with phototherapy, such as transportation costs, lost working hours, none of which are a factor in the case of biologic therapy. In many cases, all of these factors lead the dermatologist to choose biologic therapy, despite the fact that it is a much more costly option for the health care provider.

As a result, it appears that narrowband UV-B phototherapy, despite being an effective and efficient treatment, is underutilized for mainly logistic reasons.7 In order to overcome the limitations associated with phototherapy, the health care authorities in various Europe countries (Netherlands, United Kingdom) have recently changed their approach and shifted the location of phototherapy treatment to the patient's own home. Home phototherapy eliminates the main problems associated with outpatient phototherapy, namely, the lack of patient availability and the inconvenience of hospital visits.4,10,11

Home phototherapy has been shown to be a safe, effective, and inexpensive treatment for psoriasis.4,10,11 Adherence rates were higher for home phototherapy than oral acitretin in one study.23 Moreover, home phototherapy allows patients to increase the number of weekly sessions from 3 to 5, if necessary, to achieve increased treatment effectiveness without the inconvenience this would entail if they had to spend time traveling to and from the hospital for treatment. Narrowband UV-B phototherapy administered in the patient's home has been shown to be at least as effective in the treatment of psoriasis as the same therapy administered in an outpatient setting, and the total cost of treatment is the same in both cases.12

Despite being a safe and efficient therapeutic option, home phototherapy has not yet been used or regulated by the Spanish national health system. In some countries, there are other obstacles to home phototherapy treatment, including copayment by patients and the scant interest shown by health insurance companies in promoting this type of therapy,10 as well as difficulties in obtaining the lamps and the lack of the specific training needed to prescribe the therapy among dermatologists.24

Several authors have advocated home phototherapy as the treatment of choice for patients with psoriasis because of its efficiency, lower indirect costs, high patient satisfaction, and the increased adherence to treatment observed.10,22

One of the risks associated with home phototherapy is the possibility that the patient will misuse the lamp, a risk that can be minimized through minimal patient training on the operation of the unit.25 With respect to carcinogenicity, there is currently no evidence of an increased risk of skin tumors with narrowband UV-B therapy,26 while such an increase has been shown in the case of PUVA therapy. However, caution is recommended, and patients should not exceed 450 sessions. The total cumulative dose that would pose an increased risk of carcinogenesis has not yet been determined.27,28

The effectiveness of home phototherapy in our study (66%) is similar to that reported in the literature for outpatient phototherapy.6,7 There are very little data in the literature concerning the cost of home phototherapy. Koek et al.12 (the PLUTO study) reported an estimated cost of €800 per patient (of which €727 were direct costs) for an average treatment period of 17.6 weeks. Our analysis of the costs associated with home phototherapy (direct cost of €602 per patient) is the first published study on the cost of this modality in the Spanish health system and our findings are similar to those reported by Koek et al.12 The cost of home phototherapy is comparable to that of outpatient phototherapy.5,12 The advantage of the outpatient modality is that several patients can be treated each day with a single device, while in home phototherapy the lamp is used by only 1 patient during the whole treatment period. It is therefore our opinion that home phototherapy would be an interesting addition to outpatient phototherapy for use in certain patients, and that the outpatient modality would also continue to be useful.

The main limitation of our study was the small sample size (12 patients). However, the sizeable differences observed in the cost-effectiveness both in the base case scenario (cost per PASI-75 of €8256 for biologic therapy and €903 for home phototherapy) and between the best case scenario for biologic therapy and worst case scenario for home phototherapy (cost per PASI-75 of €5848 for biologic therapy and €3141 for home phototherapy) show home phototherapy to be a very attractive treatment option for patients with psoriasis. This hypothesis can be confirmed by larger studies. Other limitations of our study include the use of a 16-week time horizon (biologic drugs can achieve better effectiveness if measured through week 24) and the heterogeneity of the biologic therapy group, which included different drugs with differing response profiles.

The usefulness of biologic drugs in certain cases (severe psoriasis, very high PASI, and contraindications or resistance to other treatments) is not in question. Moreover, these drugs operate systemically decreasing inflammation, an effect not demonstrated with phototherapy. However, in view of the adverse events and the high cost associated with biologic therapy, we should use this treatment option with caution and consider treating patients with moderate to severe psoriasis and a moderate PASI with other alternatives, such as phototherapy (if possible) in view of its greater efficiency and good safety profile. It is interesting to note that the target patient groups for biologic agents and phototherapy appear to be different. In fact, the median PASI of patients prescribed biologic drugs in our study was slightly higher than that of the patients who received phototherapy. In recent years we have seen a gradual shift from the use of phototherapy to the prescription of biologic drugs in patients with moderate to severe psoriasis and a PASI between 10 and 15. This has occurred largely because biologic therapy is more convenient for the patient because, unlike phototherapy, it does not involve traveling to the hospital on a regular basis to receive treatment. In fact, the criterion for considering a patient as a candidate for biologic treatment is that he or she should have moderate to severe psoriasis and contraindications to or intolerance of other systemic therapies, including ciclosporin, methotrexate and PUVA; in practice, this often includes patients who are unable to travel to the hospital for PUVA therapy.2

In conclusion, our study represents the first experience of home phototherapy in the Spanish public health system and we have achieved excellent results in terms of efficiency. We do not advocate replacing treatment with biologic agents in patients who have severe psoriasis or extensive multiple resistance, but we do propose home phototherapy as an alternative option for patients with moderate psoriasis who are candidates for phototherapy but who have difficulty attending the outpatient clinic regularly for treatment.

Although the biologic drugs were more effective, the results of our pilot study indicate that home phototherapy was more efficient than biologic therapy in patients with moderate to severe psoriasis. Home-based phototherapy represents a cost-effective treatment for patients with psoriasis and may be appropriate for use in the Spanish health care system.

The authors declare that they have no conflicts of interest.