Phototherapy can be used as a treatment modality for the management of psoriasis patients. Determining when to use phototherapy can be based on a number of factors. The first factor to consider is the percent of body surface area that is involved. Often phototherapy should be considered as a treatment modality when the body surface area (BSA) is 5% or more. A second consideration is the failure or refractory response to topical medications. In this event, phototherapy should be considered for management. It is also important to note that phototherapy is not the best option in patients with symptoms of arthritis.
What if a patient stops taking phototherapy for whatever reason, how do you resume therapy? Many situations can cause a lapse in therapy such as time constraints, stress, location of the treatment center, or even lack of adherence. In these cases, it is unwise to maintain the same dosage as previously given and instead either narrowband or broadband UVB light should be used based on the patient’s skin phototype. Often a reduction of about 50% in broadband therapy and about 25% in narrowband therapy should be incorporated for the starting dose.
The starting dose for phototherapy should be determined based on minimal erythema dose (MED) and attention to a full slightly pink area presents throughout the square that was irradiated. Another option is to determine the patient’s skin phototype (I-VI) and follow the guidelines set forth by the manufacturer of the device.
The wave length is another parameter that should be reviewed to decide when to use broadband light vs narrowband light. As a reminder, broadband light ranges from 280-320 nm and is more energetic, than the narrowband that peaks at approximately 311 nm. As the broadband wavelengths are shorter, the energy level is higher which accounts for the 7-fold difference in the MED dose (Table). See also the AAD Guidelines - Psoriasis: General principles for phototherapy.
Methotrexate systemic therapy
Phototherapy is one of the options present in the guidelines; however, other therapies have proven effective as well. Mark Lebwohl, Sol and Clara Kest Professor and Chairman, Department of Dermatology at the Mount Sinai School of Medicine, New York, USA discusses some of the challenges of systemic therapy that dermatologists face when initiating and managing patients on methotrexate. Characteristic laboratory findings during methotrexate use include an increase in liver function tests, as well as an increase in bone marrow suppression. It is important to monitor these patients by regularly reviewing lab data. Guidelines also recommend liver biopsies in patients who receive high cumulative doses of methotrexate. However, the implementation of liver biopsies must be weighted carefully with the patient risks. Liver biopsies have certain risks and may lead to hemorrhages, both fatal and nonfatal, Hemorrhages after liver biopsy has also been reported in the literature.
Lebwohl went on to present data that helped to predict those patients who would be more at risk for hepatic fibrosis to help differentiate those patients in whom liver biopsy would be most helpful. Increased risk factors for hepatic fibrosis included patients who were obese, diabetic, and alcoholics, along with abnormal liver function tests, family history of liver disease, exposure to hepatotoxic drugs, lack of folate supplementation, and hyperlipidemia. It was interesting to note in Langman et al. 2001 presented by Lebwohl, increased liver functions tests were not associated with fibrosis nor increased risk for the development of fibrosis. The guidelines were eventually updated and the 2009 National Psoriasis Foundation (NPF) Consensus now recommends that liver biopsies are not indicated in patients without risk factors and the frequency of liver biopsies be markedly reduced. In place of the frequent biopsies, physicians should monitor patients by obtaining liver function tests on a monthly basis for the first 6 months of therapy, and then every 1-2 months thereafter.
Baseline monitoring with methotrexate should continue as complete blood counts with platelets, BUN/creatinine, and liver function tests. Other testing should be sought when indicated such as hepatitis B and C serologies, HIV, and pregnancy tests. A recent addition was the inclusion of the PPD (purified protein derivative) test as latent reactivation of tuberculosis is higher with the use of methotrexate.
Systemic therapies other than methotrexate should be considered in patients with a high risk of liver fibrosis or toxicity, such as cyclosporine or others depending on clinical findings. Again, baseline liver biopsies are not recommended with methotrexate, and placing a patient through this trauma is unacceptable practice. However, a delayed baseline liver biopsy is suggested after 2-6 months of therapy to determine the medications efficacy and tolerability. Repeat liver biopsies should also be obtained after approximately 1-1.5 g of therapy.
Folic acid therapy is strongly encouraged during methotrexate therapy as it has been shown to have a protective hepatic effect minimizing the increase of liver function test. Folic acid reduces the nausea associated with methotrexate therapy and protects against megaloblastic anemia.