Recommendations issued on screening for latent tuberculosis infection in patients with psoriasis treated with systemic therapies
Tumor necrosis factor (TNF) antagonists (infliximab, etanercept, and adalimumab) are new medications that have proven to be very effective in the treatment of psoriasis. However all these medications have been implicated in an increased rate of tuberculosis (TB) infection, th to reactivation of latent TB infection. For this reason screening for latent of active or latent TB has been recommended in these patients. In a recent publication at the Journal of the American Academy of Dermatology the medical board of the National Psoriasis Foundation (a patient-driven non-profit organization form the United States) has made a consensus statement based on an extensive review of the literature.
This medical board recommends to screen for TB by using tuberculin skin tests all patients before initiating any of the TNF antagonists. In additio these authors recommend that this also should be done ton any patient before initiating any immunosuppressive medication (such as methotrexate, cyclosporine, alefaceft, or efalizumab). This would not be needed for topical therapies or phototherapy.
Tuberculin skin tests are considered positive if there is an induration equal or greater than 5 mm at 48 hours. Some person might have false negative tests due and in Europe anergy testing and ‘‘booster’’ tuberculin tests are recommended, but this is not the current practice in the United States. The wholeblood interferon-g release There are more sensitive and specific assays based in whole-blood interferon-gamma release. These can be positive in individuals with latent TB whose tuberculin skin tests are negative, or help to diagnose a latent TB in patients with a history of BCG vaccination (where a positive tuberculin skin test is the rule). However these assays are not widely available.
When these tests are positive and an active TB has been ruled out (by chest radiograph), TB infection prophylaxis with 9 months of isoniazid (preferred) or 4 months ryphampycin has to be started. Treatment with TNF antagonists should be initiated only after 1-2 months ot prophylaxis has been done.
National Psoriasis Foundation consensus statement on screening for latent tuberculosis infection in patients with psoriasis treated with systemic and biologic agents
Doherty SD et al.
J Am Acad Dermatol 2008;59:209-17.
Background: Chronic immunosuppression is a known risk factor for allowing latent tuberculosis (TB) infection to transform into active TB. Immunosuppressive/ immunomodulatory therapies, while highly efficacious in the treatment of psoriasis and psoriatic arthritis, may be associated with an increased rate of active TB in patients receiving some of these therapies.
Objective: Our aim was to arrive at a consensus on screening for latent TB infection in psoriasis patient treated with systemic and biologic agents.
Methods: Reports in the literature were reviewed regarding immunosuppressive therapies and risk of TB.
Results: Screening patients for latent TB infection before commencement of treatment is of utmost importance when beginning treatment with the tumor necrosis factorea inhibitors, T-cell blockers, cyclosporine, or methotrexate. The currently recommended method for screening is the tuberculin skin test. It is preferable that positively screened patients be treated with a full course of latent TB infection prophylaxis before immunosuppressive/immunomodulatory therapy is initiated. However, in the opinion of many experts, patients may be started on the immunosuppressive/immunomodulatory therapy after 1 to 2 months, if their clinical condition requires, as long as they are strictly adhering to and tolerating their prophylactic regimen.
Limitations: There are few evidence-based studies on screening for latent TB infection in psoriasis patients treated with systemic and biologic agents.
Conclusions: The biologic TNFea inhibitors are very promising in the treatment of psoriasis. However, because TNFea is also an important cytokine in preventing TB infection and in keeping latent TB infection from becoming active disease, the use of TNFea inhibitors has been associated with an increased risk of developing active TB. A higher incidence of TB has also been reported with other immunosuppressive/immunomodulatory treatments for psoriasis. It is, therefore, of utmost importance to appropriately screen all patients for latent TB infection prior to initiating any immunologic therapy. Delaying immunologic therapy until latent TB infection prophylaxis is completed is preferable. However, if the patient is adhering to his prophylactic regimen and is appropriately tolerating the regimen, therapy may be started after 1 to 2 months if the clinical condition requires.
