Final answer:
Before starting treatment with TNF-α inhibitors like etanercept, patients must be screened for latent tuberculosis and possibly other infections or conditions such as HIV that may lead to or indicate immunodeficiency.
Step-by-step explanation:
Patients about to begin therapy with TNF-α inhibitors, such as etanercept, which impair cell-mediated immunity, should be screened for latent tuberculosis. TNF-α is critical in the control of tuberculosis infection; hence, inhibiting it can reactivate latent tuberculosis. Additionally, screening may be necessary for other infections or for conditions such as HIV, which could be exacerbated by immunosuppression.
This is crucial since etanercept and other TNF-α inhibitors can increase susceptibility to infections and exacerbate pre-existing immunodeficiencies. Prior to initiation of these immunosuppressive treatments, it is important to assess the patient's immune system status to ensure safe administration of the drug.