Rumsfeldometer
- Known-knowns - there are things we know that we know
- Unknown-knowns - these are the things we know will occur
- Known-unknowns - there are things that we now know we don't know
- Unknown-unknowns - there are things we do not know we don't know
"One of the things I predicted in my section of 'Known-Unknowns' is that because we haven't seen opportunistic infection X after immunosuppressive drug A doesn't mean that drug A is not associated with this particular infection. Based on scientific principles given the right time frame and the environment, or exposure risk, opportunistic infection X will occur in patients with MS treated with immunosupporessive drug A. Therefore it comes as no supprise no to me that a very unfortunate person with MS developed a relatively rare opportunistic infection of the brain, 4 months after having a course of alemtuzumab. The Known-Unknown infection was Nocardia which is a genus of gram-positive bacteria that forms beaded branching filaments or chains similiar to fungi. There are over 80 species of Nocardia that are found in soil rich in organic matter."
"I have personally seen two cases of Nocardia in my career as a neurologist; my first case a neurology trainee in a patient with a renal transplant and my second case a young consultant in a patient with a recent bone marrow transplant. As people with MS on immunosuppressive treatments and as neurologists with a increasing number of patients who are immunocompromised we need to be more vigilant of this issue; the more patients we treat aggressively with immunosuppressive therapies the more opportunistic infections we will see. The one bit of good news with alemtuzumab the drug in question is that the risk of opportunistic infections is front-loaded. The risk of infection only occurs when the immune system is depleted; once the immune system has reconsituted itself the risk of opportunistic infections will fall. With drugs such as fingolimod the risk does not decrease; in fact in may increase and becomes cumulative over time. Using simple maths, or statistics, the risk of developing an opportunistic infection on maintenance immunosuppressive therapies will rise the longer you have been on the drug."
"I now tell patients about front-loading of risk and cumulative risk. It may make things more complicated, but most of the pwMS I have discussed this with understand the concept. It is an important concept as it may be the difference between someone choosing a particular treatment stragtegy or not. Saying this most people don't like the concept of their immune systems being suppressed, be it short-term or long-term. Despite this risk the chance of acquring an opportunistic infection on alemtuzumab, fingolimod or the the other MS DMTs is low."
Excerpt: An MSer was abmitted with reduced ambulation and personality change. She had been treated with natalizumab (80 infusions), which was discontinued because of repeated relapses and seroconversion to become JC virus positive. She was treated alemtuzumab in February 2015 (EDSS 4.5), 18 weeks after the cessation of natalizumab treatment. On admission in June 2015, she was wheelchair-bound. She was found to have a brain lesion, which on biopsy was found to be an abscess. Culture of intracranial abscess material grew Nocardia farcinica.