SAN DIEGO—Early detection of progressive multifocal leukoencephalopathy (PML) may reduce mortality and disability levels in patients with multiple sclerosis (MS), according to a study presented at the 65th Annual Meeting of the American Academy of Neurology. The research could have implications for patients with MS who receive natalizumab, which increases the risk of PML.
Tuan Dong-Si, MD, Medical Director at Biogen Idec in Weston, Massachusetts, and colleagues examined 319 individuals with MS who were treated with natalizumab and diagnosed with PML. The investigators compared patients who had symptoms of PML at the time of diagnosis with patients who had no symptoms of PML but were diagnosed with the disease by brain scans and spinal fluid tests for John Cunningham virus. Patients' level of disability was assessed before the PML diagnosis, at the time of the diagnosis, six months after the diagnosis, and one year after the diagnosis.
Twenty-one participants had no PML symptoms at the time of their diagnosis, and 298 individuals had symptoms. The study's preliminary data suggest that patients who have no symptoms at diagnosis may have improved survival and less disability than those who had developed symptoms before their diagnosis, according to Dr. Dong-Si.
At the time of PML diagnosis, individuals without symptoms had an average score of 67 on the Karnofsky Performance Scale. In contrast, participants with symptoms had an average score of 54. One year after PML diagnosis, the average Karnofsky score of patients with no symptoms at diagnosis was 70, compared with 47 for patients with symptoms at diagnosis.
Karnofsky scores lower than 50 indicate that the patient may not be able to care for himself or herself and may require institutional care. A Karnofsky score of 70 suggests that the person can care for himself or herself, but may not be able to engage in normal activities or work. A Karnofsky score of 50 indicates that a person may require considerable assistance and frequent medical care.
As of January 1, 2013, all 21 participants with no symptoms at the time of PML diagnosis were alive, compared with 77% of those with symptoms at the time of diagnosis. "These results suggest that the consequences of PML infection can be mitigated by early detection of the disease," said Dr. Dong-Si.