VANCOUVER, British Columbia — In addition to being a common problem, misdiagnosis of multiple sclerosis (MS) exposed patients to unnecessary and potentially harmful treatments, as well as inadequate treatment for their correct diagnoses, concluded a study presented at the 2016 annual meeting of the American Academy of Neurology (AAN).
“Misdiagnosis of MS is not rare and has significant consequences for patients,” study investigator Andrew J. Solomon, MD, of the University of Vermont College of Medicine, in Burlington, Vermont, said in an interview. “Although it may not be possible to eliminate diagnostic error in the evaluation of patients for MS, strict adherence and conservative application of MS clinical and corresponding radiographic diagnostic criteria and education concerning proper use of MS diagnostic criteria may prevent misdiagnosis.”
Dr Solomon noted that data are lacking on the types of diagnoses frequently mistaken for MS, as well as for the reasons for misdiagnosis, hampering the ability of physicians to develop strategies for the prevention of this problem.
“The few prior studies of large groups of patients misdiagnosed with MS were published 20 years ago or longer,” Dr. Solomon said. “The types of diseases mistaken for MS, and reasons for misdiagnosis, have likely changed along with the evolution of our diagnostic criteria and the increasing reliance on the interpretation of [magnetic resonance imaging (MRI)] data.”
To better characterize patients misdiagnosed with MS and to determine common misdiagnosis causes, Dr Solomon and colleagues culled data from 4 academic MS centers submitted during a 13-month period regarding patients whom the neurologist had evaluated and concluded had been misdiagnosed with MS.
Among 110 patients misdiagnosed with MS, 46% had “definite” misdiagnosis and 54% had “probable” misdiagnosis, according to study definitions.
Researchers reported the following most common primary diagnoses: migraine alone or in combination with other diagnoses (21%); fibromyalgia (15%); nonspecific or nonlocalizing neurologicl symptoms with abnormal MRI (12%); and conversion or psychogenic disorder (11%). They also reported 27 additional diagnoses.
The time for carrying a misdiagnosis was 3 to 9 years in 29% of patients and 10 to 20 years in 26% of patients.
Overall, 70% of patients had taken disease-modifying therapy such as natalizumab (13%), mitoxantrone (2%), and cyclophosphamide (1%), while 4% had participated in a study of an MS therapy.
Participating neurologists reported evidence of an earlier missed opportunity to make a correct diagnosis in 72% of patients, and 31% of patients experienced unnecessary morbidity as a result of a misdiagnosis.
Additional observations indicated 3 factors that contributed to misdiagnoses: inappropriate attribution of symptoms to demyelinating disease (65%); reliance on historical symptoms without supporting objective evidence of a lesion (48%); and over-reliance on MRI abnormalities to satisfy dissemination in space among patients with nonspecific neurologic symptoms (60%).
“Although a large number of diseases may be mistaken for MS, the majority of disorders that we identified in this cohort … were common disorders,” Dr Solomon said. “The correct diagnoses in many of these cases are reliant upon clinical skills and correct interpretation of MS diagnostic criteria, rather than extensive testing.”
Dr Solomon noted that further clinical and radiographic monitoring may be most prudent in patients with atypical clinical presentations and/or with nonspecific MRI abnormalities, as new data may confirm a diagnosis of MS or an alternative diagnosis.
“Such an approach can seem difficult in light of mounting evidence supporting early initiation of [disease-modifying therapies] in patients with MS or at high risk for the development of MS,” he said. “Continued vigilance for ‘red flags’ for alternative diagnoses in patients with existing diagnoses of MS also remains important, especially in those with atypical clinical or radiographic features.”
Solomon AJ, Bourdette DN, Cross AH, et al. The spectrum of multiple sclerosis misdiagnosis in the era of McDonald criteria: a multicenter study. Presented at: The 68th Annual Meeting of the American Academy of Neurology; April 15-21, 2016; Vancouver, British Columbia, Canada. Abstract PL01.003.