Some diagnostic tests for MS, such as magnetic resonance imaging (MRI), can also be misinterpreted.
“Nonspecific MRI abnormalities that can mimic those of MS are very common in healthy individuals, and widespread use of MRI as a diagnostic tool increases the rate of misdiagnosis,” said Weinshenker.
The 110 patients included in the study were identified by MS subspecialist neurologists at Mayo Clinic, University of Vermont, Washington University and Oregon Health & Science University.
Twenty two percent of the misdiagnosed patients actually had migraine; 15% had fibromyalgia; 12% had a nonspecific condition flagged by an abnormal MRI; 11% had a conversion or psychogenic disorder; and 6% had neuromyelitis optica spectrum disorder.
“This study suggests significant and long-term unnecessary risks for these patients,” said lead author Andrew Solomon, MD, a neurologist at the University of Vermont College of Medicine. “While there may be different reasons for misdiagnoses by subspecialists and nonspecialists, this study suggests that we all make mistakes, and I think we can all do better.”
A previous survey of MS specialists found that more than 95% had seen at least one patient in the past year that was misdiagnosed with MS by another provider.
Some treatments for MS carry serious side effects. One drug, taken by 13 percent of the misdiagnosed patients in the current study, can cause a potentially fatal brain infection. Other patients suffered from the discomfort and inconvenience of daily injections; others experienced side effects from medications or lacked treatment for the conditions they actually had.
There are also enormous financial costs involved. The cost of medications to treat MS in the United States now exceeds $50,000 a year.
“Premature diagnosis of MS should be avoided,” says Weinshenker. “When in doubt, physicians often can defer a diagnosis if it is not clear that there is a serious neurological problem or if a patient is stable. Physicians should request a second opinion when they are unsure but concerned that it might be harmful to delay a definitive diagnosis of MS.”
Weinshenker and Solomon hope their study will encourage better education of clinicians on the proper use of MS diagnostic criteria and to further studies on how to recognize patients incorrectly diagnosed with MS.