TORONTO - A new study suggests there might be delays in diagnosing multiple sclerosis after the onset of the first symptoms if the patient has an existing health condition.
And doctors treating patients with chronic illnesses such as diabetes should not automatically attribute new neurological symptoms to the existing condition without careful consideration, the researchers say.
The study analyzed the records of 8,983 people living in the United States who were enrolled in the North American Research Committee on Multiple Sclerosis Registry, and asked questions about health conditions, smoking habits and weight history.
It took longer for people who were obese, smoked, or had physical or mental health conditions to be diagnosed with MS compared to people without such conditions, they found.
"The key finding here is that in patients with multiple sclerosis, pre-existing health conditions are associated with a longer diagnosis delay between symptom onset and diagnosis," said study author Dr. Ruth Ann Marrie, a neurologist and assistant professor of medicine and community health sciences at the University of Manitoba.
Depending on the particular existing condition, the delays varied from less than a year to a few years, she said in an interview from Winnipeg.
In addition, those with existing health conditions tended to have greater degrees of disability at the time of diagnosis, "particularly with respect to walking," she said.
Marrie, who is also an epidemiologist, did the research with various colleagues while she was at the Cleveland Clinic.
The paper was published Wednesday in the online issue of Neurology, the medical journal of the American Academy of Neurology.
Marrie said she couldn't say whether the findings would apply elsewhere.
"And of course this is just a group of people from the United States, so I can't say it applies everywhere. And it's a first look. But it's not surprising given what we've heard of in other diseases, which is one of the reasons we want to pursue this further."
Still, there is a message for patients and clinicians: they shouldn't assume a new symptom is due to an existing ailment, she said.
"What we're trying to suggest is that ... when people develop new neurologic symptoms, that patients and practitioners just pause a little longer to take a little more careful thought as to whether it's appropriate to attribute those new symptoms to an existing condition, or whether they should be thinking about looking for something else."
An estimated 55,000 to 75,000 Canadians have multiple sclerosis, according to the MS Society of Canada, and it is usually diagnosed between the ages of 15 and 40.
Symptoms of MS can include sudden vision loss or double vision, numbness and tingling sensations, fatigue, weakness and difficulty walking.
Dr. Paul O'Connor, scientific and clinical adviser to the society, said the symptoms in someone who's undiagnosed with MS are often blamed on other problems.
"Sometimes I see patients who've had another medical diagnosis, say stroke, when in fact their actual diagnosis turns out to be MS; or patients who've had diabetes with symptoms for several years, and they turn out to have MS."
There's a definite statistical association - although not a strong one - between MS and the presence of other illnesses like diabetes or other immune conditions, for example, inflammatory bowel disease, he noted.
O'Connor said it would be interesting to see Marrie's study replicated by other researchers.
"I think it's a very interesting study, and I think that clinicians will find this information of benefit."
