People with medical conditions such as obesity and high blood pressure may experience a delay in being diagnosed with multiple sclerosis, and the disease may be more severe once it is diagnosed, a new study suggests.

In Wednesday's issue of the journal Neurology, researchers in Manitoba reported that it took one to 10 years longer for people who were obese, smoked, or had physical or mental health conditions to be diagnosed with MS compared with people without such conditions.

"The balance is not on automatically assuming everything is due to an existing [condition] because that leads to delays, but balancing that against assuming that everything new that happens requires the million-dollar work-up," study author Dr. Ruth Ann Marrie of the University of Manitoba in Winnipeg suggested for doctors.

"Let's pause for a second and think about this carefully when somebody has a new symptom and they have an existing health condition, so you can make a well-thought decision about it," she added in a telephone interview.

Studies suggest that for some diseases, such as cancer, patients may run to their doctor sooner than average. But in other cases, patients may chalk up new symptoms such as numbness and tingling to an existing condition, potentially leading to delays in an MS diagnosis. Delays on the order of months are not a problem, but years could be, Marrie noted.

Differences in severity of disease found

In the study, Marrie and her colleagues examined records of 2,375 MS patients in the U.S. who filled in questionnaires about their pre-existing health conditions as well as weight and smoking status.

It took between one to 10 years longer for people who were obese, smoked or had physical or mental health conditions to be diagnosed with MS compared with people without those conditions, the researchers found.

"People with multiple medical problems on top of MS may need more health-care resources or might respond differently to medication," Marrie said. "This needs more study."

The more medical problems someone with MS had, the more severe the disease became by the time they were diagnosed, the researchers found.

People who had a mental disorder or any muscle or joint problem along with MS were nearly two times more likely to be severely disabled when diagnosed compared with those with a mild disability, according to the study.

Those with vascular problems such as diabetes, high blood pressure or high cholesterol, were about 1.5 times more likely to be moderately disabled when diagnosed compared with people who had MS but no heart or weight problems.

This study was supported by the National Institutes of Health and the National Institute of Child Health and Human Development and Consortium of MS Centers.

Some of the study's authors reported receiving research support or working as consultants for pharmaceutical companies.