MS Disability At Diagnosis and Diagnostic Delay Linked to Comorbidities

Posted Oct 29, 2008.By Elizabeth Mechcatie

Obesity, smoking, and physical and mental comorbidities delayed the diagnosis of multiple sclerosis and were associated with a greater degree of disability at the time of diagnosis in a study of nearly 9,000 individuals enrolled in a multiple sclerosis registry.

The results "suggest that practitioners treating persons with chronic diseases should not attribute new neurologic signs or symptoms to existing conditions without careful consideration," concluded Dr. Ruth Ann Marrie of the University of Manitoba, Winnipeg, and her coauthors in the paper that was published online Oct. 29 in Neurology (doi: 10.1212/01.wnl.0000333252.78173.5f).

With 2006 data from the North American Research Committee on Multiple Sclerosis Registry, they compared duration between symptom onset and MS diagnosis in patients with and without vascular, musculoskeletal, mental, and other types of comorbidities.

The presence of obesity or smoking, or the presence of physical or mental comorbidities delayed the diagnosis by a mean of 7 years, after adjustment for demographic and clinical characteristics, the authors found.

The associated delay between symptom onset and diagnosis was shorter with advancing age at symptom onset. Patients were analyzed by age group: younger than 25 years, aged 25-39 years, and aged 40 years and older.

Among the different age groups, the mean diagnostic delay was consistently longer if people had vascular, autoimmune, musculoskeletal, or gastrointestinal comorbidities, but this effect waned as people aged.

For example, the mean time to diagnosis among those with vascular comorbidities (including diabetes, heart disease, peripheral vascular disease, and hypercholesterolemia) was almost 9 years longer among those under age 25, compared with those with no vascular comorbidities in this age group. But this difference dropped to a mean of 3 years among those aged 25-39 years, and a mean of 1 year among those aged 40 and over.

The presence of a musculoskeletal comorbidity increased the delay of diagnosis by a mean of 9 years among those under age 25, a mean of almost 5 years among those aged 25-39, and a mean of 2 years among those age 40 years and older.

The association between comorbidity and the degree of disability at the time of diagnosis was also assessed in a subgroup of 2,375 survey participants who were enrolled within 2 years of being diagnosed with MS, because their degree of disability would not be expected to change markedly during that period of time.

In that analysis, the risk of having moderate rather than mild disability at diagnosis increased by 51% among those with a vascular comorbidity and by 38% among obese patients. The likelihood of having severe disability at the time of diagnosis increased by 81% among those with a musculoskeletal comorbidity and by 62% among those with a mental comorbidity.

The findings suggest that health care professionals might attribute MS symptoms to a preexisting condition, which would delay the diagnosis and as a result, increase the degree of disability at the time of diagnosis, the authors wrote. Alternatively, "comorbidities could act pathophysiologically to increase disease progression," they added.

Study limitations include a low rate of black responders. Most of the responders were white; however their characteristics were similar to the general MS population. Two-thirds of the responders were women. The size of the study was among its strengths, the authors wrote.