medwireNews: Survival of patients with multiple sclerosis (MS) is still reduced, despite recent improvements, say researchers.
But much of the mortality among MS patients is due to comorbidities, report Ruth Ann Marrie (University of Manitoba, Winnipeg, Canada) and co-workers.
“Although comorbidity did not have greater effect on mortality in the MS population than in the matched population, optimizing the management of comorbidity may be a means of improving survival”, they suggest in Neurology.
Over the study period, from 1984 to 2012, survival improved among the 5797 MS patients identified within the province of Manitoba, Canada. The gains were greatest in the 40- to 59-year-old and 60- to 69-year-old age groups, with annual mortality reductions of 0.23 and 0.52 per 1000 people, respectively.
However, there were similar reductions among the 28,807 people in the matched control group, and mortality in the MS group was a significant 2.4-fold increased, after accounting for birth year, gender, socioeconomic status, area of residence and duration of exposure to MS. The increased mortality risk was most striking among patients younger than 60 years.
The median survival was to age 75.9 years in the MS group and age 83.4 years in the control group.
The survival of both groups was worsened by the presence of comorbidities, with diabetes, ischaemic heart disease and depression having the strongest impact in patients with MS. Depression was also one of the most common comorbidities; it was present in 41.5% of MS patients by the end of the study – second only to anxiety, which did not increase mortality – and was significantly more frequent in MS patients than controls.
Over the whole study period, 34.4% of the MS patients who died had MS recorded on their death certificate. From 2000, when it became possible to record multiple causes of death, 35.9% of the 690 people who died had MS as the primary cause of death and 54.1% had it as a primary or underlying cause.
However, over the whole study period, competing causes were a more common cause of death than MS, and there was a “slight shift” towards more deaths from competing causes during the study. Besides MS, the most common causes of death were other neurological disorders, cardiovascular diseases, neoplasms and respiratory diseases, which together accounted for 82.8% of deaths.
“At least 50% of deaths in the MS population are due to competing causes”, conclude the researchers. They therefore suggest that treating comorbidities could help to reduce the 7-year survival disadvantage conferred by MS.
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