BERLIN – Depression and bipolar disorder are major risk factors for worsening disability in people with multiple sclerosis, according to the results of a large Swedish registry-based study.
The presence of depression increased the risk of having a sustained Expanded Disability Status Scale (EDSS) score of 3.0 by 54% and 4.0 by 87%, and it doubled the risk of an EDSS of 6.0.
Selective serotonin reuptake inhibitor treatment also upped the risk of greater disability, with patients exposed to SSRIs having a 40% increased risk of a sustained EDSS of 3.0, a 97% chance of having a sustained EDSS of 4.0, and 2.2-fold increased risk of a sustained EDSS of 6.0.
“We know that mood disorders are highly prevalent in people with multiple sclerosis,”, said at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis. She gave her presentation at the meeting on Oct. 10, which was .
The presence of mood disorders is associated with reduced quality of life, said Dr. Binzer of the department of clinical neuroscience at the Karolinska Institute in Stockholm. Furthermore, depression is the major risk factor for suicidality in patients with MS. However, before this study the effect of having a comorbid mood disorder on MS patients’ disability levels had not been established.
The investigators analyzed data from 5,875 patients in the Swedish MS registry between 2001 and 2014. By matching these patients to records in the Swedish National Patient Registry and the Swedish National Prescribed Drug Registry, they found that 8.5% (n = 502) had an International Classification of Diseases, 10th revision (ICD-10), code for depression. Of these, 261 had received a diagnosis of depression before their diagnosis of MS.
Of 3,817 patients with MS onset between 2005 and 2014, 27.4% (n = 1,048) had collected at least one prescription for an SSRI.
“What we found was that MS patients with either an ICD code for depression or having been exposed to SSRIs had a significantly increased risk of reaching EDSS 3.0,” Dr. Binzer reported. The age at which patients reached these milestones were younger in both groups when compared with MS patients without depression, she observed.
“The difference between the groups [MS with and MS without depression] seemed to increased with EDSS,” Dr. Binzer said.
Although not statistically significant, there was a trend for patients with depression to be more likely to convert to secondary progressive MS, with a hazard ratio of 1.38 (95% confidence interval, 0.91-2.1).
“For a sensitivity analysis, we found that those who had depression prior to their first MS symptom, the median age when they reached EDSS 3.0 and 4.0 was reduced by 3 and 7 years, respectively,” Dr. Binzer said, adding that, unfortunately, there wasn’t enough power to look at the other endpoints.
In regard to bipolar disorder, 1.5% (n = 200) of 13,125 MS patients diagnosed between 1973 and 2014 were identified with this mood disorder. Its presence significantly increased the risk of MS patients reaching an EDSS score of 4.0 by 58% (95% CI, 1.1-2.28), but not EDSS 3.0 (HR = 1.34; 95% CI, 0.94-1.92) or 6.0 (HR = 1.16; 95% CI, 0.79-1.69). The latter could be due to smaller sample size, Dr. Binzer suggested.
The investigators’ analysis of the results stratified by sex, conducted because men tend to fare worse than women with MS and progress faster, showed that for both depression and bipolar disorder, men were at significantly higher risk of reaching sustained disability milestones. Indeed, compared with women, men with depression had a 61% increased risk and those with bipolar disorder a 31% increased risk of reaching an EDSS score of 6.0. They also had 51% and 32% increased risks of conversion to secondary progressive MS.
“We don’t know the mechanisms that underlie these associations,” Dr. Binzer noted. “Irrespective of the underlying mechanisms, [the study] clearly shows that it’s imperative that we recognize, early, mood disorders in MS patients, and manage them effectively in order to provide better care and hopefully reduce MS disability worsening.”
The research was funded by the Swedish Research Council and the Swedish Brain Foundation. Dr. Binzer has received speaker fees and travel grants from Biogen.
SOURCE: Binzer S et al..