BERLIN—Depression and bipolar disorder are major risk factors for worsening disability in people with multiple sclerosis (MS), according to the results of a large Swedish registry-based study.
Depression increased the risk of having a sustained Expanded Disability Status Scale (EDSS) score of 3.0 by 54%. Depression increased the risk of having a sustained EDSS score of 4.0 by 87%. Depression also doubled the risk of having an EDSS of 6.0.
SSRI treatment also increased the risk of greater disability, with patients exposed to SSRIs having a 40% increased risk of a sustained EDSS of 3.0, a 97% increased risk of having a sustained EDSS of 4.0, and a 2.2-fold increased risk of a sustained EDSS of 6.0.
“We know that mood disorders are highly prevalent in people with MS,” said Stefanie Binzer, MD, at ECTRIMS 2018.
Mood disorders are associated with reduced quality of life, said Dr. Binzer, of the Department of Clinical Neuroscience at the Karolinska Institute in Stockholm. Furthermore, depression is a major risk factor for suicidality in patients with MS. However, prior studies have not established the effect of having a comorbid mood disorder on disability levels of patients with MS.
Dr. Binzer and her coinvestigators 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% of the patients with MS (n = 502) had an International Classification of Diseases, 10th revision (ICD-10) code for depression. Of these patients, 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.
Patients with MS who had an ICD code for depression or who had received 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 said.
“The difference between the groups [with and without depression] seemed to increase with EDSS,” Dr. Binzer said.
Patients with depression tended to be more likely to convert to secondary progressive MS, with a hazard ratio (HR) of 1.38.
Disability at Younger Ages
A sensitivity analysis found that among those who had depression before their first MS symptom, “the median age when they reached EDSS 3.0 and 4.0 was reduced by three and seven years, respectively,” Dr. Binzer said.
In addition, 1.5% (n = 200) of 13,125 patients with MS diagnosed between 1973 and 2014 were identified with bipolar disorder. It significantly increased the risk of reaching an EDSS score of 4.0 by 58%, but not did not affect the risk of reaching EDSS 3.0 (HR = 1.34) or 6.0 (HR = 1.16).
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 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, respectively.
“We do not know the mechanisms that underlie these associations,” Dr. Binzer said. “Irrespective of the underlying mechanisms, [the study] clearly shows that it is imperative that we recognize early mood disorders in MS patients and manage them effectively 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.