Pauline Anderson

October 08, 2015

BARCELONA — Patients with multiple sclerosis (MS) are more than twice as likely as the general population to attempt suicide and almost twice as likely to actually complete suicide, a new study shows.

The study also had some interesting results with regard to education. Although highly educated patients with MS are less likely to attempt suicide than their counterparts without MS, this is not the case when it comes to completed suicide.

Patients with MS should be screened for psychiatric disorders, said lead researcher Philip Brenner, MD, PhD student, Department of Neuroscience, and resident psychiatrist, Karolinska University Hospital, Stockholm, Sweden.

"Since neurologists are primarily the ones treating MS patients, they should be aware of the increased suicide risk and the risk for suicide attempts among these patients," Dr Brenner told Medscape Medical News. "It's very important to include screening measures for mental health in clinical practice."

As well as depression, which is probably the most important risk mediator for suicide prevention in MS, physicians might also watch for personality changes, for example, having less impulse control and increased substance abuse, he said.

He presented their results here at the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) 2015.

Attempted Suicide

Previous research showed an elevated risk for completed suicide among patients with MS. For example, a 2001 Swedish study found that the completed suicide rate was 2.3 times higher among patients with MS, and a 2006 study found the rate was 2.12 times higher.

However, attempted suicide among patients with MS has been much less studied, with only two studies focusing on this area, said Dr Brenner. One was a 1998 Canadian study of hospitalized patients with MS that found the risk for attempted suicide was three times higher among patients with MS. A 2011 Danish study found no statistically significant increased risk for attempted suicide among patients with MS but, according to Dr Brenner, this study "was probably underpowered."

The current study included 29,617 patients with MS from the combined Swedish National Patient Register and Swedish MS Register. It also included 10 controls without MS for each case from the Swedish general population (n=296,164) who were matched with the MS group for year of birth, sex, and county of residence.

Researchers used diagnostic codes for intentional self-poisoning or injury to identify attempted suicides, and the Swedish Cause of Death register to identify completed suicides. They excluded deaths in which the intent was unclear.

There were 423 attempted suicides among patients with MS during the follow-up period (1968 to 2012) for an incident rate (IR) of 116.5 per 100,000 person-years. In patients without MS, the IR was 50.8. The adjusted hazard ratio (HR) was 2.18 (95% confidence interval [CI], 1.97 - 2.43).

Women were at 30% higher risk for attempted suicide compared with men in both the MS and control groups.

From census data, the researchers determined categories of education level achieved by study participants. As expected, they found that the risk for attempted suicide was lowest among patients with MS and controls with the highest level of education (14 or more years).

During the follow-up period, 114 patients with MS who committed suicide, for an IR of 30.31 per 100,000 person-years. This compared to an IR in patients without MS of 16.8. The adjusted HR for completed suicide was 1.87 (95% CI, 1.53 - 2.30).

Dr Brenner commented that patients with MS who committed suicide chose means that were less violent than those without MS — for example, taking an overdose of pills rather than other means. "We don't have a good explanation for this," he said.

In contrast to suicide attempts, women were at lower risk for completed suicide than men among both the MS and control groups.

The risk among patients with MS compared to controls was highest among younger patients — 18 to 40 years (2.11) — and lowest among those 66 years and older (0.8; 95% CI, 0.45 - 1.44). It's possible, said Dr Brenner, that the lower rate among the elderly could be explained by physical and cognitive impairments that could make them more "emotionally flat."

Interestingly, the risk for completed suicide was not lower among highly educated patients with MS, although it was for educated controls. There's evidence that an adverse event in adulthood (such as an MS diagnosis) can counteract the protective effect of socioeconomic status in terms of depression rates. "Maybe that's also true for MS," said Dr Brenner.

Education Effect

But why then would higher education have an effect on attempted suicides but not on completed suicides? As Dr Brenner explained, those who attempt suicide are different from those who actually succeed in ending their lives. Research shows that non-MS suicide attempters are more often women who may have other psychiatric conditions other than depression (eg, borderline personality disorder). They also use different methods to attempt suicide than those who are "suicide completers," he said.

"With this difference in mind, it's possible that the effect of education is different in the two groups," he said. "But this needs to be investigated further."

For both attempted and completed suicides, the rates haven't changed much over the years. "There has been no great decrease over the decades," commented Dr Brenner.

Dr Brenner believes the suicide risk is higher among patients with MS than among patients with a chronic disease such as rheumatoid arthritis. "MS is a neuroinflammatory disease, so it may have a more direct connection with depression than rheumatoid arthritis, which is more peripheral," he said.

He added that the unpredictable nature of MS relapses may also play a role in the increased risk.

The study was partly funded by unrestricted research grants from Novartis Pharma AG and F. Hoffman-La Roche Ltd. Dr Brenner has received speaker's fees from Novartis.

European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) 2015. Platform presentation 93. Presented October 8, 2015.

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