People with multiple sclerosis (MS) show a high occurrence of comorbidities — two diseases occurring in one person at the same time — with psychiatric and cardiovascular diseases being the most common, a new study reports.
Having another co-existing disorder was found to have an impact on MS progression, which highlights the key role played by comorbidities when decisions about treatments are made.
The study, “The prevalence of comorbidities in patients with multiple sclerosis: population-based registry data,” was published in the journal Neurological Sciences.
Comorbidities occur frequently in people with MS, oftentimes having a great impact on their lives. However, there are only limited data about the frequency and global distribution of such co-occurring diseases, as well as their relationship with the different MS types.
To address these gaps, a team led by researchers at the University of Belgrade, in Serbia, determined the prevalence (occurrence) of the most common comorbidities in a population of Serbian MS patients. The researchers also examined the impact of these co-existing disorders on MS disease progression.
In total, data from 2,725 patients, with a mean age of 55.8 years, were analyzed. Of these patients, 62.9% had relapsing-remitting MS (RRMS), 24.1% had secondary progressive MS (SPMS), and 13.0% had primary progressive MS (PPMS).
Among the list of comorbidities explored by the researchers were cardiovascular diseases — disorders of the heart and blood vessels — malignant disorders, and autoimmune diseases, as well as type 2 diabetes and epilepsy. The team also examined psychiatric disorders. The prevalence of each was calculated according to age, gender, and MS type.
Of the patients analyzed, 534 had been treated with disease-modifying therapies (DMTs) to reduce the activity and progression of MS. A total of 457 patients were given interferon beta (available under several brand names), 72 received glatiramer acetate (sold as Copaxone and Glatopa), and 80 were treated with Novantrone (mitoxantrone).
Results showed that the most common comorbidities were psychiatric disorders, with a prevalence of 20.59%. Depression was the most prevalent (11.82%).
Several studies have reported a link between MS and psychiatric disorders, the team noted. In particular, anxiety and depression have been associated with relapse risk in RRMS.
“It is well known that the prevalence of depression and anxiety in MS population is higher compared with the general population,” the researchers wrote.
The second most common comorbidity was cardiovascular disease (15.23%), which occurred more frequently in older patients of both sexes. The most common cardiovascular co-condition was hypertension (11.41%), otherwise known as high blood pressure.
Cardiovascular comorbidities led to disease worsening compared with MS patients without these co-existing disorders.
“Having this in mind, more attention should be paid on early detection and appropriate management of vascular comorbidities in MS, in order to minimize its adverse effects on MS outcomes,” the researchers wrote.
The co-occurrence of autoimmune disorders was 6.06%, with thyroid disease being the most frequent (4.44%). It is believed that having other autoimmune diseases may be a slightly higher risk factor for developing MS.
Epilepsy occurred in 2.60% of patients in the group analyzed. Although the frequency of this comorbidity is lower than others analyzed, epilepsy and MS have a reasonable chance of occurring in the same person, it has been previously reported.
The overall occurrence of malignant diseases was 2.53%. Breast cancer was the most common one (0.95%). Research on cancer in MS has assumed a great importance since the immune system is involved in the origin of both diseases.
“For that reason, investigation of cancer comorbidity could potentially provide assistance in elucidating MS etiology,” the team wrote.
Type 2 diabetes occurred in 2.06% of the patients and was significantly more common in people with PPMS (4.7%) compared with those with RRMS (1.5%). The possible association between MS and diabetes has previously been reported. The findings from this study “warrant further investigations to elucidate the potential association between MS and type 2 diabetes,” the researchers wrote wrote.
Psychiatric disorders, and autoimmune and malignant diseases, were more common in women compared with men, the team observed.
The existence of an association between comorbidities and MS progression also was observed. The progression index (PI) was significantly higher in patients who had at least one comorbidity (PI of 0.31) in comparison with those without comorbidities (PI of 0.27).
The possible association between comorbidities and DMTs also was analyzed, and the researchers found that people treated with these therapies were at higher risk of developing comorbidities, after beginning a treatment, compared with those who were untreated.
“These findings implicate that comorbidities may have significant impact on treatment decisions regarding DMTs in MS,” the researchers wrote.
Overall, the “findings implicate the necessity of screening and early and adequate management of different co-occurring diseases in MS patients, especially bearing in mind its association with range of adverse outcomes in these persons,” the team concluded.
Additionally, this study “confirmed the association of comorbidities with progression of disability and emphasized their role in treatment decision-making in MS,” the researchers added.