Swedish Study Examines Impact of Comorbidities on Cost of MS Over Time

Which types of comorbidities have the greatest impact on direct and indirect costs of multiple sclerosis (MS) over time?

Chronic comorbidities, including mental and musculoskeletal disorders, at the time a patient is diagnosed with multiple sclerosis (MS) leads to greater direct and indirect costs over the different courses of illness, according to a recent study from Sweden.

The study, using data from 5 nationwide registers, sought to examine the diversity in the cost-of-illness (COI) among individuals with MS in relation to their comorbidity. COI looks at not only health care costs but also indirect costs, such as time lost in work productivity and other factors.

It is well-known that patients with MS are affected differently depending on the level of disability and severity associated with the disease, and that comorbidities are common, both mental and physical, including depression, anxiety, hypertension, and diabetes.

The researchers said they conducted the nationwide longitudinal study in order to get a better understanding of the link between comorbidities and the differences in the COI of MS.

Using Sweden’s National Patient Register, researchers identified 793 patients, aged 25 to 60 years, who had their first MS diagnosis in 2006. The estimated annual COI was estimated until 2013.

Patients were categorized by 6 comorbidities (ocular; cardiovascular, genitourinary or cancer disease; musculoskeletal; mental; neurological other than MS; and injuries) and patients could also belong to more than 1 group.

Of the 793 patients, 639 were included in the final analysis, with 499 belonging to any of the 6 groups and 140 without any comorbid condition.

Results were analyzed using group-based trajectory modeling to see how variables changed over time. The COI included both productivity losses and annual inpatient and outpatient health care and prescription drug costs.

Researchers identified 4 different trajectories for patients:

  • Low health care costs and low productivity losses
  • High health care costs and low productivity losses
  • Low health care costs and high productivity losses
  • High health care costs and high productivity losses

Most patients fell into the group with both high health care costs and high productivity losses, whether they had a comorbidity or not.

Similar to previous studies, patients with the highest COI trajectory were those with mental health illnesses (nearly 60%), followed by injuries (54.6%) and musculoskeletal conditions. This could be partly explained by disability in MS and concurrent risk of falling, although the authors said it is unknown what long-term impact, if any, injuries that may occur after MS diagnosis may have.

Patients with mental or neurological comorbidities with high productivity losses were significantly older and had a lower educational level, and those with mental health concerns had the highest average annual COI €36,48 (US $43,516).

Those with any of the 5 comorbidities had an average annual COI of €25,930 (US $30,669), and patients without any comorbidity in the year around the MS diagnosis had the lowest average annual COI.

However, the researchers cautioned that the results could be affected by factors not taken into account by the study. For instance, some patients with MS may have symptoms prior to actual diagnosis or have their symptoms attributed to other conditions, which would affect what was seen at baseline. In addition, the study did not take into account MS disease phenotype and disease severity and activity grading.

While the use of group-based trajectory modeling was seen as a strength of the study, defining the comorbidity groups at a single point in time was also seen as a limitation.

Additional research is needed to assess the impact of comorbidities on the COI of MS, the authors wrote.


Bütepage G, Esawi A, Alexanderson K, et al. Cost-of-illness trajectories among people with multiple sclerosis by comorbidity: A register-based prospective study in Sweden. Mult Scler J Exp Transl Clin. Published online October 23, 2020. doi:10.1177/2055217320968597