“Have you heard of the term ‘in silico’? It means doing research using computer modeling or analysing data without the need for any lab work on data collection. The in silico study below on the impact of comorbidity on DMT use in MS is fascinating. It shows that if you have MS and have a comorbidity, in particular anxiety and ischemic heart disease, you are less likely to start a DMT. Why? Is this a negative bias of the healthcare system against these MSers? Or could MSers with comorbidities be less likely to go onto a DMT for personal reasons? In other words they are refuseniks. Answering these questions is clearly important to see if something needs to be done to address this problem. If there is prescriber bias we may be disadvantaging these MSers; if they are refuseniks we need better education about DMTs. Interestingly, MSers with comorbid depression were more likely to start a DMT than MSers without depression. I wonder of this is linked to disease severity? The more severe your disease is the more likely you are to be depressed and hence your healthcare professional is more likely to suggest, and start, a DMT. It is interesting what is possible with big data. More reasons for us to invest in these in silico studies.”
OBJECTIVE: Comorbidities are common in multiple sclerosis (MS) and adversely affect health outcomes. However, the effect of comorbidity on treatment decisions in MS remains unknown. We aimed to examine the effects of comorbidity on initiation of injectable disease-modifying therapies (DMTs) and on the choice of the initial DMT in MS.
METHODS: We conducted a retrospective observational analysis using population-based health administrative and linked clinical databases in 3 Canadian provinces. MS cases were defined as any individual with ≥3 diagnostic codes for MS. Cohort entry (index date) was the first recorded demyelinating disease-related claim. The outcomes included choice of initial first-line DMTs and time to initiating a DMT. Logistic and Cox regression models were used to examine the association between comorbidity status and study outcomes, adjusting for sex, age, year of index date, and socioeconomic status. Meta-analysis was used to estimate overall effects across the 3 provinces.
RESULTS: We identified 10,698 persons with incident MS, half of whom had ≥1 comorbidities. As the total number of comorbidities increased, the likelihood of initiating a DMT decreased. Comorbid anxiety and ischemic heart disease were associated with reduced initiation of a DMT. However, patients with depression were 13% more likely to initiate a DMT compared to those without depression at the index date (adjusted hazard ratio 1.13; 95% confidence interval 1.00-1.27).
CONCLUSIONS: Comorbidities are associated with treatment decisions regarding DMTs in MS. A better understanding of the effects of comorbidity on effectiveness and safety of DMTs is needed.