Information on causes of death (CODs) for patients with multiple sclerosis (MS) is hampered by inherent limitations in standard categorization of CODs on death certificates. Listing MS as the underlying COD for a patient, as frequently occurs, provides little insight on conditions that more directly led to death. Identifying such conditions may be more informative for understanding the reasons for death among MS patients. Research comparing patients with MS and matched non-MS comparators in a US health plan database (OptumInsight Research [OIR]) using an algorithm designed to identify more direct conditions leading to death (CLD) found excess mortality rates (MR) among patients with MS largely attributed to infectious, cardiovascular, or pulmonary causes.
To analyze subcategories within identified CLD categories to gain further insight into pathways more directly leading to death in MS patients.
MS patients enrolled in OIR (1996-2009) were matched to non-MS comparators on age/residence at index year and sex. CLDs were determined using an algorithm that systematically prioritized clinically relevant CODs and reduced the rate at which MS or cardiac/pulmonary arrest were determined to be the COD. CLDs were categorized as MS, cancer, cardiovascular, infectious, suicide, accidental, pulmonary (non-infectious), other, or unknown. Infectious, cardiovascular, and pulmonary CODs were then further subcategorized.
31,051 patients with MS were matched to 92,511 controls, with MR of 899 and 446 deaths/100,000 person-years, respectively. Total excess mortality in patients with MS from infections was 95 per/100,000 and from pulmonary causes was 46 per/100,000 person-years. Pulmonary infections (41 of 95 [43.2%] excess deaths per 100,000) or sepsis (45 of 95 [47.4%] excess deaths per 100,000 person-years) accounted for 90.6% of the excess mortality attributable to infectious CLDs. 58.7% of the difference in pulmonary CLD MR was due to aspiration (27 of 46 excess deaths per 100,000 person-years). No single diagnostic entity predominated for the 60 deaths per 100,000 person-years of excess mortality attributable to cardiac CLDs.
Fatal pulmonary infections, sepsis, and aspiration occurred more frequently in patients with MS than in non-MS comparators. Increased awareness of the potential for death due to these causes may improve care for patients with MS. Implications of these data for clinical practice will be discussed.