Good news people with MS are living longer and catching-up with their peers. #ResearchSpeak #MSBlog
We have posted several times in the past on MS and mortality.
The latest data to published from Norway, with 60 years of follow-up, confirms what we already know that MS reduces life expectancy. Importantly the so called standardised mortality ratio (SMR) of pwMS is higher than the general population and puts MS high-up the SMR league tables. In short MS is a bad disease, but has it changed its spots?
The SMR, is a quantity, expressed as a ratio quantifying the increase, or decrease, in mortality of a study cohort with respect to the general population. The SMR is simply the ratio of observed deaths in the study group to expected deaths in the general population. Hence a SMR of 2.7 amongst MSers means that 2.7 people died to every one person in the general population. A SMR of 2.7 is high. Of interest the SMR is higher for women with MS (2.9) than men with MS (2.5); this is because in the general population men are more likely to die young than women, hence a larger number of male deaths is the denominator. Life expectancy for pwRRMS was longer (77.8 years) than for pwPPMS (71.4 years).
Mortality decreased over the course of the study, as pwMS with onset from 1997 to 2012 showed lower rates than those who fell sick from 1953 to 1974. In comparison, pwMS younger than 20 years of age at disease onset or diagnosis showed greater mortality than those above 60 years.
Interestingly, despite the high SMR the life expectancy of someone with MS is only shown to be ~7 years lower than the general population; this is a lower figure than previous studies. What this means is that pwMS in Norway tend to live a relatively long life. With an average age of MS onset of 30 years it means that the average MS must expect to live the majority of their lives with disabilities.
As usual this is not necessarily a pleasant narrative, or is it? Overall survival from MS disease onset was more than twice as long as reported in the first study from 1969. The increase in survival over time is almost certainly the result of better MS treatments, improved diagnosis, socioeconomic factors, better treatment of co-morbidities and other lifestyle changes.
Do you think this is a good news story?
Bøe Lunde et al. Survival and cause of death in multiple sclerosis: a 60-year longitudinal population study. JNNP April 2017.
Objective: Survival and causes of death (COD) in multiple sclerosis (MS) provide ultimate endpoints. We aimed to investigate survival and COD in a 60-year population-based MS cohort compared with the general population.
Methods: All patients with incident multiple sclerosis (MS) (N=1388) with onset during 1953–2012 in Hordaland County, Western Norway, were included. Data were obtained from patient records at Haukeland University Hospital and linked to the Norwegian COD registry. Survival adjusted for sex, age and disease course were estimated by Kaplan-Meier analyses from birth and from disease onset. Mortality and COD in MS relative to the general population were examined by standardised mortality ratio (SMR).
Results: Of 1388 patients, 291 had deceased, mainly of MS (56.4%). Median life expectancy was 74.7 years for MS and 81.8 years for the general population (p<0.001); 77.2 years for women with MS and 72.2 years for men with MS (p<0.001). Life expectancy for patients with relapsing remitting MS (RRMS) was 77.8 years and 71.4 years for primary progressive MS (PPMS) (p<0.001). Overall SMR was 2.7 (p>0.0001); 2.9 in women and 2.5 in men (p=0.0009). SMR was 2.4 in RRMS and 3.9 in PPMS (p<0.0001). SMR from disease onset during 1953–1974 was 3.1; 2.6 during 1975–1996 and 0.7 during 1997–2012 (p<0.0083). No difference in cause-specific deaths were found (p=0.0871).
Conclusion: We found a 7-year shorter life expectancy and almost threefold higher mortality in MS compared with the general population. A rise in survival in MS was observed during the entire observation period.