A retrospective, descriptive study to evaluate trends in yearly diagnoses of Primary Progressive Multiple Sclerosis (PPMS) in Greater Manchester, UK.

Although the overall incidence of Multiple Sclerosis (MS) is increasing, a declining trend was described for the PPMS subtype in various regional studies.

Electronic records of all 2192 patients under the care of the Greater Manchester Neurosciences Centre, UK, were evaluated and the date of PPMS diagnosis was recorded.

PPMS was confirmed in 190/2192 patients diagnosed with MS between 2011 and 2020. The median age of the PPMS patient group was 46 years. 102/190 patients were male and 88/190 were female. Overall, a declining trend in the yearly number of PPMS diagnoses was observed between 2011 and 2020 (correlation coefficient= -0.85332), with 12% of all MS diagnoses accounted for by PPMS in 2012 and only 3% in 2019.

The population of Greater Manchester has increased from 2.69 million people in 2011 to 2.85 million in 2020.  Parallel to this, the number of patients diagnosed with PPMS has decreased, which suggests the incidence of PPMS may be declining over the study period.  Until 2019, no disease-modifying therapies (DMTs) for PPMS were licensed and reimbursed in the UK and further studies will determine if DMT availability affects the diagnosis rates of PPMS.