One register, three analysis populations
Rodgers et al., Methods. These are overlapping subsets, not numbers to add and not a timetable for personal recovery.
| Analysis | Participants | Question it addresses |
|---|---|---|
| Baseline comparison | 7,983 | Smoking status and at least one initial questionnaire |
| Annual measures over four years | 923 | Repeated yearly scores in a smaller follow-up group |
| Time to worsening | 4,642 | Regular questionnaire sequences eligible for event analysis |
What the study actually counted
Rodgers and colleagues used registry information collected in 2011–2020; the paper appeared online in 2021 and in Brain in 2022. The physical measures were patient-completed MSIS-29-Phys and MSWS-12 questionnaires. They capture the impact of MS and difficulty walking, not an MRI lesion count, a clinical relapse or a neurologist's disability examination. The walking questionnaire also excluded people unable to walk.
The headline population of 7,983 is not a group in which every person completed four years of follow-up. Different questions used different subsets, shown in the comparison table. The time-to-worsening analysis looked for a specified deterioration in questionnaire scores and compared how quickly it happened. An event in this analysis is a score change, not a newly diagnosed relapse.
Slower worsening and recovered function are different claims
Current smoking was associated with a shorter time to worsening after accounting for factors including age, initial score, MS type and disease-modifying treatment. Former and never smokers showed no statistically significant difference in event rates. That does not establish exact equality: the study was not an equivalence trial, and a similar rate can still mean worsening in both groups.
The authors did not find a pattern of better questionnaire scores with more years since quitting. The four-year analysis also showed worsening of physical measures over time across the smoking groups. Therefore a claim that quitting ‘resets disability’ does not follow from the results. Nor can this study provide a deadline for improvement, a number of relapse-free years or evidence to change MS treatment.
Use the evidence to ask for support, not to judge yourself
Participants volunteered for an online registry; those supplying regular follow-up were not identical to the full sample. Smoking was largely self-reported, and people who stopped may also have changed other health behaviours. Statistical adjustment cannot remove every such difference or turn the comparison into randomized proof. These limitations are reasons for careful wording, not for blaming someone whose function worsens after quitting.
A practical question for the MS team is: ‘How can smoking-cessation support fit into my existing follow-up?’ This article cannot decide whether a new symptom is MS, withdrawal or something else; discuss new or changing symptoms with qualified care rather than interpreting them through the registry result. In England, NHS local stop-smoking services provide a separate help route. No symptoms, treatment names or smoking history need to be entered on this page.
What to keep in mind
Sources
The central claims on this page were checked against the sources below.
- Brain / University of Plymouth author repository: Rodgers et al.: The impact of smoking cessation on multiple sclerosis disease progression (online 2021; Brain 2022), accepted manuscript: Methods, Results and Discussion
Sources checked: 2026-10-08
- NHS: England: access to local stop-smoking services
Sources checked: 2026-10-08
General population evidence; not diagnosis, an individual MS prognosis, symptom attribution or advice to choose or change treatment.