Completeness and generalizability of the Swedish MS register

Area of Science:

• Neurology
• Epidemiology
• Public Health

Background:

• The Swedish Multiple Sclerosis (MS) Register is a vital national resource for clinical care and research.
• Assessing the representativeness of the MS register is crucial for the generalizability of its findings.
• Previous studies have not comprehensively evaluated the register's completeness and potential biases.

Purpose of the Study:

• To determine the completeness of the Swedish MS Register.
• To identify and quantify potential demographic and socioeconomic disparities between individuals included in the register and those not included.
• To inform the interpretation of research findings derived from the Swedish MS Register.

Main Methods:

• Utilized linked national registers to identify all individuals with Multiple Sclerosis (MS) in Sweden up to December 2020.
• Defined prevalent and incident MS cases based on diagnostic criteria in the National Patient Register.
• Employed overlap weighting to adjust for age differences when comparing included versus non-included individuals.

Main Results:

• The Swedish MS Register achieved 85% completeness for prevalent cases and 87% for incident cases in 2020.
• Completeness varied significantly by county, ranging from 67% to 94%.
• Individuals not included in the register were generally older, had lower socioeconomic status (less income and education), and had higher healthcare utilization (hospitalizations, prescribed drugs).

Conclusions:

• The Swedish MS Register demonstrates high overall completeness but exhibits potential underrepresentation of older individuals, those diagnosed later in life, and those from lower socioeconomic backgrounds.
• These identified disparities may impact the generalizability of findings from the register.
• Researchers and clinicians should consider these limitations when utilizing data from the Swedish MS Register.