Rising prevalence of vascular comorbidities in multiple sclerosis: validation of administrative definitions for diabetes, hypertension, and hyperlipidemia

Background: Despite the importance of comorbidity in multiple sclerosis (MS), methods for comorbidity assessment in MS are poorly developed. Objective: We validated and applied administrative case definitions for diabetes, hypertension, and hyperlipidemia in MS. Methods: Using provincial administrative data we identified persons with MS and a matched general population cohort. Case definitions for diabetes, hypertension, and hyperlipidemia were derived using hospital, physician, and prescription claims, and validated in 430 persons with MS. We examined temporal trends in the age-adjusted prevalence of these conditions from 1984–2006. Results: Agreement between various case definitions and medical records ranged from kappa (κ) =0.51–0.69 for diabetes, κ =0.21–0.71 for hyperlipidemia, and κ =0.52–0.75 for hypertension. The 2005 age-adjusted prevalence of diabetes was similar in the MS (7.62%) and general populations (8.31%; prevalence ratio [PR] 0.91; 0.81–1.03). The age-adjusted prevalence did not differ for hypertension (MS: 20.8% versus general: 22.5% [PR 0.91; 0.78–1.06]), or hyperlipidemia (MS: 13.8% versus general: 15.2% [PR 0.90; 0.67–1.22]). The prevalence of all conditions rose in both populations over the study period. Conclusion: Administrative data are a valid means of tracking diabetes, hypertension, and hyperlipidemia in MS. The prevalence of these comorbidities is similar in the MS and general populations.