Table e-4. The association between comorbidity and rates of hospitalizationa in the multiple sclerosis (MS) and matched populations

Variable / Matched population
All Hospitalizations / MS population
All Hospitalizations / MS population
Non-MS- Related Hospitalizations / MS population
MS-Related Hospitalizations
Rate Ratio / 95% CI / Rate Ratio / 95% CI / Rate Ratio / 95% CI / Rate Ratio / 95% CI
Comorbidity Model 1
No comorbidity / 1.0 / 1.0 / 1.0 / 1.0
Any comorbidity / 3.69 / 3.27, 4.16 / 2.04 / 1.59, 2.63 / 2.29 / 1.74, 3.01 / 1.28 / 0.80, 2.06
Comorbidity Model 2
(Number of comorbidities)
0 / 1.0 / 1.0 / 1.0
1 / 1.76 / 1.52, 2.05 / 1.35 / 0.99, 1.83 / 1.31 / 0.93, 1.83 / 1.59 / 0.90, 2.79
2 / 2.80 / 2.41, 3.26 / 1.69 / 1.26, 2.27 / 1.82 / 1.33, 2.49 / 1.15 / 0.62, 2.16
3 / 4.06 / 3.51, 4.70 / 2.05 / 1.52, 2.76 / 2.22 / 1.62, 3.04 / 2.39 / 0.67, 2.48
≥4 / 7.51 / 6.56, 8.59 / 3.28 / 2.48, 4.33 / 3.89 / 2.89, 5.23 / 1.08 / 0.63, 1.84
Comorbidity Model 3
Hypertension / 1.81 / 1.67, 1.96 / 1.67 / 1.41, 1.98 / 1.64 / 1.41, 1.91 / 1.74 / 1.04, 2.89b
Hyperlipidemia / 1.15 / 1.07, 1.24 / 0.96 / 0.84, 1.33 / 0.99 / 0.87, 1.14 / 0.73 / 0.46, 1.16
Diabetes / 1.67 / 1.54, 1.82 / 1.41 / 1.20, 1.66 / 1.49 / 1.26, 1.76 / 1.02 / 0.62, 1.68
Heart disease / 2.24 / 2.06, 2.44 / 1.98 / 1.65, 2.36 / 2.01 / 1.68, 2.40 / 1.07 / 0.65, 1.77
Fibromyalgia / 1.22 / 1.07, 1.40 / 1.20 / 0.99, 1.44 / 1.26 / 1.05, 1.51 / 0.75 / 0.43, 1.31
Thyroid disease / 1.21 / 1.11, 1.32 / 0.98 / 0.82, 1.17 / 1.02 / 0.86, 1.21 / 0.69 / 0.43, 1.12
Migraine / 1.14 / 1.05, 1.24 / 0.91 / 0.77, 1.07 / 0.91 / 0.78, 1.07 / 0.83 / 0.48, 1.43
Depression / 1.31 / 1.20, 1.42 / 1.42 / 1.21, 1.66 / 1.47 / 1.25, 1.72 / 1.14 / 0.69, 1.90
Anxiety / 1.18 / 1.10, 1.27 / 1.06 / 0.91, 1.23 / 1.12 / 0.96, 1.30 / 0.72 / 0.47, 1.11
Bipolar disorder / 1.43 / 1.25, 1.63 / 1.31 / 1.05, 1.64 / 1.31 / 1.06, 1.63 / 1.06 / 0.54, 2.10
Chronic lung disease / 1.40 / 1.30, 1.51 / 1.24 / 1.06, 1.45 / 1.27 / 1.10, 1.47 / 1.15 / 0.67, 1.99

a- Include acute care, long-term care and respite admissions. Long-term care admissions do not include admissions to personal care homes. All findings adjusted for age, sex, socioeconomic status. b- After additional adjustment for number of physician visits RR 1.44 (95% CI: 0.88-2.37). Whether or not the other comorbidities were statistically significant was unchanged in all of the MS models.