Statistical Analyses
multimorbidity, TOAST, intracerebral hemorrhage, stroke death, stroke, dementia, χPrestroke, prestroke multimorbidity, ischemic stroke, Comorbidity, cryptogenic stroke
INTRACEREBRAL HEMORRHAGE, STROKE, METASTATIC CANCER, ISCHEMIC STROKE, REGRESSION
Patients with incomplete data (usually <2%) were excluded from analyses and no data were imputed. Continuous data were reported as either mean (SD) or median (interquartile range), as appropriate. Categorical data were presented as counts (percentages). Differences between multimorbidity groups were explored using 1-way analysis of variance, χPrestroke multimorbidity was quantified using the both the weighted and unweighted versions of the Charlson Comorbidity Index (CCI).Associations between multimorbidity (using unweighted CCI) and stroke severity were analyzed using crude and adjusted logistic regression models for NIHSS 5–9 and ≥10 vs 0–4. Because the longer distribution of the weighted CCI allowed for linear regression analysis, a further set of analyses was also performed using linear regression with the weighted CCI and full ordinal NIHSS score. Analyses were performed including all patients and stratified by TOAST subtype, with subtype-specific associations then pooled by fixed-effects meta-analysis. To explore possible associations between prestroke multimorbidity and subtype, crude and adjusted (age/sex) logistic regression models were used, with cryptogenic stroke used as the reference group for TOAST subtypes. Additional analyses were also performed with stratification by age (younger than 75 years/75 years or older) and sex.Associations between multimorbidity and premorbid disability were analyzed using crude and adjusted (age/sex) logistic regression models for mRS ≥2 vs 0–1. Associations between multimorbidity and all-cause mortality within 90 days were assessed with Cox proportional hazard models (unadjusted, age/sex adjusted, additionally adjusted for NIHSS and/or mRS, and stratified by TOAST subtype).We also performed 3 sensitivity analyses. First, a small number of patients had a stroke death in the community or died very shortly after arrival at hospital and therefore did not have NIHSS assessed. To avoid potential bias due to exclusion of such cases, we did a set of analyses examining the within-subtype associations between multimorbidity and severity in which these cases were classified as NIHSS ≥10 and allocated to either the intracerebral hemorrhage category or the TOAST Unknown ischemic stroke subtype. Second, in an attempt to minimize potential bias relating to delayed presentation or initial clinical assessment in patients with multimorbidity, we ran analyses excluding patients who received thrombolysis or thrombectomy. Third, to limit possible bias due to patient or physician decisions to limit investigation/treatment on the association of multimorbidity with 90-day mortality, we repeated analyses after excluding patients with metastatic cancer, hematologic malignancy, dementia, or care home residence.All analyses were performed using Stata (version 16; StataCorp., College Station, TX). Significance was set at 