Impact of body mass index on recurrent stroke in stroke survivors: An updated systematic review and meta-analysis.

BACKGROUND

This updated systematic review and meta-analysis aimed to re-evaluate the potential impact of body mass index (BMI) on the risk of recurrent stroke among stroke survivors.

METHODS

We systematically searched PubMed, EMBASE, and Cochrane CENTRAL databases for studies published up to January 20, 2025. Eligible studies included randomized controlled trials, cohort studies, or case-control studies enrolling adult stroke or transient ischemic attack (TIA) survivors, with at least one year of follow-up, and reporting stroke recurrence by BMI categories. Studies were required to define stroke using clinical diagnosis or the International Classification of Disease (ICD) codes, and to categorize BMI using the World Health Organization (WHO) or Asia-Pacific classifications. The primary outcome was recurrent stroke risk between individuals with and without obesity, assessed using risk ratios (RRs). Secondary outcomes evaluated recurrent stroke risk across WHO BMI categories using adjusted hazard ratios (HRs). (PROSPERO: CRD42024580168)

RESULTS

Fourteen studies (136,581 subjects) were included in the qualitative review (systematic review). Two using Asia-Pacific criteria were excluded, leaving 12 studies using WHO-classified BMI for quantitative synthesis (meta-analysis). Meta-analysis showed no significant difference in stroke recurrence between individuals with and without obesity (RR = 0.89, 95 % CI: 0.71-1.13). Meta-analysis of adjusted HRs showed no significant difference in stroke recurrence risk for individuals with underweight or overweight compared to those with normal weight. However, in the subgroup with ≥ 3 years follow-up, overweight was significantly associated with lower recurrent stroke risk (HR = 0.91). Also, individuals with obesity had a significantly lower stroke recurrence risk than normal weight individuals (HR = 0.85), particularly among those aged ≥ 65 years (HR = 0.82).

CONCLUSIONS

Overweight and obesity may be associated with a lower risk of stroke recurrence, particularly in older adults and during long-term follow-up (≥ 3 years). These findings suggest a potential obesity paradox in stroke survivors, warranting further investigations.