About half of older adults have two or more chronic conditions at the same time: a systematic review and meta-analysis.

Background: Population aging has led to a rising prevalence of multimorbidity among older adults, posing a significant global public health challenge. This study aims to comprehensively integrate the evidence regarding the prevalence of multimorbidity among the older adults and the influencing factors through a systematic review and meta-analysis. Methods: We conducted a systematic review and meta-analysis in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The research question was structured using the PICOS framework: Population: adults aged ≥60 or ≥65; Intervention/Phenomenon of Interest: multimorbidity (≥2 chronic conditions); Comparator: not applicable (prevalence synthesis) or various demographic groups (risk factor analysis); Outcomes: prevalence of multimorbidity and pooled odds ratios (OR) of risk factors; Study design: cross-sectional studies. We conducted a comprehensive search of multiple databases up to July 2025 to identify cross-sectional studies that reported the prevalence and/or risk factors of multimorbidity (defined as ≥2 chronic conditions) in adults aged ≥60 or ≥65. The pooled prevalence was estimated using a random-effects model, and heterogeneity was explored through subgroup analysis and meta-regression. Results: Forty-nine studies involving 729,043 older adults were included. The global pooled prevalence of multimorbidity was 46.0% (95% CI: 38.0%-55.0%), with substantial heterogeneity (I 2 = 99.98%). Meta-regression identified survey location as a key source of heterogeneity. Subgroup analyses revealed a higher prevalence in females (48%) than males (41%) and a lower prevalence in studies from China (40%) compared to other countries (53%). Significant risk factors included age ≥ 70 years (OR = 1.43), female sex (OR = 1.59), BMI ≥ 28 kg/m2 (OR = 1.97), low education (OR = 1.44), single status (OR = 1.32), and low income (OR = 1.46). Conclusion: Multimorbidity is highly prevalent among the global older adults, with significant geographical and demographic variations. Modifiable risk factors such as obesity, low education, and low income are crucial targets for intervention to alleviate the burden of multimorbidity.