The multimorbidity in the elderly has become an important issue that needs urgent attention in the field of public health. Therefore, it is of great significance to explore the influencing factors of multimorbidity in the elderly.

To investigate the prevalence of multimorbidity and related influencing factors in the elderly population in northern and southern China, in order to better manage and intervene the development and prognosis of multimorbidity in the elderly in different regions.

PubMed, Embase, Web of Science, Cochrane Library, Scopus, China Biology Medicine Disc, China National Knowledge Infrastructure, Wanfang Data Knowledge service platform were searched for relevant studies on influencing factors of multimorbidity in the elderly. Two researchers independently searched, screened, extracted data, and cross-checked. Any disagreements were resolved through consultation with a third researcher for arbitration. The search time limit was from the establishment of the database to July 2024. Stata 18.0 software was used for meta-analysis.

The research incorporated 10 articles from the southern region and 10 from the northern region, with sample sizes of 2 342 507 and 75 871 cases, respectively. The prevalence of multimorbidity among elderly patients in the southern and northern regions was 34% (95%CI=29%-38%, P<0.001) and 36% (95%CI=22%-50%, P<0.001), respectively. Among them, the influencing factors of elderly patients with multimorbidity in southern China were age (OR=1.92, 95%CI=1.26-2.94, P=0.003), gender (OR=1.51, 95%CI=1.03-2.21, P=0.034), and household per capita monthly income (OR=1.62, 95%CI=1.03-2.54, P=0.036), education level (OR=1.47, 95%CI=1.25-1.73, P<0.001), BMI (OR=1.72, 95%CI=1.52-1.96, P<0.001), smoking (OR=1.53, 95%CI=1.11-2.11, P=0.009), drinking (OR=1.39, 95%CI=1.26-1.54, P<0.001), regular physical exercise (OR=0.67, 95%CI=0.55-0.80, P<0.001) ; age (OR=1.67, 95%CI=1.00-2.79, P=0.048), BMI (OR=2.39, 95%CI=1.80-3.18, P<0.001), drinking (OR=1.63, 95%CI=1.32-2.02, P<0.001), regular physical exercise (OR=0.84, 95%CI=0.71-0.99, P<0.037) were the influencing factors of elderly patients with multimorbidity in northern China. Sensitivity analysis showed that the results of Meta-analysis were stable, and Egger's test (multimorbidity prevalence: P=0.826; influencing factors: P=0.841) suggested that the risk of publication bias of the included literature was not significant.

The prevalence of multimorbidity among the elderly was relatively high in both the northern and southern regions. The risk factors for multimorbidity in both regions included: age≥70 years, overweight or obese BMI status, and alcohol consumption. Conversely, regular physical exercise served as a protective factor. In southern China, male sex, household per capita monthly income≥¥2 000, education below college level, and smoking were the risk factors for multimorbidity. These disparities may stem from dietary habits, economic levels, lifestyle pace, and uneven medical resource distribution. Enhancing inter-regional medical resource coordination and sharing is advised to improve health equity and resource balance, boosting elderly health overall. Additionally, healthcare providers should tailor interventions based on these factors to optimize disease management in elderly with multimorbidity.