Associations of the Charlson comorbidity index with asthma and mortality (NHANES 2007–2018): a cross-sectional study

Background: Patients with asthma often suffer from multiple comorbid conditions, which can exacerbate disease severity and elevate the risk of mortality. This study aims to investigate the relationship between the Charlson Comorbidity Index (CCI) and asthma, as well as their combined impact on mortality. Methods: This is an observational cross-sectional study based on the NHANES database conducted from 2007 to 2018. The study included a total of 26,002 adult participants. Logistic regression was performed to assess the relationship between the CCI and asthma. Survival analysis, including Kaplan–Meier analysis and Cox regression, was conducted to investigate the combined effect of the CCI and asthma on all-cause mortality. Subgroup analyses were performed to confirm the reliability of the outcomes. Results: After adjusting for sex, age, race, body mass index, and other relevant covariates, our analysis showed an association between CCI and asthma (OR, 1.120; 95% CI, 1.059–1.186). Moreover, a higher CCI score was closely associated with increased mortality risk (HR, 1.143; 95% CI, 1.109–1.179) after adjustment of confounding factors. The risk of mortality was substantially higher for individuals with both asthma and a CCI score of ≥ 2 compared to those with no asthma and a CCI score of 0 (HR, 1.853; 95% CI, 1.440–2.383). Subgroup analyses further confirmed the trend that higher CCI levels are associated with poorer survival outcomes across multiple subgroups. Conclusion: The study indicates an association between the CCI and the risk of asthma, as well as their combined impact on elevated all-cause mortality. Since a high CCI score is associated with an increased risk of asthma and mortality, further studies are warranted to explore the causal relationship between these factors.