ELEVATED levels of the atherogenic index of plasma (AIP), a marker of lipid imbalance, may be associated with earlier onset of chronic lung disease (CLD), according to findings from a nine-year prospective cohort study in China.
Researchers identified a nonlinear relationship between AIP and time to CLD onset, with individuals in the high AIP category experiencing a shorter time to disease development compared with those in the low category. The findings suggest that lipid metabolism may be relevant to respiratory health, although the association requires further validation.
Systemic inflammation and disturbances in lipid metabolism are increasingly recognised as potential contributors to chronic respiratory disease.
AIP, calculated from circulating triglyceride and high-density lipoprotein cholesterol concentrations, is an established marker of lipid imbalance that has been extensively investigated in relation to cardiovascular risk.
However, its potential relationship with CLD development remains less understood.
To investigate this association, researchers analysed data from 3,639 participants enrolled in the China Health and Retirement Longitudinal Study between 2011 and 2020.
The prospective analysis examined whether AIP was associated with the time taken to develop CLD over the nine-year follow-up period.
Researchers used weighted Kaplan–Meier survival curves, accelerated failure time models, and restricted cubic spline analyses to assess associations, while sensitivity analyses were conducted to evaluate the robustness of the findings.
During follow-up, 830 participants developed CLD, representing approximately 22.8% of the study population.
Initial analyses comparing AIP tertiles found no statistically significant differences in time to CLD onset (p=0.101).
However, subsequent adjusted analyses identified a more complex relationship.
Restricted cubic spline analysis demonstrated a statistically significant U-shaped association between AIP and time to CLD onset, with an overall p-value of 0.027 and a p-value for nonlinearity of 0.007.
In the fully adjusted model, participants in the high AIP category experienced a shorter time to CLD onset compared with those in the low AIP category.
The reported time ratio was 0.95 (95% CI 0.92–0.98; p<0.001), corresponding to an estimated 5% shorter time to disease onset under the accelerated failure time model.
However, the very high AIP category did not demonstrate a statistically significant difference compared with the low AIP group.
These findings indicate that the association was not consistently stronger at increasingly elevated AIP levels, highlighting the importance of considering potential nonlinear relationships.
Sensitivity analyses produced consistent findings, supporting the stability of the observed association.
Beyond AIP, researchers identified several additional factors associated with shorter time to CLD onset.
Smoking, retired status, treatment for dyslipidaemia, and elevated white blood cell counts above 10 × 10⁹/L were all significantly associated with earlier disease development in the fully adjusted model.
Conversely, higher household income and greater peak expiratory flow were associated with a longer time to CLD onset.
These findings highlight the potential contribution of respiratory function, inflammatory status, and socioeconomic characteristics to chronic lung disease risk.
The association between elevated white blood cell counts and earlier CLD onset may also be consistent with a role for systemic inflammation, although the study did not establish a causal mechanism.
The researchers suggested that AIP could provide additional insight into the relationship between metabolic health and chronic respiratory disease.
However, the nonlinear findings complicate its potential use as a straightforward risk marker, particularly because the very high AIP group did not show a significant association with earlier disease onset.
Furthermore, the observational design means that the findings cannot establish whether lipid imbalance directly contributes to CLD development.
The researchers concluded that high AIP levels were associated with a shorter time to CLD onset, but emphasised that the nonlinear relationship requires confirmation in independent populations.
Further research is needed to determine whether AIP offers clinically useful information beyond established respiratory risk factors and whether incorporating lipid-related measures could improve chronic lung disease risk assessment.
Reference
Tan, F., Huang, T. & Li, G. Association between the atherogenic index of plasma and time to onset of chronic lung disease: a nine-year prospective cohort study in China. BMC Pulm Med (2026). https://doi.org/10.1186/s12890-026-04867-y
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