High CALLY index is independently associated with lower odds of preserved ratio impaired spirometry (PRISm) and provides incremental predictive value: a retrospective observational study

Zelian Zhang, X Y Huang, Tan Wei, Ming Min, Minghua Zhang, Qianfei Liu

Objective To characterize the link of the C-reactive protein-albumin-lymphocyte index (CALLY index) to preserved ratio impaired spirometry (PRISm), and to determine its incremental contribution to PRISm risk prediction in clinical practice. Methods A total of 189 participants were included in this study and were classified into the PRISm group ( n = 70) and the non-PRISm group ( n = 119) according to the presence or absence of PRISm. Baseline demographic characteristics, comorbidities, and laboratory parameters were collected. Multivariable Logistic regression models with sequential adjustment for confounding factors were used to assess the independent association between the CALLY index and PRISm. Restricted cubic splines (RCS) and subgroup analyses were performed to evaluate the robustness of this association. Receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA) were used to assess the incremental clinical predictive value of the CALLY index. Results The CALLY index was significantly lower in the PRISm group than in the non-PRISm group (1.4 ± 2.5 vs. 4.7 ± 8.1, P < 0.001). In the fully adjusted model controlling for 11 confounding factors (adjusted model II), each one-unit increase in the CALLY index as a continuous variable was associated with 16% lower odds of PRISm (OR = 0.84, 95% CI: 0.74–0.95, P = 0.007). After dichotomizing the CALLY index, the high-level group showed 73% lower odds of PRISm than the low-level group (OR = 0.27, 95% CI: 0.13–0.57, P < 0.001). The RCS curve demonstrated a significant inverse trend between the CALLY index and the odds of PRISm. Subgroup analyses indicated that this inverse association remained robust across populations stratified by age, gender, smoking history, and comorbidities. In addition, after the CALLY index was incorporated into a model containing baseline clinical characteristics, the area under the ROC curve (AUC) increased significantly from 0.611 to 0.703 ( P = 0.003), and DCA further confirmed a higher net clinical benefit. Conclusion A high CALLY index is independently associated with lower odds of PRISm. Integrating the CALLY index into routine clinical assessment can significantly improve the predictive performance for PRISm and provide net clinical benefit.