[Analysis of the association between CD4+T lymphocytes counts test index and immunological failure of antiretroviral therapy among HIV-infected patients in Taizhou, Zhejiang Province, from 2006 to 2024].

Objective: To investigate the association between CD4+T lymphocytes (CD4) counts test index and immunological failure among HIV-infected patients receiving antiretroviral therapy in Taizhou, Zhejiang Province. Methods: A retrospective cohort study was conducted. A total of 4 609 HIV-infected patients aged 18 and above who received antiretroviral therapy (ART)were derived from Chinese Disease Prevention and Control Information System from 2006 to 2024.The CD4 counts test index was defined as the ratio of actual CD4 counts test times to theoretical test times, and were divided into four groups: 0.00-0.30 (extremely low detection group), 0.31-0.80 (low detection group), 0.81-1.20 (regular detection group), and ≥1.21 (enhanced detection group). Immunological failure was defined as the last CD4 counts after ART that did not exceed the baseline level or persistently below 100 cells/μl. Restricted cubic splines (RCS) and piecewise Cox proportional hazards models were used to analyze the dose-response relationship between the CD4 counts testing index and immunological failure. Results: Among 4 609 cases of HIV-infected patients, a non-linear U-shaped association was observed between the CD4 counts testing index and immunological failure (P<0.001), with an inflection point at 0.93. Below 0.93, each 0.1-unit increase in the index was associated with a 29% reduction in the risk of immunological failure (aHR=0.71, 95%CI: 0.65-0.77). Above 0.93, each 0.1-unit increase was associated with a 13% increase in risk (aHR=1.13, 95%CI: 1.09-1.16). Compared with the regular detection group, the risk of immunological failure was significantly higher in the extremely low, low, and enhanced detection groups. (aHR=7.60, 1.49, and 1.37, respectively). Subgroup analyses indicated that the association between a high testing index and immunological failure was positively correlated among patients with low BMI, sexual transmission, and low baseline CD4 counts levels. Conclusions: Among HIV-infected patients in Taizhou City, Zhejiang Province from 2006 to 2024, insufficient frequency of CD4 count testing or intensive testing based on clinical indications were both associated with the risk of immunological failure of ART. In the follow-up management of HIV-infected patients, on the basis of evaluating individual clinical indications and the efficacy of ART, the frequency of CD4 count testing should be reasonably arranged to provide precise and personalized ART and follow-up management plans for HIV-infected patients.