Performance comparison of CD4 T-cell count instruments based on data from the national proficiency testing program in China, 2016-2023.

BACKGROUND

The number of CD4 T cells is an important indicator of immune status in people living with HIV (PWH). In China, numerous CD4 count instruments have been approved; however, no studies have been conducted to systematically compare the performance of these instruments.

METHODS

We retrospectively analyzed data from the national proficiency testing program for CD4 T-cell counts in China from 2016 to 2023. We conducted comparative analysis to evaluate the performance of 10 mainstream CD4 count instruments. Passing-Bablok regression and mix-effects model analyses were used to analyze the agreement and interchangeability of test results among instruments.

RESULTS

The proportion of laboratories participating in the CD4 proficiency testing program and using Chinese-manufactured and point-of-care testing instruments has increased annually, from 4.7% to 29.7% and from 3.3% to 8.1%, respectively. The results of the 10 devices tested showed strong correlations and agreement with target values, with correlation coefficients (R²) ranging from 0.952 to 0.983 and with the mean bias ranged from -1 to + 95 cells/µL across the 10 devices. Strong agreement was observed among the results for the 10 instruments, slopes ranged from 0.866 to 1.214, while the intercepts varied from  -42.3 cells/µL to + 24.0 cells/µL. After adjusting for sample and laboratory effects using a linear mixed-effects model, eight instruments (B, C, D, M, J, FP, LP, H) produced significantly lower values than the reference instrument A (adjusted mean = 613.0; differences: -92.0 to -20.3; all p < 0.05). Tukey-adjusted pairwise comparisons identified H, LP, and FP as a distinct low-value subgroup, although their measurements remained within the acceptable range.

CONCLUSIONS

The performance of commonly used CD4 count instruments was comparable and can meet the needs of HIV testing laboratories.

CLINICAL TRIAL: Not applicable.