Cardiovascular

Dynamic lactate dehydrogenase/lymphocyte ratio and C-reactive protein as predictors of mortality after plasma exchange in ANCA-associated vasculitis: A retrospective case control study.

Yuksel H, Kilincer Bozgul S, et al. • Medicine • 2026

PubMed 42629677 DOI 10.1097/MD.0000000000050314

TL;DR

Dynamic changes in LDH-to-lymphocyte ratio and CRP after plasma exchange may serve as early, readily available predictors of in-hospital mortality in critically ill AAV patients.

Key Findings

Results

In-hospital mortality among critically ill AAV patients undergoing plasma exchange was 39.4%.

13 of 33 adult AAV patients died in-hospital.
Median age of the cohort was 55 years (range 20–83).
57.6% of patients were male.
All patients received at least 3 PLEX sessions between January 2010 and June 2021.
This was a retrospective, single-center cohort study.

Results

Non-survivors exhibited significantly greater post-PLEX increases in LDH/lymphocyte ratio compared to survivors.

Median post-PLEX LDH/lymphocyte ratio increase was 1.1 in non-survivors versus 0.3 in survivors.
This difference was statistically significant (P < .001).
Biochemical parameters were measured immediately before the first and after the final PLEX session.
Univariate comparisons employed Mann-Whitney U tests.

Results

Non-survivors had significantly higher final CRP levels after PLEX compared to survivors.

Median final CRP was 10.2 mg/L in non-survivors versus 2.8 mg/L in survivors.
This difference was statistically significant (P = .008).
CRP was measured after completion of the final PLEX session.
Univariate comparisons employed Mann-Whitney U and chi-square tests as appropriate.

Results

A CART model identified post-PLEX LDH/lymphocyte ratio >0.55 as the primary discriminator for in-hospital mortality.

Secondary stratification in the CART model was by CRP > 0.67 mg/dL.
The CART model was constructed following variable selection, variance inflation factor analysis, and recursive feature elimination.
Model performance AUC was 0.89 on the training set and 0.71 on the test set.
Model performance was assessed by AUC and cross-validation.

Results

The CART model combining post-PLEX LDH/lymphocyte ratio and CRP demonstrated good discriminatory performance for predicting mortality.

Training AUC was 0.89, indicating strong in-sample discrimination.
Test AUC was 0.71, indicating moderate out-of-sample discrimination.
Cross-validation was used to assess model generalizability.
The two-variable model used post-PLEX LDH/lymphocyte ratio as the primary node and CRP as the secondary stratifier.

Conclusions

The authors concluded that dynamic assessment of LDH-lymphocyte ratio and CRP after PLEX may help refine patient selection for PLEX and tailor adjunctive therapies.

The findings were described as warranting validation in larger, prospective cohorts.
Early identification of patients unlikely to benefit from PLEX could optimize immunosuppressive strategies.
The efficacy of plasma exchange in AAV was characterized as remaining controversial.
Both biomarkers were described as 'early, readily available predictors of mortality.'

What This Means

This research suggests that two simple blood test measurements — the ratio of an enzyme called lactate dehydrogenase (LDH) to lymphocyte (a type of white blood cell) count, and a protein called C-reactive protein (CRP) — taken after plasma exchange treatment can help predict which patients with a rare immune disease called ANCA-associated vasculitis (AAV) are more likely to die in the hospital. The study looked back at 33 critically ill AAV patients who received plasma exchange at a single center over about 11 years, and found that nearly 40% died during their hospital stay. Patients who died tended to have much larger increases in the LDH-to-lymphocyte ratio and higher CRP levels after their plasma exchange sessions were completed. Using a statistical modeling technique called a classification and regression tree (CART), the researchers found that a post-treatment LDH/lymphocyte ratio above 0.55 was the strongest single indicator separating patients who survived from those who did not, with CRP levels providing additional predictive information. The model performed well in identifying at-risk patients, though its accuracy was somewhat lower when tested on new data, reflecting the small study size. This research suggests that tracking these two blood markers before and after plasma exchange could give clinicians an early warning sign about treatment response in critically ill AAV patients, potentially allowing them to adjust treatment plans sooner. However, the authors note that because this was a small, single-center, retrospective study, the findings need to be confirmed in larger prospective studies before they can be used to guide clinical decisions.

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Citation

Yuksel H, Kilincer Bozgul S, Acar C, Celebi G, Yargucu Zihni F, Gunes A, et al.. (2026). Dynamic lactate dehydrogenase/lymphocyte ratio and C-reactive protein as predictors of mortality after plasma exchange in ANCA-associated vasculitis: A retrospective case control study.. Medicine. https://doi.org/10.1097/MD.0000000000050314

Key Findings

What This Means

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