CHEST Guidelines-Response_chest

Response_chest_57 (1)

Pdf Summary

The correspondence between medical professionals revolves around the potential for immortal time bias in a study on the effectiveness of anticoagulation treatment for patients with antiphospholipid syndrome (APS). The critique by Chen et al. suggests that some patients, particularly those who died early, might not have had the opportunity to receive anticoagulation or corticosteroids, which could exaggerate the perceived effectiveness of the treatment. They propose using methods such as time-varying covariates or time-dependent propensity score matching to address this bias. Additionally, they mention that selection bias could arise because the indications for treatment may differ between patient groups, making it challenging to draw causal inferences about treatment efficacy.<br /><br />In response, Pineton de Chambrun and colleagues discuss their study's limitations due to its retrospective and observational design, which included data from 20 centers over nearly 20 years. They acknowledge the potential biases but emphasize that anticoagulation is a widely recommended treatment for APS and catastrophic APS (CAPS) and argue that the criticism does not significantly undermine their findings. They highlight the importance of anticoagulation, noting that nonsurvivors in their study often did not receive this therapy, potentially due to contraindications like severe bleeding complications.<br /><br />Additionally, a separate dialogue discusses the role of bronchoscopy in diagnosing the source of hemoptysis (coughing up blood). While a previous study misinterpreted the ability of bronchoscopy to locate bleeding sites, the authors clarify their findings, indicating that the timing of bronchoscopy does not affect its ability to diagnose bleeding sources, regardless of the severity of symptoms. They underline the importance of not delaying treatment in cases of potential severe bleeding, emphasizing bronchoscopy’s diagnostic role in stable patients with varying severity of hemoptysis.

Keywords

immortal time bias

anticoagulation treatment

antiphospholipid syndrome

APS

corticosteroids

time-varying covariates

time-dependent propensity score

selection bias

bronchoscopy

hemoptysis