Patient selection before endobronchial valve treatment
- Zhen Yang,
- Jie Chen and
- Liang An Chen⇑
- L.A. Chen, Dept of Respiratory Disease, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, 100853, China. E-mail: chenla301{at}263.net
To the Editor:
We read with great interest the study by Herth et al. [1]. They investigated the ability of the bronchoscopic Chartis Pulmonary Assessment System to predict the response to unidirectional endobronchial valve (EBV) treatment by determining the presence of collateral ventilation (CV) and the Chartis system showed an accuracy level of 75% in predicting whether or not the target lobe volume reduction (TLVR) cut-off (≥350 mL) would be reached.
As previously reported [2], EBV treatment brought emphysema patients significant but modest improvement of forced expiratory volume in 1 s (FEV1), exercise capacity and quality of life compared with controls, while another type of unidirectional valve, intrabronchial valve treatment, did not [3]. However, only a subgroup of patients could benefit more from EBV treatment. Therefore, defining and selecting this subgroup of patients is of great help to improve the clinically significant benefit of EBV treatment. To date, three methods can be used before EBV placement to predict therapeutic effect, which are CV detected by Chartis [1], and heterogeneity and fissure completeness assessed by high-resolution computed tomography (HRCT) [2, 4, 5]. This raises two questions.
First, which of these three methods has the highest capability to predict response to EBV treatment? Regrettably, Herth et al. [1] did not provide information about heterogeneity and fissure completeness. Gompelmann et al. [6] studied whether the accuracy of CV assessment was comparable to fissure analysis from HRCT in predicting clinically significant lung volume reduction following EBV treatment. Preliminary results of this study showed that Chartis and HRCT matched 24 (77.4%) times in 31 patients, and did not match seven (22.6%) times. Complete results of this study were not available when we were reviewing the literature, so we could not know the difference in the accuracy of predicting response to EBV treatment between these two methods. Therefore, we tried to extract comparable data from other studies. Herth et al. [1] reported that CV-negative patients had a median TLVR of 752.7 mL compared to 98.6 mL in CV-positive patients; 43% of CV-negative patients showed change in (Δ)FEV1 ≥15% at 1 month from baseline after EBV treatment. Sciurba et al. [2] reported patients with complete fissure had a median TLVR of 713 mL compared to 196 mL in patients with incomplete fissure; 42.6% of patients with complete fissure showed ΔFEV1 ≥15% at 6 months from baseline after EBV treatment. Herth et al. [4] reported that 35.2% of patients with more heterogeneous emphysema showed ΔFEV1 ≥15% at 6 months from baseline after EBV treatment. So, it seems that CV detected by Chartis and fissure completeness assessed by HRCT are comparable in predicting response to EBV treatment.
Second, does combining those two or three methods have a higher capability to predict response to EBV treatment than a single one? Data from Herth et al. [1] showed that the false-positive value and the false negative value for Chartis system were 38% and 12%, respectively. Lindquist et al. [7] reported that nine out of 49 patients screened with HRCT had intact fissures and went onto Chartis assessment and EBV placement, seven of whom were CV-negative and two were CV-positive on Chartis. The CV-negative group showed clinically significant improvement of lung function and St George’s Respiratory Questionnaire, while the CV-positive group did not. Thus, combining these methods may further improve the predictive value.
As discussed here, further studies are warranted to investigate these two questions, which may help build an effective workflow for patients selection before EBV treatment.
Footnotes
Conflict of interest: None declared.
- Received July 23, 2013.
- Accepted September 1, 2013.
- ©ERS 2014