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Peripherally inserted central catheter‐related deep vein thrombosis: contemporary patterns and predictors: comment

We read with great interest the recently published paper by Chopra et al. [1] on peripherally inserted central catheter (PICC)-related deep vein thrombosis (DVT). As the authors point out, a recent diagnosis of cancer and PICC gauge are associated with PICC-associated DVT. This conclusion is consistent with previous reports [2]. However, several issues described in this article warrant further discussion. First, the type of cancer and metastasis can influence the risk of venous thromboembolism (VTE). Patients with hematologic malignancies have a high incidence of PICCassociated DVT [3]. Lung cancer patients with advanced disease and/or receiving chemotherapy were at higher risk of VTE [4]. Patients with malignant processes involving the right lung, lymph nodes or other mediastinal structures may present with catheter thrombosis as a consequence of central vein compression and thrombosis. Metastasis is a risk factor for the development of VTE [5,6]. A retrospective cohort study found that metastatic cancer increased the risk of developing PICC-related DVT in chemotherapy patients [7]. Second, it was reported that the presence of a PICC is a risk factor for VTE [8,9]. In these studies, the VTE was usually identified through ICD-9 codes. The ICD-9 codes for VTE may include not only lower-extremity DVT (LEDVT), but also upper-extremity DVT (UEDVT), superficial thrombophlebitis, and chronic DVT [10]. It is well established that the pathophysiology of UEDVT is quite different from that of LEDVT [11]. Over 50% of patients with LEDVT had pulmonary embolism (PE) [12], whereas the incidence of PE resulting from UEDVT was 1% [13]. Furthermore, patients with asymptomatic DVT were not included in this retrospective study, and the incidence of this may be 14–18% [14]. The conclusion that PICC was associated with LEDVT was questionable because of these confounding factors. Third, a large number of prospective studies have found that increasing catheter size is significantly associated with an increased risk of UEDVT [15]. There may be an interaction between lumens and the diameter of PICCs. Evans et al. [15] found that the UEDVT incidence rates with the use of triple-lumen 5 Fr PICCs and the use of double-lumen 5 Fr PICCs were similar, and lower than the incidence rate with the use of triple-lumen 6 Fr PICCs. POWER-PICCs were usually 5 Fr and 6 Fr, which might increase the risk of UEDVT, although POWERPICCs did not confer a greater risk of thrombosis than non-POWER devices. We assume that, if fewer 5 Fr and 6 Fr PICCs are used in the non-POWER device group, the risk of VTE in this group might decrease. Fourth, in this study, 97.1% (n = 938) of the patients were male, and gender was not included in the logistic analysis. It was reported that male patients tend to develop catheter-related VTE [16]. Therefore, the demographics suggest a potential for bias, and could have an impact on the observed incidence. Additionally, several other risk factors that have been reported previously were not included in the logistic analysis, such as chronic obstructive pulmonary disease and diabetes mellitus [7]. In conclusion, the conceptual model may not be suitable for cancer patients and patients with asymptomatic PICC-related DVT. A further prospective study involving asymptomatic UEDVT is needed. Correspondence: Wei Chen, 1# Shuai Fu Yuan, Dongcheng District, Beijing 100730, China. Tel.: +86 1013911006820; fax: +86 1069154095 E-mail:txchenwei@sina.com