**2. Individual factors**

The individual risk factors associated with DIVA are age, gender, ethnicity, body mass index, health status, medical history, and vein characteristics of the patients [7, 12–14].

#### **2.1 Age**

The age of the individual might affect the intravenous catheter insertion. With increasing age, the vein diameter expands, thereby increasing the visibility and palpability of the veins [13, 15]. Therefore, it could be relatively difficult to determine the appropriate vein in neonates and children. According to the literature, the success rate of catheter insertion in the first attempt observed in the pediatric clinics varies between 44% and 86% [15, 16]. However, similar rates are observed in older ages. This might be because of the decreased elasticity of the blood vessels at an advanced age, which could contribute to DIVA. In the studies conducted by Van Loon et al. with 3586 participants and by Armenteros-Yeguas et al. (2017) with 135 participants, no relationship between the age of the individuals and DIVA was observed, although DIVA was observed to be related to the presence of chronic disease and medical treatment. The increased possibility of chronic diseases in advanced age would result in a medical treatment history, leading to DIVA [12, 13].

#### **2.2 Gender**

Studies have reported that gender is a risk factor for difficult venous access. Jacobson and Winslow (2005) reported that catheter insertion procedure is more difficult in women compared to men. This could be explained by the smaller caliber of peripheral veins in women [17]. Piredda et al. (2019) also reported gender as one of the risk factors for difficult venous access and that the procedure could be relatively difficult in women. In the same study, 99.4% of the women who underwent lymph node dissection experienced DIVA, suggesting an association; the multivariate analysis conducted in the study revealed that lymph node dissection did not exert a statistically significant effect on difficult cannulation [7].

#### **2.3 Ethnicity**

Individuals with different ethnicities may have different skin colors, and peripheral intravenous cannulation (PIVC) might be difficult in certain individuals of particular skin color. A narrative review published in 2010 by Sabri et al. reported an association between skin color and DIVA [18]. Jacobson and Winslow (2005) also reported that catheter insertion was more difficult in individuals with dark and/or tough skins [17].

#### **2.4 Body mass index**

Body mass index (BMI) is a measure of body fat based on the height and weight of the individual. An increase in weight may cause an increase in the adipose tissue and, therefore, a decrease in the visibility of the veins, rendering the catheter insertion difficult [14, 17]. Several studies have reported body mass index as a risk factor for difficult catheter insertion [7, 13, 14]. Sebbane et al. (2013) reported that underweight patients (BMI < 18.5 kg/m2) face a higher risk of DIVA. They stated that this result may be related to vein mobility [19]. However, Lapostolle et al. (2007) found no association with BMI and IV failure [20]. Fields et al. (2014) also did not find an association between obesity and DIVA [21]. This results may be related to patients characteristic.
