To the Editor—In 2015, we reported on the risk of central venous catheter (CVC)–related bloodstream infections (CRBSIs) in obese patients with hematological malignancies. ^{Reference Schalk, Färber, Fischer and Heidel1} Considering together definite, probable, and possible CRBSIs, ^{Reference Hentrich, Schalk and Schmidt-Hieber2} we detected no difference in the CRBSI rate between obese and nonobese patients (22.1% vs 23.3%). ^{Reference Schalk, Färber, Fischer and Heidel1} However, this analysis was based on only 335 CVC cases from the Magdeburg cohort of the SECRECY registry (German Clinical Trial Register, no. DRKS00006551). ^{Reference Schalk, Hanus, Färber, Fischer and Heidel3} Furthermore, we did not distinguish between obese and overweight patients. Although both obesity and overweight are associated with increased disease-specific morbidity for some diseases, obesity mostly confers a higher risk than overweight. ^{Reference Lenz, Richter and Mühlhauser4} Therefore, we updated our analysis on the CRBSI risk in both obese and overweight patients from the Magdeburg cohort of the SECRECY registry.

Patients with a body mass indexes (BMIs) of 18.5–24.9 kg/m² were considered normal weight, those with 25.0–29.9 kg/m² were considered overweight, and patients with a BMI ≥30 kg/m² were considered obese. ⁵ For a diagnosis of definite or probable CRBSI we used the 2012 definitions of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO). ^{Reference Hentrich, Schalk and Schmidt-Hieber2} From March 2013 to September 2021, 1,046 nontunneled jugular or subclavian vein CVCs were inserted in patients with a BMI of >18.5 kg/m². Patient and CVC characteristics as well as CRBSI features are shown in Table 1. A median of 1 CVC was inserted per patient (mean, 1.9; range, 1–7). In 699 cases (66.8%), CVCs were inserted in patients with BMI ≥25 kg/m²: 405 (38.7%) were overweight and 294 (28.1%) were obese. The median BMI of both overweight and obese patients was 26 kg/m² (range, 19–56). With respect to the entire group of patients, 21.7% were neutropenic at time of CVC insertion and 87.6% were neutropenic at at CRBSI onset, with no significant differences between groups. Most CVCs were inserted in the internal jugular vein and had chlorhexidine-coated CVC dressings.

Table 1.

Patients/CVCs Characteristics and CRBSI Features

Note. CVC, central venous catheter; CRBSI, central venous catheter–related bloodstream infection; dCRBSI, definite CRBSI ^{Reference Hentrich, Schalk and Schmidt-Hieber2} ; BMI, body mass index; IQR, interquartile range; HR, hazard ratio; CI, confidence interval. All P values are 2-sided.

^a Neutrophile granulocytes <500/µL or leucocytes <1,000/µL.

^b Combined definite or probable CRBSI. ^{Reference Hentrich, Schalk and Schmidt-Hieber2}

^c Mid-P exact test.

The median number of CVC days was lower in obese compared to normal weight or overweight patients (14 vs 17 days). However, the median time to CRBSI onset was similar between the groups (11 and 12 days, respectively). The CRBSI rate was significantly higher in the overweight as compared to the normal weight group (12.1% vs 7.5%; hazard ratio [HR], 1.66; 95% confidence interval [CI], 1.03–2.68; P = .04), whereas it was not significantly different between obese and normal weight patients (10.2% vs 7.5%; HR, 1.26; 95% CI, 0.97–1.64; P = .09).

Furthermore, the incidence of CRBSI was higher in overweight than the normal weight patients (7.4 per 1,000 CVC days vs 4.5 per 1,000 CVC days; P = .04) but not in obese compared to normal weight patients (7.0 per 1,000 CVC days vs 4.5 per 1,000 CVC days; P = .10).

These findings are somewhat surprising. Notably, the proportion of men in the overweight group was higher than in the obese group (68.1% vs 55.1; P < .001). Male sex was previously identified as an independent risk factor for CRBSI in patients with hematological malignancies, ^{Reference Schalk, Toelle and Schulz6} and this may have contributed to the higher CRBSI rate and incidence in the overweight group. However, in another sex-matched analysis of the whole cohort, we detected no significant difference in the CRBIS rate between the overweight and the normal weight group [22 (8.5%) of 258 vs 23 (7.7%) of 298; P = .73] nor between the obese and the normal weight group [26 (9.8%) of 264 vs 23 (7.7%) of 298; P = .38]. In addition, we detected no difference in the CRBSI incidence between the overweight and the normal weight group (5.1 per 1,000 CVC days vs 4.7 per 1,000 CVC days; P = .76) nor between the obese and the normal weight group (6.7 per 1,000 CVC days vs 4.7 per 1,000 CVC days; P = .20).

In summary, our results show that neither obesity nor overweight are risk factors for CRBSI in patients with hematological malignancies. However, we cannot rule out that both potential risk factors were merely masked by neutropenia, a well-established risk factor for CRBSI in hematological patients, ^{Reference Hentrich, Schalk and Schmidt-Hieber2,Reference Tölle, Hentrich and Pelzer7} which was present in ∼90% at CRBSI onset in our cohort. Apart from this, obesity has been shown to be an independent risk factor for CRBSIs in the ICU setting, ^{Reference Dossett, Dageforde and Swenson8,Reference Buetti, Souweine and Mermel9} possibly because of inadequate CVC dressings or CVC dressing disruption. ^{Reference Buetti, Souweine and Mermel9,Reference Trick, Miranda, Evans, Charles-Damte, Reilly and Clarke10}