Among individuals with chronic kidney disease (CKD), impaired immune function is a risk factor for infection. The high prevalence of obesity in that patient population may also be a risk factor for developing serious infections.
Yefei Yu, MPH, and colleagues analyzed data from 5,499 participants in the Chronic Renal Insufficiency Cohort Study to identify the association between measures of obesity and body composition and time to first hospitalization for infection. Body mass index was stratified as underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), and class 1 (30.0-34.9 kg.m2), class 2 (35.0-39.9 kg/m2), and class 3 (≥40.0 kg/m2) obesity. Measures of body cell mass (phase angle) and tissue hydration status (vector length) were grouped into quartiles. The researchers used multivariable Cox models to estimate adjusted hazard ratios (aHRs) for all-cause infection and by infection subtype.
Follow-up continued for a median of 4.7 years. During that time, 2,913 participants were hospitalized with infection. Class 3 obesity and underweight were associated with a higher risk for all-cause infection compared with normal weight (aHR, 1.35; 95% CI, 1.16-1.57 and 1.76; 95% CI, 1.06-2.93, respectively). Compared with the highest quartile, there were significant associations between the lowest quartiles of phase angle and vector length with a higher risk of all-cause infection (aHR, 1.39; 95% CI, 1.22-1.57 and 1.17; 95% CI, 1.02-1.33, respectively).
The association between obesity and the risk for infection was particularly strong for skin and soft tissue infection (aHR, 1.98; 95% CI, 1.54-2.54), but not for other infections, such as respiratory tract infection (aHR, 0.96; 95% CI, 0.77-1.19). Across subtypes, underweight and shallow phase angle were broadly associated with the risk of infection.
“Among people with CKD, both obesity and underweight were significantly associated with the risk of infection,” the authors said. “The association of obesity with skin infection, relative to other infection subtypes, warrants further investigation.”