Given my background in nephrology, a recent paper by Sharon Nessim and colleagues from the Jewish General Hospital, Montreal, Quebec, published in Peritoneal Dialysis International caught my attention.
This paper looked at the relationship between BMI and the risk of peritonitis and catheter infections in about 1000 peritoneal dialysis (PD) patients in the province of Manitoba who received PD during the period 1997 – 2007.
In unadjusted analyses, patients in the highest BMI quartile (median: 33.5) had an increased risk of peritonitis overall, and also an increased risk of peritonitis with gram-positive organisms and coagulase-negative Staphylococcus (CNS).
However, after multivariate adjustment for age, sex, diabetes, cause of renal disease, Aboriginal race, PD modality, and S. aureus nasal carriage, the relationship between overall peritonitis risk and BMI disappeared, but the increased risk of CNS peritonitis among patients in the highest BMI quartile persisted (hazard ratio: 1.80).
Thus, while patients with higher BMI on PD are clearly at greater risk of experiencing infections, this risk is largely explained by other concomitant factors than by BMI itself. If anything, obese patients in the highest weight category appear more prone to CNS peritonitis.
Obviously this risk is certainly not high enough or specific enough to deter anyone from chosing PD as a mode of dialysis. Nevertheless, it is probably a finding that clinicians (especially nephrologists) may need to be aware of.
Nessim SJ, Komenda P, Rigatto C, Verrelli M, & Sood MM (2012). FREQUENCY AND MICROBIOLOGY OF PERITONITIS AND EXIT-SITE INFECTION AMONG OBESE PERITONEAL DIALYSIS PATIENTS. Peritoneal dialysis international : journal of the International Society for Peritoneal Dialysis PMID: 22942268