Introduction Obesity is a major health problem worldwide. It carries a markedly increased risk for multiple diseases such as type 2 diabetes mellitus, hypertension, cardiovascular disease (CVD) and chronic kidney disease (CKD). To complicate an already difficult topic a new subtype of obesity has been defined lately, the metabolically healthy obese. Our study aimed to clarify the association between obesity, metabolic syndrome and kidney disease progression. Methods Observational retrospective single centre study including 212 patients with stage 3–4 CKD with no previous history of rapid kidney disease progression. Patients were divided according to BMI status and presence of metabolic syndrome. Anthropometric, clinical and laboratory data were collected to follow-up. Propensity score matching was performed for age, albuminuria and baseline renal function. During follow-up renal and cardiovascular events were recorded. Results After a mean follow-up of 88.44 ± 36.07 months a total of 18 patients reached the renal outcome in the non-obese group and 21 in the obese group. Differences were not statistically significant (log rank = 0.21: p = 0.64). Multiple Cox regression analysis showed that obesity was not predictor for worse renal outcomes [HR 1.01, 95% CI 0.45–2.24; p = 0.97]. When stratifying the sample according to baseline metabolic syndrome and obesity presence there was no difference in renal survival (log rank = 0.852; p = 0.35) A total of 48 cardiovascular events were registered: seventeen in the non-obese group and thirty-one in the obese group. Differences in event-free time between both groups were statistically significant (log rank = 4.44; p = 0.035), especially after four years of follow-up. After stratifying for MS and obesity presence at baseline the event-free time differences where again statistically significant (log rank = 16.86; p = 0.001), specially for the obese patients with metabolic syndrome. Conclusions Obesity has little impact on chronic kidney disease progression despite the presence or absence of metabolic syndrome in a cohort matched for age, baseline renal function and albuminuria. Obesity conferred greater cardiovascular risk when combined with metabolic syndrome.
