Obesity, smoking, and physical inactivity as risk factors for CKD: are men more vulnerable?
ABSTRACT The incidence of end-stage renal disease is especially high in men, and some studies indicated that smoking is a risk factor for men only. We investigated associations between obesity, smoking, and physical inactivity and chronic kidney disease (CKD) in the general population and whether risk for CKD was restricted to men.
This was a cross-sectional health survey of the entire adult population of Nord-Trondelag County, Norway, 1995 to 1997, with a 70.6% participation rate. Glomerular filtration rate (GFR) was estimated in all subjects 20 years and older from calibrated serum creatinine levels by using the simplified Modification of Diet in Renal Disease Study formula, and CKD cases are defined as those with a GFR less than 45 mL/min/1.73 m2 (< 0.75 mL/s).
A total of 30,485 men and 34,708 women were included, and prevalences of GFR less than 45 mL/min/1.73 m2 (< 0.75 mL/s) were 0.8% and 1.1%, respectively. Age- and sex-adjusted logistic regression analyses showed dose-response relations for body mass index, smoking history, and physical activity. Relative risks were 1.77 (95% confidence interval [CI], 1.47 to 2.14) for obesity (body mass index > or = 30 kg/m2), 1.52 (95% CI, 1.13 to 2.06) for smoking (> 25 pack-years), and 2.14 (95% CI, 1.39 to 3.30) for physical inactivity (no or some physical activity in leisure time). For subjects with all these risk factors, relative risk was 5.10 (95% CI, 2.36 to 11.01). These results remained significant after adjusting for other known risk factors. No biological interactions between sex and obesity, smoking, or physical activity were found.
Obesity, smoking, and physical inactivity were associated significantly with CKD. Men were not more susceptible to these risk factors than women.
Article: Association of morbid obesity and weight change over time with cardiovascular survival in hemodialysis population.[show abstract] [hide abstract]
ABSTRACT: In maintenance hemodialysis (MHD) outpatients, a reverse epidemiology is described, ie, baseline obesity appears paradoxically associated with improved survival. However, the association between changes in weight over time and prospective mortality is not known. Using time-dependent Cox models and adjusting for changes in laboratory values over time, the relation of quarterly-varying 3-month averaged body mass index (BMI) to all-cause and cardiovascular mortality was examined in a 2-year cohort of 54,535 MHD patients from virtually all DaVita dialysis clinics in the United States. Patients, aged 61.7 +/- 15.5 (SD) years, included 54% men and 45% with diabetes. Time-dependent unadjusted and multivariate-adjusted models, based on quarterly-averaged BMI controlled for case-mix and available time-varying laboratory surrogates of nutritional status, were calculated in 11 categories of BMI. Obesity, including morbid obesity, was associated with better survival and reduced cardiovascular death, even after accounting for changes in BMI and laboratory values over time. Survival advantages of obesity were maintained for dichotomized BMI cutoff values of 25, 30, and 35 kg/m2 across almost all strata of age, race, sex, dialysis dose, protein intake, and serum albumin level. Examining the regression slope of change in weight over time, progressively worsening weight loss was associated with poor survival, whereas weight gain showed a tendency toward decreased cardiovascular death. Weight gain and both baseline and time-varying obesity may be associated with reduced cardiovascular mortality in MHD patients independent of laboratory surrogates of nutritional status and their changes over time. Morbidly obese patients have the lowest mortality. Clinical trials need to verify these observational findings.American Journal of Kidney Diseases 10/2005; 46(3):489-500. · 5.43 Impact Factor
Report of the World Health Organization Consultation of Obesity.
Article: Beyond body mass index.[show abstract] [hide abstract]
ABSTRACT: Body mass index (BMI) is the cornerstone of the current classification system for obesity and its advantages are widely exploited across disciplines ranging from international surveillance to individual patient assessment. However, like all anthropometric measurements, it is only a surrogate measure of body fatness. Obesity is defined as an excess accumulation of body fat, and it is the amount of this excess fat that correlates with ill-health. We propose therefore that much greater attention should be paid to the development of databases and standards based on the direct measurement of body fat in populations, rather than on surrogate measures. In support of this argument we illustrate a wide range of conditions in which surrogate anthropometric measures (especially BMI) provide misleading information about body fat content. These include: infancy and childhood; ageing; racial differences; athletes; military and civil forces personnel; weight loss with and without exercise; physical training; and special clinical circumstances. We argue that BMI continues to serve well for many purposes, but that the time is now right to initiate a gradual evolution beyond BMI towards standards based on actual measurements of body fat mass.Obesity Reviews 09/2001; 2(3):141-7. · 7.04 Impact Factor
General discussion and summary
The main objective of this thesis was to study the association between nutritional
status and survival in end-stage renal disease patients who are maintained on a
chronic dialysis treatment. The majority of the studies presented in this thesis have
been performed in the Netherlands Cooperative Study on the Adequacy of Dialysis-2
Study (NECOSAD-II), a prospective, longitudinal, observational multi-center cohort
study that has been performed since 1997 in The Netherlands. The first part of this
general discussion will reflect on the strengths and limitations of the nutritional
status information and other data in NECOSAD-II. The second part will translate our
findings into implications and recommendations for future research.
STRENGTHS AND LIMITATIONS
Strengths of NECOSAD-II include its large sample size, the 6-monthly measurements
and the long follow-up. Another important strength of the NECOSAD-II study design
is that only incident dialysis patients were included. Most large cohort studies in the
dialysis population have been performed in prevalent populations.1;2 Studies in
prevalent patient populations can be very valuable for public health planning, but
outcome studies in prevalent patient populations may lead to inconsistent results.
The reason for this is that dialysis patients who have a better health status may live
longer and may represent a relatively large proportion in a prevalent dialysis cohort.
A cohort of incident dialysis patients who are included and followed from the start
of their dialysis treatment, like NECOSAD-II, provides valid information about the
prognosis of a patient with end-stage renal disease starting hemodialysis or
peritoneal dialysis treatment.
Assessment of nutritional status
Several nutritional parameters have been measured at the start of dialysis and every
six months of follow-up in NECOSAD-II. In principle, nutritional status may be best
measured with reference standards such as magnetic resonance imaging, total body
potassium, or total body nitrogen. However, since epidemiological studies
investigating survival need to have large sample sizes, these methods are too
expensive and time-consuming and surrogate measures are needed. The following
paragraphs will discuss the strengths and limitations of each nutritional parameter