Association of a reduction in central obesity and phosphorus intake with changes in urinary albumin excretion: the PREMIER study.
BACKGROUND
Excess adiposity and dietary factors may be important determinants of urinary albumin excretion (UAE).


STUDY DESIGN
Observational analysis of PREMIER, a randomized trial designed to lower blood pressure using behavioral interventions (counseling on weight loss, healthy diet, and exercise).


SETTING & PARTICIPANTS
481 participants with normal kidney function who provided adequate 24-hour urine collections at baseline and 6 months.


PREDICTORS
Change in waist circumference; 24-hour urine sodium, potassium, and phosphorus excretion; and protein intake estimated from urea nitrogen.


OUTCOMES & MEASUREMENTS
The primary outcome was change in log-transformed 24-hour UAE over 6 months.


RESULTS
After 6 months, the proportion of individuals with UAE ≥10 mg/d decreased from 18.7% to 12.7% (P < 0.001). Changes in mean waist circumference (-4.2 ± 6.6 [SD] cm), 24-hour excretion of sodium (-28.2 ± 71.7 mmol/d), potassium (+8.4 ± 27.8 mmol/d), phosphorus (-27.7 ± 314.1 mg/d), and protein intake (-1.7 ± 19.4 g/d) were observed. After adjustment for relevant covariates, the following variables were associated significantly with reduction in ln(UAE) in separate models: decrease in waist circumference (P = 0.001), decrease in 24-hour urine phosphorus excretion (P < 0.001), and decrease in protein intake (P = 0.01). In a multivariable model including these 3 predictors, decreases in waist circumference (P = 0.002) and 24-hour urine phosphorus excretion (P = 0.03), but not change in protein intake (P = 0.5), remained associated significantly with reduction in ln(UAE). These associations remained significant even after adjustment for changes in blood pressure and insulin resistance. Baseline UAE and metabolic syndrome modified the relationship of waist circumference with ln(UAE); specifically, individuals with higher UAE and baseline metabolic syndrome experienced greater reductions in ln(UAE) from decreases in waist circumference.


LIMITATIONS
Observational study with potential for confounding.


CONCLUSIONS
In adults with normal kidney function, decreases in waist circumference and 24-hour urine phosphorus excretion are associated with reductions in UAE. These findings support the rationale for clinical trials to determine whether reducing dietary phosphorus intake or waist circumference could prevent chronic kidney disease or slow its progression.
['Chang|Alex|A|', 'Batch|Bryan C|BC|', 'McGuire|Heather L|HL|', 'Vollmer|William M|WM|', 'Svetkey|Laura P|LP|', 'Tyson|Crystal C|CC|', 'Sanguankeo|Anawin|A|', 'Anderson|Cheryl|C|', 'Houston|Jessica|J|', 'Appel|Lawrence J|LJ|']
D000328:Adult D000419:Albuminuria D003131:Combined Modality Therapy D015444:Exercise D005260:Female D006801:Humans D006973:Hypertension D007674:Kidney Diseases D008297:Male D008875:Middle Aged D056128:Obesity, Abdominal D010758:Phosphorus D016226:Phosphorus, Dietary D011188:Potassium D058246:Prehypertension D012964:Sodium D016896:Treatment Outcome D055105:Waist Circumference
phosphorus urinary albumin excretion Weight loss waist circumference protein