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. 2021 Mar 30;2021(3):CD013119. doi: 10.1002/14651858.CD013119.pub2

Ikizler 2018.

Study characteristics
Methods

  • Study design: prospective RCT (2 x 2 factorial design)

  • Recruitment: October 2010 to February 2014.

  • Study duration: 4 months
Participants

  • Country: USA

  • Setting: multicentre (medical centre (2), medical research centre (1), University (1))

  • Inclusion criteria: CKD stages 3 and 4 (eGFR 15 to 60 mL/min/1.73 m²); aged 18 to 75 years; BMI ≥ 25 kg/m²; life expectancy ≥ 1 year; ability to understand and provide informed consent

  • Number: aerobic exercise + energy restriction group (24); usual activity + energy restriction group (28); aerobic exercise + usual diet group (27); usual activity + usual diet group (26)

  • Median age, IQR (years): aerobic exercise + energy restriction group (53.5, 49.2 to 59.8); usual activity + energy restriction group (58.5, 45.8 to 62.0); aerobic exercise + usual diet group (58.0, 48.5 to 62.0), usual activity + usual diet group (58.55,45.8 to 64.0)

  • Sex (M/F): aerobic exercise + energy restriction group (17/13); usual activity + energy restriction group (15/13); aerobic exercise + usual diet group (15/12); usual activity + usual diet group (17/9)

  • Baseline characteristics

    • Nationality: not reported

    • Ethnicity (white/black/other): aerobic exercise + energy restriction (22/7/1); usual activity + energy restriction (19/9/0); aerobic exercise + usual diet (17/1/3); usual activity + usual diet (16/8/2)

    • Median baseline BMI, IQR (kg/m²): aerobic exercise + energy restriction group (32.8, 30.4 to 35.8); usual activity + energy restriction group (32.8, 28.7 to 37.1); aerobic exercise + usual diet group (31.0,28.0 to 36.2); usual activity + usual diet group (35.5, 30.6 to 41.5)

    • Stage of CKD: CKD stages 3 to 4

    • Median baseline eGFR, IQR (mL/min/1.73 m²): aerobic exercise + energy restriction group (41.8, 27.1 to 483); usual activity + energy restriction group (44.6, 31.9 to 52.9); aerobic exercise + usual diet group (44.0, 30.2 to 51.2); usual activity + usual diet group (39.1, 31.1 to 49.8)

    • Median baseline SBP, IQR (mmHg): aerobic exercise + energy restriction group (128, 109 to 141); usual activity + energy restriction group (132, 118 to 141); aerobic exercise + usual diet group (134, 114 to 144); usual activity + usual diet group (136, 118 to 142)

    • Median baseline DBP, IQR (mmHg): aerobic exercise + energy restriction group (75.0, 68.0 to 84.2); usual activity + energy restriction group (78.0, 71.5 to 86.5); aerobic exercise + usual diet group (78.0, 73.5 to 84.0); usual activity + usual diet group (76.5, 72.0 to 83.0)

    • Mean baseline energy intake, IQR (kcal/day): not reported

    • Comorbid conditions: type 2 diabetes (25%); hypertensive (91%)

  • Exclusion criteria: any acute inflammatory condition (including chronic infection requiring treatment and collagen vascular disease, including active gout); pregnancy; taking high‐dose antioxidants (vitamin E or C); chronic use of anti‐inflammatory medication, except low‐dose (< 10 mg/day) prednisone and aspirin (< 100 mg/day); significant cardiac or vascular disease (symptomatic disease or CVD event, including congestive heart failure, within 6 months); significant occlusive atherosclerotic disease or Ischaemic disease (on non‐invasive or invasive diagnostic procedures); significant physical immobility or disabilities (joint replacement or muscular disorders); type 1 diabetes mellitus or type 2 diabetes mellitus requiring insulin therapy; history of poor adherence to medical regimen
Interventions

  • Intervention type classification: lifestyle

  • Weight loss intervention/s used: dietary + physical activity


Aerobic exercise + energy restriction group

  • Supervised aerobic exercise physical activity for a maximum of 30 to 45 minutes, 3 times/week and 10% to 15% reduction in total daily energy intake (300 kcal to 500 kcal reduction) from the usual daily energy consumption for 4 months duration. The exercise sessions were delivered by an exercise specialist and clinical exercise physiologists. The goal was for a training intensity of approximately 60% to 80% VO²Max. It is not reported who delivered the dietary intervention nor what educational materials and counselling were provided.


Usual activity + energy restriction group

  • 10% to 15% reduction in total daily energy intake (300 kcal to 500 kcal reduction) from the usual daily energy consumption for 4 months duration. It is not reported who delivered the dietary intervention nor what educational materials and counselling were provided


Aerobic exercise + usual diet group

  • Supervised aerobic exercise physical activity for a maximum of 30 to 45 minutes, 3 times/week for 4 months duration. The exercise sessions were delivered by an exercise specialist and clinical exercise physiologists. The goal was for a training intensity of approximately 60 to 80% VO²Max


Usual activity + usual diet group

  • Advised to continue with usual diet and usual activity


Co‐interventions

  • All study participants received information as part of a CKD diet. They were advised to include large amounts of fresh unprocessed plant foods with moderate levels of lean protein and fats and avoid high energy rich meals in processed, easily digestible, quickly absorbable foods and drinks
Outcomes

  • Body weight (kg)

  • Weight loss (kg)

  • BMI (kg/m²)

  • Waist‐to‐hip ratio

  • Body composition (% body fat)

  • SBP (mmHg)

  • DBP (mmHg)

  • HbA1c (%)

  • Fasting blood glucose (mg/dL)

  • Adverse events

  • Adherence to treatment
Notes

  • Founding source: National Institutes of Health grants R01HL070938 from National Heart, Lung, and Blood Institute; K24DK62849, P30DK020593, and P30DK035816 from National Institute of Diabetes and Digestive and Kidney Diseases; P30ES000267 from the National Institute of Environmental Health Sciences; and Clinical Translational Science Awards UL1‐TR000445 and UL1TR000423 from the National Center for Advancing Translational Sciences

  • Trial registration: ClinicalTrials.gov No. NCT01150851

  • Possible conflicts of interest for study author: none declared
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Quote: "Participants were assigned to one of the study arms using a permuted block randomisation strategy 1:1 ratio"
Allocation concealment (selection bias) Unclear risk Insufficient information about the sequence generation process to permit judgment
Blinding of participants and personnel (performance bias)
All outcomes High risk Quote: "Because of the nature of the intervention, the study was unblinded"
Blinding of outcome assessment (detection bias)
All outcomes Unclear risk Insufficient information about the blinding of outcome assessments to permit judgment
Incomplete outcome data (attrition bias)
All outcomes Low risk 11.5% attrition rate with balanced dropouts across each groups with similar reasons across groups for withdrawal
Selective reporting (reporting bias) Unclear risk No study protocol paper published. Authors appear to report on what they intended to report on as described in the study aims
Other bias Low risk The study appears to be free of other sources of bias