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

Kittiskulnam 2014.

Study characteristics
Methods

  • Study design: prospective RCT (299 patients assessed for eligibility; 26 randomised)

  • Recruitment: enrolment July 2012 to February 2013

  • Study duration: 6 months
Participants

  • Country: Thailand

  • Setting: single centre, outpatient hospital clinic

  • Inclusion criteria: aged 18 to 65 years; biopsy‐proven IgAN with persistent proteinuria > 1 g/day (despite maximal tolerated doses of ACEIs or ARBs) on at least 3 consecutive determinations in the 6‐month period before the study; overweight or obese (defined by BMI > 23 kg/m² obesity criteria in Asia Pacific); BP control below 125/75 mmHg. For the patients who were receiving steroid and/or immunosuppressive agents, the dose adjustment was prohibited for the previous 6 months before enrolment

  • Number: low energy diet group (13); usual dietary intake group (13)

  • Mean age ± SD (years): low energy diet group (45.5 ± 11.9); usual dietary intake group (45.4 ± 16.2)

  • Sex (M/F): low energy diet group (6/7); usual dietary intake group (6/7)

  • Baseline characteristics

    • Nationality: not reported

    • Ethnicity: not reported

    • Mean baseline BMI ± SD (kg/m²): low energy diet group (28.5 ± 4.8); usual dietary intake group (28.7 ± 4.8)

    • Stage of CKD: stages 1 to 4

    • Mean baseline eGFR ± SD (mL/min/1.73 m²): low energy diet group (60.1 ± 25.5); usual dietary intake group (56.6 ± 29.6)

    • Mean baseline SBP ± SD (mmHg): low energy diet group (125.1 ± 8.5); usual dietary intake group (124.8 ± 14.7)

    • Mean baseline DBP ± SD (mmHg): low energy diet group (75.1 ± 5.3); usual dietary intake group (74.9 ± 10.0)

    • Mean baseline energy intake (kJ/day): not reported

    • Comorbid conditions: type 2 diabetes (15%); metabolic syndrome (50%)

  • Exclusion criteria: rapid loss of GFR > 30% in 6 months; nephrotic‐range proteinuria requiring immunosuppressive treatments; presence of crescent formation more than 10% in kidney biopsy; GFR < 15 mL/min/1.73 m²; BMI > 40 kg/m²; diabetic kidney disease; pregnancy or lactation; malignancy‐state patients with clinical malnutrition
Interventions

  • Intervention type classification: lifestyle

  • Weight loss intervention/s used: dietary


Intervention group (low‐energy diet group)

  • Participants were instructed to reduced energy intake by 500 kcal/day and prescribed low‐protein diet (0.6 to 0.8 g/kg/day), and restriction of sodium intake to < 2 g/day with macronutrient content of 25% to 30% fat and 55% to 60% carbohydrates for a 6‐month period

  • Participants also received standard treatments of care including maximal dosage of ACEi or ARB and other antihypertensive agents to achieve a BP < 125/75 mmHg. Participants were also advised about diet that retards CKD progression. Participants received once a month clinic visits and phone calls in‐between. The intervention was delivered by a clinician and nutritionist


Control group (usual dietary intake group)

  • Participants received standard treatments of care including maximal dosage of ACEi or ARB and other antihypertensive agents to achieve a BP < 125/75 mmHg and prescribed low‐protein diet (0.6 g/kg to 0.8 g/kg/day), and restriction of sodium intake to < 2 g/day. Participants were also advised about diet that retards CKD progression. Participants received once a month clinic visits and phone calls in‐between. The intervention was delivered by a clinician and nutritionist


Co‐interventions

  • Participants in both groups were also informed to stop smoking and avoid NSAIDs

  • Participants in both groups were encouraged to engage in moderate‐intensity aerobic exercises at least 3 to 5 days/week that lasted 30 minutes for each session
Outcomes

  • Body weight (kg)

  • Weight loss (kg)

  • BMI (kg/m²)

  • Waist circumference (cm)

  • Body composition (% body fat, % muscle)

  • SCr (mg/dL)

  • Proteinuria (g/day)

  • SBP (mmHg)

  • DBP (mmHg)

  • Fasting blood glucose (mg/dL)

  • Total cholesterol (mg/dL)

  • LDL cholesterol (mg/dL)

  • HDL cholesterol (mg/dL)

  • Triglycerides (mg/dL)

  • Dietary intake energy intake (kcal/day)
Notes

  • Founding source: Ratchadapiseksompotch Fund, Chula‐longkorn University

  • Additional data: not requested

  • Trial registration: Clinical trial registration (clinicaltrial.gov NCT01773382)

  • Possible conflicts of interest for study author: not declared
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Quote: "patients were randomised by block randomisation using varying blocks into two groups"
Allocation concealment (selection bias) Unclear risk Insufficient information to permit judgement
Blinding of participants and personnel (performance bias)
All outcomes High risk Neither participants nor personnel were blinded
Blinding of outcome assessment (detection bias)
All outcomes High risk Quote: "The clinician and nutritionist who gave dietary advice were not blinded". These same clinicians were responsible for measuring and recording a number of outcome data including body weight
Incomplete outcome data (attrition bias)
All outcomes Low risk No study dropouts and no missing data
Selective reporting (reporting bias) Unclear risk Insufficient information to permit judgement. Not study protocol published. Dietary compliance information collected but not reported
Other bias Unclear risk Study appears free of other biases. Quote: "The study statistician was blinded throughout the study"