SP409PSYCHOLOGICAL ASPECTS OF THE COMPLIANCE TO LOW PROTEIN DIETS IN PRE-DIALYSIS CHRONIC KIDNEY DISEASE PATIENTS

Abstract

Introduction and Aims: Low-protein diets (LPDs) were associated with ammelioration of metabolic disorders of Chronic Kidney Disease (CKD), preserving the nutritional status in compliant patients. Their use was not extended, mainly because of reported poor compliance; interest recently resurged. Psychological aspects of CKD patients could be involved in compliance, with impact on subjects selection and long-term compliance. This cross-sectional single-center study aimed to evaluate psychological characteristics of CKD patients in relation with their compliance to LPDs (NCT 022173241). Methods: All the 112 consecutive adult patients, stage 4+ CKD (estimated GFR<30 mL/min-yr, MDRD4) following one of the LPDs [(i) ketodiet (KD: vegetarian very LPD - 0.3 g/kg ideal bw-day supplemented with ketoanalogues of essential amino acids-Ketosteril) or (ii) conventional mixed low protein diet (LPD - 0.6 g/kg per day] with scheduled visits were enrolled during 6 mo. Apart of nephrological monitoring according to Best Practice Guidelines, psychological assessment was performed by a single examiner, using a questionnaire focusing on potential predictors of dietary compliance and including parts of questionnaires validated for Romanian language, with 4 dimensions: auto-efficacy scale, illness perception questionnaire, items related to mental component in Short Form 36 (SF-36) and a diet-focused questionnaire. Parameters related to renal function and complications of CKD, as well as safety variables (dietary compliance, nutritional status, occurrence of adverse events) were registered. Data were compared between patients on KD and those on LPD. Results: Analysis was performed on 88 subjects [44% males, median age 57.6 (54.1-61.1) yrs, eGFR 22.2 (21.3-24.2) mL/min, 32% primary glomerulopathies, 30% vascular, 15% interstitial and 15% other kidney diseases], 56 on KD and 32 on LPD, with no difference between groups in age, gender or cause of CKD. A significantly lower percentage of diabetics followed KD (20 vs 44% LPD, p=0.01). Subjects compliant to KD had longer CKD duration [84 (48-108) vs 42 (24-60) mo, p=0.01], lower eGFR at diet initiation [20.3 (18.1-22.2) vs 24.5 (23.2-27.5), p<0.01] and poorer metabolic control as compared to those on LPD: at the beginning of nutritional intervention, patients in KD group had higher serum levels of urea [203 (181-224) vs 154 (129-177) mg/dL, p<0.01] and phosphates [5.6 (4.9-6.2) vs 4.3 (3.9-5.4) mg/dL, p=0.02), lower serum bicarbonate [18.2 (17.4-18.5) vs 17.5 (15.9-18.4) mEq/L, p<0.01)] and serum calcium [3.9 (3.8-4.0) vs 4.1 (3.9-4.2) mg/dL p=0.01]. Patients compliant to KD had superior knowledge on CKD and diet [right answers: 35 vs 12%, p<0.01], lower emotional impact of the disease [10 (9-12) vs 14 (11-16), p<0.01], higher confidence in diet effectiveness [1.1 (0.9-1.3) vs 2.1 (1.7-2.5), p<0.01], greater anticipated rate of success [8.3 (8.1-8.6) vs 6.8 (6.3-7.3), p<0.01], higher self-efficacy [19 (17-20) vs 16 (14-18), p=0.05], vitality [75 (70-75) vs 65 (55-75), p=0.04)] and mental health scores [80 (76-80) vs 72 (64-76), p<0.01], greater marital satisfaction and expected long-term support [4.6 (4.4-4.8) vs 4.1 (3.9-4.3), p<0.01] and better relationship with nephrologist [4.9 (4.8-5.0) vs 4.6 (4.4-4.7), p<0.01]. Conclusions: Non-diabetic patients, those with longer CKD duration, with lower level of renal function and poorer metabolic control are more proned to follow severe LPDs. Psychological factors seem to be involved in dietary compliance and should be considered in subjects selection and monitoring.