Association of socio-psychological factors with the effects of low protein diet for the prevention of the progression of chronic renal failure

Abstract

Objective: Our objectives were to investigate the therapeutic effects of low protein diet (LPD) for chronic renal failure (CRF) in compliant patients with the diet, and to clarify the relationships to the socio-psychological factors. Patients and methods: Sixty-five patients (47 men and 18 women) with CRF who followed LPD (0.69 g/kg/day) for more than 3 months were recruited in this study. Compliance with the diet therapy was strictly assessed by the patients' dietary records, subsequent interviews regarding the status of daily dietary intake and estimated protein intakes calculated from urinary nitrogen excretion by 24-hour urine collections. The changes of glomerular filtration rate (GFR), serum creatinine (Cr), blood urea nitrogen (BUN), the reciprocal of serum creatinine (1/Cr), scores of Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), scales of Profile of Mood States (POMS), scores of self-efficacy and social support were investigated. Results: Decline rate of GFR, elevation of Cr and BUN and reduction in 1/Cr were significantly lower in compliant patients than in non-compliant patients (p<0.05). There were no differences in SF-36 scores between compliant and non-compliant patients. The POMS scales of depression/dejection were high in female non-compliant patients compared to other groups of patients (p<0.05). Self-efficacy score was higher in compliant patients than in non-compliant patients (p<0.05). Social support scores were significantly higher in male compliant patients than in others (p<0.05), and both emotional support and behavioral support showed interaction with both gender and compliance with diet therapy (p<0.05). Conclusion: LPD therapy is effective in suppressing the progression of CRF when it is well-adhered to. There are no correlations of this diet therapy to health-related QOL. Social support and high self-efficacy for men and high self-efficacy for women are associated with improvement of the compliance with LPD therapy, leading to good therapeutic effects. © 2006 The Japanese Society of Internal Medicine.