Background: People with end-stage kidney disease (ESKD) develop impaired excretion of phosphate. Hyperphosphatemia develops in ESKD as a result of the kidney's reduced ability to excrete ingested phosphate load and is characterized by high bone turnover and increased musculoskeletal morbidity including bone pain and muscle weakness. Increased serum phosphate levels are also associated with cardiovascular disease and associated mortality. These effects are significant considering that cardiovascular disease is the leading cause of death in ESKD, making phosphate control a crucial treatment goal.
Objectives: To determine the effectiveness of education or behavioral interventions on adherence to phosphate control in adults with ESKD receiving hemodialysis (HD).
Inclusion criteria types of participants: Adults aged over 18 years with ESKD undergoing HD, attending dialysis facilities regardless of frequency and duration of treatment sessions per week. Studies with participants receiving hemodiafiltration were excluded.
Types of intervention(s)/phenomena of interest: All types of educational and behavioral interventions aimed at improving adherence to dietary phosphate restriction, phosphate binder medication and HD.
Types of studies: Randomized controlled trials (RCTs), non-RCTs, before and after and cohort studies.
Outcomes: Outcome measures included serum phosphate levels, patient knowledge and adherence to phosphate control methods, chronic kidney disease (CKD) self-management behavior and perceived self-efficacy for CKD related to phosphate control.
Search strategy: A search was conducted in CINAHL, MEDLINE, The Cochrane Library, Embase, Web of Science, PsycINFO and ProQuest Dissertations and Theses Global to find published studies between January 2005 and December 2015.
Methodological quality: Risk of bias was assessed by three reviewers prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI).
Data extraction: Data were extracted using the standardized data extraction tool from JBI-MAStARI.
Data synthesis: Data were pooled using JBI software. Mean differences (95% confidence interval [CI]) and effect size estimates were calculated for continuous outcomes. Meta-analysis using a random-effects model was performed for serum phosphate levels, and where the findings could not be pooled using meta-analysis, results have been presented in a narrative form. Standard GRADE (Grading of Recommendations Assessment, Development and Evaluation) evidence assessment of outcomes has been reported.
Results: A total of 18 studies were included in the review: seven studies focused on dietary phosphate, four studies focused on medications (phosphate binders) and six studies focused on dietary phosphate and medications. Only one study taught patients about diet, medications and HD to control phosphate. Sixteen studies showed significant improvements in phosphate levels. Meta-analysis of eight RCTs favored educational or behavioral interventions over standard care for serum phosphate control, with a weighted mean reduction of -0.23 mmol/l (95% CI -0.37, -0.08) in treatment groups.
Conclusion: Overall, educational or behavioral interventions increase adherence to phosphate control. Studies in this systematic review revealed improved outcomes on serum phosphate levels, patient knowledge and adherence to phosphate control methods, CKD self-management behavior and perceived self-efficacy for CKD related to phosphate control. However, there is a lack of sufficient data on how some of the studies implemented their interventions, suggesting that further research is required. Successful strategies that improve and optimize long-term adherence to phosphate control still need to be formulated.