Development of a 'Phosphate Counting Program'

Overview

Hypothesis: The use of a program that assists with selection of the appropriate number of phosphate binders for a meal based on patient specific factors will result in improved serum phosphate control, a reduction in overall number of phosphate binders used and enhanced patient satisfaction. Primary Aim: To determine if teaching patients to use a 'phosphate counting' program installed on an iTouch that selects the appropriate amount of phosphate binder to be taken with each meal is associated with better phosphate control than usual care. Research Plan: There will be 3 phases to the study. Phase 1: Recruitment of 60 peritoneal dialysis (PD) patients. The information generated from this phase will be used to develop the iTouch program for phosphate counting and matching binder number. Phase 2: iTouch program once developed will be pilot tested on a convenience sample of 10 PD patients and modified if required. Phase 3: Randomized controlled trial of 92 PD patients to determine if using the iTouch phosphate counting program reduces serum phosphate compared to controls. Success would be based on seeing a statistically significant difference in serum phosphate as expected from our sample size calculation

Project approach and work plan: Phase 1: In the week prior to the collection of standard pre-clinic blood work (to include calcium, phosphate, PTH), PD patients will keep a 3-day diary that will include all foods and beverages consumed in addition to the portion sizes. At the time of standard pre-clinic bloodwork collection, patients will perform an adequest. Medication lists will be reviewed for: 1) Proton pump inhibitors/ H2 receptor antagonists 2) 25-hydroxyvitamin D3 and 1,25 dihydroxyvitamin D3 and 3) phosphate binders. Doses taken the week prior to standard pre-clinic blood work when the diet diaries are compiled will be recorded. This information will be used for 2 separate purposes: 1) A list of the foods that are actually being eaten by the PD patients will be generated 2) The 3-day average phosphate content will be estimated from each PD patient's food diaries. A regression equation that predicts serum phosphate concentration taking into account phosphate intake, the amount of phosphate binders taken, the dose of vitamin D, use of proton pump inhibitors/H2 antagonists, dialysis adequacy, and serum PTH concentration will be generated. Phase 2: An iTouch program will be developed using Phase 1 information to assist patients in meal phosphate counting and appropriate binder selection. Processes used to develop similar programs such as the pilot study in patients with diabetes mellitus will be used. A convenience sample of 10 PD patients will use the iTouch program for one month and document their impressions about ease of use, convenience and applicability to their diet choices. Changes to the program will be incorporated based on the patient's comments and laboratory values. If substantial changes are required, another convenience sample of 10 PD patients will be invited to use the program and provide feedback. Phase 3: 80 consenting PD patients from the Ottawa Hospital and St. Michael's Hospital (if required) will be randomized to usual care for managing phosphate versus use of the iTouch program for meal phosphate counting and matching binder use. This phase of the trial will last 3 months. As simply recording meal phosphate intake in the iTouch program may have an impact on patient behavior, the control group will be asked to enter this data into the program but no binder therapy information will be provided to the patients. During the course of the study, the dose of vitamin D and PD prescription will be held constant in both groups. Expected Outcome: Phase 1: All 60 PD patients will be recruited over a 6-month period. Data entry and statistical analysis are expected to take another 2-4 months. Phase 2: Actual development of the iTouch program using the data generated in phase 1 is expected to take about 6 months. It is anticipated that all 10 patients will be recruited over a 2-month period with a further one-month of follow-up. Interviews with the patients and collation of the data are expected to take another month. It is unclear how much time will be required to make adjustments to the iTouch program but we anticipate \<3months. Phase 3: We anticipate that we can recruit the 80 patients from the greater than 250 patients at the Ottawa Hospital and St Michaels Home Dialysis programs and complete the 3 months of follow-up in approximately 12-18months. Data analysis and manuscript preparation should take another 4-5 months. Feasibility Given the large number of PD patients in the two programs, the novelty of Phase 2 and 3 and the incentives in Phase 3, we do not anticipate difficulties with recruitment. The laboratory tests are all standard and visits will occur during a patient's regularly scheduled PD visit.