title: Patient-Reported Factors Associated With Poor Phosphorus Control in a Maintenance Hemodialysis Population.
abstract: The purpose of this study was to determine the influence of patient-reported medication adherence and phosphorus-related knowledge on phosphorus control and pharmacy-reported adherence to phosphorus binding medication among patients on maintenance hemodialysis.
  
  
  
  Retrospective, cross-sectional cohort study.
  
  
  
  Seventy-nine hemodialysis patients (mean age 64.2 years, SD = 14 years; 46.8% female) in a stand-alone hemodialysis unit within an integrated learning healthcare system. Ten percent (10%) of subjects were Caucasian, 42% Latino, 19% African American, and 29% Asian. Forty-eight percent had diabetes; 72% had BMI ≥ 30. Inclusion criteria included the provision of survey data and having medication refill data available in the pharmacy system. 77.2% had mean phosphorus levels ≤ 5.5 mg/dL; 22.8% had mean phosphorus levels > 5.5 mg/dL.
  
  
  
  Subjects were administered the 8-item Morisky Medication Adherence Scale (MMAS-8) and also reported on their phosphorus-related knowledge.
  
  
  
  Phosphorus levels within an adequate range.
  
  
  
  The mean serum phosphorus level was 4.96 mg/dL (SD = 1.21). In the well-controlled group, mean phosphorus was 4.44 mg/dL (SD = 0.76). In the poorly controlled group, mean phosphorus was 6.69 mg/dL (SD = 0.74). A total of 61% of patients reported at least some unintentional medication nonadherence, and 48% reported intentional medication nonadherence. Phosphorus-specific knowledge was low, with just under half of patients reporting that they could not name two high-phosphorus foods or identify a phosphorus-related health risk. Phosphorus binder-related nonadherence was substantially higher in the uncontrolled than the controlled group. Adjusting for age, individuals with poorer self-reported binder adherence were less likely to have controlled phosphorus levels (odds ratio = 0.71, P = .06).
  
  
  
  Phosphorus-related non-adherence, but not low phosphorus-specific knowledge, was associated with poorer phosphorus control. Such findings provide important information for the development of evidence-based strategies for improving phosphorus control among patients on dialysis.
authors.affiliation: Division of Nephrology & Hypertension, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California.
authors.forename: Cherriday G
authors.initials: CG
authors.lastname: Joson
authors.affiliation: Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California. Electronic address: shayna.l.henry@kp.org.
authors.forename: Shayna L
authors.initials: SL
authors.lastname: Henry
authors.affiliation: Kaiser Permanente Los Angeles Medical Center, Los Angeles, California.
authors.forename: Sue
authors.initials: S
authors.lastname: Kim
authors.affiliation: Renal Business Group, Kaiser Permanente Southern California, Pasadena, California.
authors.forename: Mandy Y
authors.initials: MY
authors.lastname: Cheung
authors.affiliation: Kaiser Permanente Los Angeles Medical Center, Los Angeles, California.
authors.forename: Prajakta
authors.initials: P
authors.lastname: Parab
authors.affiliation: Division of Nephrology & Hypertension, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California.
authors.forename: Antoine C
authors.initials: AC
authors.lastname: Abcar
authors.affiliation: Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Jacobsen
authors.affiliation: Department of Community Health Sciences, University of California Los Angeles Fielding School of Public Health, Los Angeles, California.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Morisky
authors.affiliation: Division of Nephrology & Hypertension, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California.
authors.forename: John J
authors.initials: JJ
authors.lastname: Sim
mesh_terms: D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D054559:Hyperphosphatemia / Q000517:prevention & control; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D010758:Phosphorus / Q000097:blood*; D016226:Phosphorus, Dietary / Q000008:administration & dosage; D006435:Renal Dialysis; D012189:Retrospective Studies; D057566:Self Report
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus