title: Association of suboptimal prescribing and change in lower extremity physical function over time.
abstract: BACKGROUND
  Previous studies have found inconsistent links between suboptimal prescribing and negative patient outcomes. While suboptimal prescribing consists of multiple components, e.g. drugs to avoid in the elderly (DAE), potential drug interactions (PDI) and polypharmacy, most research has focused on the impact of drugs to avoid. This study explores the relationship between suboptimal prescribing, comorbid disease, and change in lower extremity functional limitation (LEFL).
  
  
  METHODS
  This prospective cohort study used data from the Hispanic Established Population for the Epidemiologic Study of the Elderly. Baseline data collection occurred between 1993 and 1994 with three additional waves of data collected approximately every 2 years. Based on the disablement process model, the dependent variable was change in LEFL over the 7-year study period. Independent variables included suboptimal prescribing: DAE, PDI and polypharmacy. Measures of pathology included comorbid diseases (stroke, cancer, hypertension, cardiovascular disease, arthritis, and diabetes). Age, gender, education, smoking, cognitive status, depression, body mass index, marital status, and self-reported health were controlled in analyses.
  
  
  RESULTS
  Diabetes, stroke, and arthritis were associated with a decline in LEFL. Polypharmacy mediated the relationship between diabetes and LEFL, and polypharmacy was also significantly associated with decrements in LEFL.
  
  
  CONCLUSIONS
  The effect of suboptimal prescribing on change in LEFL was limited to both direct and mediational effects of polypharmacy. Additional research exploring the association between suboptimal prescribing and a variety of quality measures using a diverse set of outcomes would improve our understanding of the impact of suboptimal prescribing more broadly defined.
authors.affiliation: South Texas Veterans Health Care System (VERDICT), University of Texas Health Science Center at San Antonio, San Antonio, Tex., USA. pughm@uthscsa.edu
authors.forename: Mary Jo V
authors.initials: MJ
authors.lastname: Pugh
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Palmer
authors.forename: Michael L
authors.initials: ML
authors.lastname: Parchman
authors.forename: Eric
authors.initials: E
authors.lastname: Mortensen
authors.forename: Kyriakos
authors.initials: K
authors.lastname: Markides
authors.forename: David V
authors.initials: DV
authors.lastname: Espino
mesh_terms: D000368:Aged; D001168:Arthritis / Q000503:physiopathology; D003920:Diabetes Mellitus / Q000503:physiopathology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D017058:Mexican Americans; D051346:Mobility Limitation; D019338:Polypharmacy; D011446:Prospective Studies; D020521:Stroke / Q000503:physiopathology