title: Adherence with levodopa/carbidopa/entacapone versus levodopa/carbidopa and entacapone as separate tablets in patients with Parkinson's disease.
abstract: BACKGROUND
  Observational studies suggest that single-tablet formulations are associated with improved adherence versus the same components taken as separate tablets. The objective of this study was to compare adherence in patients with Parkinson's disease (PD) receiving levodopa therapy as levodopa/carbidopa/entacapone tablets (LCE) versus levodopa/carbidopa (LC) tablets and entacapone (E) as separate tablets (LC and E).
  
  
  METHODS
  This was a retrospective, observational cohort study using a large health insurance claims database. Subjects included persons with a PD diagnosis who were receiving LC without E and then received either an add-on therapy with E as a separate tablet (LC and E) or LCE as one tablet (LCE). The primary study outcome was treatment adherence, estimated from pharmacy refills based on the 'percent of days covered' (PDC) with LCE or LC and E during follow-up and compared for patients receiving LCE and LC and E using multivariate regression analyses.
  
  
  RESULTS
  In multivariate analyses controlling for differences between groups in baseline characteristics, including pre-index dosage of and adherence with LC, receipt of LCE (n = 388) was associated with 79% lower mean non-adherence during follow-up (95% CI: 73-83%; p < 0.001) versus LC and E (n = 823), 86% lower odds of unsatisfactory adherence (95% CI: 80-91%; p < 0.001), and a 26% lower risk of discontinuation (95% CI: 6-42%; p < 0.013).
  
  
  CONCLUSIONS
  This was an observational study with the inherent potential for selection bias. Pharmacy claims may not provide an accurate estimate of adherence. Requiring subjects to have a certain number of prescriptions before and after the index date may yield a sample that is not representative of all patients initiating levodopa therapy in typical clinical practice.
  
  
  CONCLUSIONS
  Better adherence with LCE may have important implications for maintaining function in patients receiving chronic oral levodopa therapy. Further research is needed to confirm these results and examine the association between improved adherence and clinical and economic outcomes.
authors.affiliation: Policy Analysis Inc., Brookline, MA 02245, USA. tdelea@pai2.com
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Delea
authors.forename: Simu K
authors.initials: SK
authors.lastname: Thomas
authors.forename: May
authors.initials: M
authors.lastname: Hagiwara
authors.forename: L
authors.initials: L
authors.lastname: Mancione
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000978:Antiparkinson Agents / Q000008:administration & dosage / Q000009:adverse effects; D002230:Carbidopa / Q000008:administration & dosage* / Q000009:adverse effects; D002396:Catechols / Q000008:administration & dosage* / Q000009:adverse effects; D015331:Cohort Studies; D004304:Dosage Forms; D004338:Drug Combinations; D005260:Female; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009570:Nitriles / Q000008:administration & dosage* / Q000009:adverse effects; D010300:Parkinson Disease / Q000188:drug therapy* / Q000453:epidemiology; D010349:Patient Compliance / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D013607:Tablets
chemical_list: D000978:Antiparkinson Agents; D002396:Catechols; D004304:Dosage Forms; D004338:Drug Combinations; D009570:Nitriles; D013607:Tablets; D007980:Levodopa; C071192:entacapone; D002230:Carbidopa