title: Refill rates of accessories for positive airway pressure therapy as a surrogate measure of long-term adherence.
abstract: OBJECTIVE
  To identify and validate a surrogate measure of long-term adherence to positive airway pressure (PAP) therapy in patients with obstructive sleep apnea (OSA).
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Academic center.
  
  
  METHODS
  220 consecutive patients with OSA.
  
  
  METHODS
  N/A.
  
  
  METHODS
  In patients with OSA who were receiving PAP therapy (for > 1 year), PAP adherence measured by device-download and defined by Medicare criteria was compared to refill rates for mask and other PAP therapy accessories. First, receiver operating characteristic (ROC) curves were constructed to identify a threshold value of refills per year that discriminated best between PAP adherent and non-adherent patients (derivation set; n = 100). Then the predictive accuracy of the threshold value of refills per year was tested in an additional 120 consecutive patients (validation set).
  
  
  RESULTS
  From the derivation set, ROC curve with good discriminant characteristics (ROC 0.83; 95% confidence intervals [CI], 0.75, 0.91, p < 0.0001) was used to identify a threshold value of refills (0.7 refills/year) for distinguishing PAP adherent and non-adherent patients. Subsequently, when the threshold was applied to the validation set, the likelihood ratio for a positive test (weighted for prevalence) predicting adherence to PAP therapy was 7.3 (95%CI, 3.8, 14), and likelihood ratio for a negative test was 0.6 (95%CI; 0.4, 0.8).
  
  
  CONCLUSIONS
  Refill rate of PAP accessories exhibited good test characteristics for predicting long-term PAP adherence. Such a surrogate measure based upon insurance claims data can be a powerful epidemiological tool in bioinformatics-aided comparative-effectiveness research and to monitor clinical performance of health systems.
authors.affiliation: Southern Arizona Veterans Administration Healthcare System, Tucson, AZ, USA.
authors.forename: Nimesh
authors.initials: N
authors.lastname: Patel
authors.forename: Afshin
authors.initials: A
authors.lastname: Sam
authors.forename: Alexandra
authors.initials: A
authors.lastname: Valentin
authors.forename: Stuart F
authors.initials: SF
authors.lastname: Quan
authors.forename: Sairam
authors.initials: S
authors.lastname: Parthasarathy
mesh_terms: D045422:Continuous Positive Airway Pressure / Q000295:instrumentation / Q000523:psychology* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000523:psychology / Q000706:statistics & numerical data; D012372:ROC Curve; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000523:psychology / Q000628:therapy*; D013997:Time Factors