title: New chronic disease medication prescribing by nurse practitioners, physician assistants, and primary care physicians: a cohort study.
abstract: Medications to treat and prevent chronic disease have substantially reduced morbidity and mortality; however, their diffusion has been uneven. Little is known about prescribing of chronic disease medications by nurse practitioners (NPs) and physician assistants (PAs), despite their increasingly important role as primary care providers. Thus, we sought to conduct an exploratory analysis to examine prescribing of new chronic disease medications by NPs and PAs compared to primary care physicians (PCPs).
  
  
  
  We obtained prescribing data from IMS Health's Xponent™ on all NPs, PAs, and PCPs in Pennsylvania regularly prescribing anticoagulants, antihypertensives, oral hypoglycemics, and/or HMG-Co-A reductase inhibitors pre- and post-introduction of five new drugs in these classes that varied in novelty (i.e., dabigatran, aliskiren, sitagliptin or saxagliptin, and pitavastatin). We constructed three measures of prescriber adoption during the 15-month post-FDA approval period: 1) any prescription of the medication, 2) proportion of prescriptions in the class for the medication, and 3) time to adoption (first prescription) of the medication.
  
  
  
  From 2007 to 2011, the proportion of antihypertensive prescriptions prescribed by NPs and PAs approximately doubled from 2.0 to 4.2 % and 2.2 to 4.9 %, respectively. Similar trends were found for anticoagulants, oral hypoglycemics, and HMG-Co-A reductase inhibitors. By 2011, more PCPs had prescribed each of the newly approved medications than NPs and PAs (e.g., 44.3 % vs. 18.5 % vs. 20 % for dabigatran among PCPs, NPs, and PAs). Across all medication classes, the newly approved drugs accounted for a larger share of prescriptions in the class for PCPs followed by PAs, followed by NPs (e.g., dabigatran: 4.9 % vs. 3.2 % vs. 2.8 %, respectively). Mean time-to-adoption for the newly approved medications was shorter for PCPs compared to NPs and PAs (e.g., dabigatran, 7.3 vs. 8.2 vs. 8.5 months; P all medications <0.001).
  
  
  
  PCPs were more likely to prescribe each of the newly approved medications per each measure of drug adoption, regardless of drug novelty. Differences in the rate and speed of drug adoption between PCPs, NPs, and PAs may have important implications for care and overall costs at the population level as NPs and PAs continue taking on a larger role in prescribing.
authors.affiliation: Department of Pharmacy, School of Pharmacy, University of Washington, 1959 NE Pacific St, Box 357630, Seattle, WA, 98102, USA. zmarcum@uw.edu.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Marcum
authors.affiliation: Wolff Center at UPMC, Ross Building, Room 219, 4601 Baum Blvd, Pittsburgh, PA, 15213, USA.
authors.forename: Johanna E
authors.initials: JE
authors.lastname: Bellon
authors.affiliation: Department of Health Policy & Management, Graduate School of Public Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA, 15261, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: VA Pittsburgh Healthcare System and Department of General Internal Medicine, School of Medicine, University of Pittsburgh, 200 Meyran Avenue, Parkvale Building, Pittsburgh, PA, 15213, USA.
authors.forename: Walid F
authors.initials: WF
authors.lastname: Gellad
authors.affiliation: Department of Health Policy & Management, Graduate School of Public Health, University of Pittsburgh, 130 De Soto Street, Pittsburgh, PA, 15261, USA.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Donohue
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease / Q000188:drug therapy*; D015331:Cohort Studies; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009722:Nurse Practitioners / Q000706:statistics & numerical data*; D010414:Pennsylvania; D010823:Physician Assistants / Q000706:statistics & numerical data*; D058007:Physicians, Primary Care / Q000706:statistics & numerical data*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data; D017678:Sex Distribution; D055815:Young Adult
keywords: Health services research; Pharmacoepidemiology; Primary care; Work force