title: Nurse practitioner/physician assistant staffing and critical care mortality.
abstract: BACKGROUND
  ICUs are increasingly staffed with nurse practitioners/physician assistants (NPs/PAs), but it is unclear how NPs/PAs influence quality of care. We examined the association between NP/PA staffing and in-hospital mortality for patients in the ICU.
  
  
  METHODS
  We used retrospective cohort data from the 2009 to 2010 APACHE (Acute Physiology and Chronic Health Evaluation) clinical information system and an ICU-level survey. We included patients aged ≥ 17 years admitted to one of 29 adult medical and mixed medical/surgical ICUs in 22 US hospitals. Because this survey could not assign NPs/PAs to individual patients, the primary exposure was admission to an ICU where NPs/PAs participated in patient care. The primary outcome was patient-level in-hospital mortality. We used multivariable relative risk regression to examine the effect of NPs/PAs on in-hospital mortality, accounting for differences in case mix, ICU characteristics, and clustering of patients within ICUs. We also examined this relationship in the following subgroups: patients on mechanical ventilation, patients with the highest quartile of Acute Physiology Score (> 55), and ICUs with low-intensity physician staffing and with physician trainees.
  
  
  RESULTS
  Twenty-one ICUs (72.4%) reported NP/PA participation in direct patient care. Patients in ICUs with NPs/PAs had lower mean Acute Physiology Scores (42.4 vs 46.7, P < .001) and mechanical ventilation rates (38.8% vs 44.2%, P < .001) than ICUs without NPs/PAs. Unadjusted and risk-adjusted mortality was similar between groups (adjusted relative risk, 1.10; 95% CI, 0.92-1.31). This result was consistent in all examined subgroups.
  
  
  CONCLUSIONS
  NPs/PAs appear to be a safe adjunct to the ICU team. The findings support NP/PA management of critically ill patients.
authors.affiliation: Clinical Research, Investigation and Systems Modeling of Acute Illness (CRISMA) Center, Department of Critical Care Medicine, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA.
authors.forename: Deena Kelly
authors.initials: DK
authors.lastname: Costa
authors.affiliation: Clinical Research, Investigation and Systems Modeling of Acute Illness (CRISMA) Center, Department of Critical Care Medicine, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA; Department of Emergency Medicine, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wallace
authors.affiliation: Division of General Internal Medicine, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA.
authors.forename: Amber E
authors.initials: AE
authors.lastname: Barnato
authors.affiliation: Clinical Research, Investigation and Systems Modeling of Acute Illness (CRISMA) Center, Department of Critical Care Medicine, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA; University of Pittsburgh School of Medicine; and Department of Health Policy and Management, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA. Electronic address: kahnjm@upmc.edu.
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Kahn
mesh_terms: D018806:APACHE; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019985:Benchmarking; D003422:Critical Care / Q000379:methods; D016638:Critical Illness / Q000401:mortality* / Q000451:nursing; D016208:Databases, Factual; D005260:Female; D019538:Health Care Surveys; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D009722:Nurse Practitioners / Q000706:statistics & numerical data*; D017063:Outcome Assessment, Health Care; D010348:Patient Care Team / Q000458:organization & administration; D061214:Patient Safety / Q000706:statistics & numerical data; D010561:Personnel Staffing and Scheduling; D010823:Physician Assistants / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D018570:Risk Assessment; D014481:United States; D000078329:Workforce; D055815:Young Adult