Table 3

Level of advanced clinical practice, measured by physician ‘substitution effect’ of NPs

CountryStudy design (years)SettingParticipantsResultsReference
CanadaRCT to assess the effects of substituting NPs for physicians in primary care (1971–1972)2 suburban Ontario family practicesTotal patient N=1598 families (4325 individuals) of which 529 families (1398 individuals) were randomised to each physician; 270 families (765 individuals) were randomised to each NP67% of all primary care patient visits can be provided by NPs.
Care delivery was similar between physicians and NPs. There were no statistically significant differences between patients seen by NPs compared with patients seen by physicians in patient functional capacity, indexes of social and emotional function, mortality or satisfaction with care.
The NetherlandsQuasi-experimental study to compare the number of patients and caseloads between nurse specialists and GPs in out-of-hours services (2011–2012)Out-of-hours primary careIntervention: 1 NP and 4 GPs, control: 5 GPs working in out-of-hours services. Total patient N=12 092 from 1 GP cooperative extracted from medical recordsMore than 77% of patients fit the scope of practice of (Verpleegkundig Specialist) in out-of-hours care.
On average 16.3% of all patients were treated by nurse specialists, whereas 20.9% of patients were treated by GPs.
75–83% of clinical activities in out-of-hours primary care settings (weekend shifts in GP practices) could be taken over by nurse specialists.
USASelf-report, mailed survey to a random sample of 4000 physicians and 3000 NPs with rural addresses (all specialties)Rural primary care in 13 states with at least 2 from each US Census Region (4 regions)Final sample included 788 primary care physicians (response rate: 25%); and 918 primary care NPs (40%)75–93% of weekly primary care outpatient visits can be provided by NPs.*
In the outpatient setting, primary care clinical activities† were comparable between physicians and NPs in the outpatient setting.
  • Source: See directly in the table, see online supplementary material for more details.

  • *In an unadjusted regression model, NP average weekly number of outpatient visits was 75% of physician volume. In an adjusted model (age, sex, geographic location, and practice setting), NP average weekly number of outpatient visits was 93% of physician volume.

  • †On average, physicians conducted more well-child visits than NPs (12.6 vs 7.4, p<0.001). Differences for prenatal visits and minor procedures were non-significant.

  • GP, general practitioner; NP, nurse practitioners; RCT, randomised controlled trial.