Nurse practitioner diagnostic reasoning : a thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Nursing at Massey University, New Zealand

Abstract

Introduction: Nurse practitioners were introduced to increase patients’ access to healthcare, improve patient outcomes, and provide a sustainable solution to ongoing workforce shortages. They provide a diagnostic role previously delivered by doctors, however, their ability to perform this role has been challenged. Methodology: The study used a post-positivist mixed methods convergent parallel design to explore nurse practitioner diagnostic reasoning and compare it to that of registrars. Methods included a complex case scenario using think aloud protocol to determine diagnostic abilities, including identifying correct diagnoses, problems and actions; a previously validated intuitive/analytic reasoning instrument to identify diagnostic reasoning style; a maxims questionnaire to identify maxims used to guide diagnostic reasoning; and a demographic data sheet to identify variables influencing the results of the former. The study included 30 nurse practitioners and 16 registrars. An expert panel determined the correct diagnoses/problems and actions for the case scenario using a Delphi technique. Registrar data provided normative data and norm-referenced testing compared the nurse practitioner data to the normative data. Results: Nurse practitioners identified a mean of 10.30 (range=4-17, Mdn=10, mode=9, SD=3.09) correct diagnoses, problem and action items as identified by the expert panel whereas registrars identified a mean of 10.88 (range=6-21, Mdn=10, SD=3.88); there was no statistically significant difference between the two groups (U=238.5, z=-.04, p=.97). Nurse practitioners’ diagnostic reasoning reflected an analytic-intuitive style whereas registrars reflected an analytic style, however, this difference was not statistically significant, t(44)=1.91, p=.06. Diagnostic reasoning style was not related to diagnostic reasoning abilities in either the nurse practitioner (rs=-.14, n=30, p=.46) or registrar (rs=.03, n=16, p=.90) groups. There was no difference in how nurse practitioners and registrars employ maxims to guide their diagnostic reasoning, t(44)=-.89, p=.38. Maxims used to guide diagnostic reasoning were not related to diagnostic reasoning abilities in either the nurse practitioner (r=-.17, n=30, p=.37) or registrar (rs=-.08, n=16, p=.77) groups. Conclusion: Nurse practitioners’ diagnostic reasoning, although incorporating more System I processes than registrars, does not differ from that of registrars. This supports the nurse practitioner role as a sustainable solution firstly, to effectively meet the health needs of the New Zealand population and secondly, to address workforce shortages.