Nurse practitioners versus doctors diagnostic reasoning in a complex case presentation to an acute tertiary hospital: A comparative study

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Abstract

Background

Nurse practitioners perform a diagnostic role previously delivered by doctors. Multiple studies demonstrate nurse practitioners are as effective as doctors when managing chronic conditions and minor illnesses and injuries. No studies have focused on how nurse practitioners compare to doctors in their management of complex cases presenting for the first time.

Objective

This study assessed how nurse practitioners’ diagnostic reasoning abilities when managing a complex case compared to those of doctors’?

Design

A comparative research design.

Participants

Purposeful sampling recruited 30 nurse practitioners and 16 doctors working in multiple specialties in New Zealand. All doctors were completing postgraduate specialist training programmes. Specialties included older adults, emergency care, primary health care/general practice, cardiology, respiratory and palliative care.

Methods

A complex case scenario assessed by an expert panel and think aloud protocol was used to assess diagnostic reasoning abilities. The ability of 30 nurse practitioners to determine diagnoses, identify the problem, and propose actions was compared to that of 16 doctors. Correct responses were determined by an expert panel. Data gained from the case scenario using think aloud protocol were quantified for analysis.

Results

61.9% of doctors identified the correct diagnoses, 56.3% the problem and 34.4% the actions as determined by the expert panel. This compares to 54.7% of nurse practitioners identifying the correct diagnoses, 53.3% the problem and 35.8% the actions. Analysis revealed no difference between these groups (diagnoses 95% CI: −1.76 to −0.32, p  = 0.17, problem χ2 = 0.00, p = 1.0, or actions 95% CI: −1.23 to 1.58, p = 0.80).

Conclusion

Nurse practitioners’ diagnostic reasoning abilities compared favourably to those of doctors in terms of diagnoses made, problems identified and action plans proposed from a complex case scenario. In times of global economic restraints this adds further support to alternative models of care.

Introduction

Nurse practitioners in New Zealand (NZ) were introduced to increase patients’ access to healthcare, improve patient outcomes (Ministry of Health, 2002) and provide a solution to doctor shortages (Forde, 2008, Ministry of Health, 2009). Combining advanced nursing practice with skills from medicine, nurse practitioners diagnose, assess and manage patients and can order diagnostic tests and prescribe; historically these roles were considered exclusive to medicine (Forde, 2008, Ministry of Health, 2002). In addition nurse practitioners promote health, encourage self-care and look beyond the diagnosis to consider nonmedical interventions (Ministry of Health, 2002).

There are international differences as to how the title nurse practitioner is used. Countries, such has NZ, Australia and the United States (US) have a rigorous assessment process and require a Master's degree (Carryer et al., 2007, Kleinpell et al., 2008). New Zealand and Australia and some US states allow nurse practitioners to practice independently without supervision from a physician (Carryer et al., 2007, Kleinpell et al., 2008, Lowes, 2014). The US recommend nurse practitioner education programmes move to a Doctorate degree by 2015 (American Association of Colleges of Nursing, 2012), however laws and regulations pertaining to nurse practitioner scope of practice (including prescribing authority) remain inconsistent from state to state (Poghosyan et al., 2012). In Canada, legislation, regulations and standardisation of the nurse practitioner title are in place in most provinces and territories (Sangster-Gormley et al., 2011) unlike the United Kingdom (UK) where no legislation protects the title nurse practitioner. Many nurses working in advanced nursing practice roles in the UK have a Master's degree but nurses are still able to do a one-week course and use the title advanced nurse practitioner (Coombes, 2008). Over recent years, the Royal College of Nursing has lobbied for a registered trade title for nurse practitioner similar to NZ (Coombes, 2008) but this has not yet occurred (Santry, 2010).

Multiple studies demonstrate nurse practitioners achieve similar patient outcomes to medical doctors (Dierick-van Daele et al., 2009, Horrocks et al., 2002, Laurant et al., 2008) however many of these studies focus on patients referred by the doctor to nurse practitioners for management of chronic conditions, patients presenting for the first time with minor illnesses or injuries, and nurse practitioners working alongside general practitioners (Horrocks et al., 2002, Laurant et al., 2008, Newhouse et al., 2011).

Few studies compare nurse practitioner diagnostic reasoning abilities to those of doctors. Sakr et al. (1999) showed UK emergency care nurse practitioners and house officers had similar rates of diagnostic error (9.2% compared to 10.7%) when assessing and treating patients presenting with minor illnesses and injuries (Sakr et al., 1999). This finding was further supported in a study of Dutch emergency care nurse practitioners and senior house officers; this study also found no difference in the rate of missed injuries and inappropriate management of patients presenting with minor illnesses and injuries (van der Linden et al., 2010).

In a study of UK primary care nurse practitioners and general practitioners, Offredy (2002) attributed the differences between the diagnostic accuracy of the two groups to general practitioners having more knowledge and experience than nurse practitioners. This was related to nurse practitioners’ lack of familiarity with the case presentations due to the restrictions general practitioners placed on the type of consultations they performed. Although all the nurse practitioners in the study had completed the Royal College of Nursing nurse practitioner degree programme, their limited scope of practice means these results may not reflect the international context.

Whilst research demonstrates nurse practitioners compare favourably to doctors in their management of minor illnesses/injuries and chronic conditions, to the best of our knowledge no research compares nurse practitioners’ and doctors’ diagnostic reasoning abilities pertaining to a complex case.

Familiar case presentations automatically use intuitive processing (Croskerry, 2009, Djulbegovic et al., 2012) which is developed through experience. It allows rapid diagnosis however it is influenced by environmental information, pattern recognition and the use of mental short cuts known as heuristics (Croskerry, 2009, Stanovich, 2010), which increase the risk of diagnostic error. If the patient presentation is not initially recognised, time permits or the clinician is uncertain, analytic processing is triggered (Croskerry, 2009, Pelaccia et al., 2011, Stolper et al., 2011).

Analytic processing involves slower, step-by-step, conscious, logical and defensible processes (Coderre et al., 2010, Croskerry, 2009, Ely et al., 2011, Heiberg Engel, 2008, Szaflarski, 1997). This approach requires explicit knowledge of pathophysiology, diseases/conditions and clinical manifestations (Croskerry, 2009, Szaflarski, 1997) developed through learning that continue to develop as clinicians mature (Croskerry, 2009).

Analytic processing is triggered by complex cases. Ilgen et al. (2011) assessed the diagnostic accuracy of medical students and residents using both simple and complex cases. They defined a simple case as a typical presentation of a single diagnosis and a complex case as one that introduces features of multiple diagnoses (Ilgen et al., 2011). These definitions resonate those used by Mamede et al. (2008) measuring the effect of reflective practice on the diagnostic accuracy of 42 internal medical residents in Brazil. Their simple cases included a single diagnosis that was frequently encountered by residents. Their complex cases comprised of either a combination of different acute clinical conditions, patients with co-morbidities, an atypical disease presentation or a case rarely seen by residents (Mamede et al., 2008).

Diagnostic accuracy differs in simple and complex cases. Mamede et al. (2008) found reflective practice achieved a mean accuracy of 73% in simple cases and 42% in complex cases. Ilgen et al. (2011) in their study of 51 medical students (novices), 26 first or second year residents (intermediates) and 38 third year residents (experienced) found participants achieved high scores in simple cases but lower scores in complex cases. In simple cases novices scored a mean of 69.9%, intermediates 80.8% and experienced 89.5%. In the complex cases novices scored a mean of 31%, intermediates 47% and experienced 55% (Ilgen et al., 2011). In a study to test the relationship between speed and accuracy of Canadian emergency care residents, Sherbino et al. (2012) deliberately made the cases difficult so analytic processing could be triggered. Following a pilot study, they removed cases that were too easy (achieving a diagnostic accuracy approaching 100%) and those that were too difficult (achieved a diagnostic accuracy approaching 0%). Findings from their study showed residents achieved a mean accuracy score of 49% (Sherbino et al., 2012).

As intuitive processing is faster than analytic processing, speed in generating a diagnosis has historically been associated with a higher rate of diagnostic error. This is thought to be related to premature closure or using intuitive processing when the case requires analytic processing (Elstein, 2009, Lucchiari and Pravettoni, 2012, Norman and Eva, 2010). Premature closure is the acceptance of a diagnosis before sufficient verification has occurred and failure to consider other plausible alternatives once it has been reached (Levy et al., 2007). Sherbino et al. (2012) measured residents’ diagnostic accuracy using both intuitive and analytic processing; fast times indicated intuitive processing while slower times signified analytic processing. They found the response times varied but the most difficult case was associated with the longest time.

The ability of nurse practitioners to diagnoses complex cases has been challenged. Gorman (2009) views the doctor in the future as a health professional who has largely a cognitive function, translating patients’ signs and symptoms into a diagnosis; this role, he argues, cannot be substituted by nurse practitioners. Gorman sees medicine as having a strong diagnostic role at the front door of healthcare facilities, referring to nurse practitioners and other health professional-led intervention clinics when required. This view suggests doctors are better suited to diagnosis and treatment whereas nurse practitioners are better suited to ongoing interventions once the diagnosis is made.

Section snippets

Research aim

This study compared nurse practitioners’ and doctors’ diagnostic reasoning abilities related to a complex case. The study answered the research question, how do nurse practitioners’ diagnostic reasoning abilities of a complex case compare to those of doctors’? This question was based on the underlying assumption, that as nurse practitioners focus on health promotion and disease prevention, when compared to doctors, their diagnostic abilities when analysing a complex case may be inferior. The

Method

Using a comparative research design, this study used a complex case scenario and think aloud protocol to compare nurse practitioners’ and doctors’ diagnostic reasoning abilities. Think aloud protocol is a qualitative method (Arocha and Patel, 2008, Bucknall and Aitken, 2010, Hoffman et al., 2009, Lundgren-Laine and Salantera, 2010) used to analyse how clinicians’ use their knowledge to generate diagnoses and the complex relationships between knowledge transition and generation of diagnoses (

Results

Overall 46 participants took part in the study, 30 nurse practitioners and 16 doctors. The nurse practitioners and doctors worked in gerontology, emergency care, primary health care/general practice, cardiology, respiratory, and palliative care. In both the nurse practitioner and doctor group the largest number were from primary health care, the smallest number from palliative care.

Discussion

This study further qualifies the nurse practitioner role within the healthcare team by demonstrating no difference between NZ nurse practitioners’ and doctors’ diagnostic reasoning abilities when analysing a complex case. The result supports nurse practitioners’ ability to make diagnoses at the patient's first contact and suggests their cognitive abilities to manage a complex case compare favourably to those of doctors.

Most research comparing nurse practitioners to doctors compare them with

Limitations

This study design has a number of limitations. The case scenario using think aloud, although based on a real case, did not reflect participants’ diagnostic reasoning in their natural settings. Environmental factors influence diagnostic accuracy (Croskerry, 2009, Ferreira et al., 2010, Sevdalis et al., 2010) and therefore participants’ diagnostic reasoning abilities when working in their normal practice settings may differ from the findings illuminated in this study. The case scenario did not

Conclusion

This study demonstrated nurse practitioners analysis of a complex case compared favourably to that of doctors in terms of diagnoses made, problems identified and action plans proposed. The findings of this study suggest nurse practitioners’ diagnostic reasoning developed from education and experience enables them to diagnose and manage complex patients presenting for the first time. More research using multiple complex cases is now needed to validate these results. As the study reflects NZ

Conflict of interest

None declared.

Funding

Lead author Alison Pirret, was a successful recipient of the New Zealand Nurses’ Organisations’ Centennial Scholarship of $10,000. Alison also received Massey University Funding of $5000.

Ethical approval

Massey University Human Ethics Committee – MUHEC 10/079.

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