Miranda Laurant, Mieke van der Biezen, Nancy Wijers, Kanokwaroon Watananirun, Evangelos Kontopantelis, Anneke JAH van Vught

Current and expected problems such as ageing, increased prevalence of chronic conditions and multi-morbidity, increased emphasis on healthy lifestyle and prevention, and substitution for care from hospitals by care provided in the community encourage countries worldwide to develop new models of primary care delivery. Owing to the fact that many tasks do not necessarily require the knowledge and skills of a doctor, interest in using nurses to expand the capacity of the primary care workforce is increasing. Substitution of nurses for doctors is one strategy used to improve access, efficiency, and quality of care. This is the first update of the Cochrane review published in 2005. Our aim was to investigate the impact of nurses working as substitutes for primary care doctors on:• patient outcomes;• processes of care; and• utilisation, including volume and cost. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), part of the Cochrane Library (www.cochranelibrary.com), as well as MEDLINE, Ovid, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and EbscoHost (searched 20.01.2015). We searched for grey literature in the Grey Literature Report and OpenGrey (21.02.2017), and we searched the International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov trial registries (21.02.2017). We did a cited reference search for relevant studies (searched 27.01 2015) and checked reference lists of all included studies. We reran slightly revised strategies, limited to publication years between 2015 and 2017, for CENTRAL, MEDLINE, and CINAHL, in March 2017, and we have added one trial to 'Studies awaiting classification'. Randomised trials evaluating the outcomes of nurses working as substitutes for doctors. The review is limited to primary healthcare services that provide first contact and ongoing care for patients with all types of health problems, excluding mental health problems. Studies which evaluated nurses supplementing the work of primary care doctors were excluded. Two review authors independently carried out data extraction and assessment of risk of bias of included studies. When feasible, we combined study results and determined an overall estimate of the effect. We evaluated other outcomes by completing a structured synthesis. For this review, we identified 18 randomised trials evaluating the impact of nurses working as substitutes for doctors. One study was conducted in a middle-income country, and all other studies in high-income countries. The nursing level was often unclear or varied between and even within studies. The studies looked at nurses involved in first contact care (including urgent care), ongoing care for physical complaints, and follow-up of patients with a particular chronic conditions such as diabetes. In many of the studies, nurses could get additional support or advice from a doctor. Nurse-doctor substitution for preventive services and health education in primary care has been less well studied.Study findings suggest that care delivered by nurses, compared to care delivered by doctors, probably generates similar or better health outcomes for a broad range of patient conditions (low- or moderate-certainty evidence):• Nurse-led primary care may lead to slightly fewer deaths among certain groups of patients, compared to doctor-led care. However, the results vary and it is possible that nurse-led primary care makes little or no difference to the number of deaths (low-certainty evidence).• Blood pressure outcomes are probably slightly improved in nurse-led primary care. Other clinical or health status outcomes are probably similar (moderate-certainty evidence).• Patient satisfaction is probably slightly higher in nurse-led primary care (moderate-certainty evidence). Quality of life may be slightly higher (low-certainty evidence).We are uncertain of the effects of nurse-led care on process of care because the certainty of this evidence was assessed as very low.The effect of nurse-led care on utilisation of care is mixed and depends on the type of outcome. Consultations are probably longer in nurse-led primary care (moderate-certainty evidence), and numbers of attended return visits are slightly higher for nurses than for doctors (high-certainty evidence). We found little or no difference between nurses and doctors in the number of prescriptions and attendance at accident and emergency units (high-certainty evidence). There may be little or no difference in the number of tests and investigations, hospital referrals and hospital admissions between nurses and doctors (low-certainty evidence).We are uncertain of the effects of nurse-led care on the costs of care because the certainty of this evidence was assessed as very low. This review shows that for some ongoing and urgent physical complaints and for chronic conditions, trained nurses, such as nurse practitioners, practice nurses, and registered nurses, probably provide equal or possibly even better quality of care compared to primary care doctors, and probably achieve equal or better health outcomes for patients. Nurses probably achieve higher levels of patient satisfaction, compared to primary care doctors. Furthermore, consultation length is probably longer when nurses deliver care and the frequency of attended return visits is probably slightly higher for nurses, compared to doctors. Other utilisation outcomes are probably the same. The effects of nurse-led care on process of care and the costs of care are uncertain, and we also cannot ascertain what level of nursing education leads to the best outcomes when nurses are substituted for doctors.