Overall, NP consultations were associated with higher patient age, and a higher share of multimorbid and polypharmaceutical patients in comparison to GP consultations. Age appeared to be the decisive factor for assigning patients to the NP, as there were no more significant associations between NP consultations and multimorbidity or polypharmacy after adjusting for potential confounders. During NP consultations, vital signs and anthropometric data were measured more frequently, and lab tests were ordered more often. By contrast, medications were prescribed or changed more frequently in GP consultations than in NP consultations.
Interpretation & comparison to existing literature
Bryant-Lukosius et al.  suggested in their evaluation framework “PEPPA Plus” to determine the characteristics of patients seen and treated by Swiss NPs in the early stages of role introduction. Our results indicate that the NP had a focus on multimorbid, polypharmaceutical elderly. This might be a consequence from her postgraduate education, which focused on care for older patients with complex health care needs . In their qualitative study, Gysin et al.  found that most NPs who work in Swiss family practices had a similar focus. This goes in line with current political efforts to address the increase in chronic conditions. In many other countries, such as Canada  or Sweden , nurses in advanced roles also have a focus on chronically ill elderly. International studies showed that these nurses provide at least equivalent care for people with chronic conditions as physicians, and offer holistic care through patient education, multidimensional assessments and coordination of multiple providers [21, 22]. In Veterans Health Administration facilities, Morgan et al.  found that patient age did not differ between NP and GP consultations in primary care offices. However, in the US, NPs can specialize in gerontology, and a study by Hendrix et al.  found that these geriatric NPs might be the most appropriate providers of coordinated chronic care to the elderly population. Interestingly, a Dutch study from Van Der Biezen et al.  showed that GPs saw more patients aged 65 + in comparison to the NPs. However, this study analyzed out-of-hours primary care consultations. Therefore, comparability might be limited.
The NP in our study measured the vital signs and anthropometric data more frequently compared to the GPs, and ordered lab tests more often. This might be because she had more multimorbid, polypharmaceutical elderly, which usually need closer monitoring, e.g. regular blood pressure measurements in hypertension, weight control in heart failure or frequent HbA1c measurements in diabetes. However, the significant differences remained after adjusting for age, multimorbidity and polypharmacy. This could have several reasons. As a novice and pioneer, the NP was maybe more careful and measured clinical and lab parameters more often in order not to miss something. Several pioneering NPs in Swiss primary care mentioned similar behavior before . International studies found that nurse-led care can result in improved blood pressure control and outcomes, e.g. in diabetes care or cardiovascular prevention [26, 27]. These findings were often attributed to stricter guideline adherence. Similarly, Chan et al.  found that NP care for patients who suffered from dyspepsia and underwent gastroscopy was effective because of the adherence to standardized follow-ups which included weight measurement. Ohman et al.  found that practices with NPs were more likely to measure lab values (e.g. HbA1c, lipid levels or urinary microalbumin levels) compared to practices with physicians and physician assistants or physicians only. These findings are in accordance with our study results.
The two GPs in our study changed and prescribed new drugs more often than the NP. This could be explained by the fact that NPs do not have prescription rights in Switzerland yet, and educational programs still lack several hours on pharmacology compared to international standards, which could yield in hesitation of prescribing new drugs. According to a legal report, NPs are allowed to prescribe or adjust certain medications under the delegation of physicians . De Bruijn-Geraets et al.  found that prescription rates of Dutch NPs increased after obtaining full legal practice authority. However, during out-of-hours consultations, Van Der Biezen et al.  found that NPs still prescribed less medications compared to GPs. The authors hypothesized that this could result from more patient education. Venning et al.  found no difference between prescription rates of NPs and GPs in the UK. This aligns with the findings of an international systematic review by Laurant et al. , which is mostly based on studies from countries at advanced stage of NP role implementation. Furthermore, in the US, Barnes et al.  found that independent prescription rights for NPs (i.e. same rights as doctors) lead to higher employment of NPs in primary care.
First, we only had data from one family practice with one NP, which limits the external validity of this study as it was influenced by personal factors (e.g. the NP’s previous experience as a registered nurse) and politically-driven project factors (e.g. the goal to address chronically ill elderly). However, these political factors might reflect what is considered important when new professionals are introduced to a health care system, and may be present even if larger cohorts are investigated. Second, the practice did not use ICPC-2 codes; hence, we did not have any information on the reasons for encounter. However, Busato et al.  showed that using drugs to identify morbidity within FIRE data is as reliable as using ICPC-2 codes. Third, we did not know how much the NP’s activities were influenced by the two supervising GPs. Lastly, we could not assess whether missing information (e.g. blood pressure measurement) was due to non-performance or non-documentation in the EMR. This limitation has been discussed by Djalali et al.  when using FIRE data.
Implications and outlook
Quantitative data from pilot projects provide valuable insights into the NP role and activities in Swiss primary care. These insights might trigger suitable regulations and promote further role implementation. Standardized curricula with more pharmacology, and defined scope of practices could allow NPs to focus on a certain groups of patients and prescribe certain drugs more independently, i.e. without GP supervision. This could then lead to more role attractiveness and clarity, and subsequently to higher numbers of NPs working in Swiss family practices. The wider use of EMRs and reimbursement data on NPs could facilitate future research. Further studies with larger numbers are needed to scrutinize the quality of care provided by NPs, and to determine their exact use in Swiss primary care. For example, health insurance data could be used to assess the costs and length of NP consultations once there are separate billing options for NPs.