Professional practice models for nurses in low-income countries: an integrative review

Background Attention is turning to nurses, who form the greatest proportion of health personnel worldwide, to play a greater role in delivering health services amidst a severe human resources for health crisis and overwhelming disease burden in low-income countries. Nurse leaders in low-income countries must consider essential context for nurses to fulfill their professional obligation to deliver safe and reliable health services. Professional practice models (PPMs) have been proposed as a framework for strategically positioning nurses to impact health outcomes. PPMs comprise 5 elements: professional values, patient care delivery systems, professional relationships, management approach and remuneration. In this paper, we synthesize the existing literature on PPMs for nurses in low-income countries. Methods An integrative review of CINAHL-EBSCO, PubMed and Scopus databases for English language journal articles published after 1990. Search terms included nurses, professionalism, professional practice models, low-income countries, developing countries and relevant Medical Subject Heading Terms (MeSH). Results Sixty nine articles published between 1993 and 2014 were included in the review. Twenty seven articles examined patient care delivery models, 17 professional relationships, 12 professional values, 11 remuneration and 1 management approach. One article looked at comprehensive PPMs. Conclusions Adopting comprehensive PPMs or their components can be a strategy to exploit the capacity of nurses and provide a framework for determining the full expression of the nursing role.


Background
The global health workforce deficit projected to reach 12.9 million personnel by 2035 presents both an opportunity and a dilemma for nurses worldwide, but especially for colleagues in low-income countries [1]. With more than 35 million nurses comprising the greatest proportion of health personnel globally, members of the profession are strategically positioned to contribute significantly to health services delivery [2]. Organizational systems -structures, processes and values-create a blueprint to guide professional nursing practice; without proper organizational systems, nurses cannot optimize patient surveillance and deliver interventions safely and reliably [3,4]. Nurses in low-income countries contend with an overwhelming disease burden and persistent health human resources crisis that manifests in deep personnel shortages, inappropriate skill mix and maldistribution of health workers [5,6]. Yet, the state of organizational systems in low-income countries, which form the essential context for professional nursing practice, has not been fully examined in spite of a robust discourse on strengthening the capacity of nurses in these regions. With an urgent global agenda exerting pressure to curb preventable and premature mortality, nurses in low-income countries facing worsening health workforce shortages over the next 20 years are compelled to find ways to mobilize and meet the demands of a rapidly evolving health services delivery milieu.
Professional practice models (PPMs) have been proposed as a means of instilling organizational systems that mobilize nurses by granting them control over delivery of patient care and the overall work environment [7]. Hoffart and Woods posited that PPMs encompass five essential building blocks: professional values, patient care delivery systems, professional relationships, management approach and remuneration [7]. Professional values are the central tenets that guide professional nursing practice and form a foundation for the other elements of a PPM [7]. The nursing code of ethics constitutes one type of professional value [7]. Patient care delivery systems signify the manner in which responsibility for the gamut of patient care duties is configured [7]. One example of a patient care delivery system is the delineation of nursing roles from nonnursing roles [7]. Professional relationships refer to nurseto-nurse interactions and exchanges between nurses and other members of the multidisciplinary team that are essential for effective collaboration on patient-related matters [7]. The management approach is concerned with the decision making structures and processes employed in an organization [7]. Finally, remuneration describes how nurses are compensated and rewarded in recognition of their performance [7].
Attaining simultaneously all five components of a PPM is difficult regardless of high-or low-income country status. Worldwide, only 400 select hospitals located in Australia, Lebanon, Singapore, the United Kingdom and the United States have succeeded in implementing the most prominent example of a PPM, the Magnet® model [8]. In Magnet®-designated facilities, the signature characteristic is nurses' representation in all hospital affairs; this includes a visible nursing leadership, autonomous nursing care, collaborative nurse-physician relationships and opportunities for professional development [9]. Facilities that have achieved the highly coveted Magnet® designation exhibit higher levels of patient and nurse satisfaction as well as significantly lower rates of morbidity and mortality [10,11].
The case of more than 30,000 nurses in 12 European countries responding to the RN4CAST survey demonstrates how professional nurses and nursing practice are undermined when the ideals of a PPM are unevenly implemented or unavailable [4,12]. More than a third of nurses reported that opportunities for career advancement were absent in their facilities (range: 33 % in Switzerland to 84 % in Spain) [12]. More than half of nurses in 11 of the 12 countries reported lack of opportunities to participate in policy decision making (range: 63 % in the Netherlands to 88 % in Spain) [12]. More than half of all nurses in the 12 countries disagreed with the item enough nurses on staff to provide quality patient care (range: 52 % in Switzerland to 85 % in Poland). In addition, the researchers showed that in 6 of the 12 countries, more than half of nurses perceived their chief nursing officers not to have equal standing with other high level hospital executives (range: 51 % in Finland to 82 % in Sweden) [12].
Practice environments or facilities that deny nurses PPMswhich confer authority over the environment of care, including to make appropriate and timely care related decisions in response to changes in patient conditionsare problematic because quality of care can be compromised leading to adverse outcomes [13]. European nurses in the RN4CAST study acknowledged leaving important patient care related tasks undone due to a burdensome workload and time constraints [12]. At least one third of nurses in Germany, Greece, the Netherlands and Spain rated the quality of care in their wards as poor or fair [4]. Up to two thirds of nurses in the RN4CAST study were not confident that patients could manage their own conditions upon discharge [4].
Similar lapses in care have been reported in low-income countries. In India, for example, nurses working in New Delhi maternity homes attributed impolite and disrespectful treatment of impoverished women to long hours, poor pay and overcrowding of facilities [14]. In turn, the women shunned safer facility deliveries in favor of childbirth at home supervised by traditional birth attendants with little or no training to identify complications and implement necessary interventions [14]. PPMs provide nurses with the necessary infrastructure to fulfill their professional obligation to deliver optimal health services. Tangible improvements realized in patient outcomes, as well as in patient and nurse satisfaction, when PPMs are in place outweigh the inherent difficulties of installing them and suggest their utility even in low-income country settings. To date, this remains unexplored.
Seventy per cent of the 83 countries failing to meet the recommended level of 23 nurses, midwives and physicians necessary to provide 80 % coverage of essential services, such as attendance of childbirth by skilled personnel, are located in sub-Saharan Africa and south East Asia [1]. At the same time, 85 % of all maternal deaths aggregate in the two regions with the majority of deaths (56 %) occurring in sub-Saharan Africa [15]. Together, sub-Saharan Africa and south East Asia account for the highest incidence of new cases of HIV infection [16]. The rise of risk factors, such as hypertension, tobacco smoking and high body mass index, likely to lead to noncommunicable and chronic illnesses, including cardiovascular disease and diabetes, threaten to exacerbate the existing disease burden in low-income countries [17].
An increasingly common response to meet demand for essential health services in low-income countries, such as emergency obstetric care and antiretroviral therapy (ART), requires nurses to assume an expanded role in the practice known as task-shifting. Task-shifting is defined as the transfer of responsibilities normally assigned to health personnel with advanced training to cadres with less pre-service education [18]. Focusing on nurses as essential partners in meeting global health goals is the right stepone that has been endorsed by global nurse leaders, including the newly formed Global Advisory Panel on the Future of Nursing (GAPFON) [19]. Yet, the extent to which organizational systems low-income countries are equipped to support nurses in fulfilling their professional obligation within underresourced and over-stretched settings has not been fully articulated. In this paper, we propose PPMs as a framework for galvanizing the capacity of nurses and appraise the existing literature to gauge the degree to which elements of PPMs have been implemented for nurses in low-income countries.

Methods
CINAHL-EBSCO, PubMed and Scopus databases were searched for journal articles published in English after January 1, 1990 using the following key words: nurses, professionalism, professional practice models, developing countries, low-income countries and relevant Medical Subject Heading Terms (MeSH). Low-income or developing country status was assigned based on World Bank classifications [20]. Articles were included in the review if the purpose of the paper was to describe theoretically or evaluate empirically in a low-income nation one or more elements of a PPM as defined by Hoffart and Woods [7]. Articles discussing these elements in highincome or developed countries were excluded. Also excluded were articles reporting programmatic initiatives in low-income countries where nurses have been involved but their professional development was not intrinsic to the intervention. The first author retrieved articles from the 3 databases using the predetermined search terms and selected relevant titles based on the eligibility criteria. Both authors independently assessed 20 % of the abstracts for eligibility allowing for measures of agreement and reliability between the two researchers to be calculated. The resulting inter-rater agreement of 86 % and Cohen's kappa of 0.73 were judged sufficiently high to allow only the first author to proceed with the selection procedure. Any disagreements were resolved by consensus. The quality of each article was quantified by a score of 0 or 1 (low or high) assigned by consensus on four criteria: authenticity, informational value, methodological quality and representativeness [21,22]. Data analysis comprised categorizing articles according to year of publication, study methodology used and the country in which the research was conducted. Then studies were clustered according to the element of a PPM discussed and results synthesized to elucidate the state of the evidence on PPMs for nurses in low-income countries. We applied to this integrative review the same standards of rigor reserved for primary research [23].

Results
The initial search led to more than 20,000 articles. Query limits applied to enhance the specificity of this initial search included the terms professional values, code of ethics, patient care, care delivery systems, management approach, decision making, professional relationships, interdisciplinary relationships, salary and compensation [24]. The high specificity of the augmented search did not correspond to a high sensitivity, which meant numerous articles captured using the initial search terms were excluded [24]. The tradeoff was to proceed with the initial time-consuming search strategy that ensured all relevant articles meeting specified criteria were included.
Titles of the 20,295 articles retrieved using the initial search terms were scanned for key words relevant to the eligibility criteria outlined previously. After 20,035 duplicates and non-eligible titles were put aside, the abstracts of the remaining 260 titles were extracted. From these, 153 full text articles were retrieved and assessed for eligibility and relevance. Eighty four articles did not meet the eligibility criteria when the full text was reviewed and were subsequently eliminated from the review. The remaining 69 articles met the eligibility criteria and were included in the integrative review. The article selection process is represented schematically in Fig. 1.
The majority of articles (n = 19) examined aspects of PPMs in the World Health Organization (WHO) sub-Saharan Africa region compared to 14 in the South-East Asia region, 9 in the Eastern Mediterranean region, 8 in the Western Pacific region, 6 in the Americas and 1 in the European region. Twelve articles addressed PPMs in more than one region or country. The studies we analyzed applied a myriad of quantitative and qualitative research methodologies. A summary of the results is presented in Table 1. The first study was published in 1993 and almost all (n = 65) were published in the 2000s, with the period after 2010 accounting for 52 % of articles as is depicted in Fig. 2. Only 1 article dealt with PPMs as a comprehensive entity; the other 68 addressed one or more, but not all, of the individual elements encompassed in the model put forward by Hoffart and Woods [7]. The distribution of articles according to the element of a PPM addressed is presented in Fig. 3. The study outcome was literature describing or examining PPMs for nurses in developing countries. We have grouped our findings according to the elements of a PPM described by Hoffart and Woods [7].

Professional values
Twelve articles looked at issues surrounding professional values, which are defined as the underlying beliefs guiding nursing practice. The literature highlighted dissonance between knowledge of ethical principles and their application in clinical practice, which was largely attributed to cultural norms and beliefs beyond the boundaries prescribed by codes of ethics, such as the International Council of Nurses (ICN) code [25][26][27][28][29][30]. These practices ranged from negating to perform appropriate evidencebased health education [27] to verbal and physical abuse of patients [30,31]. In other reports, nurses were forced to forfeit proper procedures when inadequately staffed to manage an overwhelming patient load or sufficient quantities of medications and equipment were unavailable [26,29,32,33]; these instances were said to induce moral distress on nurses [26]. Still, nurses verbalized awareness that their role was to deliver patientcentered care [26,34,35], but broader health systems failures were sometimes unfairly attributed to them [26]. Some authors highlighted the tension between nursing and under-resourced health systems by juxtaposing the fact that nurses in low-income countries, especially in rural areas, are subject to the same poor environments as their patients with the notion that nurses are expected to somehow overcome difficult circumstances and facilitate health [29,31]. Calls were made for strategies to support nurses in upholding professional codes of conduct, such as value-based education [28,31,36].

Patient care delivery systems
Twenty seven articles addressed patient care delivery systems or the methods applied to assign responsibility for patient care. Of these, 3 papers described development and evolution of clinical specialist and case management roles in which nurses facilitate interdisciplinary coordination of care and perform advanced assessments of adult and pediatric patients in intensive care, oncology and medical/surgical units [37][38][39]. International nursing associations endorsed differentiation of nursing in low-income countries into sub-specialties, such as dermatology and neonatology, as a means of enhancing quality of care [40,41]. Evidence pointed to parity between measures of patient outcomes and patient satisfaction obtained when specialized neurologic and obstetric care was delivered by trained nurses and physicians [42,43].
Problems with excessive workload were said to persist due to overall personnel shortages [44][45][46] and lack of standardized plans to match staffing to patient volume and acuity [47][48][49][50]. One paper reported a surge in workload after top-down directives to integrate HIV/AIDS care into regular clinics were implemented to scale up access to ART [51]. In facilities where workload surpassed staffing, family members assumed responsibility for activities of daily living and other nursing duties for hospitalized relatives [44,52]. Sanctioned or sometimes unauthorized clinical practice beyond the permitted scope of nursing practice, such as prescribing medications and performing deliveries, were another response to health personnel shortages amidst overwhelming demand for services [53][54][55][56][57][58]. Potential benefits of expanded clinical roles      were overshadowed by reservations about nurses' competence and the medico-legal implications of poorly supervised and unregulated nursing practice [55,56].
Discordance between actual and expected nursing practice was also described in terms of non-nursing roles performed by nurses [49,[59][60][61]. Ongoing interventions to demarcate nursing practice included reassigning "head nurse" roles performed by physicians to nurses [59] and development of international classifications of nursing practice (ICNP®) [62,63]. Other strategies used to bolster nursing practice were alignment of patient care delivery closer to internationally accredited Joint Commission standards [64] and instilling problem solving skills that encourage nurses to take ownership of local problems by designing and implementing contextually appropriate solutions [65].

Professional relationships
Seventeen articles examined collaboration and communication between nurses and other members of the profession as well as interdisciplinary team members. In 2 studies, nurses reported high levels of satisfaction with their nursing colleagues [66,67]. Cases where poor relationships between nurses existed were attributed to generational differences, gender biases, divergent views held by nurses entering into practice through assorted levels of pre-service training and perceptions of favoritism by superiors [48]. Similarly, nursephysician relationships elicited mixed reviews. While some nurses rated their relationships with physicians highly [68,69], others described harsh treatment enabled by a wide hierarchical distance that induced subservience and intimidation to the point physicians' actions with the potential to harm patients were overlooked [48,60,70]. Across borders, exemplars of relationships between nurses in high-and low-income countries established through short-term humanitarian ventures aimed at strengthening clinical and research capacity in lowincome countries were abundant [47,64,[71][72][73][74][75][76][77][78][79][80]. Challenges inherent to these international collaborations were cultural and bureaucratic differences [74] as well as lack of validated paradigms against which brief volunteerism could be modeled and measured [76]. Indeed an assessment of partnerships between nurses in high-and low-income countries found that most failed to create sustainable projects capable of thriving past the departure of high-income country partners and many did not ensure development of lowincome country counterparts to their highest potential [81]. We found one example of a long-term mentorship program that has led to measurable improvements in nursing-specific quality indicators [47,64].
Within their borders, nurses in low-income countries capitalized on their relationships with each other and with providers from other disciplines to coordinate care [47,53,57,82,83]. In one article, palliative care nurses described themselves as "spiders in a web" weaving a network between patients, other health care providers, family members, religious leaders and community volunteers [82]. Another paper reported psychiatric nurses routinely sought consults from physicians and were relied upon by other nurses to provide consultations on their patients [53].

Management approach
Only 1 article assessed the capacity of nurses to fulfill the management role. In this study, researchers found that community health nurses were ill prepared to assume management responsibilities necessary to mobilize other health providers and translate the principles of evidence-based practice and research into meaningful changes in health services delivery [84]. Supervision activities in some settings were carried out inconsistently, which meant some nurses rarely received support from their superiors [53] and left others dissatisfied with management [66,67].

Remuneration
Eleven articles appraised the rewards and compensation nurses receive for their performance. While no one type or amount of compensation appealed to all nurses, low salaries were a source of dissatisfaction universally [25, 49, 53, 57, 66-68, 85, 86]. Still, some nurses expressed willingness to accept an even lower salary in exchange for non-monetary incentives, such as job security in the form of permanent employment [87]. Non-financial benefits emerged as an important source of satisfaction, including access to health care for family members, accompanying religious pilgrims as a member of the health corps, free uniforms and transportation, recognition for employees of the month [49], national Florence Nightingale Awards in commemoration of international nurses' day [88,89], comfortable working space, tea with sugar and adequate toilet facilities [57]. Others desired eligibility for paid vacation days, maternity leave, subsidized child care, retirement plans, low-interest loans and life-insurance policies [68,90]. Lack of competitive salary schemes was said to negatively impact personnel retention [53] and reduce motivation to seek additional academic qualifications because salaries did not increase in tandem with added credentials [91,92]. Job security and stable incomes associated with employment in government-run facilities were considered more desirable than private or nongovernmental organization facilities whose bonus payments were sometimes dependent on periodic funding cycles and therefore not guaranteed [83,92].

Discussion
Our integrative review of the literature on PPMs for nurses in low-income countries provides encouraging evidence of focus and interest in examining elements within organizational systems that influence nurses and nursing practice in low-income countries. Although we discovered only one article that addressed PPMs as a comprehensive and integrated model in the low-income country context [93], it is apparent that individual components of the model have been applied, described and evaluated. Due to the heterogeneity of studies and regions assessedas is typical of integrative reviewsthe level of evidence from our review of the literature alone is not sufficient to support PPMs as a framework for configuring the nursing workforce across all low-income countries. Nevertheless, we shed light on some patterns that are worrisome and indicate the need for better organizational systems to support nursing workforce performance. Conceptually, the PPM paradigm could be such a system.
Innovations in health services delivery, such as task shifting, whose successes are largely attributed to nurses playing a leading role, relieve urgent health personnel shortages to provide quality care that is efficient, costeffective and accessible [94,95]. The task shifting approach executed within well designed and managed program-specific domains whereby nurses are properly supported and compensated must not be confused with circumstances in low-income countries that compel nurses to take on additional responsibilities without adequate organizational backing and with unrealistic expectations this will increase production of health services. The latter can be a double edged sword. On one hand, nurses in these settings are at the forefront of health services delivery, holding a position that would otherwise wield considerable influence over health outcomes. On the other hand, being under-qualified, ill-equipped, poorly supervised, earning meager wages and resigned to a subordinate status to physicians prevents the full expression of nursing expertise in resource deprived milieu where it is needed the most.
PPMs emphasize that clinical decisions made at the point of interface between nurse and patient mark the critical juncture at which the trajectory of illness can lead to improvements in health or worse, the cascade to death [13]. Therefore, PPMs are concerned with bolstering nurses' surveillance of patients so that appropriate decisions are made and suitable actions taken time after time [13]. Seminal research conducted in United States facilities has shown that the odds of both failure to rescue and preventable mortality increase as additional patients are assigned to a nurse and in poor environments of care [96,97]. One example of an inappropriate configuration of care applied in low-income countries as a result of extreme shortages of health workers that can compromise patient outcomes is the assignment of an inadequately trained nurse to be the only primary care provider serving an underserved population [98]. A qualitative investigation by Bossyns and van Lerberghe [99] found that front line nurses in Niger withheld referring patients to higher levels of care, even when those patients faced life threatening emergencies, such as postpartum hemorrhage, in order to preserve their public image as knowledgeable and competent. They concluded that poorly skilled nurses were a major hurdle preventing patients and their families from gaining access to proper health care, alongside such barriers as cost of care and distance to health facilities.
The critical role of nursing education became clear in this review of the literature. Formal education remains the ideal conduit through which nurses acquire necessary skills, become socialized to the profession and empowered as a health care force [100]. The global nursing community has united to create and advocate for a universal standard for initial education in order to gain entry into nursing practice [100]. These standards endorse contextually appropriate pedagogy to better prepare nurses for the complex practice reality they will encounter upon entry into the work environment [100]. However, efforts to better prepare nurses to achieve national and local health goals must be matched by well-defined and appropriately legislated nursing practice standards. The case of Botswana highlights the case that producing a qualified workforce is only half the battle. A Family Nurse Practitioner (FNP) program has been in place there since 1973 and intended to prepare nurses who can fulfill a primary care role at an advanced level [101]. A well trained pool of FNPs was envisioned to provide enhanced coverage in a country with no medical school and concomitant severe shortages of physicians. However, both the health system and legislature remain unprepared to absorb this higher level cadre causing instances of confusion about the role of FNPs [101,102]. With the role of FNPs misunderstood, they are often utilized as nurses or midwives, moving further away from their intended role as primary care providers [102].
Emphasis should be placed on developing a competent, autonomous and dynamic cadre of nursing leaders poised to contribute to organizational decision making. Although management approaches were notably the least examined component of PPMs in our review, their importance cannot be negated. Studies of high performing United States hospitals attributed their success to managers whose commitment to quality of care prompted implementation of processes to attract and retain personnel well-suited to fulfill organizational quality-driven goals and providing "staff the right tools to do their job" [103,104]. In dynamic clinical milieu, the human resources management practices executed by nurse leaders indirectly influence the quality of health services. However, the capacity of health human resources managers in some low-income regions has been found to be deficient. In 26 sub-Saharan African countries, human resources units within ministries of health were understaffed and subject to frequent turnover [105]. Managers at the ministry of health and district levels were reported not to possess mandated qualifications for their role [105]. Programs like the Global Nursing Leadership Institute and Leadership for Change™, both offered by the International Council of Nurses, present opportunities for nurses in low-income countries to develop leadership skills necessary to overcome complex health systems challenges and drive a nurse-centered agenda. While there is a cost associated with participation in these programs, attendees can apply for sponsorship.
Global health as a discipline has exploded and introduced the need for a new paradigm to define relationships between health personnel in low-and high-income countries. According to the Consortium of Universities for Global Health (CUGH), there are more than 130 universities offering global health programs in Australia, Canada, Denmark, France, Italy, Japan, The Netherlands, Sweden, United States and United Kingdom [106]. Increasingly, schools of nursing are developing dedicated centers for global health scholarship and sending students abroad on international clerkships, but while these enterprises may have been well intentioned, they have not always been without deleterious effects to host institutions and communities in low-income countries [107]. Collaborations between nursing faculty, clinical experts and researchers in low-and high-income countries must be entered into with the view to strengthen health systems in low-income countries; programs should be developed to align with national health goals and adhere to codes of conduct that benefit low-income country partners [108].
One troubling reality emerging from our review is the mistreatment and neglect suffered by some patients while under the care of nurses [26,27,[29][30][31][32][33]. Unfortunately, disrespect and abuse of patients by some nurses has been a known but largely ignored problem until recently; a symptom of vulnerable health systems unable to respond adequately to multiple pressing needs [109]. However, patients know they want and deserve better. In the case of rural Tanzanian women responding to a discrete choice experiment asking them to rank preferences for place of delivery, respectful treatment by staff was valued higher than other factors, such as distance and cost, in deciding to seek safer facility births [110]. Freedman and Kruk [109] posit that individual actions in violation of patients' rights occur at the convergence of complex personal, normative and systemic circumstances. Nurses in low-income countries often work in extremely difficult conditions that exert undue pressure on their physical and psychological wellbeing, which can manifest in poor treatment of patients [109]. A discussion about quality improvement in health services delivery, Freedman and Kruk [109] argue, must include interventions that empower health providers to meet the demand for quality care.

Limitations
A limitation of this review was the time commitment necessary to analyze the large cache of articles retrieved using the prescribed search strategy. As described previously, we found that enhancing the search with additional terms compromised sensitivity, which meant numerous relevant articles would have been left out. This paradox can be explained by an imprecise alignment between the key words describing our concepts of interest and vocabulary contained in the databases we searched [24]. For example, the term closest in resemblance to the conceptual meaning of patient care delivery systems in PubMed was professional delegation, which when combined with nursing and low-income countries did not yield any results. Therefore, we concluded that although it was time consuming, our approach yielded the most pertinent collection of articles for our analysis. It is important to note that we only looked at published articles written in English. As a result, our review could be subject to publication bias. It is possible there are related studies that have not been published or published in a language other than English or indexed in databases not targeted in our search. Nevertheless, our results provide a valuable lens through which capacity building for nurses in low-income countries can be viewed and used to inform future research.

Conclusion
In low-income countries facing unrelenting health workforce shortages and an overwhelming disease burden, nurses overseeing the bulk of health services delivery require more than an adequate supply of equipment and medications. Functional organizational systems are necessary to support nurses in fulfilling their professional obligations. The discourse on reinforcing the nursing workforce in low-income countries should consider the elements of PPMs, wholly or individually, as a framework around which nursing practice can be structured.