Applying Evidence at the Population Level

Ann L. Cupp Curley and Margaret M. Conrad

Nurses in advanced practice have an obligation to improve the health of the populations that they serve by providing evidence-based care. The American Association of Colleges of Nursing (AACN) has outlined eight essentials that represent the core competencies for the education of doctorally prepared advanced practice registered nurses (APRNs). The first essential listed is scientific underpinnings for practice (American Association of Colleges of Nursing, 2006). This competency stresses the integration of evidence-based practice into advanced nursing practice. APRNs are educated at the graduate level in research and critical appraisal skills and possess specialized clinical knowledge. These specialized abilities prepare the APRN to demonstrate the importance of evidence-based practice to others and to facilitate the incorporation of such evidence into practice (DeBourgh, 2001).

In this chapter, the APRN will learn how to integrate and synthesize information in order to design interventions that are based on evidence to improve population outcomes. Nurses need a sound knowledge of research methodology to support an evidence-based practice. They also require a wide array of knowledge gleaned from the sciences and the ability to translate that knowledge quickly and effectively to benefit patients (Porter-O’Grady, 2003). The goal of this chapter is to summarize the skills required for evidence-based practice and to provide specific examples of how APRNs use these skills to improve population outcomes.

ASKING THE CLINICAL QUESTION

There are many situations that drive clinical questions. Clinical practice and observation, as well as information obtained by reading the professional literature, can lead nurses to ask questions such as “Why is this happening?” “Would this approach to care work in my clinical practice?” or “What can we do to improve this outcome?” An APRN who reads an article about an innovation in practice that leads to an improvement in a population outcome might wonder whether such an intervention would work in another setting. The observation that the readmission rates for a particular diagnosis are increasing, or that rates for a particular disease are higher in one population than in another, or that patient satisfaction scores for a particular group of patients are lower can all lead to a search of the literature for evidence to change and improve outcomes. It may also lead to further research to improve outcomes or the implementation of new interventions to change outcomes. But before the search can begin, it is important that clinical questions are defined clearly and in a way that can be answered and applied to practice.

The second step is to determine what intervention or process you want to study. As mentioned earlier, defining the method of study early on can help develop the PICO question more fully. In this particular example, the APRN hypothesized that increasing the self-efficacy of inmates with diabetes through a self-management course might help inmates manage their diabetes better. Having read in the professional literature about self-management courses for chronic illnesses used in other settings, the APRN postulates that a chronic disease self-management course might increase compliance rates with inmates through an increase in self-efficacy.

•  Intervention: A chronic disease self-management program (CSMP).

In this particular example, the APRN wants to measure self-efficacy and diabetes management before and after the CSMP. The comparison is, therefore, diabetes management before and after the intervention.

•  Comparison: Diabetes management in mentally ill inmates housed in state prisons, diagnosed with diabetes before and after implementation of the CSMP.

The last step is the outcome: What does the APRN want to see improved? What does the APRN expect to accomplish? The objective in this case was to increase self-efficacy and improve diabetes management in a targeted population of mentally ill inmates with diabetes after implementing a CSMP.

•  Outcome: Self-efficacy (measured using a validated self-efficacy scale) and hemoglobin A_1c levels (as a measure of diabetes management).


Using these steps, the APRN can compose the final PICO question: “Will a 6-week chronic disease self-management program increase the self-efficacy of insulin-dependent diabetic mentally ill inmates in a state prison setting?” (Conrad, 2008). Development of the PICO question provides the APRN with a better understanding of the clinical problem, allows for specific measures to be introduced, and provides the foundation for a well-designed study. The next step is to perform a thorough and comprehensive literature review.

The literature search should further define and clarify the clinical problem; summarize the current state of knowledge on the subject; identify relationships, contradictions, gaps, and inconsistencies in the literature; and finally, suggest the next step in solving the problem (American Psychological Association [APA], 2009). The search of the literature can be conducted by the APRN, or the APRN can engage the assistance of a research librarian if available. Librarians are educated to find and access information and are excellent resources for assisting with literature reviews. Navigating databases in order to find relevant information can be a complex process. The searcher needs to use the correct terms, search the correct databases, and use a well-designed and systematic search strategy. The searcher should also document each step of the process in order to provide an audit trail and avoid duplication of work (Hallyburton & St. John, 2010). An audit trail provides clarity to the method used to find the evidence and allows others to follow the decision-making process (Houde, 2009). In the absence of a librarian, there are steps that the APRN can take to increase the likelihood of a successful search.

Searches of a single keyword can result in a very large number of articles. For example, a CINAHL search for full-text articles using the keyword “diabetes” yielded a list of 81,693 articles. Including more than one concept in the search is more likely to provide relevant and useful articles. Boolean logic is the term used to describe certain logical operations that are used to combine search terms in many databases. Using the Boolean connector AND narrows a search by combining terms; it will retrieve documents that use two keywords. Combining words with a Boolean connector such as AND (e.g., prisoners AND diabetes) can narrow the search. In CINHAL, using prisoners AND diabetes yielded 33 articles. Using OR, on the other hand, broadens a search to include results that contain either of the words that are typed in the search. OR is a good tool to use when there are several common spellings or synonyms of a word. An example in this case would be inmate OR prisoner. Using NOT will narrow a search by excluding certain search terms. NOT retrieves documents that contain one but not the other of the search terms entered. It is appropriate to use when a word is used in different contexts. An example would be prisoners NOT captives. Parentheses indicate relationships between search terms. When they are used, the computer will process the search terms in a specified order and also combine them in the correct manner. For example, (inmate OR prisoner) AND diabetes combines inmate or prisoner and diabetes to get the most relevant results. A search conducted in the full-text database of CINAHL using these words and connectors yielded 232 articles.

There are other methods that can be used to make searches more relevant and useful. Specifying limits, such as English language only, peer-reviewed journals only, randomized controlled trials only, and a date range can narrow a search and increase the relevance of the information retrieved. Keep in mind that the more limits that are placed on the search, the fewer the results. A search using (inmate OR prisoner) AND diabetes, full text only, English only, limited to articles published in the past 5 years yielded 36 articles. However, it is recommended that the initial search should be broad and explored before restricting the search limits, as this could lead to information bias. For this PICO question, the following keywords were used both alone and in combinations: chronic disease, chronic disease management program, diabetes, incarcerated, mentally ill, mental illness, prison, self-efficacy, and self-management.