A Historical Overview of Pressure Ulcer Literature of the Past 35 Years

  Pressure ulcers constitute a pervasive problem in healthcare. They cause a great deal of suffering and frustration to patients, their relatives, and their caregivers. Furthermore, pressure ulcers increase the workload of healthcare clinicians and, as a consequence, increase healthcare costs dramatically.^1-4

High prevalence rates have been documented. In the Netherlands, for instance, a prevalence rate of 23% has been found for hospitals and 32% for nursing homes.^5-7 The Dutch Health Council has calculated that at least 1.3% of the national healthcare budget is used for the prevention and treatment of pressure ulcers.⁸ This means that pressure ulcers are one of the biggest and most expensive problems within healthcare and demand considerable attention from clinicians and scientists. This article examines the attention pressure ulcers have been getting in the clinical, and especially, scientific literature, and the topics this attention has targeted.

  In general, clinicians rely on several sources of knowledge: tradition; authority; experience and trial and error; logical reasoning; and scientific methods.⁹ Pressure ulcer knowledge is mostly based on the first four sources. For example, the frequent use of "massages" as a preventive method¹⁰ is being perpetuated by tradition or custom, and ultimately by authority – ie, that of the physician.¹¹ Furthermore, many methods are developed by experience or trial and error, as in the choice of support surfaces.¹² Although these sources of knowledge are very useful, they have one common problem: The conclusions they elicit can be affected by personal experience, emotions, and other sources of bias. The scientific method uses a range of checks to minimize these biases. As the guidelines of the Panel for the Prediction and Prevention of Pressure Ulcers in Adults¹³ and the European Pressure Ulcer Advisory Panel (EPUAP) guidelines¹⁴ show, most knowledge is still not based on scientific research; therefore, building a scientific knowledge base is important in order to temper personal experience and other forms of bias from affecting clinical decisions.

Research Questions

  The present article tries to answer the following research questions:
    1. What proportion of the articles published from 1965 to 1999 relate to pressure ulcers?
    2. In what proportion of the clinical and research articles published from 1965 to 1999 was pressure ulcers the main topic?
    3. What topics are examined and what designs are used in the research articles published from 1965 to 1999?
    4. What (if any) are the differences between publications of authors from the United States and Europe?

Method

  A Medline search was performed, using the terms "pressure ulcers," "pressure sore," and "decubitus." No other sources (such as Cumulative Index to Nursing and Allied Health Literature® [CINAHL]) were used, because many clinicians agree that Medline provides a good representation of what has been written about pressure ulcers. Medline includes articles of medical and nursing journals. Between 1965 and 1999, a total of 6,056 articles regarding pressure ulcers were found. All editorials, comments, and letters (n = 330) then were excluded. To further reduce the number of articles, the search terms offered by Medline were used. These were not sufficiently reliable to select the research articles. Hence, all articles would have to be classified manually by the first author. Because this was not feasible, only a selected number of years starting with 1965 and then every fifth year were examined. The year 2000 was not used because the Medline data for this year were not yet complete; articles from the year 1999 were used instead.

  The following information, as provided by Medline, was gathered for each paper:
    * the year of publication
    * the main topic
    * designation as a research article
    * design use
    * the country of origin of the first author.

  The main topics were categorized as follows: anamnesis, prevention, treatment, quality improvement, basic research and "other topics." Each topic was divided into subtopics (eg, the subtopics for anamnesis were general, incidence, prevalence, assessing tissue damage, and risk-assessment tools).

  Four types of design were distinguished:
    1. Trials (studies using a control group and an experimental group or in some way providing a comparison between using and not using an intervention)
    2. Descriptive studies (all other studies using an empirical design)
    3. Reviews (articles which were classified as reviews in Medline, or which the authors of this article interpreted to be reviews)
    4. Case studies (articles describing one or more specific cases).

  This design classification was very rough and imperfect, but a more reliable classification would have required studying each article, which was not possible in the present study. In interpreting the findings, the reader should keep in mind that the trials and reviews were not randomized clinical trials or systematic reviews as presently defined.

  The country of origin of the first author proved to be very difficult to classify before 1990; most articles from the early years failed to mention the addresses of the authors. Therefore, only the information for the period 1990 to 1999 was used for this factor. Even in this period, 39% of the articles failed to mention the country of the author. In those cases, the authors classified that data as "missing." The categories included United States, Europe, and "other countries."

  In all, 1,109 articles were classified; in 243 of these articles, pressure ulcers were not the main topic. Instead, the phrase pressure ulcers was only used to describe a population or as one of the outcomes. These articles subsequently were removed from the set, leaving 866 articles for further analysis.

Results

  Medline included a total of 6,065 articles about pressure ulcers from 1965 to 1999, out of a total of 10,430,376 articles. This means that pressure ulcer articles constituted .06% of all articles. In other words, for each article on pressure ulcers, 1,666 articles were about other healthcare topics.

  Figure 1 shows the development of the number of pressure ulcer articles included in Medline from 1965 to 1999 in comparison to the total number of articles. Note: the total number of articles has been divided by 1,000 to allow the two curves to be compared in one figure. The figure shows that the focus on pressure ulcers has grown during these years. Although the total number of articles on all kinds of topics during this period increased as well, the number of articles did not grow as fast as the number of pressure ulcer articles. In fact, the percentage of pressure ulcer articles of the total number of articles grew from .03% (1965 to 1969) to .08% (1995 to 1999), an almost threefold increase between 1965 and 1999. This means that the attention paid to the problem in the clinical and scientific literature is growing faster than the volume of literature in general.

  For the next analysis, all editorials, comments, and letters (n = 330) were excluded and the database was reduced to each fifth year, starting at 1965 and ending at 1999. After excluding articles in which the term decubitus was used in a different sense (position of the body), or in which pressure ulcers were not the main topic, 866 articles were left for further analysis.

  Of the remaining 866 articles, 49% could be classified as research articles. All other articles (51%) were more or less popularized descriptions of how to prevent or treat pressure ulcers, which meant they should be classified as clinical articles. Such articles are often based on the author's personal experience, ideas, and expertise.

  Figure 2 shows the increased number of clinical and research articles with respect to pressure ulcers. The proportion of research articles started to grow from 1985. In 1990, more research articles than clinical articles were published. Although the number of clinical articles had also increased in 1995, this trend was not continued in 1999.

  The next step in the analysis concerned the study designs reported in the research articles. Figure 3 shows that most studies were based on descriptive designs. From 1990 on, a growth in the use of trials and reviews is evident; the number of studies with descriptive designs continued to grow as well.

  Figure 4 shows that most studies concerned anamnesis, prevention, or treatment, although in recent years, more studies focus on other topics. Figure 5 illustrates the most frequently studied specific topics, showing that most research has been done on support surfaces, followed by surgical procedures, especially the effect of using flaps and dressings. From 1990 on, a steadily increasing number of research projects on risk assessment tools were initiated. One of the new topics is the economic impact of pressure ulcers.

  The total number of all articles written by American and European authors (155 versus 149) are comparable. The largest number of research articles was written in the United States (120 versus 94); the largest number of clinical articles was written in Europe (35 versus 55). The greatest growth in the number of research articles has taken place in Europe (1990: 24 versus 7; 1995: 35 versus 24; 1999: 61 versus 63). The number of articles written by European authors was highest in 1999.

  A comparison of the research topics studied in the United States and Europe shows that research in the United States has tended to focus on treatment of pressure ulcers (40 versus 22) and on basic research (22 versus 11). European researchers have been paying more attention to prevention (18 versus 26). Figure 6 depicts the most frequently studied specific topics. It shows that United States' researchers have paid more attention to dressings and the etiology of pressure ulcers while their European counterparts are focusing attention on prevention, mainly regarding support surfaces.

Conclusion

  This overview of articles from the past 35 years shows that the clinical and scientific literature has not paid a great deal of attention to pressure ulcers. Of all articles included in Medline, .06% relate to pressure ulcers. Although the level of attention to this subject is now growing, it is still far from adequate because a comparison of the percentage of articles with the costs of pressure ulcers in healthcare shows that the two are out of proportion. At least 1.3% of the annual healthcare budget in the Netherlands is directed toward the prevention and treatment of pressure ulcers.⁸ This means that the percentage of total costs is more than 20 times higher than the percentage of the total number of clinical and scientific papers devoted to pressure ulcers. It can be concluded that the problems inherent in pressure ulcers are greatly underestimated by clinicians and scientists, despite the growing number of pressure ulcer articles.

  Secondly, only half of the articles published about pressure ulcers were research articles. Research articles were written more often by United States' authors; clinical articles were more often from European authors. Although clinical articles are important for the diffusion of knowledge to clinicians, research is needed to build up a knowledge base on pressure ulcers. Available scientific knowledge about pressure ulcers is still poor. For instance, clinicians still use a theoretical model (eg, Bergstrom¹⁵ and Defloor¹⁶) that assumes that pressure ulcers develop due to pressure or shear and friction in interaction with tissue tolerance, even though good quality research on this model is still scarce. Fortunately, the proportion of research articles is growing, especially in Europe.

  The present study also shows that most research articles have focused on anamnesis, prevention, and treatment, with American authors paying more attention to treatment and basic research and European authors concentrating particularly on prevention. The most frequently studied specific topics include support surfaces (especially in Europe) and surgical procedures (especially in the United States), while the number of studies of incidence, prevalence, and risk assessments scales has recently been growing. Most topics have been studied using a descriptive design.

  A remarkable development is the rapid growth in the number of review articles. Most of these review articles were not systematic reviews in the current sense of the term. The authors classified articles as reviews if Medline classified them as such (or if the authors determined they were reviews). Because it seems strange to write reviews when only a few studies have been done, the authors writing this article assumed that many of these reviews were clinical articles rather than actual scientific reviews. This meant that the true proportion of research articles may well be lower than 49%, as reported.

Discussion

  The present study has some limitations. First, only articles appearing in Medline were used, and analysis was based purely on the information provided by Medline, rather than on the articles themselves. The Cumulative Index to Nursing and Allied Health Literature® (CINAHL) could have served as a source. However, Medline includes all relevant nursing journals as well as all relevant journals for pressure ulcers. Possibly, CINAHL includes more clinical nursing journals, especially journals not published in English. This could have influenced some results, especially when considering the country of origin of the first authors. Furthermore, articles were classified only by the first author. To obtain a general overview of publications on pressure ulcers with broad classification categories, this seemed adequate.

  In addition, the information gathered does not allow the reader to assume any conclusion regarding the quality of the articles counted. The fact that insufficient knowledge still exists about the etiology of pressure ulcers (as well as, for example, the effect of support surfaces, even though a great deal of research has been done) suggests that the quality of the research needs improvement. What may be even more important is that research efforts need to be coordinated and concentrated on specific aspects, allowing a sound scientific knowledge base on pressure ulcers to be compiled. The National Pressure Ulcer Association Panel and EPUAP could take the initiative for coordinating this effort by stimulating researchers who are studying the same topic to form international working groups. The European Pressure Ulcer Advisory Panel already has started to collect information on ongoing research into pressure ulcers. A questionnaire has been developed and is available on the EPUAP website (www.epuap.org). All researchers are invited to complete the questionnaire to help provide a complete picture of all ongoing research.

  Topics requiring urgent attention include the etiology of pressure ulcers, identifying high-risk patients, the effectiveness of preventive and treatment methods, and the diffusion of knowledge. Although scientific knowledge remains inadequate, some knowledge based on theory and experience is available. However, several studies have shown that this knowledge is not being implemented in practice. Research on the implementation and diffusion of knowledge has revealed considerable variation in the effectiveness of these processes, although a combination of information transfer and learning through social influence or management support seems to be effective. One should note that most studies of implementation and diffusion have been done among general practitioners and not among nurses. Whether these methods are useful in nursing practice remains unclear.

Considerations

  The main conclusion that can be drawn from the present study is that pressure ulcers have received less attention in the literature than clinicians might expect, reflecting the lack of interest by clinicians in pressure ulcers and their prevention in practice. Why is so little attention paid to this problem? A few possible reasons can be suggested, although the list is far from complete.

  Pressure ulcers are an invisible problem, both literally and figuratively speaking. The fact that it is not a medical diagnosis but a complication of another diagnosis may mean that pressure ulcers are not adequately registered, so insufficient data on the incidence and prevalence of pressure ulcers exists. Often, the managing staff at healthcare institutions believe that pressure ulcers are no longer a problem, making it important to increase acknowledgment of the problem. In the Netherlands, a survey program has been measuring the national prevalence of pressure ulcers annually since 1998.^5-7 The resulting data have exposed concerns; as a result, pressure ulcers are now regarded as a serious problem that requires urgent attention. The Ministry of Health, the health inspectorate, and the managing staff at healthcare institutions have already initiated a number of programs at the instigation of the Dutch National Steering Group on Pressure Ulcers to bring pressure ulcers to the attention of clinicians and researchers.

  Another reason for the lack of attention paid to pressure ulcers is that the condition is not life-threatening and therefore not a sensational subject for clinicians and researchers to investigate. However, if the problem becomes more noteworthy and all participants (ministry, inspectorate, management, funding bodies) rise to their responsibilities, pressure ulcers can become a more intriguing topic for clinicians and researchers. In clinical practice, institutional management can direct attention to pressure ulcers, and funding bodies can stimulate further research into this subject. The only foreseeable problem is that if clinicians pay adequate attention to pressure ulcers, they will, in the ideal circumstance, see nothing, because no pressure ulcers will develop. Hence, other reinforcements must be considered, such as offering clinicians incidence or prevalence feedback data that illustrate the success of their policy.

  A final consideration is that pressure ulcers are historically regarded as a nursing problem. Until a few decades ago, nurses had no research tradition. Unfortunately, most nursing research does not focus on basic nursing problems like pressure ulcers, but rather on organizational problems (eg, stress among nurses, workload, disease management, case management), as well as on more qualitative research to investigate the needs, beliefs, and experience of patients. Without arguing that these topics are less important, the authors conclude that more attention and quantitative research should be focused on the basic needs of patients, including rest/activity patterns, feeding, mobility, and incontinence. A prevalence assessment similar to the study discussed herein could focus attention on these topics and their attendant problems.

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