Bibliometric analyses are useful for providing an overview of published literature, identifying knowledge gaps, uncovering emerging trends, and deriving novel ideas for future investigation (28). The present study analysed the research quantity (i.e., publication output, areas of research focus and trends over time) and quality (i.e., the level of evidence, degree of collaboration, impact factor and citation rates) of NZ DFD-related research.
Whilst the number of articles is relatively small, between 1988 and 2020, the number of NZ produced DFD publications has steadily increased. Notably from 2006 onwards there was an increase in published articles with a peak of six new articles in 2018, and an increase in research growth and national collaboration. The underlining reasons for the increase in DFD research are not attributable to any one factor but may be resultant from numerous diabetes quality of care strategies, policies and initiatives implemented in the early 2000s in NZ. Additional File 1 presents a timeline of policies/strategies/initiatives that may have potentially influenced NZ DFD research. Notably during this period, the NZ Government strategy elevated the importance of diabetes with the release of The NZ Health Strategy (2001) (29). Reducing the incidence and impact of diabetes was one of the 13 health objectives chosen for implementation in the short to medium term.
Whilst the significance of diabetes in context of NZ came to the fore with changes in health policy and strategy, research development prior to 2000 was hindered by limited research funding. In 2000, health research accounted for only 1% of the national health budget (30). It was not until 2005 that the Health Research Council (HRC) of NZ became a Crown agent, charged with putting into effect government policy in relation to health research. The opportunities for NZ researchers to obtain funding has improved in the past 15 years, however our results indicate DFD research by NZ researchers is still poorly funded with only 32% of the included articles declaring research funding support. Most of these studies were funded by national organisations (DHBs, universities, HRC; n = 11, 23%) and represent studies that were largely observational in nature. Consequently, as these types of studies are of a lower level of evidence, they are often insufficient to change clinical practice in comparison to large international multicentre and randomised studies funded through multiple international sources. Without significant investment, resourcing to implement high level of evidence locally relevant studies such as RCTs will remain limited.
The research collaboration post 2006 demonstrated marked growth with international and bi-national collaboration increasing. Bi-national authorship post 2006 may have been positively affected by increasing working relationships between DHBs, Primary Health Organisations (PHOs), and university research institutes, partially facilitated by health system restructures. Our data shows there has been a high level of bi-national collaboration since 2006 with 80% of national collaboration occurring between a DHB and university research institute/department. International collaborations are also indicative of the increasing global reach of NZ based research and active exchange of knowledge and research skills.
Despite the increase in number of publications and increased national and international collaborations, the majority of the identified publications (87%) represent studies classified as basic/clinical research, which represents a lower level of evidence as per the Oxford Centre for Evidence-based Medicine (level 3 or 4 evidence) (31). Based upon the Oxford levels of evidence rating, and the relatively low citations rates, the majority of the identified NZ DFD-related publications were categorised as of poor quality. Of the top five cited articles (contributing 46% of total citations), four were RCTs (one first-authored by NZ researcher) and four were multicentre studies first-authored and led by international researchers. The most cited articles are either multicentre national or international RCTs representing high quality of evidence.
The median journal IF (4.31, IQR: 2.75-6.81) was relatively low for included publications. Only five articles were published in journals with an IF of greater than 10. Of note, most publications were published in the New Zealand Medical Journal (n = 10, 21%), which does not currently hold an IF. IF is the most common metric for evaluating bibliometric impact of published research, however the value of the research is not necessarily reflected by the IF (16). This finding is interesting as researchers often seek publication in so called higher impact/prestigious journals with the intention of improving their personal citation rate, and h-indices. Furthermore, academic staff promotions at universities often depends upon the publication of a certain number of articles in scientific journals (32). However, authors sometimes chose to publish in journals based on the intended audience/readership where the article may have the most context and/or clinical impact. This may be more common when authors come from a clinical rather than purely academic background, where their driver maybe to improve outcomes rather than produce high ranked research outputs. Alternatively, the decision to publish in a particular journal may be dictated by the availability of funding to support the fees associated with publication. A combination of the above factors may be likely reasons for many NZ authored DFD articles being published in the New Zealand Medical Journal.
Categorisation of research by type found that there was a relatively even spread number of articles categorised as screening/prevention, management of diabetes-related foot complications, and epidemiological studies. However, of the studies categorised as screening/prevention none were interventional studies. With few studies aimed at improved care or prevention of diabetic foot ulceration/amputation, coupled with recent international calls to reduce foot ulcer incidence by at least 75% and local NZ health priorities to reduce health inequities for Māori, a shift in DFD research priorities is essential (6). Therefore, the first steps towards this goal are to evaluate the performance of diabetic foot services aimed at prevention and early detection of DFD, and the ability of services to reduce inequities in access to services and health outcomes. This is a priority in NZ given the regional variation in DRLEA and significantly higher amputation rates for Māori (7, 9, 10).
The results of this study have several limitations that must be considered. All metrics were extracted based upon our pre-defined search terms, and data only from the Scopus® database, which may not include all publications that meet our inclusion criteria. Some peer-reviewed journals are not indexed in Scopus®. However, we also checked for additional publications by screening reference lists of identified articles from the initial search. As this study included only journal articles, our findings may not reflect all NZ DFD literature. It is acknowledged there may be gray literature sources that reveal a number of NZ based quality-of-care improvement initiatives related to DFD that are not published in peer reviewed journals. Finally, citation analysis and journal IF were used as markers of research quality and impact, which are vigorously debated as research quality indicators (16).