The Most Cited Research Institutes on the Topic of Opioid Use Disorders in PubMed Central Since 2000

Research Article

Austin Addict Sci. 2019; 3(1): 1013.

The Most Cited Research Institutes on the Topic of Opioid Use Disorders in PubMed Central Since 2000

Julie Chi Chow1, Tsair-Wei Chien2, Chien-Ho Lin3 and Willy Chou4,5*

1Department of Pediatrics, Chi Mei Medical Center, Taiwan

2Research Department, Chi-Mei Medical Center, Taiwan

3Department of Psychiatry, Chi-Mei Medical Center, Taiwan

4Department of Physical Medicine and Rehabilitation, Chi Mei Medical Center, Taiwan

5Department of Recreation and Health-Care Management & Institute of Recreation Industry Management, Chia Nan University of Pharmacy, Taiwan

*Corresponding author: Willy Chou, Chi-Mei Medical Center, 901 Chung Hwa Road, Yung Kung Dist., Tainan 710, Taiwan

Received: November 19, 2019; Accepted: December 16, 2019; Published: December 23, 2019


Background: Many regions are experiencing an epidemic of drug overdose (poisoning) deaths involving opioids (opioid pain relievers and heroin) in the past. A total of 47,055 drug overdose deaths occurred in the United States, representing a 1-year increase of 6.5%, from 13.8 per 100,000 persons in 2013 to 14.7 per 100,000 persons in 2014. Numerous authors have published articles regarding Opioid Use Disorders (OUD). Which research teams with the most citations is unknown.

Methods: By searching the PubMed Central (PMC), we used the keyword “opioid use disorders” and downloaded 371 articles published since 2000. A total of 1,868 articles were cited in PMC. The Authorship-Weighted Scheme (AWS) was used for quantifying coauthor contributions in an article byline when computing the credits allocated to the institutes. A visual dashboard for the most-cited countries was shown using the choropleth map on Google Maps. The x-index was applied to measure the Individual Research Achievements (IRA).

Results: We observed that the most cited countries and their corresponding x-indexes are from the United States (16.77), the United Kingdom (3.91), and Demmak (3.31). The author Rose A Rudd (the US) ranks the highest (i.e., x=12.69) with one paper (PMID: 26720857, 2016) cited 250 times. The most cited research institute is Department of Medicine, Massachusetts (US) with the x-index=4.37.

Conclusion: There has a rapid increase of scientific research productivity on OUD The US has special contributions to the body of opioid use disorders. The AWS used for quantifying the IRAs for countries and institutes is recommended to scientific disciplines in the future.

Keywords: Pubmed central; Authorship-weighted scheme; Research team; X-index; Google maps; Opioid use disorders


AWS: Authorship-Weighted Scheme; IRA: Individual Research Achievements; OUD: Opioid Use Disorders; PMC: PubMed Central; VBA: Visual Basic for Application


The United States is experiencing an epidemic of drug overdose (poisoning) deaths with the rate of deaths increased 137% since 2000, including a 200% increase involving Opioid Use Disorder (OUD) [1,2] (e.g., fentanyl, heroin, oxycodone) that leads to clinically significant impairment [3]. A total of 47,055 drug overdose deaths occurred in the US with a 1-year increase of 6.5%, from 13.8 per 100,000 persons in 2013 to 14.7 per 100,000 persons in 2014 [1].

The OUD diagnoses have risen substantially over the past decade. The treatment services have struggled and strived to meet the OUD demand [3]. Treatment for OUD is important, but adherence to treatment can be a challenge [4].

Meanwhile, fatal drug poisonings have already surpassed firearm injuries as the leading cause of injury deaths. Mortality from drug overdoses and opioid poisonings in the US were 50 and 70 % higher compared to national rates in 2012–2014, respectively [5]. Despite a total of 1711 articles have been searched by the keyword “opioid use disorder [All Fields] as for November 17, 2019 in PubMed Central (PMC) library, which countries (or research institutes) contributed most to the academics remain unknown. We are motivated to investigate the most cited institutes and countries on OUD.

The main changes encountered to us are those two: (1) which Author-Weighted Scheme (AWS) is appropriate for quantifying author credits in the article byline; (2) which metric can be truly reflected Individual Research Achievements (IRA). In the past, many articles [6-8] addressed the issues about quantifying author contributions. Only the one AWS [8] has incorporated with the x-index [9] to the disciplines [10-12] before. We are thus interested in using the two methods (i.e., the AWA and the x-index) for reporting the most cited institutes on the OUD in the past.

In this study, we attempt to identify the most cited countries and research institutes on the OUD topic.


Data source

By searching the PubMed database ( based on PMC, we used the keywords “opioid use disorders” on October 7, 2018, and downloaded 371 articles published since 2000. An authormade Microsoft Excel visual basic for application module was used to analyze the data. All the downloaded abstracts were based on the type of journal article. All the data used in this study were downloaded from PMC, which means that the study required no ethical approval according to the regulation promulgated by the Taiwan Ministry of Health and Welfare.

Two approaches for displaying research results

(1) Author-based perspective: The AWS was proposed for quantifying the author’s contributions [8,10-12]. The sum of authorships equals 1 for each paper referred. More importance is given to the first (primary) and the last (corresponding or supervisory) authors [13], whereas the others (middle authors) are assumed to have made smaller contributions [14,15]. Similarly, the smallest portion) is assigned to the last second author with the odds = 1 as the basic reference [8,10-12].

(2) Bibliometric perspective: The x [9] was calculated and defined as x = , where all the number of cited papers (denoted by ci) in descending order are based on cited publications at i.

The most highly-cited countries/areas can be plotted using the choropleth map [10] on Google Maps. The most cited research institutes with x-indexes can be highlighted using the contingency table to display. The most cited authors were displayed on a dashboard using Google Maps to display.

The most cited articles

The most cited articles on the OUD topic were retrieved from the PMC. The first authors’ institutes were displayed in a contingency table.


Task 1: The most productive countries and journals on the OUD

The x-indexes for countries on the opioid use disorders in (Table 1), we can see that the most cited countries with x-index 16.77, 3.91, and 3.31 are the US, the UK, and Denmark, respectively. The number of publications might yield high citations and x-indexes (i.e., a high correlation of 0.98 between x-indexes and outputs). The U.S. (195, 83.69%) and Canada (8, 3.43%) rank as the top two published papers on the OUD topic since 2000. The affiliated countries/areas are dispersed on Google Maps, (Figure 1).