|Year : 2009 | Volume
| Issue : 3 | Page : 167-172
Pulmonary hypertension in the south east Asia region: An analysis of indexed publication profile
Pulmonary Vascular Research Institute, South East Asia Region, PVRI India Office, Department of Pediatric Cardiology, Amrita Institute of Medical Sciences & Research Center, Ponekkara, Kochi - 682041, Kerala, India
|Date of Web Publication||27-Jul-2009|
Center for Digital Health, Amrita Institute of Medical Sciences & Research Center, Ponekkara, Kochi - 682041. Kerala
| Abstract|| |
According to the World Health Organization (WHO), the South East Asia Region (SEAR) consists of eleven countries with diverse population size, land area, sociopolitical environment, economy and health care systems. Each country has epidemiological and geographical factors that may contribute to risks for developing pulmonary hypertension (PH). Currently, there are no published estimates of the number of people suffering from PH in these countries. This article started as an attempt to capture a general overview of available, indexed publications on PH from the South East Asia region. Publications on PH from the SEAR originated almost entirely from India and Thailand. Further, virtually all of the Medline0 indexed research literature from the SEAR comes from these two countries. The type of available PH literature from this region were analyzed using data such as age groups in human studies, top publishing journals and topics of study (MeSH terms). A web-based tool called MedSum that provides numerical summaries of Medline literature, based on user-provided PubMed style search terms and field tags was used for this work.
|How to cite this article:|
Menon S. Pulmonary hypertension in the south east Asia region: An analysis of indexed publication profile. PVRI Review 2009;1:167-72
| The South East Asia Region|| |
According to the WHO, the countries Bangladesh, Bhutan, India, Indonesia, DPR Korea, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timor-Leste constitute the South East Asian Region (SEAR).  At the PVRI annual general body meeting held at Mexico in January 2009, it was suggested that the PVRI South East Asia Region may be defined accordingly.
As shown in [Table 1], the WHO SEAR countries show a wide disparity in land area, population and HDI. The human development index (HDI) is used as a composite indicator of human development. It is calculated by the UNDP for 177 countries of the world, taking into account the life expectancy at birth, adult literacy rate and enrolment at primary, secondary and tertiary levels of education as well as GDP per capita.  Thailand with the best HDI in the SEAR stands 78 th in the world ranking of HDI for 177 countries.  Bangladesh, Bhutan, Nepal, India and Timor-Leste show adult literacy rates in the range of about 40%-60%, while all other SEAR countries have literacy rates above 90%. There is also disparity between the countries in terms of government versus private spending on health care, health awareness, the number of hospitals, beds, qualified healthcare professionals and specialists available to the population, as well as uniformity of access to healthcare for all regions of a country. 
|Table 1: Profi les of countries constituting the World Health Organization South East Asia Region (WHO SEAR)|
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Looking at the political histories of these countries, modern day India, Sri Lanka, Bangladesh, Indonesia, Myanmar and DPR Korea were formed or, achieved self-rule, in the mid to late twentieth century. Nepal and Thailand were declared sovereign states in the late eighteenth century. Bhutan has been under theocratic rule since 1907. Maldives and Timor Leste are small island nations. Timor Leste, formerly called East Timor, was part of the Indonesian archipelago and obtained international recognition as a republic only in 2002. India and Sri Lanka are countries, which have had consistently democratic forms of government after formation. Some countries in the region have been under stable sovereign rule. Some have been subjected to periods of non-democratic military rule or apparent democratic rule, with largely autocratic control of the state and media.
To summarize, the eleven South East Asia Region countries differ widely in population size, land area, geographic features, years of independent governance and periods of democratic rule. These factors, in turn, affect the sociopolitical milieus and stability, basic human development indices and technological progress in these countries. As a result, the economy and health care systems as well as biomedical research focus are diverse and reflective of each country's composite, unique situation.
| Pulmonary Hypertension in the SEAR|| |
Till date, there are no published estimates or registries documenting PH incidence or prevalence in the SEAR. PH registries in many of these countries would not reflect the true burden of disease due to multiple reasons.  The symptoms of PH being general and being obscured by primary cardiac, respiratory or other etiology in the case of secondary PH, makes diagnosis difficult even in developed nations. Further, low awareness of PH among primary or secondary care givers as well as socioeconomic constraints of patients will lead to a very low percentage of PH patients actually being encountered at the few tertiary centers equipped to perform definitive diagnoses.  Thus, each of the SEAR countries may have specific socioeconomic and epidemiological factors that contribute to the, as yet, unknown burden of PH. For instance, hypoxia due to high altitude dwelling may contribute to higher risk for developing PH in the Himalayan countries of Bhutan and Nepal as well as DPR Korea, which is an 80% mountainous territory.  Further, COPD and respiratory diseases are major causes of mortality in the Himalayan reaches of Bhutan and Nepal, respectively.  Smoking is a major health problem in DPR Korea, with about 60% of adult males indulging in this habit that may predispose to COPD.  Diseases of pulmonary circulation and COPD are listed among the leading causes of mortality in Sri Lanka.  Maldives has a significant prevalence of thalassemia with about 200 registered cases per 100, 000 population.  Thailand has the biggest estimated burden of HIV infection and HIV-related deaths in the SEAR, followed by India, Indonesia and Myanmar, each of which have less than half the estimated infection prevalence of Thailand.  Cardiovascular diseases are a major health burden in most SEAR countries, as is the case in most parts of the globe. Uncorrected congenital heart disease leading to Eisenmenger's syndrome, rheumatic heart disease and mitral valve stenosis may all contribute to the higher prevalence of PH in countries, where specialist healthcare delivery is inadequate or non-uniform.  Various other region-specific etiologies such as incidence of parasitic infections, e.g. schistosomiasis, need to be investigated.
The current work was initiated in order to explore the trend of medical literature regarding PH, originating from the SEAR countries. To provide the subjective context for studying these statistics, the publication profile for PH from all over the world is also reported.
| Total Indexed Publications Versus Those on Pulmonary Hypertension of Who SEAR|| |
To begin with, the total number of Medline0 indexed publications for each SEAR country was found by restricting the search with the name of the country to the "affiliation" field [Table 2]. Using this method, a total of over 100,000 Medline0 indexed publications were found to originate from India. Similarly, Thailand gave under 20,000 publications, while Bangladesh, Sri Lanka, Indonesia and Nepal had about 1600-2000, Myanmar had about 200 publications and only a couple of publications from the rest of the countries. Thus, the majority of biomedical research being carried out and communicated through indexed literature in the SEAR is accounted for by India and Thailand.
Next, the indexed research literature on PH, originating from these countries was explored. The keyword "pulmonary hypertension" was chosen for simplicity's sake, while acknowledging the fact that this would be a broad term, including both pulmonary arterial and pulmonary venous hypertension. The number of PH publications originating from the world over and from the SEAR countries is shown [Table 3].
| South East Asian Region Publication Profile on Pulmonary Hypertension|| |
A free web-based bioinformatics tool called MedSum,  short form for Medline summary, from the University of Ljubljana, Slovenia, was used in this study. Some points noted while examining the data are as follows:
Data represented in all Tables and Figures were obtained from MedSum on April 25, 2009, using the appropriate query and the "Profile" button or PubMed.
- The profile button can process only the most recent 10,000 articles for any given query. The years 1997-2009 were covered for PH publications worldwide, with very few publications from the year 1997 among the 10,000.
- Data under the "worldwide" heading, except [Figure 1] and [Figure 2] and [Table 4], refer to 9480 of 10000 most recent PH articles in PubMed, which had Medline entries such as research ratios, age groups and MeSH Tables associated with them.
- Data under the heading 'SEAR,' except [Figure 1] and [Figure 2] and [Table 4], refer to 145 of the total of 152 PH articles in PubMed, which had Medline entries such as research ratios, age groups and MeSH Tables associated with them. It must be noted that India and Thailand contributed 114 and 32 publications, respectively out of the total of 152 [Table 3]. Further, unlike "worldwide" publications, they covered the decades from 1987-2009.
- Data shown in [Figure 2] and [Table 4] refer to 141 SEAR publications and 7848 worldwide publications indexed as human studies.
South East Asian Region publication profile
Estimating from the absolute numbers listed in [Table 5], roughly 97% of SEAR publications were human studies, while approximately 3% were indexed as animal studies. About 83% of the first 9473 worldwide PH publications were indexed as human studies, while 25% were indexed as animal studies. This indicates that some articles were indexed as both human and animal studies and may be review articles. The male to female ratio in human studies remains roughly equal worldwide; this trend is maintained in SEAR publications.
[Figure 1] shows the timeline trend of PH publications over the recent decade (1998-2008). Percentage publications were calculated based on number of publications for a particular year in proportion to total PH publications for the decade 1998-2008. The Table to the right of the chart shows the absolute numbers of publications per year. For worldwide PH publications, the year 2000 proved the turning point for the decade marking an increase of 600-700 publications from previous two years. Numbers of SEAR publications begin to show increase in the middle of the decade (year 2004) with a significant high in 2007.
Age groups in human studies
[Table 4] and [Figure 2] display the data on age categories that are included in the Medline indexed human studies on PH. Medline0 indexed age categories are defined in the first two columns of [Table 4]. 7848 worldwide publications are indexed as human studies on PH, while 141 publications from the SEAR are similarly indexed. In this publication, these starting numbers will be referred to as "true total" and are the actual numbers of publications being analyzed by MedSum for age categories. However, a single study may include more than one age category and thus would be indexed under multiple age categories in Medline0 . Therefore, the numbers of studies are not additive across age groups. Adding the number of publications in each age category for a region would give a sum higher than "true total." The former sum is referred to as the "categories total" in this paper.
[Figure 2] plots the percentage of publications calculated from the number of publications in each age category versus the true total for worldwide and SEAR publications. It is seen that percentage of worldwide PH publications appear skewed towards adult studies, with 33% studies including the adult category and 30% including the middle-aged category. 16% studies include the aged population (over 65 years); studies including various neonate and pediatric age groups constitute less than 11% each of the total published PH studies.
On the other hand, 51% of SEAR publications are indexed as being studies on adults aged 19-44 years. Other age categories from infant, child and adolescent to middle-aged, ranging from 28% to 46% of publications, seem well represented percentage wise when compared to worldwide percentages. However, there is a significant difference in the absolute number of publications between worldwide and SEAR PH literature. Premature infants and geriatric populations <80 years appear under-represented in human studies from SEAR countries. This data may indicate that the study design of PH studies in the SEAR is more broadly inclusive of various age categories from infants to older adults. This is further corroborated by the fact that the "categories total" of SEAR publications is almost twice that of the "true total."
The MedSum profiling also gave the top 10 journals in which the maximum recent 10,000 worldwide PH publications or SEAR publications appeared. The results are listed in [Table 6]. SEAR publications predominantly appear in national journals. Only two international journals, appearing in the worldwide list, published multiple articles from the SEAR countries. Forty-three of the 141 SEAR publications appeared in Indian Heart J, J Med Assoc Thai or Int J Cardiol. Thirty papers appeared in the rest of the top 10 SEAR journals. SEAR publications on PH receive maximal exposure in cardiovascular journals, followed by general medical journals. In contrast, four journals from the respiratory field and others from the cardiovascular or thoracic fields publish the maximum publications in PH worldwide.
Major MeSH headings and starred MeSH terms
Seventy-one percent of worldwide Medline0 publications and similar percentage of SEAR articles were indexed under the major MeSH topic of "pulmonary hypertension" [Table 7]. Nineteen percent of both worldwide and SEAR publications were indexed under "pulmonary artery." Other common topics were "treatment outcome" and "hemodynamics."
In order to uncover the general trend of all literature published in the journals listed in [Table 7], journal names were placed as queries in MedSum. "Pulmonary hypertension" did not appear as a major MeSH topic on profiling any of the 20 journals listed. "Pulmonary artery" appeared as a major MeSH topic only in one journal in each of the two lists, viz., Am J Physiol Lung Cell Mol Physiol and Pediatr Cardiol, respectively. Thus, none of the top publishing 20 journals, except two appear to publish articles mainly on pulmonary circulation related topics. Further, it was noted that 8 out of top 10 journals in worldwide PH publications and 7 out of top 10 SEAR journals had "treatment outcome" as a Major MeSH topic. Also, 9 of top 10 SEAR journals had "follow-up studies" as a Major MeSH topic. Two each of the top 10 SEAR journals had "retrospective studies" or "prospective studies" as a major MeSH topic, while another journal had both these as major MeSH topics.
The worldwide articles that did not map under MeSH topics common with SEAR publications constituted about 9%-11% of the total 9473 [Table 7]. Among these, some mapped to "Lung," which was a common major topic for the respiratory journals. PH therapy/diagnostics-related major topics such as "nitric oxide," "vasodilator agents," "antihypertensive agents" and "anoxia" also figured among the major MeSH topics. The only basic research-related major MeSH topic was "Rats," which was also the major topic for the Am J Physiol Lung Cell Mol Physiol. Among the SEAR publications, topics related to cardiovascular diagnostics or intervention included "mitral valve stenosis" and "heart catheterization."
The major MeSH topic is the heading or broad term under which an article is classified. More specific terms called starred MeSH terms are used to describe the specifics in the MeSH hierarchy. These identify more specific topics within a broader field and are listed in [Table 8].
To summarize, virtually all MeSH headings and subheadings for literature on PH are mapped to diagnostics, therapy or clinical trials.
| Discussion|| |
Recapitulating the observations on SEAR publications, India and Thailand contribute to almost all the indexed PH publications arising from the SEAR. Most of the publications appear in a Thai or Indian journals catering to national readership and review in the general medicine and cardiovascular fields. The MeSH Tables also suggest that publications are restricted to clinical/cardiovascular diagnosis and PH therapy. Indexing indicates a paucity of pathophysiology studies. These observations indicate the need to involve more medical specialties, including the respiratory, critical care and pathology branches, to begin with, in the study of PH in the SEAR countries (see Appendix 1). Moreover, more clinical studies focusing on special age group populations in the region may be warranted.
At a more basic level, with regard to health information management, electronic health records and health information systems would be expected to be the norm only in countries with advanced healthcare systems or corporate healthcare centers in other SEAR countries. Many of the existing healthcare institutions still rely on paper-based records. Thus, while certain cardiac or pulmonary centers may be providing good quality standards of care to PH patients, lack of organized, community or nationwide electronic databases or registries may be a bottleneck in information dissemination.
The burden of PH need not be emphasized, given the population size as well as the combined burden of various risk factors associated with secondary PH in this region. Starting with clinical registries for various etiologies, the most urgent and basic questions that need to be answered are
- Which are the major etiologies contributing to PH burden in the region, in each country?
- How does one effectively address the issue of early diagnosis?
- How does one ensure most cost-effective management practical with respect to each situation?
It needs to be acknowledged that centers that encounter and manage PH patients in the SEAR may be largely tertiary referral centers that cater to a large outpatient and inpatient population. This would place constraints on time and skilled health workers available for focused academic activities or information management. However, indexed publications will serve as a medium for the progress of clinical intervention in PH in the SEAR. As clinicians formulate the basic questions about PH in their regions, they will also be able to pass the baton to biomedical researchers in order to address the most pertinent and urgent translational questions of the hour and the place.
| Acknowledgments|| |
I would like to thank Dr. R. Krishna Kumar for valuable discussions, review and input. I would also like to thank Pr. Ghazwan Butrous and Dr. Harikrishnan S. for their review and suggestions.
| References|| |
|1.||Available from: http://www.searo.who.int/EN/Section864/Section1007/Section1012.htm [accessed on 2009 Feb 7]. |
|2.||"11 health questions about the 11 SEAR countries" by WHO regional office for South East Asia, 2007. |
|3.||UNAIDS/WHO Epidemiological Fact Sheets on HIV and AIDS, 2008 update. |
|4.||Kumar RK. "Pulmonary Hypertension in India and the Developing World", ECAB Clinical Update: Cardiology "Pulmonary Hypertension", November-December 2008, Vol. 1, Issue 6: 12-16. |
|5.||"MEDSUM: an online MEDLINE summary tool by Galsworthy, MJ. Hosted by the Institute of Biomedical Informatics (IBMI), Faculty of Medicine, University of Ljubljana, Slovenia. Available from: http://www.medsum.info" [accessed on 2009 Apr 25]. |
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]