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  Table of Contents  
ORIGINAL ARTICLE
Year : 2011  |  Volume : 2  |  Issue : 1  |  Page : 35-38  

Study design and statistical methods in Indian medical journals


1 Department of Pharmacology, Govt. Medical College, Surat, India
2 Department of Community Medicine, Govt. Medical College, Surat, India

Date of Web Publication15-Jul-2011

Correspondence Address:
Jaykaran
Department of Pharmacology, Govt. Medical College, Surat - 395001
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-9234.82983

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   Abstract 

Aims and Objectives: Types of study designs and statistical method utilized by authors for articles published in foreign journals has been widely documented. Few such attempts are also done for articles published in Chinese and Pakistani Journals but no such attempt has been documented for articles published in Indian Medical Journals. This manuscript is an attempt to appraising articles published in Indian Medical Journals in terms of study designs and statistical methods used. Materials and Methods: All the original articles published in 2009 from 14 PubMed indexed Indian Medical Journals were analyzed for study designs and statistical methods. These journals were Annals of Indian Academy of Neurology (AIAN), Indian Journal of Orthopedics (IJOrtho), Indian Journal of Critical Care Medicine (IJCCM), Indian Journal of Dermatology, Venereology and Leprology (IJDVL), Indian Journal of Nephrology (IJN), Indian Journal of Dermatology (IJD), Indian Journal of Ophthalmology (IJO), Indian Journal of Urology (IJU), Indian Journal of Anesthesia (IJA), Indian Journal of Psychiatry (IJPsy), Indian Pediatrics (IP), Indian Journal of Medical Research (IJMR), Indian Journal of Medical Science (IJMS) and Indian Journal of Community Medicine (IJCM). Values are shown as frequency and percentages. Results: Majority of the published articles were based on prospective study designs (60.8%). Clinical trials were as method of study was documented in 12.5% articles. Three most common tests were t test (23.2%), Chi-square test (21.9%) and analysis of variance (ANOVA) (10.5%). However, statistical methods were not at all used by 26.2% articles. Conclusions: Knowledge regarding prospective studies and statistical methods related to contingency table, t test and ANOVA needs to be updated to the Undergraduate and Postgraduate students.

Keywords: Study designs, Statistical methods, Indian medical journals


How to cite this article:
Jaykaran, Solanki P, Saxena D, Kantharia N D. Study design and statistical methods in Indian medical journals. J Pharm Negative Results 2011;2:35-8

How to cite this URL:
Jaykaran, Solanki P, Saxena D, Kantharia N D. Study design and statistical methods in Indian medical journals. J Pharm Negative Results [serial online] 2011 [cited 2017 Jun 22];2:35-8. Available from: http://www.pnrjournal.com/text.asp?2011/2/1/35/82983


   Introduction Top


As a prerequisite for an article to get published in medical journals, manuscripts should incorporate appropriate study design and statistics. More so article narrating sufficient validity and outcome but utilizing an inappropriate study design and statistics cannot be termed as sound scientifically. Poor knowledgeable regarding study designs and statistical methods amongst clinicians and physicians has been adequately documented. [1],[2] It is essential that clinician should be trained in basic research methods and biostatistics so as to help them to conduct research and interpret their findings. Such training will also help them for critical appraise published articles in various journals and can use in better patient care management. New guideline as proposed by Medical Council of India (MCI) envisages inclusion of course of research methodology for undergraduate as well as postgraduate. [3] Although research methods and biostatistics being a vast domain, basics should be included in the curriculum and once they develop interest, clinicians and physicians can develop advance expertise. One of the methods to list out the priority areas related to research methodology and biostatistics is to survey already published articles in various journals for appropriateness of study design and statistical methods used. Studies exploring the reporting of research design and statistical methods in articles published in various western journals has already been done. [4],[5],[6] Attempts for such documentation has also been done for journals from China and Pakistan. [7],[8],[9] Except for very attempts that too with smaller samples for statistical reporting and methodological aspects of clinical trials, this issue is not adequately addressed for articles published in various Indian Medical Journals. [10],[11],[12] Present study aims to document use of various study designs and statistical methods used by authors in articles published in Indian Medical Journals.


   Materials and Methods Top


All the PubMed indexed journals subscribed by central library of Govt. Medical College, Surat, were included in the present study. These journals were Annals of Indian Academy of Neurology (AIAN), Indian Journal of Orthopedics (IJOrtho), Indian Journal of Critical Care Medicine (IJCCM), Indian Journal of Dermatology, Venereology and Leprology (IJDVL), Indian Journal of Nephrology (IJN), Indian Journal of Dermatology (IJD), Indian Journal of Ophthalmology (IJO), Indian Journal of Urology (IJU), Indian Journal of Anesthesia (IJA), Indian Journal of Psychiatry (IJPsychy), Indian Pediatrics (IP), Indian Journal of Medical Research (IJMR), Indian Journal of Medical Science (IJMS) and Indian Journal of Community Medicine (IJCM). All the original articles published in 2009 from these journals were analysed independently by first and second author for study design and statistical methods (k = 0.85 for study design and 0.89 for statistical analysis). Different types of statistical methods were categorized according to definition and standard established by the Centre for Evidence Based Medicine, Oxford, UK, and by modified Emerson's methods. [13],[14] All the statistical methods used in articles were noted ensuring that there is no repetition if the statistical methods were repeated more than once in the same article.


   Statistics Top


Values were expressed by frequency and percentages and 95% confidence interval around percentages.


   Results Top


Total of 271 original articles from 14 Indian Medical Journals subscribed by central library of GMC, Surat, were included in the present study. [Table 1] Most common utilized study design was prospective study (60.8%) and least common was cross-sectional study (6.2%). Clinical trials were calculated separately to prospective clinical studies and clinical trial as a study design was used in 12.5% articles.. [Table 2]
Table 1: Number of original articles analyzed from each journals

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Table 2: Study designs in articles published in Indian Medical Journals (n=271)

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Three hundred and seventy eight different types of statistical methods were used in 271 articles (1.3 per article). Out of these the most common tests were the t test (23.2%) followed by Chi-square test (21.9%) and analysis of variance (10.5%). Statistical test were not used in 71 original studies (26.2%, 95% CI 21.3% to 31.7%). [Table 3]
Table 3: Statistical methods used in articles published in Indian Medical Journals (n = 378)

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   Discussion Top


Clinical trials are considered as gold standard for exploration of any new interventions but present study shows that clinical trials are not amongst the commonly used study designs in the articles published in Indian Medical Journals. This finding corresponds to reporting of fewer studies of clinical trials amongst articles published in Chinese Medical Journals. [7] However in a similar study done by McDermott et al for the articles published in JAMA, The Lancet and New England Journal of Medicine, it was observed that 35% articles were clinical trials. [4] In the present study most common study design was prospective study designs including clinical studies, cohort studies, prospective observational studies, case series etc. One of the possible reasons for less inclination towards clinical trials can be ethical or poor orientation and understanding of young researchers for clinical trials.

In the present study it was also observed that statistical tests were utilized in 73% articles included. This was also similar to the observations in a study done for Chinese Medical Journals. In the study done for article published in Chinese Medical Journals by Jin Z et al it was observed that statistical test was used in about 78% articles. In a similar study done for Pakistani journals by Masood Hussain Rao et al it was observed that statistics was used in about 50% articles. [15] It is also documented for Western and Chinese journals that use of statistics to analyse the results is on increase with the time. [6],[7],[16]

Simple statistical methods were most commonly used in the articles published in Indian Medical Journals. Most of the statistical tests were related to contingency table (Chi-square test, Fishers exact test, McNemar's test), t test and analysis of variance. It is equally important for a reader to understand the concepts related to these statistical concepts and interpret the results. In a study done by Emerson JD et al. for statistical methods in New England Journal of Medicine, it was concluded that if a reader understand "contingency tales" and "t statistics" he/she should able to understand 73% articles. [6],[7] Hence, orientation to the concepts of "contingency table" and "t test" should be taught in detail to medical students and young researchers during their training. Knowledge about interpretation of results as shown by these tests should also be taught in detail so that they may be able to analyse the results shown in articles published in various Indian Medical Journals. In present study, non-parametric tests were utilized by only 12% of the article published, similar results were also observed for Chinese Journals but this frequency when compared to studies done for western journals is very scarce. [4],[17] One important reason for this low utilization of non-parametric tests can be ignorance of researchers about the assumptions of normality.

Limitation of the present study is utilization of articles published in Journals indexed with PubMed and subscribed to an institutional library.

 
   References Top

1.Horton NJ, Switzer SS. Statistical methods in Journal. N Eng J Med 2005;353:1977-9.  Back to cited text no. 1
    
2.West CP, Ficalora RD. Clinician attitude towards biostatistics. Mayo Clin Proc 2007;82:939-43.  Back to cited text no. 2
    
3.Medical Council of India. Available from: http://www.mciindia.org/MediaRoom/Announcements.aspx.  Back to cited text no. 3
    
4.McDermott MM, Lefevre F, Feinglass J, Reifler D, Dolan N, Potts S, et al. Changes in study design, gender issues, and other characteristics of clinical research published in three major medical journals from 1971 to 1991. J Gen Intern Med 1995;10:13-8.  Back to cited text no. 4
    
5.Emerson JD, Colditz GA. Use of statistical analysis in the New England Journal of Medicine. N Engl J Med 1983;309:709-13.  Back to cited text no. 5
    
6.Rigby AS, Armstrong GK, Campbell MJ, Summerton N. A Survey of Statistics in Three UK General Practive Journal. BMC Med Res Methodol 2004;4:28.  Back to cited text no. 6
    
7.Wang Q, Zhang B. Research design and statistical methods in Chinese medical journals. JAMA 1998;280:283-5.  Back to cited text no. 7
    
8.Jin Z, Yu D, Zhang L, Meng H, Lu J, Gao Q, et al. A Retrospective Survey of Research Design and Statistical Analyses in Selected Chinese Medical Journals in 1998 and 2008. PLoS ONE 2010;5:e10822.   Back to cited text no. 8
    
9. Hussain Rao M, Khan N. Comparison of statistical methods, type of articles and study design used in selected Pakistani medical journals in 1998 and 2007. JPMA 2010;60:745.  Back to cited text no. 9
    
10.Jaykaran, Kantharia ND, Yadav P, Deoghare S. Reporting of the methodological quality and ethical aspects in clinical trials published in Indian journals: A survey. J Postgrad Med 2011;57:82-3. Available from: http://www.jpgmonline.com/preprintarticle.asp?id=74300none .[ Last cited on 2011 Jan 26].  Back to cited text no. 10
    
11.Karan J, Kantharia ND, Yadav P, Bhardwaj P. Reporting statistics in clinical trials published in Indian journals: A survey. Pak J Med Sci Q 2010;26:212-6. Available from: http://www.pjms.com.pk/issues/janmar2010/pdf/article44.pdfnone   Back to cited text no. 11
    
12.Jay Karan, JP Goyal, P Bhardwaj, Preeti Yadav. Statistical Reporting in Indian Pediatrics. Indian Pediatr 2009;46:811-2.  Back to cited text no. 12
    
13.Study Design. The Centre for Evidence-Based Medicine in Oxford in the UK. Available from: http://www.cebm.net/index.aspx?o=1039none .  Back to cited text no. 13
    
14.Emerson JD, Colditz GA. Use of statistical analysis in the New England Journal of Medicine. N Engl J Med 1983;309:709-13.  Back to cited text no. 14
    
15.Rao HM, Khan N. Comparison of statistical methods, type of articles and study design used in selected Pakistani medical journals in 1998 and 2007. J Pak Med Assoc 2010;60:745-50.  Back to cited text no. 15
    
16.Kurichi JE, Sonnad SS. Statistical methods in the surgical literature. J Am Coll Surg 2006;202:476-84.  Back to cited text no. 16
    
17.Schwart SJ, Sturr M, Golberg G. Statistical methods in rehabilitation literature: A survey of recent publications. Arch Phys Med Rehabil 1996;77:497-500.  Back to cited text no. 17
    



 
 
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