INTRODUCTION TO SCIENTIFIC PAPERS Joe Pozdol, MLIS Evans Whitaker, MD, MLIS Norris Medical Library University of Southern California 2003 Zonal Ave. Los Angeles, CA 90089-9130 [email protected] [email protected] Before We Begin… • Ask! • PowerPoint at www.usc.edu/nml under Key Resources for Students • Interactive questions • Handouts • Article later • Evaluation • Unwanted handouts Outline For Today I. Parts of a paper A. Abstract B. Introduction/Background C. Methods D. Results E. Discussion F. References (Bibliography) II. Study types A. Primary 1. Observational 2. Experimental B. Secondary III. Group work IV. Evaluations PART I SECTIONS OF A PUBLISHED SCIENTIFIC PAPER Part I Objectives • Learn the basic structure of papers • Develop an approach to reading papers • Learn how to interpret an article citation The Basic Parts • Title • Abstract • Introduction • Methods • Results • Discussion • References Read In This Order • Title • Abstract • Introduction/ Discussion • Methods/ Results The discussion section occurs before the author presents the results of the study. 1. True 2. False Which occurs first in a scientific journal article? 1. 2. 3. 4. 5. Abstract Discussion Introduction Methods Results Abstract • • • • Summarizes Often only part read Don’t act on abstracts alone Structured abstracts are norm – Background – Methods – Results – Conclusions Introduction • • • • • • • Context What is known Supporting literature (citations) Gaps in literature The research question Newness Relevance to field Methods • Steps taken to – gather data – analyze data • Statistical methods • Not a “cookbook” • Replicable Results • • • • Report of data Tables and graphs Statistical results No interpretation Discussion • Interpretation of results • Answer to research question • Goals met? • Often includes – relation to previous research – limitations – future directions Which should allow other researchers to replicate the study? 1. 2. 3. 4. 5. Abstract Discussion Introduction Methods Results Limitations of the study are found in the… 1. 2. 3. 4. 5. Abstract Discussion Introduction Methods Results References • List of sources cited in intro • Usually other journal articles • Previous studies in same field • Citation styles differ depending on – field of study (e.g. AMA vs. APA) – journal • EndNote and RefWorks Understanding Journal Article References Weiss, PA. Does smoking marijuana contribute to the risk of developing lung cancer? Clinical Journal of Oncology Nursing. 2008;12(3):517-519. Journal Volume Number Issue Number Researcher’s Article Which cannot be determined from a reference list citation? 1. Title of the journal 2. Title of the journal article 3. Number of pages in the journal 4. Number of pages in the journal article 5. None of the above Whether marijuana use causes lung cancer is still unknown and will likely be a subject of research in the next 5 years. 1. True 2. False PART II TYPES OF SCIENTIFIC PAPERS Part II Objectives • Learn the common study types • Be able to extract the research question • Be able to identify an article’s study type • Be able to determine the conclusions Outline For This Section • Focus on 4 study designs o Case-control o Cohort o Randomized Control Trial o Review • Narrative • Systematic • Meta Analysis “3 questions to get your bearings” * 1. What was the research question? 2. What was the research design? 3. Was the research design appropriate to the question? Will try to find answers to 1 and 2 in excerpts of 4 articles (A-D) provided * - Greenhalgh, T. (2006). How to read a paper: the basis of evidence-based medicine. Malden, MA: Blackwell Study Designs •Primary Literature oObservational • Case-Control • Cohort oExperimental • Randomized Control Trial •Secondary Literature oNarrative (Subject/Journalistic) Reviews oSystematic Review oMeta Analysis Case-Control Patients with a disease or exposure --compared to-Similar group without disease or exposure • Best uses o Rare conditions o Diseases or conditions time to develop that may take a long Background: DES • Used in the United States from 1947 until 1971 • Boston area doctors noted an unusual cancer • Study compared the group with the cancer to similar people without the cancer • The major difference between the cases and the controls was DES exposure Example: DES and Cancer • Herbst, A.L., Ulfelder, H., & Poskanzer,D.C. (1971). Adenocarcinoma of the vagina: association of maternal stilbestrol therapy with tumor appearance in young women. NEJM, 284(16), 478-481. • Look at article: – Last sentence in Introductory area = research question – First paragraph in methods = research design Why did the authors match cases and controls by the type of service mothers received?* To de ov e al A ll o ft he m ic ci de if ch e w he am in e ex To ab ... .. rt th e co ... ci oe so e 4. du c 3. 25% 25% 25% 25% re 2. * -see page 879 To reduce socioeconomic differences To examine whether the cancer was related to infectious disease exposures To decide if chemical disinfectants used to clean wards caused cancer All of the above To 1. Cohort • Two groups compared over time • One group with “exposure”, the other without the “exposure” • Best used: o when exposures can’t be controlled o when outcomes occur infrequently o when RCT is not ethical Example: Smoking vs. Non-Smoking British Physicians • Doll, R., Peto, R., Boreham, J., & Sutherland, I. (2004). Mortality in Relation to Smoking: 50 years' observations on male British doctors. BMJ, doi:10.1136/bmj.38142.554479.AE • 50 years (and counting) Cohort Study of British doctors • Most recent of a series of reports • Compared health outcomes of smokers vs. health outcomes of non-smokers • Research question = • Research design = When was there enough evidence from this study to show the link between smoking and lung cancer? 25% 25% 19 91 25% 19 78 25% 19 66 1954 1966 1978 1991 19 54 1. 2. 3. 4. Randomized Control Trial • A treatment group is compared to a control group • Group members are assigned randomly • Best uses: – Drug therapies – Medical treatments Example: Smoking cessation intervention • An, L.C., Klatt, C., Perry, C.L., Lein, E.B., Hennrikus, D.J., et al. (2008). The RealU online cessation intervention for college smokers: a randomized control trial. Preventive Medicine, 47(2)194-199. • Look at the article: o The last paragraph of the introduction - research question o The last paragraph of the introduction - research design o Study flow chart - pg. 196 25,000 UM students were recruited by email How many UM students ended up in the intervention group? 1. 2. 3. 4. 5. 24,007 2,407 257 107 7 What percent of RealU participants had 30 days of no smoking at week 30? 30 ne 0% no % 0% 20 % 0% 40 60 80 0% % 0% % 0% 0% 100% 80% 60% 40% 20% none 10 1. 2. 3. 4. 5. 6. Narrative (Journalistic/Subject) Reviews • The “traditional” or “classic” review • “Review” limit in Ovid/PubMed includes: – Narrative reviews – Systematic reviews • Authors choose articles included • Author bias is a concern – research verifies this effect Systematic Review • Reproducible methods to find and select articles are included • Should include both inclusion and exclusion criteria • Why? Decrease author bias Example: Is HPV Vaccine Cost-Effective? • Techakehakij, W., Feldman, R.D. (2008). Costeffectiveness of HPV vaccination compared to Pap smear screening on a national scale: a literature review. Vaccine, doi:10.1016/j.vaccine.2008.09.036 • Look at article: – Pg. 2, Section 3.1, first paragraph = research question – Pg. 3, Section 4.1, first to third paragraphs = research design It is recommended that HPV vaccine be given as a 3 shot series. How much do 3 doses of vaccine cost? 1. 2. 3. 4. $500-$1000 $300-$500 $200-$300 $100-$200 30 0% $500-$1000 0% $300-$500 0% $200-$300 0% $100-$200 Meta Analysis • Similar to Systematic Review except… • Numeric data from separate studies combined in meta analysis • Uses statistical/mathematical methods to combine numerical data from studies • Combining data increases the confidence we have in the conclusions reached by a meta analysis GROUP WORK Group Work • Groups of 3 • Everyone in group gets same article (#1, 2, 3, OR 4) • Spend 10 min. working together on questions • Class discussion ADDITIONAL SLIDES What kind of question is it good for? Strengths Weaknesses Case-Control (Herbst, 1971) (Peled, 2008) -Rare disorders or conditions -Slow developing disorders -Causation* -Short time frame to examine correlations between disorder and other factors -Susceptible to bias -Limited validity -Cross sectional Cohort** (Doll, et al, 2004) (Metcalf, 2008) - Prognosis -Causation* - Feasible when studying conditions or exposures over which the investigator has no control -Susceptible to bias -Limited validity -May require large groups, long durations, great cost -Longitudinal -Usually prospective -Can be retrospective (less cost) Randomized Control Trial (RCT) (An et al, 2008) (Gordon, 1997) -Drug treatment -Medical interventions -Strong level of evidence -Low susceptibility to bias -Feasibility (e.g. Ethical limitations) -Generalizability** -Randomization method Experimental and control groups Systematic Review (Techakehakij,2008) (Gallicchio, 2008) -Drug treatment -Medical interventions -Low susceptibility to bias -Strongest level of evidence -Many topics have no systematic review -Methods section has explicit information about information sources, how articles were chosen or excluded Article Type * - used loosely here; not distinguishing between correlation and causation (in medicine etiology is used for the cause of a disease or condition) ** - can results of an RCT be applied to groups that do not match the study group? Identifying Characteristics Thanks for your attention • We will post these slides on the Student Portal on the Norris Medical Library website • Contact us with questions – Joe Pozdol – [email protected] – Evans Whitaker – [email protected] • Please complete evaluations! References • • • • • • An, L.C., Klatt, C., Perry, C.L., Lein, E.B., Hennrikus, D.J., et al. (2008). The RealU online cessation intervention for college smokers: a randomized control trial. Preventive Medicine, 47(2)194-199. Doll, R., Peto, R., Boreham, J., & Sutherland, I. (2004). Mortality in Relation to Smoking: 50 years' observations on male British doctors. BMJ, doi:10.1136/bmj.38142.554479.AE Gallicchio, L., Boyd, K., Matanoski, G., et al. (2008). Carotenoids and the risk of developing lung cancer: A systematic review. Am.J.Clin. Nutrit., 88, 372-383. Gordon, C.M., Carey, M.P., & Carey, K.B. (1997). Effects of a drinking event on behavioral skills and condom attitudes in men: Implications for HIV risk from a controlled experiment. Health Psychology, 16(5), 490-495. Greenhalgh, T. (2006). How to read a paper: the basis of evidencebased medicine. Malden, MA: Blackwell. Guyatt, G., Rennie, D. (eds.). (2001). User’s guides to the medical literature: essentials of evidence-based clinical practice. Chicago: AMA Press. References • Herbst, A.L., Ulfelder, H., & Poskanzer,D.C. (1971). Adenocarcinoma of the vagina: association of maternal stilbestrol therapy with tumor appearance in young women. NEJM, 284(16), 478-481. • Metcalf, B.S., Voss, L.D., Hosking, J., & Wilkin, J.T. (2008). Physical activity at the government-recommended level and obesityrelatedhealth outcomes: a longitudinal study (Early Bird 37). Archives of Diseases of Childhood (Early Bird 37). 93,722-777. • Peled, R. Carmil, D., Siboni-Samocha, O., & Shoham-Vardi, I. (2008). Breast cancer, psychological distress and life events among young women. BMC Cancer, 8, 245-250.