Evidence Digest

Late-Breaking Systematic Reviewsto Inform Evidence-Based Practice

Bernadette Mazurek Melnyk, RN, PhD, CPNP/PMHNP, FNAP, FAAN

The purpose of Evidence Digest, a recurring column inWorldviews, is to provide concise summaries of well-

designed and/or clinically important recent studies alongwith implications for practice, research, administration,and/or health policy. Articles highlighted in this columnmay include quantitative and qualitative studies, system-atic and integrative reviews, outcomes evaluation studies,as well as consensus statements by expert panels. Alongwith relevant implications, the level of evidence generatedby the studies or reports highlighted in this column (seeFigure 1) is included at the end of each summary so thatreaders can integrate the strength of evidence into theirhealth care decisions.

• Level I: Evidence from a systematic review or meta-analysis of all relevant randomized controlled trials (RCTs), or evidence-based clinical practice guidelines based on systematic reviews of RCTs

• Level II: Evidence obtained from at least one well-designed RCT • Level III: Evidence obtained from well-designed controlled trials

without randomization • Level IV: Evidence from well-designed case-control and cohort studies • Level V: Evidence from systematic reviews of descriptive and

qualitative studies • Level VI: Evidence from a single descriptive or qualitative study • Level VII: Evidence from the opinion of authorities and/or reports of

expert committees

Modified from Guyatt & Rennie, 2002; Harris et al., 2001

Figure 1. Rating System for the Hierarchy of Evidence(from Melnyk & Fineout-Overholt 2005).

ASPIRIN TO PREVENT CARDIOVASCULARDISEASE

Leaberry B.A. (2010). Aspirin for the prevention of car-diovascular disease. Systematic review. Journal of NursingCare Quality, 25(1), 17–21.

Purpose: The purpose of this study was to assess theevidence on the use of aspirin as a preventive interventionfor cardiovascular events.

Copyright ©2010 Sigma Theta Tau International1545-102X1/10

Design: Systematic review.Methods: The search for evidence included the follow-

ing databases: (1) the National Guideline Clearinghouse,(2) Cochrane Library, (3) Academic Search Complete, (4)CINAHL, and (5) PubMed. Key words searched includedadult, aspirin, prevention, and cardiovascular events.

The initial search using the key words yielded 7,953hits. Next, the search was narrowed by limiting publi-cations to peer-reviewed journals, clinical trials, meta-analyses, and evidence-based materials, which yielded 798documents. Snowballing yielded three additional docu-ments. Studies were excluded if they included patientswith complex health issues and multiple medication reg-imens. Finally, the number of papers was reduced to 15by only including those that used daily aspirin for theprevention of cardiovascular events. Of those 15, 10 arti-cles were selected for this review, including one clinicalguideline, systematic reviews, and one cohort study. Crit-ical appraisal was conducted on the 10 articles using whatthe author called an appropriate appraisal tool. Althoughthe AGREE and SIGN appraisal tools were referenced, nofurther details were given regarding the methods used forcritical appraisal of the evidence. Summary findings fromeach of the papers were reviewed.

Results: There was evidence across the studies to sup-port that use of daily aspirin decreases total cardiovascularevents in adults. It was concluded that gaps in the evidencewere evident to specifically address the efficacy of aspirinfor cardiovascular disease prevention in women as well asdose-specific outcomes.

Commentary with implications for action in clinicalpractice and future research. As cardiovascular dis-ease (e.g., heart disease and stroke) continues to be aleading cause of death and disability across the globe, itis imperative that evidence-based strategies to preventit are implemented. A limitation of this manuscript isthat it was not specified exactly how critical appraisalof the studies, including the use of specific gradingcriteria, was conducted. For systematic reviews, biasshould be minimized by having at least two individuals

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review the studies using strict criteria. In this review,the author stated that she reviewed the evidence.

Despite the limitations, the synthesis of the findingsfrom this review seems to provide a sound body ofevidence that daily use of aspirin does prevent cardio-vascular events. After a thorough history and physicalexam, patients should be counseled by clinicians on thebenefits of daily aspirin use. Further research is neededthat includes more women and investigates dose re-sponse to aspirin.

The evidence from this review is in agreement withthe recommendations for aspirin use to prevent car-diovascular disease by the United States PreventiveServices Task Force (USPSTF), an independent 16-member panel of primary care experts and scientistswho make gold standard evidence-based recommen-dations about clinical preventive services. The USP-STF recommends the use of aspirin for men aged 45to 79 years when the potential benefit due to a re-duction in myocardial infarctions outweighs the po-tential harm due to an increase in gastrointestinalhemorrhage. It also recommends the use of aspirinin women aged 55 to 79 years when the potentialbenefit of a reduction in ischemic strokes outweighsthe potential harm due to an increase in gastrointesti-nal hemorrhage. The task force recommends againstthe use of aspirin for stroke prevention in womenyounger than 55 years and for myocardial infarc-tion prevention in men younger than 45 years. Ad-ditional information about this recommendation canbe accessed at http://www.preventiveservices.ahrq.gov(USPSTF 2009).

Level of Evidence: I

USE OF PROBIOTICS FOR FUNCTIONALCONSTIPATION

Chmielewska A. & Szajewska H. (2010). Systematic reviewof randomised controlled trials: Probiotics for functionalconstipation. World Journal of Gastroenterology, 16(1),69–75.

Purpose: The purpose of this study was to systematicallyreview the evidence on the efficacy and safety of probioticsupplementation for the treatment of functional constipa-tion.

Design: Systematic review.Methods: A search was conducted in MEDLINE, EM-

BASE, CINAHL, and the Cochrane Library from their in-

ception to May of 2009. Reference lists from the yieldedstudies also were reviewed. The search was limited torandomized controlled trials in children or adults andEnglish-language papers as well as papers written in lan-guages known to the authors. The key words used wereconstipation and probiotic as well as organisms consid-ered to be probiotics (e.g., Lactobacillus, Acidophilus).The outcome was treatment success as defined in the pa-pers. The yielded studies were assessed for methodologi-cal quality by two independent reviewers with the follow-ing qualities defining good quality studies: (1) adequategeneration of allocation sequences, (2) concealment of al-location, (3) blinding of investigators, participants, out-come assessors, and data analysts; (4) intention-to-treatanalysis (yes or no); and (5) comprehensive follow-up(≥80%).

Results: The search yielded six trials, however, one trialwas excluded as it was an ongoing study. The five trialsincluded a total of 377 subjects (i.e., 194 in the experi-mental group and 183 in the control group). The method-ological quality of the trials varied. Specifically, the ran-domization method was only adequate in two trials. Datafrom the studies that included adults seem to suggestthat those with constipation might benefit from supple-mentation with probiotics. However, only two random-ized controlled trials have been conducted in children.The probiotics were well tolerated in the studies andthere were no adverse events reported. The main find-ing from this review was that there is limited evidencefrom randomized controlled trials to support with cer-tainty that probiotics are efficacious in the treatment ofconstipation.

Commentary with implications for action in clinicalpractice and future research. Constipation is a com-mon condition that affects children and adults as well aspatients with certain illness conditions. Probiotics (i.e.,live microorganisms administered in healthy amounts)are increasingly being used as a treatment for consti-pation because there is evidence to support that theintestinal bacteria of individuals with chronic consti-pation are different than those without constipation.

A major strength of this study is that it was arigorously conducted systematic review, which is thestrongest level of evidence to guide intervention prac-tices. From this review, it is not known with certaintywhether probiotics are effective in treating constipa-tion in adults and even less is known about theiruse in children. More rigorously designed random-ized controlled trials are needed in order to accumulate

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evidence about the efficacy of probiotics in the treat-ment of constipation in the pediatric and adult popu-lations. Nurses and other health professionals shouldprovide this information to their patients as constipa-tion is common in both children and adults, and indi-viduals are looking for alternative strategies to treat theproblem.

Level of Evidence: I

THE EFFICACY OF HOME-BASED VERSUSCENTRE-BASED CARDIAC

REHABILITATION

Dalal H.M., Zawada A., Jolly K., Moxham T. & TaylorR.S. (2010). Home-based versus centre-based cardiac reha-bilitation: Cochrane systematic review and meta-analysis.British Medical Journal, 340, 1–15.

Purpose: The purpose of this study was to determine theeffect of home-based and supervised centre-based cardiacrehabilitation on mortality and morbidity, health-relatedquality of life, and modifiable cardiac risk factors in pa-tients with coronary heart disease.

Design: Systematic review, including a meta-analysis.Methods: Databases searched from 2001 to January of

2008 included the Cochrane Central Register of ControlledTrials in the Cochrane Library, Medline, Embase, CINAHL,and PsycINFO. Additional studies also were located inthe databases of the National Health Service Centre forReviews and Dissemination (i.e., the Health TechnologyAssessment Database and the Database of Abstracts of Re-views of Effects). In addition, conference proceedings weresearched using the Institute for Scientific Information Webof Knowledge and gray literature was identified through aweb search of major health technology appraisal agencies.The searches were limited to randomized controlled trials,systematic review, and meta-analyses. Two reviewers in-dependently screened the titles and abstracts of the studiesand assessed them independently for eligibility criteria. Asingle reviewer extracted the data and assessed quality ofthe studies, which was checked by a second reviewer. Thedata were processed using the Cochrane handbook.

Results: Twelve studies with 1,938 subjects were in-cluded, with most studies including patients with a low riskof further events after myocardial infarction. The studiesincluded were conducted in the United Kingdom, UnitedStates, Canada, Turkey, Italy, Iran, and China. The HeartManual, a home-based cardiac rehabilitation program thatconsists of a self-help manual supported by a facilitatorwas used in the largest three clinical trials included in thereview. Findings revealed that there were no differences

between home-based and centre-based cardiac rehabilita-tion in terms of mortality, cardiac events, exercise capac-ity, modifiable risk factors, total cholesterol, low densitylipoproteins, health-related quality of life, and health carecosts. However, there was superior adherence in the home-based participants.

Commentary with implications for action in clinicalpractice and future research. As coronary heart dis-ease causes much morbidity and mortality across theglobe, cardiac rehabilitation is an important strategy toaid recovery and prevent further disability. Most car-diac rehabilitation programs include education, exer-cise, healthy lifestyle behavior change strategies, coun-seling and support. Many positive outcomes have beenassociated with cardiac rehabilitation programs, how-ever, participation is often less than desired with indi-viduals citing barriers to centre-based programs, suchas accessibility, dislike for groups, and work commit-ments. Some of these barriers can be overcome byhome-based programs, which have been implementedto increase participation in cardiac rehabilitation. How-ever, many health care systems do not offer home-based programs as an alternative to hospital-based ones.Findings from this rigorously conducted systematic re-view support that positive outcomes can be achievedfrom both centre- and home-based cardiac rehabilita-tion programs. Therefore, for those patients with sta-ble coronary heart disease, their preferences should beassessed and individuals directed toward the type ofprogram that best suits them and enhances the prob-ability of full participation. Many hospitals currentlydo not have home-based programs and should stronglyconsider the implementation of evidence-based homeprograms for use with their stable cardiac patients. Fu-ture research should include comparative effectivenesstrials to assess whether these programs can have sus-tainable more long-term effects on patient outcomes.

Level of Evidence: I

ReferencesGuyatt G. & Rennie D. (2002). Users’ guides to the medical

literature. Washington, DC: American Medical Associa-tion Press.

Harris R.P., Hefland M., Woolf S.H., Lohr K.N., MulrowC.D., Teutsch S.M. & Atkins D. (2001). Current meth-ods of the U.S. Preventive Services Task Force: A reviewof the process. American Journal of Preventive Medicine,20(3 Suppl.), 21–35.

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Melnyk B.M. & Fineout-Overholt E. (2005). Evidence-based practice in nursing & healthcare. A guide tobest practice. Philadelphia: Lippincott, Williams &Wilkins.

United States Preventive Services Task Force. (2009). Theguide to clinical preventive services. Recommendations ofthe U.S. Preventive Services Task Force. Rockville, MD:The Agency for Healthcare Research and Quality.

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