Amy Earley, BS; Rebecca Persson, BS; Ann C. Garlitski, MD; Ethan M. Balk, MD, MPH; Katrin Uhlig, MD, MS
Disclaimer: The findings and conclusions in this article are those of the authors, who are responsible for its content, and do not necessarily represent the views of the Agency for Healthcare Research and Quality. No statement in this article should be construed as an official position of the Agency for Healthcare Research and Quality.
Acknowledgment: The authors thank Jenny Lamont, Minghua Chen, and Michael Miligkos for their help in screening and data extraction.
Grant Support: By the Agency for Healthcare Research and Quality to the Tufts Evidence-Based Practice Center (contract no. 290 2007 10055 I).
Potential Conflicts of Interest: Ms. Earley: Grant (money to institution): Agency for Healthcare Research and Quality. Ms. Persson: Grant (money to institution): Agency for Healthcare Research and Quality. Dr. Garlitski: Grant (money to institution): Agency for Healthcare Research and Qualilty. Dr. Balk: Grant (money to institution): Agency for Healthcare Research and Quality. Dr. Uhlig: Grant (money to institution): Agency for Healthcare Research and Quality. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M13-1787.
Requests for Single Reprints: Katrin Uhlig, MD, MS, Tufts Medical Center, 800 Washington Street, Box 391, Boston, MA, 02111; e-mail, kuhlig@tuftsmedicalcenter.org.
Current Author Addresses: Ms. Earley, Ms. Persson, and Dr. Balk: Tufts Medical Center, 800 Washington Street, Box 61, Boston, MA 02111.
Dr. Garlitski: Tufts Medical Center, 800 Washington Street, Box 197, Boston, MA 02111.
Dr. Uhlig: Tufts Medical Center, 800 Washington Street, Box 391, Boston, MA 02111.
Author Contributions:Conception and design: A. Earley, A.C. Garlitski, E.M. Balk, K. Uhlig.
Analysis and interpretation of the data: A. Earley, R. Persson, A.C. Garlitski, E.M. Balk, K. Uhlig.
Drafting of the article: A. Earley, E.M. Balk, K. Uhlig.
Critical revision of the article for important intellectual content: A. Earley, R. Persson, A.C. Garlitski, E.M. Balk, K. Uhlig.
Final approval of the article: A. Earley, A.C. Garlitski, E.M. Balk, K. Uhlig.
Statistical expertise: E.M. Balk, K. Uhlig.
Obtaining of funding: E.M. Balk, K. Uhlig.
Administrative, technical, or logistic support: K. Uhlig.
Collection and assembly of data: A. Earley, R. Persson, A.C. Garlitski, E.M. Balk, K. Uhlig.
Previous systematic reviews of implantable cardioverter defibrillators (ICDs) used for primary prevention of sudden cardiac death (SCD) concluded that ICDs are less effective in women and the elderly.
To examine ICD effectiveness for primary prevention of SCD across subgroups by sex, age, New York Heart Association class, left ventricular ejection fraction, heart failure, left bundle branch block, QRS interval, time since myocardial infarction, blood urea nitrogen level, and diabetes.
MEDLINE and the Cochrane Central Register of Controlled Trials through 3 September 2013 with no language restriction.
Researchers screened articles for studies comparing ICD versus no ICD for primary prevention.
Data were extracted about study design, patients, interventions, mortality and SCD outcomes, subgroup characteristics, and subgroup effects. Quality of subgroup analyses was determined by consensus. Relative odds ratios comparing subgroup effects were calculated, and random-effects model meta-analyses were conducted on these ratios.
Meta-analysis of 14 studies showed a decrease in deaths and SCDs due to ICD treatment. Ten studies provided subgroup analyses. Nine studies compared ICD versus no ICD, whereas one compared cardiac resynchronization therapy plus a defibrillator versus no ICD. Within-study interaction tests and across-study meta-analyses yielded weak evidence that did not show differences for all-cause mortality in subgroups by sex, age, and QRS interval. The evidence was indeterminate for other evaluated subgroups because of a paucity of data.
Many subgroup analyses were underpowered, which may have resulted in false-negative findings.
Weak evidence fails to show differences for all-cause mortality in subgroups of sex, age, and QRS interval. Evidence is indeterminate for all-cause mortality in the other subgroups and for SCD.
Agency for Healthcare Research and Quality.
Table 1. Quality Assessment of Subgroup Analyses in Studies of ICD vs. No ICD
Table 2. Subgroup Analyses Data and Meta-analysis of ICD vs. No ICD for All-Cause Death*
Men vs. women: RORs of implantable cardioverter defibrillators vs. no implantable cardioverter defibrillators for all-cause mortality.
Phet = P value for the heterogeneity across studies; ROR = relative odds ratio.
* ROR, relative risk ratio, or relative hazard ratio, as reported by studies.
† Odds ratio, risk ratio, or hazard ratio, as reported by studies.
Younger vs. older subgroups: RORs of implantable cardioverter defibrillators vs. no implantable cardioverter defibrillators for all-cause mortality.
ROR = relative odds ratio.
† Estimated by combining reported subgroups (see Table 2).
‡ Odds ratio, risk ratio, or hazard ratio, as reported by studies.
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Earley A, Persson R, Garlitski AC, Balk EM, Uhlig K. Effectiveness of Implantable Cardioverter Defibrillators for Primary Prevention of Sudden Cardiac Death in Subgroups: A Systematic Review. Ann Intern Med. ;160:111–121. doi: 10.7326/M13-1787
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© 2019
Published: Ann Intern Med. 2014;160(2):111-121.
DOI: 10.7326/M13-1787
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