A review of critical appraisal tools show they lack rigor: Alternative tool structure is proposed
Abstract
Objectives To evaluate critical appraisal tools (CATs) that have been through a peer-reviewed development process with the aim of analyzing well-designed, documented, and researched CATs that could be used to develop a comprehensive CAT.Study design and setting A critical review of the development of CATs was undertaken.Results Of the 44 CATs reviewed, 25 (57%) were applicable to more than one research design, 11 (25%) to true experimental studies, and the remaining 8 (18%) to individual research designs. Comprehensive explanation of how a CAT was developed and guidelines to use the CAT were available in five (11%) instances. There was no validation process reported in 11 CATs (25%) and 33 CATs (77%) had not been reliability tested. The questions and statements that made up each CAT were coded into 8 categories and 22 items such that each item was distinct from every other.Conclusions CATs are being developed while ignoring basic research techniques, the evidence available for design, and comprehensive validation and reliability testing. The basic structure for a comprehensive CAT is suggested that requires further study to verify its overall usefulness. Meanwhile, users of CATs should be careful about which CAT they use and how they use it.
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The use of an overall numerical score is discouraged because a single number does not provide information on what aspects of studies are problematic.
“The use of an overall numerical score is discouraged because a single number does not provide information on what aspects of studies are problematic (20).”
From The Mixed Methods Appraisal Tool (MMAT) version 2018 for information professionals and researchers (2018) · cites this paper as [20]
Cites
Tong, A., Sainsbury, P., & Craig, J. (2007) · International Journal for Quality in Health Care · doi:10.1093/intqhc/mzm042 · Cited by 42,509 · see citing works
von Elm, E., Altman, D. G., Egger, M., Pocock, S. J., Gøtzsche, P. C., Vandenbroucke, J. P., & Initiative, F. T. S. (2007) · PLoS Medicine · doi:10.1371/journal.pmed.0040296 · Cited by 23,020 · see citing works
Stroup, D. F. (2000) · JAMA · doi:10.1001/jama.283.15.2008 · Cited by 20,623 · see citing works
von Elm, E., Altman, D. G., Egger, M., Pocock, S. J., Gøtzsche, P. C., Vandenbroucke, J. P., & Initiative, F. T. S. (2007) · Annals of Internal Medicine · doi:10.7326/0003-4819-147-8-200710160-00010 · Cited by 17,796 · see citing works
Assessing the quality of reports of randomized clinical trials: Is blinding necessary?
Jadad, A. R., Moore, R. A., Carroll, D., Jenkinson, C., Reynolds, D. J. M., Gavaghan, D. J., & McQuay, H. J. (1996) · Controlled Clinical Trials · doi:10.1016/0197-2456(95)00134-4 · Cited by 17,582 · see citing works
Downs, S. H., & Black, N. (1998) · Journal of Epidemiology and Community Health · doi:10.1136/jech.52.6.377 · Cited by 8,252 · see citing works
Moher, D., Cook, D. J., Eastwood, S., Olkin, I., Rennie, D., & Stroup, D. F. (1999) · The Lancet · doi:10.1016/s0140-6736(99)04149-5 · Cited by 4,826 · see citing works
Reliability of the PEDro Scale for Rating Quality of Randomized Controlled Trials
Maher, C. G., Sherrington, C., Herbert, R. D., Moseley, A. M., & Elkins, M. (2003) · Physical Therapy · doi:10.1093/ptj/83.8.713 · Cited by 4,808 · see citing works
Development of AMSTAR: A measurement tool to assess the methodological quality of systematic reviews
Shea, B. J., Grimshaw, J. M., Wells, G. A., Boers, M., Andersson, N., Hamel, C., Porter, A. C., Tugwell, P., Moher, D., & Bouter, L. M. (2007) · BMC Medical Research Methodology · doi:10.1186/1471-2288-7-10 · Cited by 4,374 · see citing works
Assessing the quality of controlled clinical trials
Jüni, P., Altman, D. G., & Egger, M. (2001) · BMJ · doi:10.1136/bmj.323.7303.42 · Cited by 3,309 · see citing works
A Purposeful Approach to the Constant Comparative Method in the Analysis of Qualitative Interviews
Boeije, H. (2002) · Quality and Quantity · doi:10.1023/a:1020909529486 · Cited by 3,073 · see citing works
Evaluating non-randomised intervention studies
Deeks, J., Dinnes, J., D'Amico, R., Sowden, A., Sakarovitch, C., Song, F., Petticrew, M., & Altman, D. (2003) · Health Technology Assessment · doi:10.3310/hta7270 · Cited by 2,907 · see citing works
von Elm, E., Altman, D. G., Egger, M., Pocock, S. J., Gøtzsche, P. C., & Vandenbroucke, J. P. (2007) · Preventive Medicine · doi:10.1016/j.ypmed.2007.08.012 · Cited by 2,698 · see citing works
Verhagen, A., de Vet, H. D., de Bie, R. D., Kessels, A., Boers, M., Bouter, L., & Knipschild, P. (1998) · Journal of Clinical Epidemiology · doi:10.1016/s0895-4356(98)00131-0 · Cited by 2,473 · see citing works
The Hazards of Scoring the Quality of Clinical Trials for Meta-analysis
Jüni, P. (1999) · JAMA · doi:10.1001/jama.282.11.1054 · Cited by 1,981 · see citing works
Systematic Reviews in Health Care: Meta‐Analysis in Context
(2001) · doi:10.1002/9780470693926 · Cited by 1,693 · see citing works
Sanderson, S., Tatt, I. D., & Higgins, J. P. (2007) · International Journal of Epidemiology · doi:10.1093/ije/dym018 · Cited by 1,531 · see citing works
A method for assessing the quality of a randomized control trial
Chalmers, T. C., Smith, H., Blackburn, B., Silverman, B., Schroeder, B., Reitman, D., & Ambroz, A. (1981) · Controlled Clinical Trials · doi:10.1016/0197-2456(81)90056-8 · Cited by 1,349 · see citing works
Moher, D., Jadad, A. R., Nichol, G., Penman, M., Tugwell, P., & Walsh, S. (1995) · Controlled Clinical Trials · doi:10.1016/0197-2456(94)00031-w · Cited by 1,308 · see citing works
Appraising the Evidence: Reviewing Disparate Data Systematically
Hawker, S., Payne, S., Kerr, C., Hardey, M., & Powell, J. (2002) · Qualitative Health Research · doi:10.1177/1049732302238251 · Cited by 1,216 · see citing works
Pluye, P., Gagnon, M.-P., Griffiths, F., & Johnson-Lafleur, J. (2009) · International Journal of Nursing Studies · doi:10.1016/j.ijnurstu.2009.01.009 · Cited by 1,119 · see citing works
Moher, D., Jones, A., Lepage, L., & for the CONSORT Group (2001) · JAMA · doi:10.1001/jama.285.15.1992 · Cited by 1,027 · see citing works
An introduction to systematic reviews
Sutherland, S. E. (2004) · Journal of Evidence Based Dental Practice · doi:10.1016/j.jebdp.2004.02.021 · Cited by 901 · see citing works
How can systematic reviews incorporate qualitative research? A critical perspective
Dixon-Woods, M., Bonas, S., Booth, A., Jones, D. R., Miller, T., Sutton, A. J., Shaw, R. L., Smith, J. A., & Young, B. (2006) · Qualitative Research · doi:10.1177/1468794106058867 · Cited by 860 · see citing works
Scales to Assess the Quality of Randomized Controlled Trials: A Systematic Review
Olivo, S. A., Macedo, L. G., Gadotti, I. C., Fuentes, J., Stanton, T., & Magee, D. J. (2008) · Physical Therapy · doi:10.2522/ptj.20070147 · Cited by 829 · see citing works
Critically appraising qualitative research
Kuper, A., Lingard, L., & Levinson, W. (2008) · BMJ · doi:10.1136/bmj.a1035 · Cited by 784 · see citing works
The problem of appraising qualitative research
Dixon-Woods, M. (2004) · Quality and Safety in Health Care · doi:10.1136/qshc.2003.008714 · Cited by 653 · see citing works
The Integrative Research Review: A Systematic Approach
Cooper, H. M. (1986) · Educational Researcher · doi:10.2307/1175261 · Cited by 552 · see citing works
Critical appraisal of the health research literature: prevalence or incidence of a health problem.
Loney, P., Chambers, L. W., BENNETT, K. J., Roberts, J. G., & Stratford, P. W. (1998) · PubMed · Cited by 550 · see citing works
Systematic Reviews from Astronomy to Zoology: Myths and Misconceptions
Petticrew, M. (2001) · BMJ · doi:10.1136/bmj.322.7278.98 · Cited by 550 · see citing works
Appraising the quality of qualitative research
Walsh, D., & Downe, S. (2006) · Midwifery · doi:10.1016/j.midw.2005.05.004 · Cited by 523 · see citing works
Guidelines for reading literature reviews.
Oxman, A. D., & Guyatt, G. H. (1988) · Europe PMC (PubMed Central) · Cited by 492 · see citing works
Constant Comparison Method: A Kaleidoscope of Data
Dye, J., Schatz, I. M., Rosenberg, B. C., & Coleman, S. (2000) · The Qualitative Report · doi:10.46743/2160-3715/2000.2090 · Cited by 453 · see citing works
Ogrinc, G. S., Mooney, S. E., Estrada, C. A., Foster, T. C., Goldmann, D. A., Hall, L. W., Huizinga, M. M., Liu, S. K., Mills, P. D., Neily, J. B., et al. (2008) · BMJ Quality & Safety · doi:10.1136/qshc.2008.029058 · Cited by 443 · see citing works
A systematic review of the content of critical appraisal tools
Katrak, P., Bialocerkowski, A. E., Massy‐Westropp, N., Kumar, S., & Grimmer, K. A. (2004) · BMC Medical Research Methodology · doi:10.1186/1471-2288-4-22 · Cited by 389 · see citing works
Devers, K. J. (1999) · PubMed Central · Cited by 366 · see citing works
L Tate, R., Mcdonald, S., Perdices, M., Togher, L., Schultz, R., & Savage, S. (2008) · Neuropsychological Rehabilitation · doi:10.1080/09602010802009201 · Cited by 362 · see citing works
A critical appraisal tool for library and information research
Glynn, L. (2006) · Library Hi Tech · doi:10.1108/07378830610692154 · Cited by 345 · see citing works
Appraising qualitative research articles in medicine and medical education
Côté, L., & Turgeon, J. (2005) · Medical Teacher · doi:10.1080/01421590400016308 · Cited by 312 · see citing works
BOUTRON, I., MOHER, D., TUGWELL, P., GIRAUDEAU, B., POIRAUDEAU, S., NIZARD, R., & RAVAUD, P. (2005) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2005.05.004 · Cited by 308 · see citing works
An evaluation tool to assess the quality of qualitative research studies
Long, A., & Godfrey, M. (2004) · International Journal of Social Research Methodology · doi:10.1080/1364557032000045302 · Cited by 209 · see citing works
Development of a quality assessment instrument for trials of treatments for depression and neurosis
Moncrieff, J., Churchill, R., Drummond, D. C., & McGuire, H. (2001) · International Journal of Methods in Psychiatric Research · doi:10.1002/mpr.108 · Cited by 185 · see citing works
Valentine, J. C., & Cooper, H. M. (2008) · Psychological Methods · doi:10.1037/1082-989x.13.2.130 · Cited by 184 · see citing works
Instruments for Assessing the Quality of Drug Studies Published in the Medical Literature
Cho, M. K. (1994) · JAMA · doi:10.1001/jama.1994.03520020027007 · Cited by 180 · see citing works
Locating and Appraising Systematic Reviews
Hunt, D. L., & McKibbon, K. A. (1997) · Annals of Internal Medicine · doi:10.7326/0003-4819-126-7-199704010-00006 · Cited by 163 · see citing works
An epidemiological appraisal instrument – a tool for evaluation of epidemiological studies
Genaidy, A., LeMasters, G. K., Lockey, J. E., Succop, P., Deddens, J. A., Sobeih, T. M., & Dunning, K. K. (2007) · Ergonomics · doi:10.1080/00140130701237667 · Cited by 148 · see citing works
Systematic Reviews on the Basis of Methodological Criteria
de Vet, H. C. W., de Bie, R. A., van der Heijden, G. J. M. G., Verhagen, A. P., Sijpkes, P., & Knipschild, P. G. (1997) · Physiotherapy · doi:10.1016/s0031-9406(05)66175-5 · Cited by 141 · see citing works
Guides for Reading and Interpreting Systematic Reviews
Jadad, A. R., Moher, D., & Klassen, T. P. (1998) · Archives of Pediatrics and Adolescent Medicine · doi:10.1001/archpedi.152.8.812 · Cited by 135 · see citing works
Aid to the Evaluation of Therapeutic Studies
REISCH, J. S., Tyson, J. E., & Mize, S. G. (1989) · PEDIATRICS · doi:10.1542/peds.84.5.815 · Cited by 123 · see citing works
Evaluating the Level of Evidence of Qualitative Research
Cesario, S. K., Morin, K. H., & Santa‐Donato, A. (2002) · Journal of Obstetric, Gynecologic & Neonatal Nursing · doi:10.1177/0884217502239216 · Cited by 115 · see citing works
Guidelines for reading case-control studies
Lichtenstein, M. J., Mulrow, C. D., & Elwood, P. C. (1987) · Journal of Chronic Diseases · doi:10.1016/0021-9681(87)90190-1 · Cited by 105 · see citing works
Development of a quality assessment scale for retrospective clinical studies in pediatric surgery
Rangel, S. J., Kelsey, J. L., Colby, C. E., Anderson, J. M., & Moss, R. L. (2003) · Journal of Pediatric Surgery · doi:10.1053/jpsu.2003.50114 · Cited by 91 · see citing works
The Pocket Guide to Critical Appraisal: A Handbook for Health Care Professionals
Crombie, I. K. (1996) · Medical Entomology and Zoology · Cited by 89 · see citing works
Evans, M., & Pollock, A. V. (1985) · British journal of surgery · doi:10.1002/bjs.1800720403 · Cited by 85 · see citing works
The Pocket Guide to Critical Appraisal: A Handbook for Health Care Professionals
Harvey, B. J. (1997) · Europe PMC (PubMed Central) · Cited by 75 · see citing works
Critical appraisal checklist for qualitative research studies
Treloar, C., Champness, S., Simpson, P. L., & Higginbotham, N. H. (2000) · The Indian Journal of Pediatrics · doi:10.1007/bf02820685 · Cited by 63 · see citing works
Sindhu, F., Carpenter, L. M., & Seers, K. (1997) · Journal of Advanced Nursing · doi:10.1046/j.1365-2648.1997.19970251262.x · Cited by 63 · see citing works
Checklist for the evaluation of research articles
DuRant, R. H. (1994) · Journal of Adolescent Health · doi:10.1016/1054-139x(94)90381-6 · Cited by 59 · see citing works
Critical appraisal for public health: A new checklist
Heller, R. F., Verma, A., Gemmell, I., Harrison, R. S., Hart, J., & Edwards, R. (2007) · Public Health · doi:10.1016/j.puhe.2007.04.012 · Cited by 54 · see citing works
10. Meta‐analysis: Part 2: assessing the quality of published meta‐analyses
Wilson, A. J., & Henry, D. A. (1992) · The Medical Journal of Australia · doi:10.5694/j.1326-5377.1992.tb139704.x · Cited by 48 · see citing works
Melnyk, B. M., & Fineout‐Overholt, E. (2005) · PubMed · Cited by 34 · see citing works
Application of current research evidence to clinical physiotherapy practice.
Bialocerkowski, A. E., Grimmer, K. A., Milanese, S., et al. (2004) · PubMed · Cited by 33 · see citing works
Rating Methodological Quality: Toward Improved Assessment and Investigation
Moyer, A. E., & Finney, J. W. (2005) · Accountability in Research · doi:10.1080/08989620500440287 · Cited by 32 · see citing works
Reis, S. P., Hermoni, D., Van-Raalte, R., Dahan, R., & Borkan, J. (2006) · Patient Education and Counseling · doi:10.1016/j.pec.2006.07.011 · Cited by 31 · see citing works
Instruments for assessing the quality of drug studies published in the medical literature
Cho, M. K. (1994) · JAMA · doi:10.1001/jama.272.2.101 · Cited by 30 · see citing works
READER: an acronym to aid critical reading by general practitioners.
MacAuley, D. (1994) · PubMed · Cited by 26 · see citing works
A research appraisal checklist for evaluating nursing research reports.
Duffy, M. E. (1985) · PubMed · Cited by 22 · see citing works
Heacock, H. J., Koehoorn, M. W., & Tan, J. (1997) · Applied Ergonomics · doi:10.1016/s0003-6870(96)00066-x · Cited by 22 · see citing works
Critical appraisal: How to read a clinical research paper
Vickers, A. J. (1995) · Complementary Therapies in Medicine · doi:10.1016/s0965-2299(95)80057-3 · Cited by 18 · see citing works
Urschel, J. D. (2005) · World Journal of Surgery · doi:10.1007/s00268-005-7912-z · Cited by 17 · see citing works
Glenny, A.-M. (2005) · Evidence-Based Dentistry · doi:10.1038/sj.ebd.6400351 · Cited by 9 · see citing works
A Guide to Understanding and Evaluating Research Articles
Nielsen, M. E., & Reilly, P. L. (1985) · Gifted Child Quarterly · doi:10.1177/001698628502900210 · Cited by 9 · see citing works
Meijman, F. J., & MELKER, R. A. D. (1995) · Family Practice · doi:10.1093/fampra/12.1.93 · Cited by 9 · see citing works
Burnett, J., Grimmer, K. A., & Kumar, S. (2005) · Internet Journal of Allied Health Sciences and Practice · doi:10.46743/1540-580x/2005.1064 · Cited by 8 · see citing works
The Basic Research Review Checklist
Rasmussen, L. B., O'Conner, M., Shinkle, S., et al. (2000) · The Journal of Continuing Education in Nursing · doi:10.3928/0022-0124-20000101-04 · Cited by 6 · see citing works
Flagged first, then by citations
Cited by
Sorted by citations
The Cochrane Collaboration's tool for assessing risk of bias in randomised trials
Higgins, J. P. T., Altman, D. G., Gotzsche, P. C., Juni, P., Moher, D., Oxman, A. D., Savovic, J., Schulz, K. F., Weeks, L., Sterne, J. A. C., et al. (2011) · BMJ · doi:10.1136/bmj.d5928 · Cited by 33,817 · see citing works
The Mixed Methods Appraisal Tool (MMAT) version 2018 for information professionals and researchers
Hong, Q. N., Fàbregues, S., Bartlett, G., Boardman, F., Cargo, M., Dagenais, P., Gagnon, M.-P., Griffiths, F., Nicolau, B., O’Cathain, A., et al. (2018) · Education for Information · doi:10.3233/efi-180221 · Cited by 4,737 · see citing works
“Currently, there exist more than 500 critical appraisal tools (i.e., checklists including a list of criteria to judge the quality of a study) (Bai et al., 2012; Crowe & Sheppard, 2011; Heyvaert et al., 2013; Santiago-Delefosse et al., 2016).”
Development of a critical appraisal tool to assess the quality of cross-sectional studies (AXIS)
Downes, M. J., Brennan, M. L., Williams, H. C., & Dean, R. S. (2016) · BMJ Open · doi:10.1136/bmjopen-2016-011458 · Cited by 2,376 · see citing works
Pace, R., Pluye, P., Bartlett, G., Macaulay, A. C., Salsberg, J., Jagosh, J., & Seller, R. (2012) · International Journal of Nursing Studies · doi:10.1016/j.ijnurstu.2011.07.002 · Cited by 1,331 · see citing works
Hong, Q. N., Gonzalez‐Reyes, A., & Pluye, P. (2018) · Journal of Evaluation in Clinical Practice · doi:10.1111/jep.12884 · Cited by 1,107 · see citing works
Improving the content validity of the mixed methods appraisal tool: a modified e-Delphi study
Hong, Q. N., Pluye, P., Fàbregues, S., Bartlett, G., Boardman, F., Cargo, M., Dagenais, P., Gagnon, M.-P., Griffiths, F., Nicolau, B., et al. (2019) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2019.03.008 · Cited by 1,082 · see citing works
“For example, Crowe and Sheppard [36] use a generic approach by proposing one set of criteria that could be applied to any design.”
BackgroundParry, D. A., Davidson, B. I., Sewall, C. J. R., Fisher, J. T., Mieczkowski, H., & Quintana, D. S. (2021) · Nature Human Behaviour · doi:10.1038/s41562-021-01117-5 · Cited by 793 · see citing works
Hong, Q. N., Pluye, P., Bujold, M., & Wassef, M. (2017) · Systematic Reviews · doi:10.1186/s13643-017-0454-2 · Cited by 754 · see citing works
“For example, several critical appraisal tools for assessing the quality of quantitative and qualitative studies have been developed [9, 11, 12].”
BackgroundSystematically reviewing remote e-workers’ well-being at work: a multidimensional approach
Charalampous, M., Grant, C. A., Tramontano, C., & Michailidis, E. (2019) · European Journal of Work and Organizational Psychology · doi:10.1080/1359432x.2018.1541886 · Cited by 743 · see citing works
Souto, R. Q., Khanassov, V., Hong, Q. N., Bush, P. L., Vedel, I., & Pluye, P. (2015) · International Journal of Nursing Studies · doi:10.1016/j.ijnurstu.2014.08.010 · Cited by 375 · see citing works
Norwood, C., Moghaddam, N. G., Malins, S., & Sabin‐Farrell, R. (2018) · Clinical Psychology & Psychotherapy · doi:10.1002/cpp.2315 · Cited by 324 · see citing works
Pousada, M., Guillamón, N., Hernández-Encuentra, E., Muñoz, E., Redolar, D., Boixadós, M., & Gómez-Zúñiga, B. (2013) · Journal of Developmental and Physical Disabilities · doi:10.1007/s10882-013-9332-6 · Cited by 155 · see citing works
Austin, J., Drossaert, C. H. C., Schroevers, M. J., Sanderman, R., Kirby, J. N., & Bohlmeijer, E. T. (2021) · Psychology & Health · doi:10.1080/08870446.2019.1699090 · Cited by 88 · see citing works
Parents experiences of pregnancy following perinatal loss: An integrative review
Donegan, G., Noonan, M., & Bradshaw, C. (2023) · Midwifery · doi:10.1016/j.midw.2023.103673 · Cited by 84 · see citing works
- Authors
- Crowe, M., & Sheppard, L.
- Affiliations
- James Cook University (AU)
- University of South Australia (AU)
- Corresponding author
- Crowe, Michael
- Venue
- Journal of Clinical Epidemiology
- Publisher
- Elsevier BV
- Published
- 2011-01
- Volume
- 64
- Issue
- 1
- Pages
- 79-89
- ISSN
- 0895-4356 (ISSN-L)
- OpenAlex
- W2029463586
- Cited by
- 261
- References
- 75
- Citations by year
- 2026: 17 · 2025: 16 · 2024: 13 · 2023: 13 · 2022: 24 · 2021: 32 · 2020: 16 · 2019: 26 · 2018: 18 · 2017: 24 · 2016: 14 · 2015: 12 · 2014: 13 · 2013: 10 · 2012: 5
- FWCI
- 2.06
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Clinical Epidemiology (publishedVersion)
- PubMed (publishedVersion)
- ResearchOnline at James Cook University (James Cook University) (acceptedVersion)
- Topics
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Social Sciences › Education › Health Education and Validation
- Health Sciences › Health Professions › General Health Professions › Health Sciences Research and Education
- Keywords
- critical appraisal tools, tool development, validation, reliability testing, research design, tool structure, systematic reviews, evidence-based medicine
- MeSH terms
- Humans, Research Design, Review Literature as Topic, Reproducibility of Results, Peer Review, Research, Evidence-Based Medicine
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