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Intention-to-Treat Analysis: Implications for Quantitative and Qualitative Research
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Newell D J (Department of Medical Statistics, University of Newcastle upon Tyne, UK). Intention-to-treat analysis: implications for quantitative and qualitative research. International Journal of Epidemiology 1992, 21: 837–841 Intention-to-treat analysis is an important aspect of randomized controlled trials of health care interventions. The concept is now widely accepted in theory, but not always implemented in practice. Failure to analyse by intention-to-treat can give misleading and indeed life-threatening interpretations. In some studies, a case is put for estimating the effect that would have been observed if all patients had received the allocated treatment. Situations where this is valid are rare, but an example is given of such an exceptional study. The relevance of the intention-to-treat concept is not always taken into account in qualitative research. Interviews with new mothers who delivered their babies at home in a hypothetical controlled trial of home versus hospital confinement would provide fascinating accounts of the pleasures of successful delivery at home. But by definition the interviews would exclude the hazard and drama of necessary transfers to hospital due to complications in late pregnancy and early labour. The intention-to-treat approach would avoid this bias.
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“All enrolled participants who completed the baseline assessment were included in the intention-to-treat analysis [31].”
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“ITT is often recommended for estimating intervention effects in RCTs as they produce more conservative and less biased results (Newell, 1992).”
ResultDevereaux, P. J., Manns, B., Ghali, W., Quan, H., & Guyatt, G. (2002) · Controlled Clinical Trials · doi:10.1016/s0197-2456(02)00214-3 · Cited by 182
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“Second, intention-to-treat was used in the data analysis, and this provides conservative estimates of effect sizes in randomized controlled trials such as this one (Hollis & Campbell, 1999; Newell, 1992).”
BackgroundMethodEvaluating the Clinical Utility of a Biomarker
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“For confirmatory studies, an intention-to-treat analysis may be considered as potentially the least biased way to estimate intervention effects in randomized trials.(82) In clinical trials, empirical evidence has suggested more exaggerated effect estimates from per-protocol analyses compared with intention-to-treat an…”
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“Today, the ITT principle has been generally defined as: ‘All patients allocated to each arm of the treatment regimen are analyzed together as representing that treatment arm, whether or not they received or completed the prescribed regimen’ [18,19].”
BackgroundIntention-to-treat. What is the question?
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“ITT analyses are typically reported in a way that implies that they have the final say on efficacy; Newell, for example [3] insists that "In any study of a health intervention, it is essential to remember patients or clients who would not or could not complete the planned intervention, and include them appropriately i…”
InfluentialTillfors, M., Carlbring, P., Furmark, T., Lewenhaupt, S., Spak, M., Eriksson, A., Westling, B. E., & Andersson, G. (2008) · Depression and Anxiety · doi:10.1002/da.20416 · Cited by 132
Wijeyekoon, S. P., Gurusamy, K. S., El-Gendy, K., & Chan, C. L. H. (2010) · Journal of the American College of Surgeons · doi:10.1016/j.jamcollsurg.2010.06.111 · Cited by 132
Early supported hospital discharge following acute stroke: pilot study results
Rodgers, H., Soutter, J. L., Kaiser, W., Pearson, P. H., Dobson, R., Skilbeck, C. E., & Bond, J. (1997) · Clinical Rehabilitation · doi:10.1177/026921559701100403 · Cited by 133
Fang, Y., Gurusamy, K. S., Wang, Q., Davidson, B. R., Lin, H., Xie, X., & Wang, C. (2013) · British journal of surgery · doi:10.1002/bjs.9260 · Cited by 131
Day-surgery versus overnight stay surgery for laparoscopic cholecystectomy
Vaughan, J., Gurusamy, K. S., & Davidson, B. R. (2013) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd006798.pub4 · Cited by 130
Bergeron, S., Khalifé, S., Dupuis, M.-J., & McDuff, P. (2016) · Journal of Consulting and Clinical Psychology · doi:10.1037/ccp0000072 · Cited by 128
“An intent-to-treat strategy was chosen because it is a more conservative approach and preserves the comparability of groups allowed by randomization (Newell, 1992).”
Percutaneous cholecystostomy for high-risk surgical patients with acute calculous cholecystitis
Gurusamy, K. S., Rossi, M., & Davidson, B. R. (2013) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd007088.pub2 · Cited by 127
“Dealing with missing data We performed the analysis on an intention-to-treat basis (Newell 1992) whenever possible.”
BackgroundMethodLaparoscopic surgical box model training for surgical trainees with no prior laparoscopic experience
Nagendran, M., Toon, C. D., Davidson, B. R., & Gurusamy, K. S. (2014) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd010479.pub2 · Cited by 125
Desrochers, G., Bergeron, S., Khalifé, S., Dupuis, M.-J., & Jodoin, M. (2010) · Behaviour Research and Therapy · doi:10.1016/j.brat.2009.09.014 · Cited by 123
“This procedure partially helps to resolve problems such as lack of power (sample size), inclusion of both compliant and less compliant participants, and maintains the comparability of groups allowed by randomization (Newell, 1992).”
Elkins, M. R., & Moseley, A. M. (2015) · Journal of Physiotherapy · doi:10.1016/j.jphys.2015.05.013 · Cited by 122
Routine abdominal drainage for uncomplicated laparoscopic cholecystectomy
Gurusamy, K. S., Samraj, K., Mullerat, P., & Davidson, B. R. (2007) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd006004.pub2 · Cited by 121
Interventions for necrotising pancreatitis
Gurusamy, K. S., Belgaumkar, A. P., Haswell, A., Pereira, S. P., & Davidson, B. R. (2016) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd011383.pub2 · Cited by 118
Prosthetic mesh placement for the prevention of parastomal herniation
Jones, H. G., Rees, M., Aboumarzouk, O. M., Brown, J., Cragg, J., Billings, P., Carter, B., & Chandran, P. (2018) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd008905.pub3 · Cited by 117
Tsai, A. C., Weiser, S. D., Petersen, M. L., Ragland, K. E., Kushel, M., & Bangsberg, D. R. (2010) · Archives of General Psychiatry · doi:10.1001/archgenpsychiatry.2010.160 · Cited by 119
“Many subjects experienced 1 or more subsequent interruptions of antidepressant medication treatment, suggesting that our intention-to-treat assumption would yield conservative estimates of treatment effect.(35,36) The median duration of uninterrupted antidepressant medication treatment was 251 days (interquartile rang…”
MethodResultThe Clinical Development of Percutaneous Heart Valve Technology
Vassiliades, T. A., Block, P. C., Cohn, L. H., Adams, D. H., BORER, J. S., Feldman, T. E., Holmes, D. R., Laskey, W. K., Lytle, B. W., Mack, M. J., et al. (2005) · Journal of the American College of Cardiology · doi:10.1016/j.jacc.2004.12.024 · Cited by 116
Techniques for liver parenchymal transection in liver resection
Gurusamy, K. S., Pamecha, V., Sharma, D., & Davidson, B. R. (2009) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd006880.pub2 · Cited by 115
Koti, R. S., Gurusamy, K. S., Fusai, G., & Davidson, B. R. (2010) · HPB · doi:10.1111/j.1477-2574.2010.00157.x · Cited by 115
Methods to decrease blood loss during liver resection: a network meta-analysis
Moggia, E., Rouse, B., Simillis, C., Li, T., Vaughan, J., Davidson, B. R., & Gurusamy, K. S. (2016) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd010683.pub3 · Cited by 112
Methods to decrease blood loss and transfusion requirements for liver transplantation
Gurusamy, K. S., Pissanou, T., Pikhart, H., Vaughan, J., Burroughs, A. K., & Davidson, B. R. (2011) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd009052.pub2 · Cited by 114
Bonovas, S., Fiorino, G., Allocca, M., Lytras, T., Tsantes, A., Peyrin-Biroulet, L., & Danese, S. (2016) · Medicine · doi:10.1097/md.0000000000002308 · Cited by 113
Metadata
- Authors
- NEWELL, D. J.
- Affiliations
- Newcastle University (GB)
- Corresponding author
- NEWELL, DAVID J
- ORCID
- NEWELL, DAVID J
- Venue
- International Journal of Epidemiology
- Publisher
- Oxford University Press (OUP)
- Published
- 1992
- Volume
- 21
- Issue
- 5
- Pages
- 837-841
- ISSN
- 0300-5771 (ISSN-L)
- 1464-3685
- OpenAlex
- W2106051200
- Cited by
- 715
- References
- 6
- Citations by year
- 2026: 4 · 2025: 15 · 2024: 24 · 2023: 22 · 2022: 21 · 2021: 16 · 2020: 16 · 2019: 16 · 2018: 25 · 2017: 36 · 2016: 31 · 2015: 35 · 2014: 51 · 2013: 62 · 2012: 34
- FWCI
- 5.99
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- International Journal of Epidemiology (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Keywords
- intention-to-treat analysis, randomized controlled trials, health interventions, qualitative research, home birth, hospital confinement, allocation bias, treatment effect estimation
- MeSH terms
- Data Interpretation, Statistical, Evaluation Studies as Topic, Humans, Patient Compliance, Random Allocation, Research Design, Therapeutics, Cohort Studies, Randomized Controlled Trials as Topic
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