Cited by 715Statistical Methods in Clinical TrialsAdvanced Causal Inference TechniquesMeta-analysis and systematic reviews

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Intention-to-Treat Analysis: Implications for Quantitative and Qualitative Research

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NEWELL, DAVID J·1992·International Journal of Epidemiology

DOI 10.1093/ije/21.5.837

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Abstract

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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Schwartz D, Flamant R, LeUouch i. Clinical Trials. London: Academic Press, 1980.

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“• Intention-to-treat (ITT): All of the participants who received initial treatment regardless of their availability at follow-up are included, which is considered the most appropriate and least biased data analysis approach [26,32,33].”
Background
Why have meta‐analyses of randomized controlled trials of the association between non‐white‐blood‐cell‐reduced allogeneic blood transfusion and postoperative infection produced discordant results?
Vamvakas, E. C. (2007) · Vox Sanguinis · doi:10.1111/j.1423-0410.2007.00959.x · Cited by 35
Treatment for ascites in adults with decompensated liver cirrhosis: a network meta-analysis
Benmassaoud, A., Freeman, S. C., Roccarina, D., Torres, M. C. P., Sutton, A. J., Cooper, N. J., Prat, L. I., Cowlin, M., Milne, E., Hawkins, N., et al. (2020) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd013123.pub2 · Cited by 38
Techniques of flushing and reperfusion for liver transplantation
Gurusamy, K. S., Naik, P., Abu‐Amara, M., Fuller, B. J., & Davidson, B. R. (2012) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd007512.pub2 · Cited by 36
Randomized psychosocial interventions for breast cancer: impact on life purpose
Mens, M. G., Helgeson, V. S., Lembersky, B. C., Baum, A. E., & Scheier, M. F. (2015) · Psycho-Oncology · doi:10.1002/pon.3891 · Cited by 39
“Analyses were initially conducted with the intention-totreat principle [28], but the interventions had no significant effects on the primary outcomes in these analyses.”
Method
Methods of vascular occlusion for elective liver resections
Gurusamy, K. S., Sheth, H. D., Kumar, Y., Sharma, D., & Davidson, B. R. (2009) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd006409.pub3 · Cited by 35
Robot assistant for laparoscopic cholecystectomy
Gurusamy, K. S., Samraj, K., Fusai, G., & Davidson, B. R. (2009) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd006578.pub2 · Cited by 35
Gases for establishing pneumoperitoneum during laparoscopic abdominal surgery
Cheng, Y., Lu, J., Xiong, X., Wu, S., Lin, Y., Wu, T., & Cheng, N. (2013) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd009569.pub2 · Cited by 35
Antibiotic prophylaxis for the prevention of methicillin-resistant Staphylococcus aureus (MRSA) related complications in surgical patients
Gurusamy, K. S., Koti, R. S., Wilson, P., & Davidson, B. R. (2013) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd010268.pub2 · Cited by 35
A randomized controlled trial to evaluate the relative efficacy of adding voluntary counseling and testing (VCT) to information dissemination in reducing HIV-related risk behaviors among Hong Kong male cross-border truck drivers
Lau, J. T. F., Tsui, H. Y., Cheng, S. S. Y., & Pang, M. (2009) · AIDS Care · doi:10.1080/09540120903012619 · Cited by 34
“Intention-to-treat analysis (Newell, 1992 ) was used for data analyses.”
Method
Comparison of the Efficacy and Safety of Different ACE Inhibitors in Patients With Chronic Heart Failure
Sun, W., Zhang, H., Guo, J., Zhang, X., Zhang, L., Li, C., & Zhang, L. (2016) · Medicine · doi:10.1097/md.0000000000002554 · Cited by 35
Financing Recovery After Disasters: Explaining Community Credit Market Responses to Severe Events
Collier, B., & Babich, V. O. (2016) · Journal of Risk & Insurance · doi:10.1111/jori.12221 · Cited by 34
An evidence-based gamified mHealth intervention for overweight young adults with maladaptive eating habits: study protocol for a randomized controlled trial
Podina, I. R., Fodor, L. A., Cosmoiu, A., & Boian, R. (2017) · Trials · doi:10.1186/s13063-017-2340-6 · Cited by 34
“The intent-to-treat principle will be employed [58] with the last observation carried forward method.”
Method
Slow-release fluoride devices for the control of dental decay
Chong, L., Clarkson, J., Dobbyn-Ross, L., & Bhakta, S. (2018) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd005101.pub4 · Cited by 35
Are community health interventions evaluated appropriately? A review of six journals
Smith, P. J., MOFFATT, M. E. K., Gelskey, S. C., Hudson, S., & Kaita, K. (1997) · Journal of Clinical Epidemiology · doi:10.1016/s0895-4356(96)00338-1 · Cited by 34
Integrated versus non-integrated orbital implants for treating anophthalmic sockets
Schellini, S. A., Dib, R. E., Silva, L. R., Farat, J. G., Zhang, Y., & Jorge, E. C. (2016) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd010293.pub2 · Cited by 33
“Newell 1992 Newell DJ. Intention-to-treat analysis: implications for quantitative and qualitative research.”
BackgroundMethod
Central Retinal Enrichment Supplementation Trials (CREST): Design and Methodology of the CREST Randomized Controlled Trials
Akuffo, K. O., Beatty, S., Stack, J., Dennison, J. L., O’Regan, S., Meagher, K. A., Pető, T., & Nolan, J. M. (2014) · Ophthalmic Epidemiology · doi:10.3109/09286586.2014.888085 · Cited by 33
Telephone Counseling Intervention Improves Dietary Habits and Metabolic Parameters of Patients with the Metabolic Syndrome: A Randomized Controlled Trial
Fappa, E., Yannakoulia, M., Ioannidou, M., Skoumas, Y., Pitsavos, C., & Stefanadis, C. (2012) · The Review of Diabetic Studies · doi:10.1900/rds.2012.9.36 · Cited by 33
“All analyses followed the intent-totreat principle, using all randomized participants, and assuming no change from baseline for those with missing data [36-37].”
Method
Positive imagery training increases positive self-referent cognition in depression
Dainer‐Best, J., Shumake, J., & Beevers, C. G. (2018) · Behaviour Research and Therapy · doi:10.1016/j.brat.2018.09.010 · Cited by 31
“In clinical trials attempting to demonstrate treatment efficacy, intention to treat analyses are paramount (Newell, 1992).”
Background
Treatment for bleeding oesophageal varices in people with decompensated liver cirrhosis: a network meta-analysis
Roberts, D. A., Best, L. M., Freeman, S. C., Sutton, A. J., Cooper, N. J., Arunan, S., Begum, T., Williams, N. R., Walshaw, D., Milne, E., et al. (2021) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd013155.pub2 · Cited by 33
Cardiopulmonary interventions to decrease blood loss and blood transfusion requirements for liver resection
Gurusamy, K. S., Li, J., Sharma, D., & Davidson, B. R. (2009) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd007338.pub2 · Cited by 33
Evaluating the efficacy and safety of Alzheimer’s disease drugs: A meta-analysis and systematic review
Chen, Y., Lai, M., & Tao, M. (2024) · Medicine · doi:10.1097/md.0000000000037799 · Cited by 36
“[46] Additionally, standard deviations were calculated based on standard errors, CI, t , or P values, minimizing the data loss.”
Method
Primary prevention of variceal bleeding in people with oesophageal varices due to liver cirrhosis: a network meta-analysis
Roccarina, D., Best, L. M., Freeman, S. C., Roberts, D. A., Cooper, N. J., Sutton, A. J., Benmassaoud, A., Torres, M. C. P., Prat, L. I., Csenar, M., et al. (2021) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd013121.pub2 · Cited by 34
Efficacy and adverse effects of memantine treatment for Alzheimer’s disease from randomized controlled trials
Jiang, J., & Jiang, H. (2015) · Neurological Sciences · doi:10.1007/s10072-015-2221-2 · Cited by 35
Donor safety in live donor laparoscopic liver procurement: systematic review and meta-analysis
Bekheit, M., Khafagy, P., Bucur, P. O., Katri, K. M., El-Gendi, A. M., Abdelsalam, W. N., Vibert, É., & El-Kayal, E.-S. (2014) · Surgical Endoscopy · doi:10.1007/s00464-014-4045-1 · Cited by 31
Robot assistant versus human or another robot assistant in patients undergoing laparoscopic cholecystectomy
Gurusamy, K. S., Samraj, K., Fusai, G., & Davidson, B. R. (2012) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd006578.pub3 · Cited by 31
Techniques for liver parenchymal transection in liver resection
Gurusamy, K. S., Pamecha, V., Sharma, D., & Davidson, B. R. (2008) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd006880 · Cited by 31
Hormone profiling, WHO 2010 grading, and AJCC / UICC staging in pancreatic neuroendocrine tumor behavior
Morin, E., Cheng, S., Mete, Ö., Serra, S., Araújo, P. B., Temple, S. J., Cleary, S. P., Gallinger, S., Greig, P. D., McGilvray, I. D., et al. (2013) · Cancer Medicine · doi:10.1002/cam4.96 · Cited by 30
“For the biotherapy section, we included an intention-to-treat analysis [11].”
Method

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
DOI: 10.1093/ije/21.5.837
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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Intention-to-Treat Analysis: Implications for Quantitative and Qualitative Research

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