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Pragmatic Clinical Trials Unit

Our Methodological Publications

PCTU staff have written a number of methodological papers that can be located in this section, ordered by year of publication date. 


Bond C, Lancaster GA, Campbell M, Chan C, Eddy S, Hopewell S, Mellor K, Thabane L, Eldridge S. Pilot and feasibility studies: extending the conceptual framework. Pilot Feasibility Stud 2023;9:24 https://doi.org/10.1186/s40814-023-01233-1

Russell AM, Shepherd V, Woolfall K, Young B, Gillies K, Volkmer A, Jayes M, Huxtable R, Perkins A, Noor NM, Nickolls B, Wade J. Complex and alternate consent pathways in clinical trials: methodological and ethical challenges encountered by underserved groups and a call to action. Trials 2023;24(1):151 https://doi.org/10.1186/s13063-023-07159-6

Parker K, Eddy S, Nunns M, Xiao Z, Ford T, Eldridge S, Ukoumunne OC. Systematic review of the characteristics of school-based feasibility cluster randomised trials of interventions for improving the health of pupils in the UK. Pilot and feasibility studies. 2022;8(1):132 https://doi.org/10.1186/s40814-022-01098-w 

Lawson DO, Mellor K, Eddy S, Lee C, Kim KH, Kim K, Mbuagbaw L, Thabane L. Pilot and Feasibility Studies in Rehabilitation Research A Review and Educational Primer for the Physiatrist Researcher. American Journal of Physical Medicine & Rehabilitation 2022;101:372-383 https://doi.org/10.1097/Phm.0000000000001797 

Kasza J, Bowden R, Hooper R, A.B. F. The batched stepped wedge design: a design robust to delays in cluster recruitment. Stat Med 2022; https://doi.org/10.1002/sim.9438 

Kahan BC, White IR, Hooper R, Eldridge S. Re-randomisation trials in multi-episode settings: Estimands and independence estimators. Statistical Methods in Medical Research 2022; https://doi.org/10.1177/09622802221094140 

Wilson DT, Hooper R, Brown J, Farrin AJ, Walwyn REA. Efficient and flexible simulation-based sample size determination for clinical trials with multiple design parameters. Statistical Methods in Medical Research 2021;30:799-815 https://doi.org/10.1177/0962280220975790 

Turner EL, Platt AC, Gallis JA, Tetreault K, Easter C, McKenzie JE, Nash S, Forbes AB, Hemming K, Adrion C, Akooji N, Bhangu A, Bridgwood B, Budgell E, Chan CL, Campbell M, Collinson M, Copas A, Eldridge S, Forster AS, Girling A, Glasbey J, Goulao B, Hackett S, Hamborg T, Hooper R, James K, Jarvis CI, Jones B, Kahan BC, Kanaan M, Kendall L, Kristunas C, Leyrat C, Macneill SJ, Madurasinghe VW, Martin J, Mwandigha LM, Nepogodiev D, Omar O, Pankhurst LA, Perry H, Rombach I, Stuart B, Thompson JA, Wagner AP, Wilson N, Caille A, Yepnang AMM, Tavernier E, Giraudeau B, Diakou LAN, Taljaard M, Dixon SN, Moerbeek M, Grantham KL, Kasza J, Cao S, Harding M, Kusibab K, Lee HJ, McCormack K, Moran K, Parish A, Simmons R, Truong T, Vissoci JR, Wang T, Wang X, Weber J, Wilson J, Yang S, Yang Z, Bishop J, Cheed V, Gill A, Handley K, Hardy P, Hewitt CA, Ives N, Mehta S, Patel S, Sun Y, Woolley R. Completeness of reporting and risks of overstating impact in cluster randomised trials: a systematic review. Lancet Global Health 2021;9:E1163-E1168 https://doi.org/10.1016/S2214-109X(21)00200-X 

Ster AC, Phillips R, Sauzet O, Cornelius V. Improving analysis practice of continuous adverse event outcomes in randomised controlled trials - a distributional approach. Trials 2021;22: https://doi.org/10.1186/s13063-021-05343-0 

Mellor K, Eddy S, Peckham N, Bond CM, Campbell MJ, Lancaster GA, Thabane L, Eldridge SM, Dutton SJ, Hopewell S. Progression from external pilot to definitive randomised controlled trial: a methodological review of progression criteria reporting. Bmj Open 2021;11: https://doi.org/10.1136/bmjopen-2020-048178 

Madurasinghe VW, Bower P, Eldridge S, Collier D, Graffy J, Treweek S, Knapp P, Parker A, Rick J, Salisbury C, Man MS, Torgerson D, Sheridan R, Sullivan F, Cockayne S, Dack C. Can we achieve better recruitment by providing better information? Meta-analysis of 'studies within a trial' (SWATs) of optimised participant information sheets. Bmc Medicine 2021;19: https://doi.org/10.1186/s12916-021-02086-2 

Lung TM, Si L, Hooper R, Di Tanna GL. Health Economic Evaluation Alongside Stepped Wedge Trials: A Methodological Systematic Review. Pharmacoeconomics 2021;39:63-80 https://doi.org/10.1007/s40273-020-00963-x 

Khan MIU, Mbuagbaw L, Holek M, Bdair F, Durrani ZH, Mellor K, Eddy S, Eldridge SM, Chan CL, Campbell MJ, Bond CM, Hopewell S, Lancaster GA, Thabane L. Transparency of informed consent in pilot and feasibility studies is inadequate: a single-center quality assurance study. Pilot and Feasibility Studies 2021;7: https://doi.org/10.1186/s40814-021-00828-w 

Kahan BC, White IR, Eldridge S, Hooper R. Independence estimators for re-randomisation trials in multi-episode settings: a simulation study. Bmc Medical Research Methodology 2021;21: https://doi.org/10.1186/s12874-021-01433-4 

Hooper R, Eldridge SM. Cutting edge or blunt instrument: how to decide if a stepped wedge design is right for you. Bmj Quality & Safety 2021;30:245-250 https://doi.org/10.1136/bmjqs-2020-011620 

Hooper R, Copas AJ. Optimal design of cluster randomised trials with continuous recruitment and prospective baseline period. Clinical Trials 2021;18:147-157 https://doi.org/10.1177/1740774520976564 

Hooper R. Key concepts in clinical epidemiology: Stepped wedge trials. Journal of Clinical Epidemiology 2021;137:159-162 https://doi.org/10.1016/j.jclinepi.2021.04.003 

Copas AJ, Hooper R. Optimal design of cluster randomized trials allowing unequal allocation of clusters and unequal cluster size between arms. Statistics in Medicine 2021;40:5474-5486 https://doi.org/10.1002/sim.9135 

Chan CL, Taljaard M, Lancaster GA, Brehaut JC, Eldridge SM. Pilot and feasibility studies for pragmatic trials have unique considerations and areas of uncertainty. Journal of Clinical Epidemiology 2021;138:102-114 https://doi.org/10.1016/j.jclinepi.2021.06.029 

Yepnang AMM, Caille A, Eldridge SM, Giraudeau B. Authors reply: Letter to the Editor: Is the R coefficient of interest in cluster randomized trials with a binary outcome? (SMMR, First Published online 23 January 2020). Statistical Methods in Medical Research 2020;29:1765-1766 https://doi.org/10.1177/0962280220920316 

Yepnang AMM, Caille A, Eldridge SM, Giraudeau B. Is the R coefficient of interest in cluster randomized trials with a binary outcome? Statistical Methods in Medical Research 2020;29:2470-2480 https://doi.org/10.1177/0962280219900200 

Taljaard M, Goldstein CE, Giraudeau B, Nicholls SG, Carroll K, Hey SP, Brehaut JC, Jairath V, London AJ, Eldridge SM, Grimshaw JM, Fergusson DA, Weijer C. Cluster over individual randomization: are study design choices appropriately justified? Review of a random sample of trials. Clinical Trials 2020;17:253-263 https://doi.org/10.1177/1740774519896799 

Lee MJ, Dimairo M, Edwards J, Hawkins DJ, Hind D, Knowles CH, Hooper R, Brown SR, Collaborative WS. Non-randomized studies should be considered for assessing surgical techniques in rectal prolapse: prospective cohort study. Colorectal Disease 2020;22:2170-2180 https://doi.org/10.1111/codi.15293 

Khan MI, Holek M, Bdair F, Mbuagbaw L, Eldridge SM, Chan CL, Campbell MJ, Bond CM, Hopewell S, Lancaster GA, Thabane L. Assessing the transparency of informed consent in feasibility and pilot studies: a single-centre quality assurance study protocol. Bmj Open 2020;10: https://doi.org/10.1136/bmjopen-2019-036226 

Kasza J, Hooper R, Copas A, Forbes AB. Sample size and power calculations for open cohort longitudinal cluster randomized trials. Statistics in Medicine 2020;39:1871-1883 https://doi.org/10.1002/sim.8519 

Hooper R, Kasza J, Forbes A. The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures. Bmc Medical Research Methodology 2020;20: https://doi.org/10.1186/s12874-020-01155-z 

Hemming K, Kasza J, Hooper R, Forbes A, Taljaard M. A tutorial on sample size calculation for multiple-period cluster randomized parallel, cross-over and stepped-wedge trials using the Shiny CRT Calculator. International Journal of Epidemiology 2020;49:979-995 https://doi.org/10.1093/ije/dyz237 

Ettori-Ajasse I, Tatin E, Forbes G, Eldridge S, Dibao-Dina C. How pragmatic are the randomised trials used in recommendations for control of glycosylated haemoglobin levels in type 2 diabetic patients in general practice: an application of the PRECIS II tool. Trials 2020;21: https://doi.org/10.1186/s13063-020-4215-5 

Copas AJ, Hooper R. Cluster randomised trials with different numbers of measurements at baseline and endline: Sample size and optimal allocation. Clinical Trials 2020;17:69-76 https://doi.org/10.1177/1740774519873888 

Sterne JAC, Savovic J, Page MJ, Elbers RG, Blencowe NS, Boutron I, Cates CJ, Cheng HY, Corbett MS, Eldridge SM, Emberson JR, Hernan MA, Hopewell S, Hrobjartsson A, Junqueira DR, Juni P, Kirkham JJ, Lasserson T, Li TJ, McAleenan A, Reeves BC, Shepperd S, Shrier I, Stewart LA, Tilling K, White IR, Whiting PF, Higgins JPT. RoB 2: a revised tool for assessing risk of bias in randomised trials. Bmj-British Medical Journal 2019;366 https://doi.org/10.1136/bmj.l4898 

Kristunas CA, Hemming K, Eborall H, Eldridge S, Gray LJ. The current use of feasibility studies in the assessment of feasibility for stepped-wedge cluster randomised trials: a systematic review. BMC Med Res Methodol 2019;19:12 https://doi.org/10.1186/s12874-019-0658-3 

Kasza J, Hemming K, Hooper R, Matthews JNS, Forbes AB, Resource ACO. Impact of non-uniform correlation structure on sample size and power in multiple-period cluster randomised trials. Statistical Methods in Medical Research 2019;28:703-716 https://doi.org/10.1177/0962280217734981 

Hooper R, Copas A. Stepped wedge trials with continuous recruitment require new ways of thinking. Journal of Clinical Epidemiology 2019;116:161-166 https://doi.org/10.1016/j.jclinepi.2019.05.037 

Forbes G, Loudon K, Clinch M, Taylor SJC, Treweek S, Eldridge S. Improving the relevance of randomised trials to primary care: a qualitative study investigating views towards pragmatic trials and the PRECIS-2 tool. Trials 2019;20: https://doi.org/10.1186/s13063-019-3812-7 

Chan CL. A website for pilot and feasibility studies: giving your research the best chance of success. Pilot and Feasibility Studies 2019;5: https://doi.org/10.1186/s40814-019-0522-6 

Yelland LN, Kahan BC, Dent E, Lee KJ, Voysey M, Forbes AB, Cook JA. Prevalence and reporting of recruitment, randomisation and treatment errors in clinical trials: A systematic review. Clin Trials 2018;1740774518761627 https://doi.org/10.1177/1740774518761627 

Taljaard M, Weijer C, Grimshaw JM, Ali A, Brehaut JC, Campbell MK, Carroll K, Edwards S, Eldridge S, Forrest CB, Giraudeau B, Goldstein CE, Graham ID, Hemming K, Hey SP, Horn AR, Jairath V, Klassen TP, London AJ, Marlin S, Marshall JC, McIntyre L, McKenzie JE, Nicholls SG, Alison Paprica P, Zwarenstein M, Fergusson DA. Developing a framework for the ethical design and conduct of pragmatic trials in healthcare: a mixed methods research protocol. Trials 2018;19:525 https://doi.org/10.1186/s13063-018-2895-x 

Parker A, Knapp P, Treweek S, Madhurasinghe V, Littleford R, Gallant S, Sullivan F, Schembri S, Rick J, Graffy J, Collier DJ, Eldridge S, Kennedy A, Bower P. The effect of optimised patient information materials on recruitment in a lung cancer screening trial: an embedded randomised recruitment trial. Trials 2018;19:503 https://doi.org/10.1186/s13063-018-2896-9 

Parker A, Knapp P, Treweek S, Madhurasinghe V, Littleford R, Gallant S, Sullivan F, Schembri S, Rick J, Graffy J. The effect of optimised patient information materials on recruitment in a lung cancer screening trial: an embedded randomised recruitment trial. Trials 2018;19:503 https://doi.org/10.1186/s13063-018-2896-9 

Mulhern B, Feng Y, Shah K, Janssen MF, Herdman M, van Hout B, Devlin N. Comparing the UK EQ-5D-3L and English EQ-5D-5L Value Sets. Pharmacoeconomics 2018;36:699-713 https://doi.org/10.1007/s40273-018-0628-3 

Leyrat C, Morgan KE, Leurent B, Kahan BC. Cluster randomized trials with a small number of clusters: which analyses should be used? Int J Epidemiol 2018;47:321-331 https://doi.org/10.1093/ije/dyx169 

Leyrat C, Caille A, Eldridge S, Kerry S, Dechartres A, Giraudeau B. Intervention effect estimates in cluster randomized versus individually randomized trials: a meta-epidemiological study. International journal of epidemiology 2018; https://doi.org/10.1093/ije/dyy229 

Keerie C, Tuck C, Milne G, Eldridge S, Wright N, Lewis SC. Data sharing in clinical trials - practical guidance on anonymising trial datasets. Trials 2018;19:25 https://doi.org/10.1186/s13063-017-2382-9 

Kahan BC, Morris TP, Harris E, Pearse R, Hooper R, Eldridge S. Re-randomization increased recruitment and provided similar treatment estimates as parallel designs in trials of febrile neutropenia. J Clin Epidemiol 2018; https://doi.org/10.1016/j.jclinepi.2018.02.002 

Hooper R, Knowles C. Improving the efficiency of individually randomized clinical trials by staggering the introduction of the intervention. Stat Med 2018; https://doi.org/10.1002/sim.7959 

Hooper R, Forbes A, Hemming K, Takeda A, Beresford L. Analysis of cluster randomised trials with an assessment of outcome at baseline. BMJ 2018;360:k1121 https://doi.org/10.1136/bmj.k1121 

Hemming K, Taljaard M, McKenzie JE, Hooper R, Copas A, Thompson JA, Dixon-Woods M, Aldcroft A, Doussau A, Grayling M, Kristunas C, Goldstein CE, Campbell MK, Girling A, Eldridge S, Campbell MJ, Lilford RJ, Weijer C, Forbes AB, Grimshaw JM. Reporting of stepped wedge cluster randomised trials: extension of the CONSORT 2010 statement with explanation and elaboration. BMJ 2018;363:k1614 https://doi.org/10.1136/bmj.k1614 

Hemming K, Taljaard M, Forbes G, Eldridge SM, Weijer C. Ethical implications of excessive cluster sizes in cluster randomised trials. BMJ Qual Saf 2018; https://doi.org/10.1136/bmjqs-2017-007164 

Hemming K, Carroll K, Thompson J, Forbes A, Taljaard M, group S-Cr. Quality of stepped-wedge trial reporting can be reliably assessed using an updated CONSORT: crowd-sourcing systematic review. J Clin Epidemiol 2018; https://doi.org/10.1016/j.jclinepi.2018.11.017 

Campbell MJ, Lancaster GA, Eldridge SM. A randomised controlled trial is not a pilot trial simply because it uses a surrogate endpoint. Pilot Feasibility Stud 2018;4:130 https://doi.org/10.1186/s40814-018-0324-2 

Amundsen PA, Evans DW, Rajendran D, Bright P, Bjorkli T, Eldridge S, Buchbinder R, Underwood M, Froud R. Inclusion and exclusion criteria used in non-specific low back pain trials: a review of randomised controlled trials published between 2006 and 2012. BMC Musculoskelet Disord 2018;19:113 https://doi.org/10.1186/s12891-018-2034-6 

Rogozinska E, Marlin N, Yang F, Dodd JM, Guelfi K, Teede H, Surita F, Jensen DM, Geiker NRW, Astrup A, Yeo S, Kinnunen TI, Stafne SN, Cecatti JG, Bogaerts A, Hauner H, Mol BW, Scudeller TT, Vinter CA, Renault KM, Devlieger R, Thangaratinam S, Khan KS. Variations in reporting of outcomes in randomized trials on diet and physical activity in pregnancy: A systematic review. J Obstet Gynaecol Res 2017;43:1101-1110 https://doi.org/10.1111/jog.13338 

Rogozinska E, Marlin N, Thangaratinam S, Khan KS, Zamora J. Meta-analysis using individual participant data from randomised trials: opportunities and limitations created by access to raw data. Evid Based Med 2017;22:157-162 https://doi.org/10.1136/ebmed-2017-110775 

Pinnock H, Barwick M, Carpenter CR, Eldridge S, Grandes G, Griffiths CJ, Rycroft-Malone J, Meissner P, Murray E, Patel A, Sheikh A, Taylor SJ. Standards for Reporting Implementation Studies (StaRI): explanation and elaboration document. BMJ Open 2017;7:e013318 https://doi.org/10.1136/bmjopen-2016-013318 

Morgan KE, Forbes AB, Keogh RH, Jairath V, Kahan BC. Choosing appropriate analysis methods for cluster randomised cross-over trials with a binary outcome. Stat Med 2017;36:318-333 https://doi.org/10.1002/sim.7137 

Madurasinghe VW. Sequence balance minimisation: minimising with unequal treatment allocations. Trials 2017;18:207 https://doi.org/10.1186/s13063-017-1942-3 

Kahan BC, Feagan B, Jairath V. A comparison of approaches for adjudicating outcomes in clinical trials. Trials 2017;18:266 https://doi.org/10.1186/s13063-017-1995-3 

Hemming K, Eldridge S, Forbes G, Weijer C, Taljaard M. How to design efficient cluster randomised trials. BMJ 2017;358:j3064 https://doi.org/10.1136/bmj.j3064 

Froud R, Rajendran D, Patel S, Bright P, Bjorkli T, Eldridge S, Buchbinder R, Underwood M. The Power of Low Back Pain Trials: A Systematic Review of Power, Sample Size, and Reporting of Sample Size Calculations Over Time, in Trials Published Between 1980 and 2012. Spine 2017;42:E680-E686 https://doi.org/10.1097/brs.0000000000001953 

Forbes G, Loudon K, Treweek S, Taylor SJC, Eldridge S. Understanding the applicability of results from primary care trials: lessons learned from applying PRECIS-2. J Clin Epidemiol 2017;90:119-126 https://doi.org/10.1016/j.jclinepi.2017.06.007 

Chan CL, Leyrat C, Eldridge SM. Quality of reporting of pilot and feasibility cluster randomised trials: a systematic review. BMJ Open 2017;7:e016970 https://doi.org/10.1136/bmjopen-2017-016970 

Al Wattar BH, Dodds J, Placzek A, Spyreli E, Higgins S, Moore A, Hooper R, Beresford L, Roseboom TJ, Bes-Rastrollo M, Hitman G, Khan KS, Thangaratinam S. Mediterranean diet based intervention in pregnancy to improve maternal and fetal outcomes: Methodological challenges and lessons learned from the multicentre ESTEEM study. Contemporary Clinical Trials Communications 2017;6:72-77 https://doi.org/10.1016/j.conctc.2017.02.012 

Thabane L, Hopewell S, Lancaster GA, Bond CM, Coleman CL, Campbell MJ, Eldridge SM. Erratum to: Methods and processes for development of a CONSORT extension for reporting pilot randomized controlled trials. Pilot Feasibility Stud 2016;2:35 https://doi.org/10.1186/s40814-016-0078-7 

Stevens N, Edwards L, Balayah Z, Hooper R, Knowles C. Risk based survey evidence supports electronic informed consent as a recruitment method for UK clinical trials. Journal of Clinical Epidemiology 2016;77:134-136 https://doi.org/10.1016/j.jclinepi.2016.05.005 

Russell J, Berney L, Stansfeld S, Lanz D, Kerry S, Chandola T, Bhui K. The role of qualitative research in adding value to a randomised controlled trial: lessons from a pilot study of a guided e-learning intervention for managers to improve employee wellbeing and reduce sickness absence. Trials 2016;17:396 https://doi.org/10.1186/s13063-016-1497-8 

Madurasinghe VW. Guidelines for reporting embedded recruitment trials. Trials 2016;17:27 https://doi.org/10.1186/s13063-015-1126-y 

Lau R, Stevenson F, Ong BN, Dziedzic K, Treweek S, Eldridge S, Everitt H, Kennedy A, Qureshi N, Rogers A, Peacock R, Murray E. Achieving change in primary care--causes of the evidence to practice gap: systematic reviews of reviews. Implement Sci 2016;11:40 https://doi.org/10.1186/s13012-016-0396-4 

Kahan BC, Rushton H, Morris TP, Daniel RM. A comparison of methods to adjust for continuous covariates in the analysis of randomised trials. BMC Med Res Methodol 2016;16:42 https://doi.org/10.1186/s12874-016-0141-3 

Kahan BC, Forbes G, Ali Y, Jairath V, Bremner S, Harhay MO, Hooper R, Wright N, Eldridge SM, Leyrat C. Increased risk of type I errors in cluster randomised trials with small or medium numbers of clusters: a review, reanalysis, and simulation study. Trials 2016;17:438 https://doi.org/10.1186/s13063-016-1571-2 

Kahan BC, Dore CJ, Murphy MF, Jairath V. Bias was reduced in an open-label trial through the removal of subjective elements from the outcome definition. J Clin Epidemiol 2016;77:38-43 https://doi.org/10.1016/j.jclinepi.2016.05.008 

Kahan BC. Using re-randomization to increase the recruitment rate in clinical trials - an assessment of three clinical areas. Trials 2016;17:595 https://doi.org/10.1186/s13063-016-1736-z 

Hooper R, Teerenstra S, de Hoop E, Eldridge S. Sample size calculation for stepped wedge and other longitudinal cluster randomised trials. Stat Med 2016;35:4718-4728 https://doi.org/10.1002/sim.7028 

Froud R, Patel S, Rajendran D, Bright P, Bjorkli T, Buchbinder R, Eldridge S, Underwood M. A Systematic Review of Outcome Measures Use, Analytical Approaches, Reporting Methods, and Publication Volume by Year in Low Back Pain Trials Published between 1980 and 2012: Respice, adspice, et prospice. PLoS One 2016;11:e0164573 https://doi.org/10.1371/journal.pone.0164573 

Eldridge SM, Lancaster GA, Campbell MJ, Thabane L, Hopewell S, Coleman CL, Bond CM. Defining Feasibility and Pilot Studies in Preparation for Randomised Controlled Trials: Development of a Conceptual Framework. PLoS One 2016;11:e0150205 https://doi.org/10.1371/journal.pone.0150205 

Eldridge SM, Costelloe CE, Kahan BC, Lancaster GA, Kerry SM. How big should the pilot study for my cluster randomised trial be? Statistical Methods in Medical Research 2016;25:1039-1056 https://doi.org/10.1177/0962280215588242 

Eldridge SM, Chan CL, Campbell MJ, Bond CM, Hopewell S, Thabane L, Lancaster GA. CONSORT 2010 statement: extension to randomised pilot and feasibility trials. BMJ 2016;355: https://doi.org/10.1136/bmj.i5239 

Eldridge SM, Chan CL, Campbell MJ, Bond CM, Hopewell S, Thabane L, Lancaster GA. CONSORT 2010 statement: extension to randomised pilot and feasibility trials. Pilot Feasibility Stud 2016;2:64 https://doi.org/10.1186/s40814-016-0105-8 

Cheong-See F, Allotey J, Marlin N, Mol BW, Schuit E, ter Riet G, Riley RD, Moons KGM, Khan KS, Thangaratinam S. Prediction models in obstetrics: understanding the treatment paradox and potential solutions to the threat it poses. BJOG 2016;123:1060-1064 https://doi.org/10.1111/1471-0528.13859 

Caille A, Kerry S, Tavernier E, Leyrat C, Eldridge S, Giraudeau B. Timeline cluster: a graphical tool to identify risk of bias in cluster randomised trials. BMJ 2016;354:i4291 https://doi.org/10.1136/bmj.i4291 

Arnup SJ, Forbes AB, Kahan BC, Morgan KE, McKenzie JE. Appropriate statistical methods were infrequently used in cluster-randomized crossover trials. J Clin Epidemiol 2016;74:40-50 https://doi.org/10.1016/j.jclinepi.2015.11.013 

Arnup SJ, Forbes AB, Kahan BC, Morgan KE, McKenzie JE. The quality of reporting in cluster randomised crossover trials: proposal for reporting items and an assessment of reporting quality. Trials 2016;17:575 https://doi.org/10.1186/s13063-016-1685-6 

Wright N, Ivers N, Eldridge S, Taljaard M, Bremner S. A review of the use of covariates in cluster randomized trials uncovers marked discrepancies between guidance and practice. J Clin Epidemiol 2015;68:603-9 https://doi.org/10.1016/j.jclinepi.2014.12.006 

Rutterford C, Taljaard M, Dixon S, Copas A, Eldridge S. Reporting and methodological quality of sample size calculations in cluster randomized trials could be improved: a review. J Clin Epidemiol 2015;68:716-23 https://doi.org/10.1016/j.jclinepi.2014.10.006 

Rutterford C, Copas A, Eldridge S. Methods for sample size determination in cluster randomized trials. Int J Epidemiol 2015;44:1051-67 https://doi.org/10.1093/ije/dyv113 

Pinnock H, Epiphaniou E, Sheikh A, Griffiths C, Eldridge S, Craig P, Taylor SJ. Developing standards for reporting implementation studies of complex interventions (StaRI): a systematic review and e-Delphi. Implement Sci 2015;10:42 https://doi.org/10.1186/s13012-015-0235-z 

Lau R, Stevenson F, Ong BN, Dziedzic K, Treweek S, Eldridge S, Everitt H, Kennedy A, Qureshi N, Rogers A, Peacock R, Murray E. Achieving change in primary care--effectiveness of strategies for improving implementation of complex interventions: systematic review of reviews. BMJ Open 2015;5:e009993 https://doi.org/10.1136/bmjopen-2015-009993 

Kahan BC, Rehal S, Cro S. Blinded Outcome Assessment Was Infrequently Used and Poorly Reported in Open Trials. PLoS One 2015;10:e0131926 https://doi.org/10.1371/journal.pone.0131926 

Kahan BC, Rehal S, Cro S. Risk of selection bias in randomised trials. Trials 2015;16:405 https://doi.org/10.1186/s13063-015-0920-x 

Kahan BC, Harhay MO. Many multicenter trials had few events per center, requiring analysis via random-effects models or GEEs. J Clin Epidemiol 2015;68:1504-11 https://doi.org/10.1016/j.jclinepi.2015.03.016 

Kahan BC, Forbes AB, Dore CJ, Morris TP. A re-randomisation design for clinical trials. BMC Med Res Methodol 2015;15:96 https://doi.org/10.1186/s12874-015-0082-2 

Hooper R, Bourke L. Cluster randomised trials with repeated cross sections: alternatives to parallel group designs. Bmj 2015;350:h2925 https://doi.org/10.1136/bmj.h2925 

Froud R, Ellard D, Patel S, Eldridge S, Underwood M. Primary outcome measure use in back pain trials may need radical reassessment. BMC Musculoskelet Disord 2015;16:88 https://doi.org/10.1186/s12891-015-0534-1 

Froud R, Bjorkli T, Bright P, Rajendran D, Buchbinder R, Underwood M, Evans D, Eldridge S. The effect of journal impact factor, reporting conflicts, and reporting funding sources, on standardized effect sizes in back pain trials: a systematic review and meta-regression. BMC Musculoskelet Disord 2015;16:370 https://doi.org/10.1186/s12891-015-0825-6 

Weijer C, Taljaard M, Grimshaw JM, Edwards SJL, Eccles MP, Althabe F, Binik A, Brown JB, Boruch R, Brehaut JC, Chaudhry S, Donner A, Dubois-Flynn G, Eccles MP, Edwards S, Elbourne D, Eldridge S, Forster D, Gallo A, Kiefe C, Kimmelman J, Lin M, Loder E, Lohr L, McRae AD, Naughton ES, Polson RJ, Saginur R, Saxena A, Spence J, Taljaard M, White A, White G, Zwarenstein M. The Ottawa statement on the ethical design and conduct of cluster randomized trials: A short report. Research Ethics 2014;10:77-85 https://doi.org/10.1177/1747016113510668 

Rogers A, Harris T, Victor C, Woodcock A, Limb E, Kerry S, Iliffe S, Whincup P, Ekelund U, Beighton C, Ussher M, Adams F, Cook DG. Which older people decline participation in a primary care trial of physical activity and why: insights from a mixed methods approach. BMC Geriatr 2014;14:46 https://doi.org/10.1186/1471-2318-14-46 

Rick J, Graffy J, Knapp P, Small N, Collier DJ, Eldridge S, Kennedy A, Salisbury C, Treweek S, Torgerson D, Wallace P, Madurasinghe V, Hughes-Morley A, Bower P. Systematic techniques for assisting recruitment to trials (START): study protocol for embedded, randomized controlled trials. Trials 2014;15:407 https://doi.org/10.1186/1745-6215-15-407 

Lau R, Stevenson F, Ong BN, Dziedzic K, Eldridge S, Everitt H, Kennedy A, Kontopantelis E, Little P, Qureshi N, Rogers A, Treweek S, Peacock R, Murray E. Addressing the evidence to practice gap for complex interventions in primary care: a systematic review of reviews protocol. BMJ Open 2014;4:e005548 https://doi.org/10.1136/bmjopen-2014-005548 

Hooper R, Bourke L. The dog-leg: an alternative to a cross-over design for pragmatic clinical trials in relatively stable populations. Int J Epidemiol 2014;43:930-6 https://doi.org/10.1093/ije/dyt281 

Diaz-Ordaz K, Kenward MG, Cohen A, Coleman CL, Eldridge S. Are missing data adequately handled in cluster randomised trials? A systematic review and guidelines. Clin Trials 2014;11:590-600 https://doi.org/10.1177/1740774514537136 

Devine A, Taylor SJ, Spencer A, Diaz-Ordaz K, Eldridge S, Underwood M. The agreement between proxy and self-completed EQ-5D for care home residents was better for index scores than individual domains. J Clin Epidemiol 2014;67:1035-43 https://doi.org/10.1016/j.jclinepi.2014.04.005 

Taljaard M, Weijer C, Grimshaw JM, Eccles MP. The Ottawa Statement on the ethical design and conduct of cluster randomised trials: precis for researchers and research ethics committees. BMJ 2013;346:f2838 https://doi.org/10.1136/bmj.f2838 

Hooper R, Froud RJ, Bremner SA, Perera R, Eldridge S. Cascade diagrams for depicting complex interventions in randomised trials. BMJ 2013;347:f6681 https://doi.org/10.1136/bmj.f6681 

Hooper R, Diaz-Ordaz K, Takeda A, Khan K. Comparing diagnostic tests: trials in people with discordant test results. Stat Med 2013;32:2443-56 https://doi.org/10.1002/sim.5676 

Hooper R. Versatile sample-size calculation using simulation. Stata Journal 2013;13:21-38 https://www.stata-journal.com/article.html?article=st0282 

Diaz-Ordaz K, Slowther AM, Potter R, Eldridge S. Consent processes in cluster-randomised trials in residential facilities for older adults: a systematic review of reporting practices and proposed guidelines. BMJ Open 2013;3: https://doi.org/10.1136/bmjopen-2013-003057 

Diaz-Ordaz K, Froud R, Sheehan B, Eldridge S. A systematic review of cluster randomised trials in residential facilities for older people suggests how to improve quality. BMC Med Res Methodol 2013;13:127 https://doi.org/10.1186/1471-2288-13-127 

Weijer C, Grimshaw JM, Eccles MP, McRae AD, White A, Brehaut JC, Taljaard M. The Ottawa Statement on the Ethical Design and Conduct of Cluster Randomized Trials. PLoS Med 2012;9:e1001346 https://doi.org/10.1371/journal.pmed.1001346 

Teerenstra S, Eldridge S, Graff M, de Hoop E, Borm GF. A simple sample size formula for analysis of covariance in cluster randomized trials. Stat Med 2012;31:2169-78 https://doi.org/10.1002/sim.5352 

Reininghaus U, Priebe S. Measuring patient-reported outcomes in psychosis: conceptual and methodological review. British Journal of Psychiatry 2012;201:262-267 https://doi.org/10.1192/bjp.bp.111.107615 

Peacock JL, Sauzet O, Ewings SM, Kerry SM. Dichotomising continuous data while retaining statistical power using a distributional approach. Statistics in Medicine 2012;31:3089-3103 https://doi.org/10.1002/sim.5354 

Froud R, Underwood M, Eldridge S. Improving the reporting and interpretation of clinical trial outcomes. Br J Gen Pract 2012;62:e729-31 https://doi.org/10.3399/bjgp12X657008 

Froud R, Underwood M, Carnes D, Eldridge S. Clinicians' perceptions of reporting methods for back pain trials: a qualitative study. Br J Gen Pract 2012;62:e151-9 https://doi.org/10.3399/bjgp12X630034 

Froud R, Eldridge S, Diaz Ordaz K, Marinho VC, Donner A. Quality of cluster randomized controlled trials in oral health: a systematic review of reports published between 2005 and 2009. Community Dent Oral Epidemiol 2012;40 Suppl 1:3-14 https://doi.org/10.1111/j.1600-0528.2011.00660.x 

Eldridge S, Kerry S. A practical guide to cluster randomised trials in health services research. 2012 Wiley(Chichester)

Choudhury Y, Hussain I, Parsons S, Rahman A, Eldridge S, Underwood M. Methodological challenges and approaches to improving response rates in population surveys in areas of extreme deprivation. Prim Health Care Res Dev 2012;13:211-8 https://doi.org/10.1017/s1463423611000466 

Nadeem NJ, Taylor SJ, Eldridge SM. Withdrawal of inhaled corticosteroids in individuals with COPD--a systematic review and comment on trial methodology. Respir Res 2011;12:107 https://doi.org/10.1186/1465-9921-12-107 

Froud R, Eldridge S, Kovacs F, Breen A, Bolton J, Dunn K, Fritz J, Keller A, Kent P, Lauridsen HH, Ostelo R, Pincus T, van Tulder M, Vogel S, Underwood M. Reporting outcomes of back pain trials: a modified Delphi study. Eur J Pain 2011;15:1068-74 https://doi.org/10.1016/j.ejpain.2011.04.015 

Lancaster GA, Campbell MJ, Eldridge S, Farrin A, Marchant M, Muller S, Perera R, Peters TJ, Prevost AT, Rait G. Trials in primary care: statistical issues in the design, conduct and evaluation of complex interventions. Stat Methods Med Res 2010;19:349-77 https://doi.org/10.1177/0962280209359883 

Eldridge S. Pragmatic trials in primary health care: what, when and how? Fam Pract 2010;27:591-2 https://doi.org/10.1093/fampra/cmq099 

Froud R, Eldridge S, Lall R, Underwood M. Estimating the number needed to treat from continuous outcomes in randomised controlled trials: methodological challenges and worked example using data from the UK Back Pain Exercise and Manipulation (BEAM) trial. BMC Med Res Methodol 2009;9:35 https://doi.org/10.1186/1471-2288-9-35 

Eldridge SM, Ukoumunne OC, Carlin JB. The Intra-Cluster Correlation Coefficient in Cluster Randomized Trials: A Review of Definitions. International Statistical Review 2009;77:378-394 https://doi.org/10.1111/j.1751-5823.2009.00092.x 

Eldridge S, Kerry S, Torgerson DJ. Bias in identifying and recruiting participants in cluster randomised trials: what can be done? BMJ 2009;339: https://doi.org/10.1136/bmj.b4006 

Eldridge S, Ashby D, Bennett C, Wakelin M, Feder G. Internal and external validity of cluster randomised trials: systematic review of recent trials. BMJ 2008;336:876-80 https://doi.org/10.1136/bmj.39517.495764.25 

Eldridge SM, Ashby D, Kerry S. Sample size for cluster randomized trials: effect of coefficient of variation of cluster size and analysis method. Int J Epidemiol 2006;35:1292-300 https://doi.org/10.1093/ije/dyl129 

Eldridge SM, Ashby D, Feder GS. Informed patient consent to participation in cluster randomized trials: an empirical exploration of trials in primary care. Clin Trials 2005;2:91-8 https://doi.org/10.1191/1740774505cn070oa 

Eldridge S, Spencer A, Cryer C, Parsons S, Underwood M, Feder G. Why modelling a complex intervention is an important precursor to trial design: lessons from studying an intervention to reduce falls-related injuries in older people. J Health Serv Res Policy 2005;10:133-42 https://doi.org/10.1258/1355819054338942 

Eldridge SM, Ashby D, Feder GS, Rudnicka AR, Ukoumunne OC. Lessons for cluster randomized trials in the twenty-first century: a systematic review of trials in primary care. Clin Trials 2004;1:80-90 https://doi.org/10.1191/1740774504cn006rr 

Adams G, Gulliford MC, Ukoumunne OC, Eldridge S, Chinn S, Campbell MJ. Patterns of intra-cluster correlation from primary care research to inform study design and analysis. J Clin Epidemiol 2004;57:785-94 https://doi.org/10.1016/j.jclinepi.2003.12.013

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