Strategies to minimise and monitor biases and imbalances by arm in surgical cluster randomised trials: evidence from ChEETAh, a trial in seven low- and middle-income countries
Authors:   NIHR Global Research Health Unit on Global Surgery,   The Hospital Principle Investigator, Ahogni Didier , Ahounou Aristide , Boukari K. Alassan , Gbehade Oswald , Hessou Thierry K. , Nindopa Sinama , Nontonwanou M. J. Bienvenue , Guessou Nafissatou Orou , Sambo Arouna , Tchati Sorekou Victoire , Tchogo Affisatou , Tobome Semevo Romaric , Yanto Parfait , Gandaho Isidore , Hadonou Armel , Hinvo Simplice , Hodonou Montcho Adrien , Tamou Sambo Bio , Lawani Souliath , Kandokponou Covalic Melic Bokossa , Dossou Francis Moise , Gaou Antoine , Goudou Roland , Kouroumta Marie-Claire , Lawani Ismail , Malade Enrif , Dikao Anne Stredy Mkoh , Nsilu Joel Nzuwa , Ogouyemi Pencome , Akpla Marcelin , Mitima Nathan Bisimwa , Kovohouande Blaise , Kpangon Cyrille , Loupeda Stephane Laurent , Agbangla Mamonde Victorin , Hedefoun Sena Emmanuel , Mavoha Thierry , Ngaguene Juvenal , Rugendabanga Janvier , Soton Rish Romaric , Totin Martin , Agbadebo Mouhamed , Akpo Irene , Dewamon Hubert , Djeto Martin , Hada Aissatou , Hollo Monsede , Houndji Albert , Houndote Anasthasie , Hounsa Sylvestre , Kpatchassou Expedit , Yome Hugues , Alidou Mohamed Moussa , Bara Eric Jerry , Yovo B. T. Bonheur Dossou , Guinnou Robert , Hamadou Souleymane , Kola H. Pauline , Moussa Nabil , Cakpo Boniface , Etchisse Lolyta , Hatangimana Emery , Muhindo Moise , Sanni Katia , Yevide Agossou Barthelemy , Agossou Hermann , Musengo Fiston Basirwa , Behanzin Hulrich , Seto Djifid Morel , Alia Bill Armstrong , Alitonou Arnaud , Mehounou Y. Edith , Agbanda Lucien , Attinon Julien , Gbassi Marcel , Hounsou Nounagnon Rene , Acquah Regina , Banka Charles , Esssien Derick , Hussey Romeo , Mustapha Yakubu , Nunoo-Ghartey Kojo , Yeboah Grace , Aniakwo Luke A. , Adjei Margarey N. M. , Adofo-Asamoah Yvonne , Agyapong Meshach M. , Agyen Thomas , Alhassan Baba A. B. , Amoako-Boateng Mabel P. , Appiah Anthony Baffour , Ashong Josephine , Awindaogo Joseph K. , Brimpong Benjamin B. , Dayie Makafui S. C. J. K. , Enti Donald , Ghansah Wendy W. , Gyamfi Jude E. , Koggoh Patience , Kpankpari Richard , Kudoh Vincent , Mensah Samuel , Mensah Philip , Morkor Opandoh Isabella N. , Morna Martin T. , Nortey Michael , Odame Emelia , Ofori Emmanuel O. , Quaicoo Sandra , Quartson Elizabert M. , Teye-Topey Cynthia , Yigah Makafui , Yussif Safia , Adjei-Acquah Esther , Agyekum-Gyimah Vera O. , Agyemang Eric , Akoto-Ampaw Arko , Amponsah-Manu Forster , Arkorful Temitope E. , Dokurugu Moses A. , Essel Nanabanyin , Ijeoma Aja , Obiri Emmanuel L. , Ofosu-Akromah Richard , Quarchey Karen N. D. , Adam-Zakariah Leslie , Andoh Aaron B. , Asabre Esther , Boateng Ruby A. , Koomson Barbara , Kusiwaa Atta , Naah Adeline , Oppon-Acquah Ato , Oppong Benjamin A. , Agbowada Emma A. , Akosua Ameley , Armah Ralph , Asare Christopher , Awere-Kyere Lawrence K. B. , Bruce-Adjei Amanda , Christian Nana Ama , Gakpetor Delali A. , Kennedy Korankye K. , Mends-Odro Jacqueline , Obbeng Ambe , Ofosuhene Doris , Osei-Poku Dorcas , Robertson Zelda , Acheampong Dorcas O. , Acquaye Jane , Appiah Juliana , Arthur Joshua , Boakye-Yiadom Jonathan , Agbeko Anita Eseenam , Gyamfi Frank E. , Nyadu Bertina B. , Abdulai Samira , Adu-Aryee Nii A. , Agboadoh Nelson , Akoto Erica , Amoako Joachim K. , Aperkor Nicholas T. , Asman Wilfred K. , Attepor Godsway S. , Bediako-Bowan Antoinette A. , Boakye-Yiadom Kwaku , Brown George D. , Dedey Florence , Etwire Victor K. , Fenu Benjamin S. , Kumassah Philemon K. , Larbi-Siaw Linda A. , Nsaful Josephine , Olatola David O. , Tsatsu Sandra E. , Wordui Theodore , Abdul-Aziz Iddrisu I. A. , Abubakari Fatao , Akunyam Johnson , Anasara Gilbert A. G. , Ballu Cletus , Barimah Charles G. , Boateng Guy C. , Kwabena Ponala W. , Kwarteng Seidu M. , Luri Prosper T. , Ngaaso Kennedy , Ogudi David K. D. , Adobea Vivian , Bennin Amos , Doe Stanley , Kantanka Ruth Sarfo , Kobby Ephraim , Kyeremeh Collins , Osei Edwin , Owusu Prince Yeboah , Owusu Frank , Sie-Broni Clement , Zume Marshall , Abdul-Hafiz Saba , Acquah Daniel K. , Adams Shamsudeen M. , Alhassan Mohammed S. , Amadu Munira , Asirifi Samuel A. , Awe Martin , Azanlerigu Millicent , Dery Mathias K. , Edwin Yenli , Francis Abantanga Atindaana , Limann Gbana , Maalekuu Aloysius , Malechi Hawa , Mohammed Sheriff , Mohammed Ibrahim , Mumuni Kareem , Ofori Bernard A. , Quansah Jonathan I. K. , Seidu Anwar S. , Tabiri Stephen , Yahaya Shekira , Acquah Emmanuel Kojo , Alhassan Jaabir , Boakye Percy , Coompson Christian L. , Gyambibi Addo K. , Jeffery-Felix Ametepe , Kontor Bismark E. , Manu Ruth , Mensah Elijah , Naah Gifty , Noufuentes Carmen , Sakyi Abraham , Chaudhary Ramkaran , Misra Sanjeev , Pareek Puneet , Pathak Manish , Poonia Dharma R. , Rathod Kirti K. , Rodha Mahaveer S. , Sharma Naveen , Sharma Nivedita , Soni Subhash C. , Varsheney Vaibhav K. , Vishnoi Jeevan R. , Garnaik Deepak K. , Huda Farhanul , Lokavarapu Manoj J. , Mishra Neha , Ranjan Rohit , Seenivasagam Rajkumar K. , Singh Shanky , Solanki Pratik , Verma Raunak , Yhoshu Enono , John Suzan , Kalyanapu Jeffery A. , Kutma Ananta , Philips Sanish , Gautham Arun K. , Hepzibah Alice , Mary Grace , Singh Deepak S. , Abraham Eunice S. , Chetana Chetana , Dasari Amos , Dummala Prashant , Gold Chinta S. , Jacob Jurgen , Joseph Jeremiah N. , Kurien Elizabeth N. , Mary Priya , Mathew Arpit J. , Mathew Amy E. , Prakash Danita D. , Samuel Oliver , Sukumar Ashwin , Syam Niyah , Varghese Rose , Bhatt Alisha , Bhatti William , Dhar Tapasya , Ghosh Dhruva N. , Goyal Ankush , Goyal Sunita , Hans Monika A. , Haque Parvez D. , Jain Deepak , Jain Rita , Jyoti Jyoti , Kaur Savleen , Kumar Karan , Luther Anil , Mahajan Amit , Mandrelle Kavita , Michael Vishal , Mukherjee Partho , Rajappa Reuben , Sam Vivin Daniel , Singh Prashant , Suroy Atul , Thind Ravinder Singh , Veetil Sreejith K. , Williams Rahul , Sreekar D. , Daniel Esther R. , Jacob Smitha E. , Jesudason Mark R. , Kumari Pushplatha , Mittal Rohin , Prasad Soosan , Samuel Vasanth Mark , Shankar Bharat , Sharma Srujan , Sivakumar Moonish V. , Surendran Suraj , Thomas Anita , Trinity Paul , Kanchodu Sudheer , Leshiini K. , Saluja Sundeep S. , Attri Ashok K. , Bansal Ishan , Gupta Sanjay , Gureh Monika , Kapoor Simran , Aggarwal Manisha , Kanna Vinoth , Kaur Harmanjot , Kumar Ashwani , Singh Simrandeep , Singh Gurtaj , John Viju , Adnan Mohammed , Agrawal Nivesh , Kumar Uttkarsh , Kumar Pardeep , Abhishek S. , Sehrawat Vikram , Singla Deepak , Thami Gaurav , Kumar Vijay , Mathew Stanley , Pai Murlidhar V. , Prabhu P. S. , Sundeep P. T. , Akhtar Naseem , Chaturvedi Arun , Gupta Sameer , Kumar Vijay , Prakash Puneet , Rajan Shiv , Singh Mohit , Tripathi Abhilasha , Alexander Philip V. , Thomas Josy , Zechariah Pradeep , Ismavel Vijay A. , Kichu Moloti , Solomi Carolin V. , Alpheus Rahul A. , Choudhrie Ashish Victor , Gunny Rashmi Jacob , Joseph Susan , Malik Muneer A. , Peters Nitin J. , Pundir Neha , Samujh Ram , Ahmed Hafsa I. , Aziz Gowhar , Chowdri Nisar A. , Dar Rayees A. , Kour Robindera , Mantoo Imtiyaz , Mehraj Asif , Parray Fazl Q. , Saqib Najmus , Shah Zamir A. , Wani Rauf A. , Raul Subrat , Rautela Komal , Sharma Rajeev , Singh Nishu , Vakil Rakesh , Chowdhury Priyanka , Chowdhury Sona , Mathai Sonia , Nayak Pragyanmai , Roy Bipradas , Alvarez Villaseñor Andrea S. , Ascencio Díaz Kriscia V. , Avalos Herrera Victor J. , Barbosa Camacho Francisco J. , Hernández Aldo Bernal , Ahumada Elyoenai Bonilla , Brancaccio Pérez Irma V. , Calderón Llamas Miguel A. , Cardiel Guadalupe Castillo , Cervantes Cardona Guillermo A. , Guevara Gabino Cervantes , Perez Enrique Cervantes , Chávez Maria , Chejfec Ciociano Jonathan M. , Cifuentes Andrade Luis R. , Cortés Flores Ana O. , Cortes Torres Edgar J. , Cueto Valadez Tania A. , Cueto Valadez Andrea E. , Martinez Esteban Cueva , Barradas Paulina Domínguez , Estrada Isaac Esparza , Becerril Paola Flores , Flores Cardoza Jose A. , Orozco Clotilde Fuentes , García González Luis A. , Reyna Benjamín García , Sánchez Eduardo Gómez , González Bojorquez Jaime L. , Espinoza Eduardo González , Ojeda Alejandro González , González Ponce Fanny Y. , Guerrero Ramírez Cristhian S. , Guzmán Barba José A. , Guzmán Ramírez Bertha G. , Guzmán Ruvalcaba Mario J. , Hérnandez Alva Daniel A. , Ibarra Camargo Silvia A. , Ibarrola Peña Juan C. , Torres Martin Islas , Tornero Jorge Jiménez , Lara Pérez Zayra M. , País Roberto Mares , Mellado Tellez Mel P. , Miranda Ackerman Roberto C. , Santana Damián Mora , Villela Gilberto Morgan , Hinojosa Rodrigo Nájar , Escobar Cesar Nuño , Rodríguez Itzel Ochoa , Flores Oscar Olvera , Barreiro Angelica Ortega , Rubio Jacqueline Osuna , Pacheco Vallejo Luis R. , Pérez Bocanegra Víctor H. , Pérez Navarro Jose V. , Plascencia Posada Francisco J. , Quirarte Hernández María A. , Ramirez Gonzalez Luis R. , Reyes Elizalde Emilio A. , Romo Ascencio Evelia V. , Bravo Cornelio Ruelas , Ruiz Velasco Carlos B. , Sánchez Martínez José A. , Villaseñor Guillermo Sanchez , Sandoval Pulido José I. , Serrano García Alejandro G. , Suárez Carreón Luis O. , Tijerina Ávila Juan J. , Vega Gastelum Jesus O. , Vicencio Ramirez Melissa L. , Zarate Casas Maria F. , Zuloaga Fernández del Valle Carlos J. , Mata Jesus Antonion Aguilar , Vanegas Miguel Antonio Calderon , Arias Rocio Guadalupe Cano , Tinajero Carlos Colunga , Samano Fernanda Diaz , Zepeda Fernando Duque , Barajas Brenda Vanessa Enriquez , Banuelos Gerardo Gallardo , Calvillo Marijose De Cristo Gonzalez , Ortiz Francisco Ibanez , Ramirez Maryzela Lazo , Arroyo Gerardo Lopez , Angeles Laura Olivia Montano , Morales Iriarte David Giovanny I. , Lomeli Angelo Fernando Mortola , Navarro Jose Esteban Orozco , Perez Jaime Orozco , Ramirez Damaris Orozco , Baolboa Laura Gabriela Pena , Lozano Jesus Pizarro , Reyes Guillermo Yanowsky , Castillo Monica N. , Dominguez Ana Camille G. , Mellado Dorihela H. , Morales Jesus Flavio M. , del Carmen H Namur Luz , Pesquera Jose Alberto A. , Maldonado Laura Martinez Perez , De la Medina Antonio Ramos , Bozada-Gutierrez Katya , Casado-Zarate Ana Florencia , Delano-Alonso Roberto , Herrera-Esquivel Jose , Moreno-Portillo Mucio , Trejo-Avila Mario , Fonseca Roland Kevin Cethorth , Hernandez Edgard Efren Lozada , Quiros Bruno Crocco , Ramirez Jairo Arturo Rodriguez , Ambriz-González Gabriela , Becerra Moscoso Mitzi R. , Cabrera-Lozano Ishtar , Calderón-Alvarado Ana B. , León-Frutos Francisco J. , Villanueva-Martínez Erick E. , Abdullahi Aisha , Abubakar Maimuna , Aliyu Mohammed S. , Awaisu Mudi , Bakari Fadimatu , Balogun Abigail Olajumoke , Bashir Mohammed , Bello Ahmad , Daniyan Muhammad , Duromola Kehinde Michael , Gana Stephen G. , George Mukoro Duke , Gimba Justina , Gundu Isaac , Iji Lambert Onahi , Jimoh Aminat O. , Koledade Afolabi K. , Lawal Ahmad T. , Lawal Bilkisu  K , Mustapha Aisha , Nwabuoku Stanley Emeka , Ogunsua Oluseyi O. , Okafor Ifeanyi Fidelis , Okorie Ethos Ike , Oyelowo Nasir , Saidu Ibrahim A. , Sholadoye Tunde T. , Sufyan Ibrahim , Tolani Musliu Adetola , Tukur Aliyu Muhammad , Umar Ahmad Shehu , Umar Aminatu M. , Umaru-Sule Hajara , Usman Mohammed , Yahya Anisah , Yakubu Alfa , Yusuf Salisu Abeku , Abdulkarim Abdulhafiz A. , Abdullahi Lawal Barau , Abdullahi Muzzammil , Ado Khadija A. , Aliyu Nura U. , Anyanwu Lofty-John Chukwuemeka , Daneji Sulaiman M. , Magashi Mahmoud Kawu , Mohammad Mohammad A. , Muhammad Abubakar Bala , Muhammad Saminu S. , Muideen Bello Abodunde , Nwachukwu Calistus U. , Sallau Suleiman B. , Sheshe Abdulrahman A. , Soladoye Abdulmajeed , Takai Idris Usman , Umar Garzali I. , Yahaya Abubakar , Abdulrasheed Lubabatu , Adze Joel A. , Airede Lydia R. , Aminu Bashiru , Bature Stephen B. , Bello-Tukur Firdaws , Chinyio Damai , Duniya Sharon A. N. , Galadima Moses C. , Hamza Babatunde K. , Joshua Samaila , Kache Stephen A. , Kagomi Williams Y. , Kene Ifeanyi A. , Lawal Jamila , Makama Jerry G. , Mohammed Caleb , Mohammed-Durosinlorun Amina A. , Nuwam Deborah , Sale Danjuma , Sani Abdulrasheed , Tabara Salome , Taingson Mathew C. , Usam Emmanuel , Yakubu Josiah , Adegoke Folasade , Ige Oluwasuyi , Odunafolabi Tunde A. , Okereke Chukwuma E. , Oladele Oluwafemi O. , Olaleye Oluwaseun H. , Olubayo Oyetunde O. , Abiola Olukayode P. , Abiyere Henry O. , Adebara Idowu O. , Adeleye Gbadebo T. C. , Adeniyi Adebayo A. , Adewara Olumide E. , Adeyemo Olabisi T. , Adeyeye Ademola A. , Ariyibi Abimbola L. , Awoyinka Babatunde S. , Ayankunle Olumide M. , Babalola Olakunle F. , Bakare Adewumi , Bakare Tajudeen I. B. , Banjo Oluseyi O. , Egharevba Peter A. , Fatudimu Oluwafemi S. , Obateru John A. , Odesanya Oluremi J. , Ojo Owolabi D. , Okunlola Abiodun I. , Okunlola Cecilia K. , Olajide Adewale T. , Orewole Tesleem O. , Salawu Adedayo I. , Abdulsalam Moruf A. , Adelaja Aderinsola T. , Ajai Olalekan T. , Akande Olukemi , Anyanwu Noble , Atobatele Kazeem M. , Bakare Oludayo Oluwaseyi , Eke Grace , Faboya Omolara M. , Imam Zainab O. , Nwaenyi Francisca C. , Ogunyemi Ayokunle A. , Oludara Mobolaji A. , Omisanjo Olufunmilade A. , Onyeka Chinonso U. , Oshodi Olabode A. , Oshodi Yusuf A. , Oyewole Yemisi , Salami Omotade S. , Williams Omolara M. , Abunimye Esther , Ademuyiwa Adesoji O. , Adeoluwa Adebunmi , Adesiyakan Adedotun , Adeyeye Victoria Ibukunoluwa , Agbulu Moses Vincent , Akinajo Opeyemi Rebecca , Akinboyewa David O. , Alakaloko Felix M. , Alasi Iyabo O. , Amao Michael , Ashley-Osuzoka Christiana , Atoyebi Oluwole A. , Balogun Olanrewaju S. , Bode Christopher O. , Busari Maryam Oluwatobi , Duru Nnamdi Jonathan , Edet Glory Bassey , Elebute Olumide A. , Ezenwankwo Francis Chinonso , Fatuga Adedeji L. , Gbenga-Oke Christianah , Ihediwa George C. , Inyang Emmanuel Sylvester , Jimoh Adesola I. , Kuku Jubril Oladayo , Ladipo-Ajayi Oluwaseun A. , Lawal Abdulrazzaq O. , Makanjuola Ayomide , Makwe Christian Chigoze , Mgbemena Chinelo Victoria , Nwokocha Samuel U. , Ogunjimi Moses Adebisi , Ohazurike Ephraim Okwudiri , Ojewola Rufus W. , Badedale Moyosoluwa Eunice , Okeke Chike J. , Okunowo Adeyemi A. , Oladimeji Abraham T. , Olajide Thomas O. , Olanrewaju Olabisi , Olayioye Olawunmi , Oluseye Oluwaseun O. , Olutola Stephen , Onyekachi Kenneth , Orowale Adeola Ayoola , Osariemen Emili , Osinowo Adedapo Olumide , Osunwusi Benedetto , Owie Emmanuel , Oyegbola Christianah Bidemi , Seyi-Olajide Justina O. , Soibi-Harry Adaiah P. , Timo Manuella Talla , Ugwu Aloy Okechukwu , Williams Emmanuel Ojo , Duruewuru Innocent O. , Egwuonwu Ochonma A. , Ekwunife Okechukwu Hyginus , Emeka James J. , Modekwe Victor Ifeanyichukwu , Nwosu Chimdiebele Daisy , Obiechina Sylvester O. , Obiesie Ahuizechukwu E. , Okafor Celestine I. , Okonoboh Theophilus O. , Okoro Chukwuemeka , Okoye Odili A. , Onu Onyekachi A. , Onyejiaka Chukwudubem C. , Uche Chisom Faith , Ugboajah Joseph O. , Ugwu Jideofor Okechukwu , Ugwuanyi Kenneth , Ugwunne Chuka , Adeleke Akeem A. , Adepiti Akinfolarin C. , Aderounmu Adewale A. , Adesunkanmi Abdulhafiz O. , Adisa Adewale O. , Ajekwu Samuel C. , Ajenifuja Olusegun K. , Alatise Olusegun I. , Badmus Tajudeen A. , Mohammed Tajudeen O. , Olasehinde Olalekan , Salako Abdulkadir A. , Sowande Oludayo A. , Talabi Ademola O. , Wuraola Funmilola O. , Adegoke Paul Aderemi , Akinloye Abidemi , Akinniyi Ayodeji , Ejimogu Joseph , Eseile Ideyonbe Samuel , Ogundoyin Olakayode Olaolu , Okedare Amos , Olulana Dare Isaac , Omotola Omolara , Sanwo Francis , Adumah Collins C. , Ajagbe Adewale O. , Akintunde Olugbenga P. , Asafa Opeyemi Q. , Awodele Kehinde , Eziyi Amogu K. , Fasanu Adeniyi O. , Ojewuyi Olufemi O. , Ojewuyi Abiodun R. , Oyedele Abisola E. , Taiwo Oluwaseun A. , Abdullahi Habiba I. , Adewole Nathaniel D. , Agida Teddy E. , Ailunia Eunice E. , Aisuodionoe-Shadrach Oseremen , Akaba Godwin O. , Alfred Janet , Atim Terkaa , Bawa Kehinde G. , Chinda John Y. , Daluk Esther B. , Eniola Sefiu B. , Ezenwa Augusta O. , Garba Stephen E. , Mbajiekwe Ndubuisi , Mshelbwala Philip M. , Ndukwe Ngozi O. , Ogolekwu Idoko P. , Ohemu Alexander A. , Olori Samson , Osagie Olabisi O. , Sani Samuel A. , Suleiman Salisu , Sunday Helen , Tabuanu Nancy O. , Umar Aminu M. , Agbonrofo Peter I. , Arekhandia Alexander I. , Edena Morrison E. , Eghonghon Raymond A. , Enaholo Joel E. , Ida Genesis , Ideh Stanley N. , Iribhogbe Oseihie I. , Irowa Omorodion O. , Isikhuemen Maradona E. , Odutola Oluwatomi R. , Okoduwa Kester O. , Omorogbe Scott O. , Oruade David , Osagie Osasumwen T. , Osemwegie Osarenkhoe , Abdus-Salam Rukiyat A. , Adebayo Sikiru Adekola , Ajagbe Oluwasanmi A. , Ajao Akinlabi E. , Ajibola Gboyega , Ayandipo Omobolaji O. , Egbuchulem Kelvin I. , Ekwuazi Hyginus O. , Elemile Peter , Fakoya Adegbolahan , Idowu Oluwasegun C. , Irabor David O. , Lawal Taiwo A. , Lawal Olatunji O. , Ogundoyin Olakayode O. , Ojediran Oluwabukade , Olagunju Naomi , Sanusi Akinsola T. , Takure Augustine O. , Abdur-Rahman Lukman Olajide , Adebisi Mary Oluwadamilola , Adeleke Nurudeen Abiola , Afolabi Rafiat Tinuola , Aremu Isiaka Ishola , Bello Jibril Oyekunle , Bello Robiat , Lawal Abdulwahab , Lawal Saheed Abolade , Ojajuni Adeolu , Oyewale Sabur , Raji Hadijat Olaide , Sayomi Olayinka , Shittu Asimiyu , Abhulimen Victor , Igwe Patrick O. , Iweha Ikechukwu Enyinnaya , John Raphael E. , Okoi Nnyonno , Okoro Philemon E. , Oriji Vaduneme Kingsley , Oweredaba Ibiene T. , Mizero Japhet , Mutimamwiza Immaculee , Nirere Francoise , Niyongombwa Irenee , Majyabere Jean Paul , Byaruhanga Anastase , Dukuzimana Rongin , Habiyakare Jean Aimable , Nabada Marie Gloriose , Uwizeye Marcel , Ruhosha Mathias , Igiraneza Joselyne , Ingabire Faustine , Karekezi Aloys , Masengesho Jean Pierre , Mpirimbanyi Christophe , Mukamazera Lydia , Mukangabo Clemence , Niyomuremyi Jean Paul , Ntwari Gabriel , Seneza Celestin , Umuhoza Divine , Habumuremyi Sosthene , Imanishimwe Alphonsine , Kanyarukiko Salathiel , Mukaneza Francine , Mukantibaziyaremye Deborah , Munyaneza Aphrodis , Ndegamiye Gibert , Nyirangeri Pierrine , Tubasiime Ronald , Uwimana Jean Claude , Dusabe Moses , Izabiriza Emelyne , Maniraguha Hope Lydia , Mpirimbanyi Christophe , Mutuyimana Josiane , Mwenedata Olivier , Rwagahirima Elisee , Zirikana Job , Sibomana Isaie , Rubanguka Desire , Umuhoza Josine , Uwayezu Roda , Uzikwambara Leoncie , Hirwa Aime Dieudonne , Kabanda Elysee , Mbonimpaye Salomee , Mukakomite Christine , Muroruhirwe Piolette , Butana Herbert , Dusabeyezu Moise , Mukasine Athanasie , Utumatwishima Jean N. , Batangana Mediatrice , Bucyibaruta Georges , Habumuremyi Sosthene , de Dieu Haragirimana Jean , Imanishimwe Alphonsine , Ingabire Allen J. C. , Mukanyange Violette , Munyaneza Emmanuel , Mutabazi Emmanuel , Mwungura Espoir , Ncogoza Isaie , Ntirenganya Faustin , Nyirahabimana Jeannette , Nyirasebura Dancilla , Urimubabo Christian Jean , Dusabimana Anaclet , Kanyesigye Sam , Munyaneza Robert , Shyirakera Jean Yves , Fourtounas Maria , Adams Mary Augusta , Ede Chikwendu Jeffrey , Hyman Gabriella , Mathe Mpho Nosipho , Moore Rachel , Nhlabathi Ncamsile Anthea , Nxumalo Hlengiwe Samkelisiwe , Sentholang Nnosa , Sethoana Mmule Evelyn , Wondoh Paul , Ally Zain , Domingo Aimee , Munda Philip , Nyatsambo Chido , Ojo Victor , Pswarayi Rudo 
Published: April 2023

Abstract
Background
Cluster randomised controlled trials (cRCT) present challenges regarding risks of bias and chance imbalances by arm. This paper reports strategies to minimise and monitor biases and imbalances in the ChEETAh cRCT.

Methods
ChEETAh was an international cRCT (hospitals as clusters) evaluating whether changing sterile gloves and instruments prior to abdominal wound closure reduces surgical site infection at 30 days postoperative. ChEETAh planned to recruit 12,800 consecutive patients from 64 hospitals in seven low-middle income countries. Eight strategies to minimise and monitor bias were pre-specified: (1) minimum of 4 hospitals per country; (2) pre-randomisation identification of units of exposure (operating theatres, lists, teams or sessions) within clusters; (3) minimisation of randomisation by country and hospital type; (4) site training delivered after randomisation; (5) dedicated ‘warm-up week’ to train teams; (6) trial specific sticker and patient register to monitor consecutive patient identification; (7) monitoring characteristics of patients and units of exposure; and (8) low-burden outcome-assessment.

Results
This analysis includes 10,686 patients from 70 clusters. The results aligned to the eight strategies were (1) 6 out of 7 countries included ≥ 4 hospitals; (2) 87.1% (61/70) of hospitals maintained their planned operating theatres (82% [27/33] and 92% [34/37] in the intervention and control arms); (3) minimisation maintained balance of key factors in both arms; (4) post-randomisation training was conducted for all hospitals; (5) the ‘warm-up week’ was conducted at all sites, and feedback used to refine processes; (6) the sticker and trial register were maintained, with an overall inclusion of 98.1% (10,686/10,894) of eligible patients; (7) monitoring allowed swift identification of problems in patient inclusion and key patient characteristics were reported: malignancy (20.3% intervention vs 12.6% control), midline incisions (68.4% vs 58.9%) and elective surgery (52.4% vs 42.6%); and (8) 0.4% (41/9187) of patients refused consent for outcome assessment.

Conclusion
cRCTs in surgery have several potential sources of bias that include varying units of exposure and the need for consecutive inclusion of all eligible patients across complex settings. We report a system that monitored and minimised the risks of bias and imbalances by arm, with important lessons for future cRCTs within hospitals.