Correction to: Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy
Authors: Griffiths Ewen A. , Hodson James , Vohra Ravi S. , Marriott Paul , Katbeh Tarek , Zino Samer , Nassar Ahmad H. M. ,   on behalf of the CholeS Study Group, West Midlands Research Collaborative, Vohra Ravinder S. , Kirkham Amanda J. , Pasquali Sandro , Marriott Paul , Johnstone Marianne , Spreadborough Philip , Alderson Derek , Griffiths Ewen A. , Fenwick Stephen , Elmasry Mohamed , Nunes Quentin M. , Kennedy David , Khan Raja Basit , Khan Muhammad A. S. , Magee Conor J. , Jones Steven M. , Mason Denise , Parappally Ciny P. , Mathur Pawan , Saunders Michael , Jamel Sara , Haque Samer Ul , Zafar Sara , Shiwani Muhammad Hanif , Samuel Nehemiah , Dar Farooq , Jackson Andrew , Lovett Bryony , Dindyal Shiva , Winter Hannah , Fletcher Ted , Rahman Saquib , Wheatley Kevin , Nieto Tom , Ayaani Soofiyah , Youssef Haney , Nijjar Rajwinder S. , Watkin Helen , Naumann David , Emesih Sophie , Sarmah Piyush B. , Lee Kathryn , Joji Nikita , Lambert Joel , Heath Jonathan , Teasdale Rebecca L. , Weerasinghe Chamindri , Needham Paul J. , Welbourn Hannah , Forster Luke , Finch David , Blazeby Jane M. , Robb William , McNair Angus G. K. , Hrycaiczuk Alex , Charalabopoulos Alexandros , Kadirkamanathan Sritharan , Tang Cheuk-Bong , Jayanthi Naga V. G. , Noor Nigel , Dobbins Brian , Cockbain Andrew J. , Nilsen-Nunn April , de Siqueira Jonathan , Pellen Mike , Cowley Jonathan B. , Ho Wei-Min , Miu Victor , White Timothy J. , Hodgkins Kathryn A. , Kinghorn Alison , Tutton Matthew G. , Al-Abed Yahya A. , Menzies Donald , Ahmad Anwar , Reed Joanna , Khan Shabuddin , Monk David , Vitone Louis J. , Murtaza Ghulam , Joel Abraham , Brennan Stephen , Shier David , Zhang Catherine , Yoganathan Thusidaran , Robinson Steven J. , McCallum Iain J. D. , Jones Michael J. , Elsayed Mohammed , Tuck Liz , Wayman John , Carney Kate , Aroori Somaiah , Hosie Kenneth B. , Kimble Adam , Bunting David M. , Hosie Kenneth B. , Fawole Adeshina S. , Basheer Mohammed , Dave Rajiv V. , Sarveswaran Janahan , Jones Elinor , Kendal Chris , Tilston Michael P. , Gough Martin , Wallace Tom , Singh Shailendra , Mockford Justine Downing Katherine A. , Issa Eyad , Shah Nayab , Chauhan Neal , Wilson Timothy R. , Forouzanfar Amir , Wild Jonathan R. L. , Nofal Emma , Bunnell Catherine , Madbak Khaliel , Rao Sudhindra T. V. , Devoto Laurence , Siddiqi Najaf , Khawaja Zechan , Hewes James C. , Gould Laura , Chambers Alice , Rodriguez Daniel Urriza , Sen Gourab , Robinson Stuart , Carney Kate , Bartlett Francis , Rae David M. , Stevenson Thomas E. J. , Sarvananthan Kas , Dwerryhouse Simon J. , Higgs Simon M. , Old Oliver J. , Hardy Thomas J. , Hornby Reena Shah Steve T. , Keogh Ken , Frank Lucinda , Al-Akash Musallam , Upchurch Emma A. , Frame Richard J. , Hughes Michael , Jelley Clare , Weaver Simon , Roy Sudipta , Sillo Toritseju O. , Galanopoulos Giorgios , Cuming Tamzin , Cunha Pedro , Tayeh Salim , Kaptanis Sarantos , Heshaishi Mohamed , Eisawi Abdalla , Abayomi Michael , Ngu Wee Sing , Fleming Katie , Bajwa Dalvir S. , Chitre Vivek , Aryal Kamal , Ferris Paul , Silva Michael , Mohamed Simon Lammy Sarah , Khawaja Amir , Hussain Adnan , Ghazanfar Mudassar A. , Bellini Maria Irene , Ebdewi Hamdi , Elshaer Mohamed , Gravante Gianpiero , Drake Benjamin , Ogedegbe Arikoge , Mukherjee Dipankar , Arhi Chanpreet , Iqbal Lola Giwa Nusrat , Watson Nicholas F. , Aggarwal Smeer Kumar , Orchard Philippa , Villatoro Eduardo , Willson Peter D. , Mok Kam Wa Jessica , Woodman Thomas , Deguara Jean , Garcea Giuseppe , Babu Benoy I. , Dennison A. R. , Malde Deep , Lloyd David , Satheesan Steve , Al-Taan Omer , Boddy Alexander , Slavin John P. , Jones Robert P. , Ballance Laura , Gerakopoulos Stratos , Jambulingam Periyathambi , Mansour Sami , Sakai Naomi , Acharya Vikas , Sadat Mohammed M. , Karim Lawen , Larkin David , Amin Khalid , Khan Amarah , Law Jennifer , Jamdar Saurabh , Smith Stella R. , Sampat Keerthika , O’shea Kathryn M. , Manu Mangta , Asprou Fotini M. , Malik Nabeela S. , Chang Jessica , Johnstone Marianne , Lewis Michael , Roberts Geoffrey P. , Karavadra Babu , Photi Evangelos , Hewes James , Gould Laura , Chambers Alice , Rodriguez Dan , O’Reilly Derek A. , Rate Anthony J. , Sekhar Hema , Henderson Lucy T. , Starmer Benjamin Z. , Coe Peter O. , Tolofari Sotonye , Barrie Jenifer , Bashir Gareth , Sloane Jake , Madanipour Suroosh , Halkias Constantine , Trevatt Alexander E. J. , Borowski David W. , Hornsby Jane , Courtney Michael J. , Virupaksha Suvi , Seymour Keith , Robinson Sarah , Hawkins Helen , Bawa Sadiq , Gallagher Paul V. , Reid Alistair , Wood Peter , Finch J. G. , Guy Finch J. , Parmar J. , Stirland E. , Gardner-Thorpe James , Al-Muhktar Ahmed , Peterson Mark , Majeed Ali , Bajwa Farrukh M. , Martin Jack , Choy Alfred , Tsang Andrew , Pore Naresh , Andrew David R. , Al-Khyatt Waleed , Bhandari Christopher Taylor Santosh , Chambers Adam , Subramanium Dhivya , Toh Simon K. C. , Carter Nicholas C. , Tate Sophie , Pearce Belinda , Wainwright Denise , Mercer Stuart J. , Knight Benjamin , Vijay Vardhini , Alagaratnam Swethan , Sinha Sidhartha , Khan Shahab , El-Hasani Shamsi S. , Hussain Abdulzahra A. , Bhattacharya Vish , Kansal Nisheeth , Fasih Tani , Jackson Claire , Siddiqui Midhat N. , Chishti Imran A. , Fordham Imogen J. , Siddiqui Zohaib , Bausbacher Harald , Geogloma Ileana , Gurung Kabita , Tsavellas George , Basynat Pradeep , Shrestha Ashish Kiran , Basu Sanjoy , Harilingam Alok Chhabra Mohan , Rabie Mohamed , Akhtar Mansoor , Kumar Pradeep , Jafferbhoy Sadaf F. , Hussain Najam , Raza Soulat , Haque Manzarul , Alam Imran , Aseem Rabiya , Patel Shakira , Asad Mehek , Booth Michael I. , Ball William R. , Wood Christopher P. J. , Pinho-Gomes Ana C. , Kausar Ambareen , Obeidallah Moh’d Rami , Varghase Joseph , Lodhia Joshil , Bradley Donal , Rengifo Carla , Lindsay David , Gopalswamy Sivakumar , Finlay Ian , Wardle Stacy , Bullen Naomi , Iftikhar Syed Yusuf , Awan Altaf , Ahmed Javed , Leeder Paul , Fusai Guiseppe , Bond-Smith Giles , Psica Alicja , Puri Yogesh , Hou David , Noble Fergus , Szentpali Karoly , Broadhurst Jack , Date Ravindra , Hossack Martin R. , Goh Yan Li , Turner Paul , Shetty Vinutha , Riera Manel , Macano Christina A. W. , Sukha Anisha , Preston Shaun R. , Hoban Jennifer R. , Puntis Daniel J. , Williams Sophie V. , Krysztopik Richard , Kynaston James , Batt Jeremy , Doe Matthew , Goscimski Andrzej , Jones Gareth H. , Smith Stella R. , Hall Claire , Carty Nick , Ahmed Jamil , Panteleimonitis Sofoklis , Gunasekera Rohan T. , Sheel Andrea R. G. , Lennon Hannah , Hindley Caroline , Reddy Marcus , Kenny Ross , Elkheir Natalie , McGlone Emma R. , Rajaganeshan Rajasundaram , Hancorn Kate , Hargreaves Anita , Prasad Raj , Longbotham David A. , Vijayanand Dhakshinamoorthy , Wijetunga Imeshi , Ziprin Paul , Nicolay Christopher R. , Yeldham Geoffrey , Read Edward , Gossage James A. , Rolph Rachel C. , Ebied Husam , Phull Manraj , Khan Mohammad A. , Popplewell Matthew , Kyriakidis Dimitrios , Hussain Anwar , Henley Natasha , Packer Jessica R. , Derbyshire Laura , Porter Jonathan , Appleton Shaun , Farouk Marwan , Basra Melvinder , Jennings Neil A. , Ali Shahda , Kanakala Venkatesh , Ali Haythem , Lane Risha , Dickson-Lowe Richard , Zarsadias Prizzi , Mirza Darius , Puig Sonia , Amari Khalid Al , Vijayan Deepak , Sutcliffe Robert , Marudanayagam Ravi , Hamady Zayed , Prasad Abheesh R. , Patel Abhilasha , Durkin Damien , Kaur Parminder , Bowen Laura , Byrne James P. , Pearson Katherine L. , Delisle Theo G. , Davies James , Tomlinson Mark A. , Johnpulle Michelle A. , Slawinski Corinna , Macdonald Andrew , Nicholson James , Newton Katy , Mbuvi James , Farooq Ansar , Mothe Bhavani Sidhartha , Zafrani Zakhi , Brett Daniel , Francombe James , Spreadborough Philip , Barnes James , Cheung Melanie , Al-Bahrani Ahmed Z. , Preziosi Giuseppe , Urbonas Tomas , Alberts Justin , Mallik Mekhlola , Patel Krashna , Segaran Ashvina , Doulias Triantafyllos , Sufi Pratik A. , Yao Caroline , Pollock Sarah , Manzelli Antonio , Wajed Saj , Kourkulos Michail , Pezzuto Roberto , Wadley Martin , Hamilton Emma , Jaunoo Shameen , Padwick Robert , Sayegh Mazin , Newton Richard C. , Hebbar Madhusoodhana , Farag Sameh F. , Spearman John , Hamdan Mohammed F. , D’Costa Conrad , Blane Christine , Giles Mathew , Peter Mark B. , Hirst Natalie A. , Hossain Tanvir , El-Dhuwaib Arslan Pannu Yesar , Morrison Tamsin E. M. , Taylor Greg W. , Thompson Ronald L. E. , McCune Ken , Loughlin Paula , Lawther Roger , Byrnes Colman K. , Simpson Duncan J. , Mawhinney Abi , Warren Conor , McKay Damian , McIlmunn Colin , Martin Serena , MacArtney Matthew , Diamond Tom , Davey Phil , Jones Claire , Clements Joshua M. , Digney Ruairi , Chan Wei Ming , McCain Stephen , Gull Sadaf , Janeczko Adam , Dorrian Emmet , Harris Andrew , Dawson Suzanne , Johnston Dorothy , McAree Barry , Ghareeb Essam , Thomas George , Connelly Martin , McKenzie Stephen , Cieplucha Krzysztos , Spence Gary , Campbell William , Hooks Gareth , Bradley Neil , Hill Arnold D. K. , Cassidy John T. , Boland Michael , Burke Paul , Nally Deirdre M. , Hill Arnold D. K. , Khogali Elmoataz , Shabo Wael , Iskandar Edrin , McEntee Gerry P. , O’Neill Maeve A. , Peirce Colin , Lyons Emma M. , O’Sullivan Adrian W. , Thakkar Rohan , Carroll Paul , Ivanovski Ivan , Balfe Paul , Lee Matthew , Winter Des C. , Kelly Michael E. , Hoti Emir , Maguire Donal , Karunakaran Priyadarssini , Geoghegan Justin G. , McDermott Frank , Martin Sean T. , Cross Keith S. , Cooke Fiachra , Zeeshan Saquib , Murphy James O. , Mealy Ken , Mohan Helen M. , Nedujchelyn Yuwaraja , Ullah Muhammad Fahad , Ahmed Irfan , Giovinazzo Francesco , Milburn James , Prince Sarah , Brooke Eleanor , Buchan Joanna , Khalil Ahmed M. , Vaughan Elizabeth M. , Ramage Michael I. , Aldridge Roland C. , Gibson Simon , Nicholson Gary A. , Vass David G. , Grant Alan J. , Holroyd David J. , Angharad Jones M. , Sutton Cherith M. L. R. , O’Dwyer Patrick , Nilsson Frida , Weber Beatrix , Williamson Tracey K. , Lalla Kushik , Bryant Alice , Ross Carter C. , Forrest Craig R. , Hunter David I. , Nassar Ahmad H. , Orizu Mavis N. , Knight Katrina , Qandeel Haitham , Suttie Stuart , Belding Rowena , McClarey Andrew , Boyd Alan T. , Guthrie Graeme J. K. , Lim Pei J. , Luhmann Andreas , Watson Angus J. M. , Richards Colin H. , Nicol Laura , Madurska Marta , Harrison Ewen , Boyce Kathryn M. , Roebuck Amanda , Ferguson Graeme , Pati Pradeep , Wilson Michael S. J. , Dalgaty Faith , Fothergill Laura , Driscoll Peter J. , Mozolowski Kirsty L. , Banwell Victoria , Bennett Stephen P. , Rogers Paul N. , Skelly Brendan L. , Rutherford Claire L. , Mirza Ahmed K. , Lazim Taha , Lim Henry C. C. , Duke Diana , Ahmed Talat , Beasley William D. , Wilkinson Marc D. , Maharaj Geta , Malcolm Cathy , Brown Timothy H. , Al-Sarireh Bilal , Shingler Guy M. , Mowbray Nicholas , Radwan Rami , Morcous Paul , Wood Simon , Kadhim Abbas , Stewart Duncan J. , Baker Andrew L. , Tanner Nicola , Shenoy Hrishikesh , Hafiz Shazia , De Marchi Joshua A. , Singh-Ranger Deepak , Hisham Elzanati , Ainley Paul , John Terrace Stephen O’Neill. , Napetti Sara , Hopwood Benjamin , Rhys Thomas , Downing Justine , Kanavati Sam , Coats Maria , Aleksandrov Danail , Kallaway Charlotte , Yahya Salama , Weber Beatrix , Templeton Alexa , Trotter Martin , Lo Christina , Dhillon Ajit , Heywood Nick , Aawsaj Yousif , Hamdan Alhafidz , Reece-Bolton Obuobi , McGuigan Andrew , Shahin Yousef , Aymon  , Luther Ali Alison , Nicholson James A. , Rajendran Ilayaraja , Boal Matthew , Ritchie Judith 
Published: August 2018

The list of the CholeS management group, Collaborators and Data Validators were omitted from the Acknowledgments.