Importance of patient bed pathways and length of stay differences in predicting COVID-19 hospital bed occupancy in England
Authors: Leclerc Quentin J. , Fuller Naomi M. , Keogh Ruth H. , Diaz-Ordaz Karla , Sekula Richard , Semple Malcolm G. ,   ISARIC4C Investigators, Baillie J. Kenneth , Semple Malcolm G. , Openshaw Peter J. M. , Carson Gail , Alex Beatrice , Bach Benjamin , Barclay Wendy S. , Bogaert Debby , Chand Meera , Cooke Graham S. , Docherty Annemarie B. , Dunning Jake , da Silva Filipe Ana , Fletcher Tom , Green Christopher A. , Harrison Ewen M. , Hiscox Julian A. , Ho Antonia Ying Wai , Horby Peter W. , Ijaz Samreen , Khoo Saye , Klenerman Paul , Law Andrew , Lim Wei Shen , Mentzer Alexander J. , Merson Laura , Meynert Alison M. , Noursadeghi Mahdad , Moore Shona C. , Palmarini Massimo , Paxton William A. , Pollakis Georgios , Price Nicholas , Rambaut Andrew , Robertson David L. , Russell Clark D. , Sancho-Shimizu Vanessa , Scott Janet T. , de Silva Thushan , Sigfrid Louise , Solomon Tom , Sriskandan Shiranee , Stuart David , Summers Charlotte , Tedder Richard S. , Thomson Emma C. , Thompson A. A. Roger , Thwaites Ryan S. , Turtle Lance C. W. , Zambon Maria , Hardwick Hayley , Donohue Chloe , Lyons Ruth , Griffiths Fiona , Oosthuyzen Wilna , Norman Lisa , Pius Riinu , Drake Tom M. , Fairfield Cameron J. , Knight Stephen , Mclean Kenneth A. , Murphy Derek , Shaw Catherine A. , Dalton Jo , Lee James , Plotkin Daniel , Girvan Michelle , Saviciute Egle , Roberts Stephanie , Harrison Janet , Marsh Laura , Connor Marie , Halpin Sophie , Jackson Clare , Gamble Carrol , Petersen Claire , Mullaney Scott , Leeming Gary , Wham Murray , Clohisey Sara , Hendry Ross , Scott-Brown James , Greenhalf William , Shaw Victoria , McDonald Sarah , Keating Seán , Ahmed Katie A. , Armstrong Jane A. , Ashworth Milton , Asiimwe Innocent G. , Bakshi Siddharth , Barlow Samantha L. , Booth Laura , Brennan Benjamin , Bullock Katie , Catterall Benjamin W. A. , Clark Jordan J. , Clarke Emily A. , Cole Sarah , Cooper Louise , Cox Helen , Davis Christopher , Dincarslan Oslem , Dunn Chris , Dyer Philip , Elliott Angela , Evans Anthony , Finch Lorna , Fisher Lewis W. S. , Foster Terry , Garcia-Dorival Isabel , Gunning Philip , Hartley Catherine , Ho Antonia , Jensen Rebecca L. , Jones Christopher B. , Jones Trevor R. , Khandaker Shadia , King Katharine , Kiy Robyn T. , Koukorava Chrysa , Lake Annette , Lant Suzannah , Latawiec Diane , Lavelle-Langham L. , Lefteri Daniella , Lett Lauren , Livoti Lucia A. , Mancini Maria , McDonald Sarah , McEvoy Laurence , McLauchlan John , Metelmann Soeren , Miah Nahida S. , Middleton Joanna , Mitchell Joyce , Murphy Ellen G. , Penrice-Randal Rebekah , Pilgrim Jack , Prince Tessa , Reynolds Will , Ridley P. Matthew , Sales Debby , Shaw Victoria E. , Shears Rebecca K. , Small Benjamin , Subramaniam Krishanthi S. , Szemiel Agnieska , Taggart Aislynn , Tanianis-Hughes Jolanta , Thomas Jordan , Trochu Erwan , van Tonder Libby , Wilcock Eve , Zhang J. Eunice , Adeniji Kayode , Agranoff Daniel , Agwuh Ken , Ail Dhiraj , Alegria Ana , Angus Brian , Ashish Abdul , Atkinson Dougal , Bari Shahedal , Barlow Gavin , Barnass Stella , Barrett Nicholas , Bassford Christopher , Baxter David , Beadsworth Michael , Bernatoniene Jolanta , Berridge John , Best Nicola , Bothma Pieter , Brealey David , Brittain-Long Robin , Bulteel Naomi , Burden Tom , Burtenshaw Andrew , Caruth Vikki , Chadwick David , Chambler Duncan , Chee Nigel , Child Jenny , Chukkambotla Srikanth , Clark Tom , Collini Paul , Cosgrove Catherine , Cupitt Jason , Cutino-Moguel Maria-Teresa , Dark Paul , Dawson Chris , Dervisevic Samir , Donnison Phil , Douthwaite Sam , DuRand Ingrid , Dushianthan Ahilanadan , Dyer Tristan , Evans Cariad , Eziefula Chi , Fegan Chrisopher , Finn Adam , Fullerton Duncan , Garg Sanjeev , Garg Sanjeev , Garg Atul , Gkrania-Klotsas Effrossyni , Godden Jo , Goldsmith Arthur , Graham Clive , Hardy Elaine , Hartshorn Stuart , Harvey Daniel , Havalda Peter , Hawcutt Daniel B. , Hobrok Maria , Hodgson Luke , Hormis Anil , Jacobs Michael , Jain Susan , Jennings Paul , Kaliappan Agilan , Kasipandian Vidya , Kegg Stephen , Kelsey Michael , Kendall Jason , Kerrison Caroline , Kerslake Ian , Koch Oliver , Koduri Gouri , Koshy George , Laha Shondipon , Laird Steven , Larkin Susan , Leiner Tamas , Lillie Patrick , Limb James , Linnett Vanessa , Little Jeff , MacMahon Michael , MacNaughton Emily , Mankregod Ravish , Masson Huw , Matovu Elijah , McCullough Katherine , McEwen Ruth , Meda Manjula , Mills Gary , Minton Jane , Mirfenderesky Mariyam , Mohandas Kavya , Mok Quen , Moon James , Moore Elinoor , Morgan Patrick , Morris Craig , Mortimore Katherine , Moses Samuel , Mpenge Mbiye , Mulla Rohinton , Murphy Michael , Nagel Megan , Nagarajan Thapas , Nelson Mark , Otahal Igor , Pais Mark , Panchatsharam Selva , Paraiso Hassan , Patel Brij , Pattison Natalie , Pepperell Justin , Peters Mark , Phull Mandeep , Pintus Stefania , Pooni Jagtur Singh , Post Frank , Price David , Prout Rachel , Rae Nikolas , Reschreiter Henrik , Reynolds Tim , Richardson Neil , Roberts Mark , Roberts Devender , Rose Alistair , Rousseau Guy , Ryan Brendan , Saluja Taranprit , Shah Aarti , Shanmuga Prad , Sharma Anil , Shawcross Anna , Sizer Jeremy , Shankar-Hari Manu , Smith Richard , Snelson Catherine , Spittle Nick , Staines Nikki , Stambach Tom , Stewart Richard , Subudhi Pradeep , Szakmany Tamas , Tatham Kate , Thomas Jo , Thompson Chris , Thompson Robert , Tridente Ascanio , Tupper-Carey Darell , Twagira Mary , Ustianowski Andrew , Vallotton Nick , Vincent-Smith Lisa , Visuvanathan Shico , Vuylsteke Alan , Waddy Sam , Wake Rachel , Walden Andrew , Welters Ingeborg , Whitehouse Tony , Whittaker Paul , Whittington Ashley , Wijesinghe Meme , Williams Martin , Wilson Lawrence , Wilson Sarah , Winchester Stephen , Wiselka Martin , Wolverson Adam , Wooton Daniel G. , Workman Andrew , Yates Bryan , Young Peter ,   CMMID COVID-19 Working Group, Quaife Matthew , Jarvis Christopher I. , Meakin Sophie R. , Quilty Billy J. , Prem Kiesha , Villabona-Arenas C. Julian , Sun Fiona Yueqian , Abbas Kaja , Auzenbergs Megan , Gimma Amy , Tully Damien C. , Sherratt Katharine , Rosello Alicia , Davies Nicholas G. , Liu Yang , Lowe Rachel , Gibbs Hamish P. , Waterlow Naomi R. , Edmunds W. John , Simons David , Medley Graham , Munday James D. , Flasche Stefan , Sandmann Frank G. , Showering Alicia , Eggo Rosalind M. , Chan Yung-Wai Desmond , Pearson Carl A. B. , Kucharski Adam J. , Foss Anna M. , Russell Timothy W. , Bosse Nikos I. , Jit Mark , Abbott Sam , Williams Jack , Endo Akira , Clifford Samuel , Gore-Langton Georgia R. , Klepac Petra , Brady Oliver , Hellewell Joel , Funk Sebastian , van Zandvoort Kevin , Barnard Rosanna C. , Nightingale Emily S. , Jombart Thibaut , Atkins Katherine E. , Procter Simon R. , Knight Gwenan M. 
Published: June 2021

Abstract
Background
Predicting bed occupancy for hospitalised patients with COVID-19 requires understanding of length of stay (LoS) in particular bed types. LoS can vary depending on the patient’s “bed pathway” - the sequence of transfers of individual patients between bed types during a hospital stay. In this study, we characterise these pathways, and their impact on predicted hospital bed occupancy.

Methods
We obtained data from University College Hospital (UCH) and the ISARIC4C COVID-19 Clinical Information Network (CO-CIN) on hospitalised patients with COVID-19 who required care in general ward or critical care (CC) beds to determine possible bed pathways and LoS. We developed a discrete-time model to examine the implications of using either bed pathways or only average LoS by bed type to forecast bed occupancy. We compared model-predicted bed occupancy to publicly available bed occupancy data on COVID-19 in England between March and August 2020.

Results
In both the UCH and CO-CIN datasets, 82% of hospitalised patients with COVID-19 only received care in general ward beds. We identified four other bed pathways, present in both datasets: “Ward, CC, Ward”, “Ward, CC”, “CC” and “CC, Ward”. Mean LoS varied by bed type, pathway, and dataset, between 1.78 and 13.53 days.
For UCH, we found that using bed pathways improved the accuracy of bed occupancy predictions, while only using an average LoS for each bed type underestimated true bed occupancy. However, using the CO-CIN LoS dataset we were not able to replicate past data on bed occupancy in England, suggesting regional LoS heterogeneities.

Conclusions
We identified five bed pathways, with substantial variation in LoS by bed type, pathway, and geography. This might be caused by local differences in patient characteristics, clinical care strategies, or resource availability, and suggests that national LoS averages may not be appropriate for local forecasts of bed occupancy for COVID-19.

Trial registration
The ISARIC WHO CCP-UK study ISRCTN66726260 was retrospectively registered on 21/04/2020 and designated an Urgent Public Health Research Study by NIHR.