Association between body weight and tocilizumab effectiveness in rheumatoid arthritis: results from the BSRBR-RA
Authors: Tsoi Man Fung , Kearsley-Fleet Lianne , Azadbakht Narges , Watson Kath , Hyrich Kimme L , Bluett James ,   BSRBR-RA Contributors Group, Sultan Shabina , McParland Chantel , Armstrong Lisa , Dooks Emma , Reed Anna Roynon , Hodkinson Gemma , Nash Maxine , Brickley Meghan , Dell Amanda , Hall Angela , Westacott Clare , Tuffney Jemma , Sunil Roshen , Hamilton Helen , Hughes Rod , Walsh Maggie , Buckley Marie , Sharlala Hisham , Nicholson Alice , Galvin Anna , Jones Sian , Matthews Jamie , Roantree Scott , Brown Hannah , Howson Joanne , Gamble Kate , Reed Lisa , Hope Susan , Rivellese Felice , Humby Frances , Azhar Ayat , Harvey Emily , Chowdhury Mayisha , Bibi Fatima , Miah Ishraat , Nisar Muhammad , Bakker Philippa , Lovelock Ruth , Ahmad Yasmeen , Lewis Sion , Bolger Annette , Lees Caroline , Jones Caroline Mulvaney , Idowu Oluwatoyin , Garvey Victoria , Ahmad Yasmeen , Aziz Tahir , Lewis Sion , Jones Caroline Mulvaney , Ahmad Yasmeen , McIvor Emma , Jones Caroline Mulvaney , Watkins Claire , Roberts Mary , Whitehead Victoria , Caswell Melanie , Hale Christopher , Clarke Allison , Cunliffe Victoria , Sharif Omer , Boltwood Kaitlin , Kelly Molly , Haigh Andrew , Robinson Matthew , Hanson Kathryn , Bayo Lee-Ann , Usher Miranda , Anjam Sanya , Reeves Ashleigh , King Lucia , Negoescu Andra , Abercrombie Donna , Wright Samantha , Rowlands Jane , Choy Ernest , Nyland Kerry , Griebel Liz Harmer , Balan Andrea , Mirjafari-Temple Hoda , Barnes Theresa , Hughes Anna , Chard Courtney , Shaikh Firdaus , Slack Lauren , Slater Lucy , Winstanley Phoebe , Noon Rebecca , Morris Keith , Williams Anna , Pickering Charlotte , Jeffrey Helen , Grounds Jenny , Cawley Kathryn , Ahmed Tazeen , Nwajei-Agha Gloria , Wijeyekoon Bhathiya , Warner Elizabeth , Potter Debbie , Beadle Hannah , Knight Susan , Young Megan , Keenan Natalie , Holland Maureen , Pointon Kathryn , Bari Syed , Beranova Eva , Quindoyos Jhanielle , Schumacher Natasha , Solly Reanne , Turney Sharon , Rand James , Austin Liam , Allen Louise , Crisp Nikki , Owolabi Olajumoke , Hazelton Tracy , Tutt Gabriella , Weston Heather , Teh Lee-Suan , Cheung Annie , Shams Sabeeh , Chathraikkal Shanoj Keezhoppattu , Hartley Janice , Davies Karen , Desai Hawa , Abdulkader Rita , Beeby Deborah , Peters Genessa , Finch Jenny , Francis Rebecca , Malaiya Ritu , Fardeen Kazi , Hayre Rachel , Raju Tina , Malaiya Ritu , Kotecha Jalpa , Fardeen Kazi , Latheef Muhammed Russal , Hayre Rachel , Raju Tina , Steuer Alan , Khawaja Amna , Barnes Nicky , Wilson Fiona , Ashour Yasmina , Yusuf Abid , Al Sweedan Laith , Singh Narender , Suter Danielle , Gunn Jessica , Boss David , Gurung Sundip , Walker Rebecca , Westbrook Nicola , Collins David , Price Elizabeth , Moon Alison , Schlup Monica , Gurung Alina , Potter Claire , Herbert Helena , Kerton Lynne , Horton Ruth , Arnold Tracy , Kirkham Bruce , Frayna Katrina , Enverga Florence , Opena Maria , Hassan Nadia Ladha , Blanco-Gil Cristina , Brooks Lucy , Williams Emma , Defever Emmanuel , Bevan Emily , Parry Jemima , Graver Christine , Taylor Kerrie , Lungu Miyoba , Green Mike , Stemp Clare , Gordon Esther , Brown Louise , Singh Nadira 
Published: September 2024

Abstract

Objectives
Tocilizumab is an IL-6 receptor humanized monoclonal antibody for the treatment of rheumatoid arthritis (RA) with intravenous (IV) and subcutaneous (SC) preparations available. Only IV tocilizumab is dosed adjusting for weight. Therefore, we aimed to study the association between body weight and the effectiveness of tocilizumab by the route of administration.

Methods
Patients with RA-administered tocilizumab in the BSRBR-RA were included in the analysis and stratified by route of administration. Outcomes included the 6-month change in DAS28, the proportion of patients achieving DAS28 remission, 6-month EULAR response and persistence of the first route of tocilizumab administration. The exposure was every increase in 10 kg of body weight. Adjusted regression models appropriate to outcome were used to study the associations between body weight and outcomes. Multiple imputations accounted for missing data.

Results
A total of 2612 patients were included. Body weight was associated with reduced response to SC tocilizumab measured by change in DAS28: adjusted regression coefficient (95% CI) all patients 0.01 (−0.04, 0.07); IV: −0.03, (−0.1, 0.5); SC: 0.1 (0.02, 0.2) but not odds in achieving DAS28 remission or EULAR response. There was no significant association between body weight and the persistence of IV or SC tocilizumab.

Conclusion
Body weight was associated with the initial response to SC tocilizumab, although the difference in response was small, but not drug persistence. Physicians should monitor the body weight of patients and consider interventions to promote maintenance of a healthy weight.