Sarah Walker, Professor of Medical Statistics & Epidemiology

Sarah has worked at the Unit since its initiation in 1999, having previously worked at the MRC HIV Clinical Trials Centre since 1994. Her work includes the design and analysis of clinical trials and observational studies of treatment and management strategies for HIV and other infectious diseases, including serious bacterial infections and Hepatitis C. She has worked on projects involving both adults and children, in high-income and low/middle-income countries. Methdological research interests include the use of causal models to address additional non-randomised questions using data from clinical trials.

From April 2006, Sarah has worked part-time at the University of Oxford, predominantly with the NIHR Oxford Biomedical Centre Infections Theme and the "Modernising Medical Microbiology" Consortium translating new whole genome sequencing approaches into microbiology practice and service and investigating electronic health records for infectious diseases research.

Sarah is also Associate Statistical Editor for the Journal of Infectious Diseases.


Selected publications

Maitland K*, Kiguli S*, Olupot-Olupot P*, Engoru C, Mallewa M, Saramago Goncalves P, Opoka RO, Mpoya A, Aloroker F, Nteziyaremye J, Chagaluka G, Kennedy N, Namanyanga C, Nakuya M, Uyoga S, Byabazaire DK, M’baya B, Wabwire B, Frost G, Bates I, Evans JA, Williams TN, George EC*, Gibb DM*, Walker AS* for the TRACT trial group. Immediate transfusion in African children with uncomplicated severe anemia. N Engl J Med 2019;381(5):407-419. *contributed equally.

Maitland K*, Olupot-Olupot P*, Kiguli S*, Chagaluka G, Aloroker F, Opoka RO, Mpoya A, Engoru C, Nteziyaremye J, Mallewa M, Kennedy N, Nakuya M, Namanyanga C, Kayaga J, Uyoga S, Byabazaire DK, M’baya B, Wabwire B, Frost G, Bates I, Evans JA, Williams TN, Saramago Goncalves P, George EC*, Gibb DM*, Walker AS* for the TRACT trial group. Transfusion volume for children with severe anemia in Africa. N Eng J Med 2019;381(5):420-431.

Hakim J, Musiime V, Szubert AJ, Mallewa J, Siika A, Agutu C, Walker S, Pett SL, Bwakura-Dangarembizi M, Lugemwa A, Kaunda S, Karoney M, Musoro G, Kabahenda S, Nathoo K, Maitland K, Griffiths A, Thomason MJ, Kityo C, Mugyenyi P, Prendergast AJ*, Walker AS*, Gibb DM* on behalf of the REALITY trial team. Enhanced prophylaxis plus antiretroviral therapy for advanced HIV infection in Africa. N Eng J Med 2017;377:233-245.

Bwakura-Dangarembizi M, Kendall L, Bakeera-Kitaka S, Nahirya-Ntege P, Keishanyu R, Nathoo K, Spyer MJ, Kekitiinwa A, Lutaakome J, Mhute T, Kasirye P, Munderi P, Musiime V, Gibb DM*, Walker AS*, Prendergast AJ* and the ARROW Trial Team. A randomized trial of prolonged cotrimoxazole in HIV-infected children in Africa. N Engl J Med 2014; 370: 41-53.

Paton NI, Kityo C, Hoppe A, Reid A, Kambugu A, Lugemwa A, van Oosterhout J, Kiconco M, Siika A, Mwebaze R, Abwola M, Abongomera G, Mweemba A, Alima H, Atwongyeire D, Nyirenda R, Boles J, Thompson J, Tumukunde D, Chidziva E, Mambule I, Arribas JR, Easterbrook PJ, Hakim J, Walker AS*, Mugyenyi P* for the EARNEST Trial Team. Assessment of second-line antiretroviral regimens for HIV therapy in Africa. N Eng J Med 2014;371(3):234-47.

Eyre DW, Cule ML, Wilson DJ, Griffiths D, Vaughan A, O'Connor L, Ip CLC, Golubchik T, Batty EM, Didelot X, Piazza P, Bowden R, Dingle KE, Harding RM, Crook DW, Wilcox MH*, Peto TEA*, Walker AS*. Diverse sources of C. difficile infection identified on whole genome sequencing. N Eng J Med 2013;369(13):1195-205. doi: 10.1056/NEJMoa1216064.

Thwaites GE, Scarborough M, Szubert A, Nsutebu E, Tilley R, Greig J, Wyllie SA, Wilson P,  Auckland C, Cairns J, Ward D, Lal P, Guleri A, Jenkins N, Sutton J, Wiselka M, Armando GR, Graham C, Chadwick PR, Barlow G, Gordon NC, Young B, Meisner S, McWhinney P, Price DA, Harvey D, Nayar D, Jeyaratnam D, Planche T, Minton J, Hudson F, Hopkins S, Williams J, Török ME, Llewelyn M, Edgeworth JD, Walker AS on behalf of the United Kingdom Clinical Infection Research Group (UKCIRG). Adjunctive rifampicin for Staphylococcus aureus bacteraemia (ARREST): a multicentre, randomised, double-blind, placebo-controlled trial. Lancet 2018; 391(10121):668-678.

Walker AS*, Mason A*, Quan TP, Fawcett N, Watkinson P, Llewelyn M, Stoesser N, Finney J, Davies J, Wyllie DH, Crook DW, Peto TEA. Mortality risks associated with emergency admissions during weekends and public holidays: an analysis of electronic health records. Lancet 2017;390(10089);62-72.

ARROW Trial Team. ARROW: a 5-year randomised factorial trial of routine versus clinically driven laboratory monitoring and first-line antiretroviral therapy strategies in HIV-infected African children. Lancet 2013; 381(9875):1391-403. doi: 10.1016/S0140-6736(12)62198-9.

Walker AS, Ford D, Gilks C, Munderi P, Ssali F, Reid A, Katabira E, Grosskurth H, Mugyenyi P, Hakim J, Darbyshire JH, Gibb DM, Babiker AG. Daily co-trimoxazole prophylaxis in severely immunosuppressed HIV-infected adults in Africa started on combination antiretroviral therapy: an observational analysis of the DART cohort. Lancet 2010;375:1278-86.

Mead S, Burnell M, Lowe J, Thompson A, Lukic A, Porter MC, Carswell C, Kaski D, Kenny J, TzeHow M, Bjurstrom N, Gorham M, Druyeh R, Wadsworth J, Jaunmuktane Z, Brandner S, Hyare H, Rudge R, Walker AS*, Collinge J*. Clinical trial simulations based on genetic stratification and the natural history of a functional outcome measure in Creutzfeldt-Jakob disease. JAMA Neurology 2016;73(4):447-55.





Research Interests

  • HIV
  • Healthcare associated infections, particularly C. difficile
  • Transmission of C. difficile, tuberculosis, norovirus and S. aureus in the UK
  • Design of randomised trials and observational studies


Research Areas

  • HIV
  • Human prion disease
  • Paediatric infections (malaria/sepsis/tuberculosis)
  • Methodology