Imperial College London

Dr Nathan Green

Faculty of MedicineSchool of Public Health

Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 5782nathan.green Website

 
 
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Location

 

UG 1147 Praed StreetSt Mary's Campus

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Summary

 

Publications

Publication Type
Year
to

14 results found

Green N, Sherrard-Smith E, Tanton C, Sonnenberg P, Mercer C, White Pet al., 2019, Assessing local chlamydia screening performance by combining survey and administrative data to account for differences in local population characteristics, Scientific Reports, Vol: 9, ISSN: 2045-2322

Reducing health inequalities requires improved understanding of the causes of variation. Local-level variation reflects differences in local population characteristics and health system performance. Identifying low- and high-performing localities allows investigation into these differences. We used Multilevel Regression with Post-stratification (MRP) to synthesise data from multiple sources, using chlamydia testing as our example. We used national probability survey data to identify individual-level characteristics associated with chlamydia testing and combined this with local-level census data to calculate expected levels of testing in each local authority (LA) in England, allowing us to identify LAs where observed chlamydia testing rates were lower or higher than expected, given population characteristics. Taking account of multiple covariates, including age, sex, ethnicity, student and cohabiting status, 5.4% and 3.5% of LAs had testing rates higher than expected for 95% and 99% posterior credible intervals, respectively; 60.9% and 50.8% had rates lower than expected. Residual differences between observed and MRP expected values were smallest for LAs with large proportions of non-white ethnic populations. London boroughs that were markedly different from expected MRP values (90% posterior exceedance probability) had actively targeted risk groups. This type of synthesis allows more refined inferences to be made at small-area levels than previously feasible.

Journal article

Takwoingi Y, Whitworth H, Rees-Roberts M, Badhan A, Partlett C, Green N, Boakye A, Lambie H, Marongiu L, Jit M, White P, Deeks JJ, Kon OM, Lalvani A, Abdoyeku D, Branley H, Chua F, Conlon C, Cooke G, Davison R, Dedicoat M, Kunst H, Lipman M, Loebingher M, Lynn W, Macallan D, Menzies S, Nathani N, O'Connell R, Post F, Pozniak A, Wiselka M, Woltmann Get al., 2019, Interferon gamma release assays for diagnostic evaluation of active tuberculosis (IDEA): test accuracy study and economic evaluation, Health Technology Assessment, Vol: 23, ISSN: 1366-5278

BackgroundInterferon gamma release assays (IGRAs) are blood tests recommended for the diagnosis of tuberculosis (TB) infection. There is currently uncertainty about the role and clinical utility of IGRAs in the diagnostic workup of suspected active TB in routine NHS clinical practice.ObjectivesTo compare the diagnostic accuracy and cost-effectiveness of T-SPOT.TB® (Oxford Immunotec, Abingdon, UK) and QuantiFERON® TB GOLD In-Tube (Cellestis, Carnegie, VIC, Australia) for diagnosis of suspected active TB and to estimate the diagnostic accuracy of second-generation IGRAs.DesignProspective within-patient comparative diagnostic accuracy study.SettingSecondary care.ParticipantsAdults (aged ≥ 16 years) presenting as inpatients or outpatients at 12 NHS hospital trusts in London, Slough, Oxford, Leicester and Birmingham with suspected active TB.InterventionsThe index tests [T-SPOT.TB and QuantiFERON GOLD In-Tube (QFT-GIT)] and new enzyme-linked immunospot assays utilising novel Mycobacterium tuberculosis antigens (Rv3615c, Rv2654, Rv3879c and Rv3873) were verified against a composite reference standard applied by a panel of clinical experts blinded to IGRA results.Main outcome measuresSensitivity, specificity, predictive values and likelihood ratios were calculated to determine diagnostic accuracy. A decision tree model was developed to calculate the incremental costs and incremental health utilities [quality-adjusted life-years (QALYs)] of changing from current practice to using an IGRA as an initial rule-out test.ResultsA total of 363 patients had active TB (culture-confirmed and highly probable TB cases), 439 had no active TB and 43 had an indeterminate final diagnosis. Comparing T-SPOT.TB and QFT-GIT, the sensitivities [95% confidence interval (CI)] were 82.3% (95% CI 77.7% to 85.9%) and 67.3% (95% CI 62.1% to 72.2%), respectively, whereas specificities were 82.6% (95% CI 78.6% to 86.1%) and 80.4% (95% CI 76.1% to 84.1%), respectively. T-SPOT.TB was mor

Journal article

Halliday A, Jain P, Hoang L, Parker R, Tolosa-Wright M, Masonou T, Green N, Boakye A, Takwoingi Y, Hamilton S, Mandagere V, Fries A, Coin L, Deeks J, White P, Levin M, Beverley P, Kon O, Lalvani Aet al., Validation of new technologies for the diagnostic evaluation of active tuberculosis (VANTDET), Efficacy and Mechanism Evaluation, ISSN: 2050-4365

Background: Tuberculosis (TB) is a devastating disease for which new diagnostic tests are desperately needed. Objective: To validate promising new technologies (namely whole blood transcriptomics, proteomics, flow cytometry and qRT-PCR) and existing signatures for detection of active TB in samples obtained from individuals suspected of active TB. Design: Four sub-studies, each of which used the samples from biobank collected as part of the IDEA study, which was a prospective cohort of patients recruited with suspected TB. Setting: secondary care Participants: Adults (aged ≥ 16 years old) presenting as inpatients or outpatients at 12 NHS hospital trusts in London, Slough, Oxford, Leicester and Birmingham with suspected active TB. Interventions: New tests using either: genome-wide gene expression microarray (transcriptomics); SELDI TOF/ LC-MS (proteomics), flow cytometry, qRT-PCR. Main outcome measures: Area under the curve (AUC), sensitivity and specificity, were calculated to determine diagnostic accuracy. Positive and negative predictive values were calculated in some cases. A decision tree model was developed to calculate the incremental costs and quality-adjusted life-years (QALYs) of changing from current practice to using the novels tests. Results: The project and 4 sub-studies which assessed the previous published signatures measured using each of the new technologies, and a health economic analysis where the best performing tests were evaluated for cost effectiveness. The diagnostic accuracy of the transcriptomic tests ranged from AUC=0.81-0.84 for detecting all TB in our cohort. The performance for detecting culture confirmed TB or pulmonary TB (PTB) was better than for highly probable TB or extrapulmonary TB (EPTB) respectively, but not high enough to be clinically useful. None of the previously described serum proteomic signatures for active TB provided good diagnostic accuracy, not did the candidate rule-out tests. Four of six previously described cell

Journal article

Gupta RK, Gosce L, Green N, Southern J, Lipman M, Kunst H, Aldridge R, White P, Imran A, Mpofu T, Rahman A, Vaghela D, Ghimire N, Menezes D, Hack V, Abubakar Iet al., 2018, YIELD AND COST OF SCREENING FOR ACTIVE AND LATENT TUBERCULOSIS AMONG HIGH-RISK GROUPS ATTENDING LONDON EMERGENCY DEPARTMENTS, Winter Meeting of the British-Thoracic-Society, Publisher: BMJ PUBLISHING GROUP, Pages: A92-A92, ISSN: 0040-6376

Conference paper

Hayama M, Green N, Seneviratne SL, O'Donoghue M, Drey N, Kon OMet al., 2017, LATENT TUBERCULOSIS INFECTION SCREENING OF ADULT CLOSE CONTACTS IN LONDON: A COST-UTILITY ANALYSIS, Winter Meeting of the British-Thoracic-Society, Publisher: BMJ PUBLISHING GROUP, Pages: A174-A174, ISSN: 0040-6376

Conference paper

Dangerfield CE, Sherrard-Smith E, Green N, Harding-Esch E, Howell-Jones R, Choi Y, Lowndes CM, White PJet al., 2015, IMPACT AND COST-EFFECTIVENESS OF POINT-OF-CARE TESTING FOR CHLAMYDIA: ACCOUNTING FOR GEOGRAPHIC VARIATION IN INFECTION BURDEN AND TESTING RATES, HEALTH SERVICE CONFIGURATION, AND IMPLEMENTATION STRATEGY, Publisher: BMJ PUBLISHING GROUP, Pages: A152-A153, ISSN: 1368-4973

Conference paper

Harding-Esch E, Sherrard-Smith E, Dangerfield C, Choi YH, Green N, Jit M, Marshall RD, Mercer C, Nardone A, Howell-Jones R, Johnson OA, Clarkson J, Wolstenholme J, Price CP, Gaydos CA, Sadiq ST, White PJ, Lowndes CMet al., 2015, WEB-TOOL TO ASSESS THE COST-EFFECTIVENESS OF CHLAMYDIA POINT-OF-CARE TESTS AT THE LOCAL LEVEL, Publisher: BMJ PUBLISHING GROUP, Pages: A143-A143, ISSN: 1368-4973

Conference paper

Green N, 2015, Statistics for People Who (Think They) Hate Statistics (Book Review), Journal of the Royal Statistical Society Series A-Statistics in Society, Vol: 178, Pages: 784-784, ISSN: 1467-985X

Journal article

Drobniewski F, Cooke M, Jordan J, Casali N, Mugwagwa T, Broda A, Townsend C, Sivaramakrishnan A, Green N, Jit M, Lipman M, Lord J, White PJ, Abubakar Iet al., 2015, Systematic review, meta-analysis and economic modelling of molecular diagnostic tests for antibiotic resistance in tuberculosis, Health Technology Assessment, Vol: 19, ISSN: 1366-5278

Journal article

van Kleef E, Green N, Goldenberg SD, Robotham JV, Cookson B, Jit M, Edmunds WJ, Deeny SRet al., 2014, Excess length of stay and mortality due to Clostridium difficile infection: a multi-state modelling approach, JOURNAL OF HOSPITAL INFECTION, Vol: 88, Pages: 213-217, ISSN: 0195-6701

Journal article

Lowndes CM, Sherrard-Smith E, Dangerfield C, Choi YH, Green N, Jit M, Marshall RD, Mercer C, Harding-Esch E, Nardone A, Howell-Jones R, Bason J, Johnson OA, Price CP, Gaydos CA, Sadiq ST, White PJet al., 2014, Point-of-care testing versus standard practice for chlamydia: a new approach to assessing the public health effect of rapid testing and treatment at local level, European Public Health Science Conference, Publisher: ELSEVIER SCIENCE INC, Pages: 47-47, ISSN: 0140-6736

Conference paper

Green N, Johnson AP, Henderson KL, Muller-Pebody B, Thelwall S, Robotham JV, Sharland M, Wolkewitz M, Deeny SRet al., 2014, Quantifying the Burden of Hospital-Acquired Bloodstream Infection in Children in England by Estimating Excess Length of Hospital Stay and Mortality Using a Multistate Analysis of Linked, Routinely Collected Data., Journal of the Pediatric Infectious Diseases Society, Vol: 4, Pages: 305-312, ISSN: 2048-7207

BACKGROUND: Hospital-acquired bloodstream infection (HA-BSI) is associated with substantial morbidity, mortality, and healthcare costs in all patient populations. Young children have been shown to have a high rate of healthcare-associated infections compared with the adult population. We aimed to quantify the excess mortality and length of stay in pediatric patients from HA-BSI. METHODS: We analyzed data collected retrospectively from a probabilistically linked national database of pediatric (aged 1 month-18 years) in-patients with a microbiologically confirmed HA-BSI in England between January and March 2009. A time-dependent Cox regression model was fit to determine the presence of any effect. Furthermore, a multistate model, adjusted for the time to onset of HA-BSI, was used to compare outcomes in patients with HA-BSI to those without HA-BSI. We further adjusted for patients' characteristics as recorded in hospital admission data. RESULTS: The dataset comprised 333 605 patients, with 214 cases of HA-BSI. After adjustment for time to HA-BSI and comorbidities, the hazard for discharge (dead or alive) from hospital for patients with HA-BSI was 0.9 times (95% confidence interval [CI], .8-1.1) that of noninfected patients. Excess length of stay associated with all-cause HA-BSI was 1.6 days (95% CI, .2-3.0), although this duration varied by pathogen. Patients with HA-BSI had a 3.6 (95% CI, 1.3-10.4) times higher hazard for in-hospital death than noninfected patients. CONCLUSIONS: Hospital-acquired bloodstream infection increased the length of stay and mortality of pediatric inpatients. The results of this study provide an evidence base to judge the health and economic impact of programs to prevent and control HA-BSI in children.

Journal article

Green N, Clancy D, 2006, Optimal intervention for an epidemic model under parameter uncertainty, Mathematical Biosciences, Vol: 205, Pages: 297-314

Journal article

Green N, 2005, Optimal intervention of epidemic models under uncertainty

Thesis dissertation

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