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  • 1
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    Online Resource
    Longitudinal associations between neighbourhood trust, social support and physical activity in adolescents: evidence from the Olympic Regeneration in East London (ORiEL) study
    BMJ ; 2020
    In:  Journal of Epidemiology and Community Health
    Details
    In: Journal of Epidemiology and Community Health, BMJ
    Abstract: Most UK adolescents do not achieve recommended levels of physical activity (PA). Previous studies suggest that the social environment could contribute to inequalities in PA behaviours, but longitudinal evidence is limited. We examined whether neighbourhood trust and social support were longitudinally associated with four common forms of PA: walking to school, walking for leisure, outdoor PA and pay and play PA. We further assessed whether gender moderated these associations. Methods We used longitudinal data from the Olympic Regeneration in East London (ORiEL) study. In 2012, 3106 adolescents aged 11–12 were enrolled from 25 schools in four deprived boroughs of East London, UK. Adolescents were followed-up in 2013 and 2014. The final sample includes 2664 participants interviewed at waves 2 and 3. We estimated logistic regression models using generalised estimating equations (GEEs) (pooled models) and proportional odds models (models of change) to assess associations between the social environment exposures and the PA outcomes, adjusting for potential confounders. Item non-response was handled using multilevel multiple imputation. Results We found that different aspects of the social environment predict different types of PA. Neighbourhood trust was positively associated with leisure-type PA. Social support from friends and family was positively associated with walking for leisure. There was some evidence that changes in exposures led to changes in the PA outcomes. Associations did not systematically differ by gender. Conclusion These results confirm the importance of the social environment to predict PA and its change over time in a deprived and ethnically diverse adolescent population.
    Type of Medium: Online Resource
    ISSN: 0143-005X , 1470-2738
    URL: Article
    DOI: 10.1136/jech-2019-213412
    Language: English
    Publisher: BMJ
    Publication Date: 2020
    detail.hit.zdb_id: 2015405-7
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  • 2
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    Handling an uncertain control group event risk in non-inferiority trials: non-inferiority frontiers and the power-stabilising transformation
    Springer Science and Business Media LLC ; 2020
    In:  Trials Vol. 21, No. 1 ( 2020-12)
    Details
    In: Trials, Springer Science and Business Media LLC, Vol. 21, No. 1 ( 2020-12)
    Abstract: Non-inferiority trials are increasingly used to evaluate new treatments that are expected to have secondary advantages over standard of care, but similar efficacy on the primary outcome. When designing a non-inferiority trial with a binary primary outcome, the choice of effect measure for the non-inferiority margin (e.g. risk ratio or risk difference) has an important effect on sample size calculations; furthermore, if the control event risk observed is markedly different from that assumed, the trial can quickly lose power or the results become difficult to interpret. Methods We propose a new way of designing non-inferiority trials to overcome the issues raised by unexpected control event risks. Our proposal involves using clinical judgement to specify a ‘non-inferiority frontier’, i.e. a curve defining the most appropriate non-inferiority margin for each possible value of control event risk. Existing trials implicitly use frontiers defined by a fixed risk ratio or a fixed risk difference. We discuss their limitations and propose a fixed arcsine difference frontier, using the power-stabilising transformation for binary outcomes, which may better represent clinical judgement. We propose and compare three ways of designing a trial using this frontier: testing and reporting on the arcsine scale; testing on the arcsine scale but reporting on the risk difference or risk ratio scale; and modifying the margin on the risk difference or risk ratio scale after observing the control event risk according to the power-stabilising frontier. Results Testing and reporting on the arcsine scale leads to results which are challenging to interpret clinically. For small values of control event risk, testing on the arcsine scale and reporting results on the risk difference scale produces confidence intervals at a higher level than the nominal one or non-inferiority margins that are slightly smaller than those back-calculated from the power-stabilising frontier alone. However, working on the arcsine scale generally requires a larger sample size compared to the risk difference scale. Therefore, working on the risk difference scale, modifying the margin after observing the control event risk, might be preferable, as it requires a smaller sample size. However, this approach tends to slightly inflate type I error rate; a solution is to use a slightly lower significance level for testing, although this modestly reduces power. When working on the risk ratio scale instead, the same approach based on the modification of the margin leads to power levels above the nominal one, maintaining type I error under control. Conclusions Our proposed methods of designing non-inferiority trials using power-stabilising non-inferiority frontiers make trial design more resilient to unexpected values of the control event risk, at the only cost of requiring somewhat larger sample sizes when the goal is to report results on the risk difference scale.
    Type of Medium: Online Resource
    ISSN: 1745-6215
    URL: Article
    DOI: 10.1186/s13063-020-4070-4
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2040523-6
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  • 3
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    Choosing and changing the analysis scale in non-inferiority trials with a binary outcome
    SAGE Publications ; 2022
    In:  Clinical Trials Vol. 19, No. 1 ( 2022-02), p. 14-21
    Details
    In: Clinical Trials, SAGE Publications, Vol. 19, No. 1 ( 2022-02), p. 14-21
    Abstract: The size of the margin strongly influences the required sample size in non-inferiority and equivalence trials. What is sometimes ignored, however, is that for trials with binary outcomes, the scale of the margin – risk difference, risk ratio or odds ratio – also has a large impact on power and thus on sample size requirement. When considering several scales at the design stage of a trial, these sample size consequences should be taken into account. Sometimes, changing the scale may be needed at a later stage of a trial, for example, when the event proportion in the control arm turns out different from expected. Also after completion of a trial, a switch to another scale is sometimes made, for example, when using a regression model in a secondary analysis or when combining study results in a meta-analysis that requires unifying scales. The exact consequences of such switches are currently unknown. Methods and Results This article first outlines sample size consequences for different choices of analysis scale at the design stage of a trial. We add a new result on sample size requirement comparing the risk difference scale with the risk ratio scale. Then, we study two different approaches to changing the analysis scale after the trial has commenced: (1) mapping the original non-inferiority margin using the event proportion in the control arm that was anticipated at the design stage or (2) mapping the original non-inferiority margin using the observed event proportion in the control arm. We use simulations to illustrate consequences on type I and type II error rates. Methods are illustrated on the INES trial, a non-inferiority trial that compared single birth rates in subfertile couples after different fertility treatments. Our results demonstrate large differences in required sample size when choosing between risk difference, risk ratio and odds ratio scales at the design stage of non-inferiority trials. In some cases, the sample size requirement is twice as large on one scale compared with another. Changing the scale after commencing the trial using anticipated proportions mainly impacts type II error rate, whereas switching using observed proportions is not advised due to not maintaining type I error rate. Differences were more pronounced with larger margins. Conclusions Trialists should be aware that the analysis scale can have large impact on type I and type II error rates in non-inferiority trials.
    Type of Medium: Online Resource
    ISSN: 1740-7745 , 1740-7753
    URL: Article
    DOI: 10.1177/17407745211053790
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2159773-X
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  • 4
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    REFINE-Lung: A multicentre phase III study to determine the optimal frequency of pembrolizumab in non-small cell lung cancer utilising a novel multi-arm design.
    American Society of Clinical Oncology (ASCO) ; 2023
    In:  Journal of Clinical Oncology Vol. 41, No. 16_suppl ( 2023-06-01), p. TPS9145-TPS9145
    Details
    In: Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 41, No. 16_suppl ( 2023-06-01), p. TPS9145-TPS9145
    Abstract: TPS9145 Background: Pharmacological and clinical data suggest standard regimens for anti-PD1 agents nivo and pembro result in overtreatment. These agents have high target affinity, saturate PD1 at very low concentrations and maintain receptor occupancy for up to 30 wks following discontinuation. Clinical studies suggest no dose-response relationship in the wide range tested (0.1 – 10 mg/kg) and retrospective data suggest the efficacy of lower doses or longer administration frequency. Given their high costs and important implications for pt quality of life and toxicity, new approaches to optimise treatment regimens are required. However, conventional 2-arm non-inferiority designs require large numbers of patients, explore a single alternative to the standard of care and potentially require multiple trials to establish optimal parameters such as dose or frequency. Here we present a new multi-arm trial design to tackle this problem, implemented in the UK multicentre phase III REFINE-Lung study that aims to determine the optimal treatment frequency of pembro in NSCLC. Pts who are progression free after 6 months of standard therapy are randomised to 5 pembro frequency reduced arms (q6w, q9w, q12w, q15w and q18w). By evaluation of the frequency-response relationship, we will determine the longest frequency that is equivalent to standard of care within a pre-defined margin. Methods: The REFINE-Lung trial (NCT05085028) is a multicentre, randomised open-label, phase III trial in advanced NSCLC. REFINE-Lung utilises a novel Multi-Arm Multi-Stage Response Over Continuous Interventions (MAMS-ROCI) design to determine the optimal dose frequency of pembro. 1750 pts aged ≥18 and progression free at six months into 1st line pembro and planning to continue, will be enrolled from up to UK 35 hospital groups. Pts will be randomised across 5 arms to determine the optimal dose frequency. To assess safety, pts will initially be randomised 1:1 into q6w (control) and q12w arms. Interim analysis will be conducted once 37 progression free events are observed in the control arm. If PFS in the q12w arm is not significantly reduced, the remaining q9w, q15w and q18w arms will be opened. Pts who progress on a frequency reduced arm may re-escalate to q6w therapy. The primary objective is to determine the optimal continuing dose frequency of pembro, defined as the longest dose interval non-inferior to standard therapy using 2-year survival as the primary outcome. Secondary endpoints include OS, PFS, ORR, duration of response, adverse events, quality of life and cost effectiveness. An exploratory sub-study will explore fundamental aspects of cancer immunotherapy and develop novel biomarkers of response, resistance, toxicity and patient suitability for dose frequency de-escalation. Recruitment is ongoing and the trial is open at 16 centres at time of submission. Clinical trial information: NCT05085028 .
    Type of Medium: Online Resource
    ISSN: 0732-183X , 1527-7755
    URL: Article
    DOI: 10.1200/JCO.2023.41.16_suppl.TPS9145
    RVK:
    XA 52760
    RVK:
    XA 10000
    Language: English
    Publisher: American Society of Clinical Oncology (ASCO)
    Publication Date: 2023
    detail.hit.zdb_id: 2005181-5
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  • 5
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    Practical approaches to Bayesian sample size determination in non‐inferiority trials with binary outcomes
    Wiley ; 2023
    In:  Statistics in Medicine Vol. 42, No. 8 ( 2023-04-15), p. 1127-1138
    Details
    In: Statistics in Medicine, Wiley, Vol. 42, No. 8 ( 2023-04-15), p. 1127-1138
    Abstract: Bayesian analysis of a non‐inferiority trial is advantageous in allowing direct probability statements to be made about the relative treatment difference rather than relying on an arbitrary and often poorly justified non‐inferiority margin. When the primary analysis will be Bayesian, a Bayesian approach to sample size determination will often be appropriate for consistency with the analysis. We demonstrate three Bayesian approaches to choosing sample size for non‐inferiority trials with binary outcomes and review their advantages and disadvantages. First, we present a predictive power approach for determining sample size using the probability that the trial will produce a convincing result in the final analysis. Next, we determine sample size by considering the expected posterior probability of non‐inferiority in the trial. Finally, we demonstrate a precision‐based approach. We apply these methods to a non‐inferiority trial in antiretroviral therapy for treatment of HIV‐infected children. A predictive power approach would be most accessible in practical settings, because it is analogous to the standard frequentist approach. Sample sizes are larger than with frequentist calculations unless an informative analysis prior is specified, because appropriate allowance is made for uncertainty in the assumed design parameters, ignored in frequentist calculations. An expected posterior probability approach will lead to a smaller sample size and is appropriate when the focus is on estimating posterior probability rather than on testing. A precision‐based approach would be useful when sample size is restricted by limits on recruitment or costs, but it would be difficult to decide on sample size using this approach alone.
    Type of Medium: Online Resource
    ISSN: 0277-6715 , 1097-0258
    URL: Issue
    URL: Article
    DOI: 10.1002/sim.v42.8
    DOI: 10.1002/sim.9661
    RVK:
    XA 10000
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 1491221-1
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  • 6
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    Initiation and continuity of maternal healthcare: examining the role of vouchers and user-fee removal on maternal health service use in Kenya
    Oxford University Press (OUP) ; 2019
    In:  Health Policy and Planning Vol. 34, No. 2 ( 2019-03-01), p. 120-131
    Details
    In: Health Policy and Planning, Oxford University Press (OUP), Vol. 34, No. 2 ( 2019-03-01), p. 120-131
    Type of Medium: Online Resource
    ISSN: 0268-1080 , 1460-2237
    URL: Article
    DOI: 10.1093/heapol/czz004
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 1484858-2
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  • 7
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    Online Resource
    Investigating the inequalities in route to diagnosis amongst patients with diffuse large B-cell or follicular lymphoma in England
    Springer Science and Business Media LLC ; 2021
    In:  British Journal of Cancer Vol. 125, No. 9 ( 2021-10-26), p. 1299-1307
    Details
    In: British Journal of Cancer, Springer Science and Business Media LLC, Vol. 125, No. 9 ( 2021-10-26), p. 1299-1307
    Abstract: Diagnostic delay is associated with lower chances of cancer survival. Underlying comorbidities are known to affect the timely diagnosis of cancer. Diffuse large B-cell (DLBCL) and follicular lymphomas (FL) are primarily diagnosed amongst older patients, who are more likely to have comorbidities. Characteristics of clinical commissioning groups (CCG) are also known to impact diagnostic delay. We assess the association between comorbidities and diagnostic delay amongst patients with DLBCL or FL in England during 2005–2013. Methods Multivariable generalised linear mixed-effect models were used to assess the main association. Empirical Bayes estimates of the random effects were used to explore between-cluster variation. The latent normal joint modelling multiple imputation approach was used to account for partially observed variables. Results We included 30,078 and 15,551 patients diagnosed with DLBCL or FL, respectively. Amongst patients from the same CCG, having multimorbidity was strongly associated with the emergency route to diagnosis (DLBCL: odds ratio 1.56, CI 1.40–1.73; FL: odds ratio 1.80, CI 1.45–2.23). Amongst DLBCL patients, the diagnostic delay was possibly correlated with CCGs that had higher population densities. Conclusions Underlying comorbidity is associated with diagnostic delay amongst patients with DLBCL or FL. Results suggest a possible correlation between CCGs with higher population densities and diagnostic delay of aggressive lymphomas.
    Type of Medium: Online Resource
    ISSN: 0007-0920 , 1532-1827
    URL: Article
    DOI: 10.1038/s41416-021-01523-6
    RVK:
    XA 33500
    RVK:
    XA 10000
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2002452-6
    detail.hit.zdb_id: 80075-2
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  • 8
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    Online Resource
    Excess Mortality by Multimorbidity, Socioeconomic, and Healthcare Factors, amongst Patients Diagnosed with Diffuse Large B-Cell or Follicular Lymphoma in England
    MDPI AG ; 2021
    In:  Cancers Vol. 13, No. 22 ( 2021-11-19), p. 5805-
    Details
    In: Cancers, MDPI AG, Vol. 13, No. 22 ( 2021-11-19), p. 5805-
    Abstract: (1) Background: Socioeconomic inequalities of survival in patients with lymphoma persist, which may be explained by patients’ comorbidities. We aimed to assess the association between comorbidities and the survival of patients diagnosed with diffuse large B-cell (DLBCL) or follicular lymphoma (FL) in England accounting for other socio-demographic characteristics. (2) Methods: Population-based cancer registry data were linked to Hospital Episode Statistics. We used a flexible multilevel excess hazard model to estimate excess mortality and net survival by patient’s comorbidity status, adjusted for sociodemographic, economic, and healthcare factors, and accounting for the patient’s area of residence. We used the latent normal joint modelling multiple imputation approach for missing data. (3) Results: Overall, 15,516 and 29,898 patients were diagnosed with FL and DLBCL in England between 2005 and 2013, respectively. Amongst DLBCL and FL patients, respectively, those in the most deprived areas showed 1.22 (95% confidence interval (CI): 1.18–1.27) and 1.45 (95% CI: 1.30–1.62) times higher excess mortality hazard compared to those in the least deprived areas, adjusted for comorbidity status, age at diagnosis, sex, ethnicity, and route to diagnosis. (4) Conclusions: Deprivation is consistently associated with poorer survival among patients diagnosed with DLBCL or FL, after adjusting for co/multimorbidities. Comorbidities and multimorbidities need to be considered when planning public health interventions targeting haematological malignancies in England.
    Type of Medium: Online Resource
    ISSN: 2072-6694
    URL: Article
    DOI: 10.3390/cancers13225805
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2527080-1
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  • 9
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    Online Resource
    Evaluating the impact of a maternal health voucher programme on service use before and after the introduction of free maternity services in Kenya: a quasi-experimental study
    BMJ ; 2018
    In:  BMJ Global Health Vol. 3, No. 2 ( 2018-05), p. e000726-
    Details
    In: BMJ Global Health, BMJ, Vol. 3, No. 2 ( 2018-05), p. e000726-
    Abstract: From 2006 to 2016, the Government of Kenya implemented a reproductive health voucher programme in select counties, providing poor women subsidised access to public and private sector care. In June 2013, the government introduced a policy calling for free maternity services to be provided in all public facilities. The concurrent implementation of these interventions presents an opportunity to provide new insights into how users adapt to a changing health financing and service provision landscape. Methods We used data from three cross-sectional surveys to assess changes over time in use of 4+ antenatal care visits, facility delivery, postnatal care and maternal healthcare across the continuum among a sample of predominantly poor women in six counties. We conducted a difference-in-differences analysis to estimate the impact of the voucher programme on these outcomes, and whether programme impact changed after free maternity services were introduced. Results Between the preintervention/roll-out phase and full implementation, the voucher programme was associated with a 5.5% greater absolute increase in use of facility delivery and substantial increases in use of the private sector for all services. After free maternity services were introduced, the voucher programme was associated with a 5.7% higher absolute increase in use of the recommended package of maternal health services; however, disparities in access to facility births between voucher and comparison counties declined. Increased use of private sector services by women in voucher counties accounts for their greater access to care across the continuum. Conclusions Our findings show that the voucher programme is associated with a modest increase in women’s use of the full continuum of maternal health services at the recommended timings after free maternity services were introduced. The greater use of private sector services in voucher counties also suggests that there is need to expand women’s access to acceptable and affordable providers.
    Type of Medium: Online Resource
    ISSN: 2059-7908
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.1136/bmjgh-2018-000726
    DOI: 10.1136/bmjgh-2018-000726.supp1
    DOI: 10.1136/bmjgh-2018-000726.supp2
    Language: English
    Publisher: BMJ
    Publication Date: 2018
    detail.hit.zdb_id: 2851843-3
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  • 10
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    Comparison of the working alliance in blended cognitive behavioral therapy and treatment as usual for depression in Europe: Secondary data analysis from the E-COMPARED randomized controlled trial (Preprint)
    JMIR Publications Inc. ; 2023
    In:  Journal of Medical Internet Research
    Details
    In: Journal of Medical Internet Research, JMIR Publications Inc.
    Type of Medium: Online Resource
    ISSN: 1438-8871
    URL: Article
    DOI: 10.2196/47515
    Language: English
    Publisher: JMIR Publications Inc.
    Publication Date: 2023
    detail.hit.zdb_id: 2028830-X
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