Ross Harris

Published evidence suggests that aspects of trial design lead to biased intervention effect estimates, but findings from different studies are inconsistent. This study combined data from 7 meta-epidemiologic studies and removed overlaps to derive a final data set of 234 unique meta-analyses containing 1973 trials. Outcome measures were classified as "mortality," "other objective," "or subjective," and Bayesian hierarchical models were used to estimate associations of trial characteristics with average bias and between-trial heterogeneity. Intervention effect estimates seemed to be exaggerated in trials with inadequate or unclear (vs. adequate) random-sequence generation (ratio of odds ratios, 0.89 [95% credible interval {CrI}, 0.82 to 0.96]) and with inadequate or unclear (vs. adequate) allocation concealment (ratio of odds ratios, 0.93 [CrI, 0.87 to 0.99]). Lack of or unclear double-blinding (vs. double-blinding) was associated with an average of 13% exaggeration of intervention effects (ratio of odds ratios, 0.87 [CrI, 0.79 to 0.96]), and between-trial heterogeneity was increased for such studies (SD increase in heterogeneity, 0.14 [CrI, 0.02 to 0.30]). For each characteristic, average bias and increases in between-trial heterogeneity were driven primarily by trials with subjective outcomes, with little evidence of bias in trials with objective and mortality outcomes. This study is limited by incomplete trial reporting, and findings may be confounded by other study design characteristics. Bias associated with study design characteristics may lead to exaggeration of intervention effect estimates and increases in between-trial heterogeneity in trials reporting subjectively assessed outcomes.

Latent tuberculosis infection (LTBI) is characterised by the presence of immune responses to previously acquired Mycobacterium tuberculosis infection without clinical evidence of active tuberculosis (TB). Here we report evidence-based guidelines from the World Health Organization for a public health approach to the management of LTBI in high risk individuals in countries with high or middle upper income and TB incidence of <100 per 100 000 per year. The guidelines strongly recommend systematic testing and treatment of LTBI in people living with HIV, adult and child contacts of pulmonary TB cases, patients initiating anti-tumour necrosis factor treatment, patients receiving dialysis, patients preparing for organ or haematological transplantation, and patients with silicosis. In prisoners, healthcare workers, immigrants from high TB burden countries, homeless persons and illicit drug users, systematic testing and treatment of LTBI is conditionally recommended, according to TB epidemiology and resource availability. Either commercial interferon-gamma release assays or Mantoux tuberculin skin testing could be used to test for LTBI. Chest radiography should be performed before LTBI treatment to rule out active TB disease. Recommended treatment regimens for LTBI include: 6 or 9 month isoniazid; 12 week rifapentine plus isoniazid; 3-4 month isoniazid plus rifampicin; or 3-4 month rifampicin alone.

OBJECTIVES: To determine whether BCG vaccination protects against Mycobacterium tuberculosis infection as assessed by interferon γ release assays (IGRA) in children. DESIGN: Systematic review and meta-analysis. Searches of electronic databases 1950 to November 2013, checking of reference lists, hand searching of journals, and contact with experts. SETTING: Community congregate settings and households. INCLUSION CRITERIA: Vaccinated and unvaccinated children aged under 16 with known recent exposure to patients with pulmonary tuberculosis. Children were screened for infection with M tuberculosis with interferon γ release assays. DATA EXTRACTION: Study results relating to diagnostic accuracy were extracted and risk estimates were combined with random effects meta-analysis. RESULTS: The primary analysis included 14 studies and 3855 participants. The estimated overall risk ratio was 0.81 (95% confidence interval 0.71 to 0.92), indicating a protective efficacy of 19% against infection among vaccinated children after exposure compared with unvaccinated children. The observed protection was similar when estimated with the two types of interferon γ release assays (ELISpot or QuantiFERON). Restriction of the analysis to the six studies (n=1745) with information on progression to active tuberculosis at the time of screening showed protection against infection of 27% (risk ratio 0.73, 0.61 to 0.87) compared with 71% (0.29, 0.15 to 0.58) against active tuberculosis. Among those infected, protection against progression to disease was 58% (0.42, 0.23 to 0.77). CONCLUSIONS: BCG protects against M tuberculosis infection as well as progression from infection to disease.Trial registration PROSPERO registration No CRD42011001698 (www.crd.york.ac.uk/prospero/).

Background: The SARS-CoV-2 Delta (B.1.617.2) variant was first detected in England in March 2021. It has since rapidly become the predominant lineage, owing to high transmissibility. It is suspected that the Delta variant is associated with more severe disease than the previously dominant Alpha (B.1.1.7) variant. Methods: Individual-level data on 43,338 COVID-19-positive cases (median age 31 years, inter-quartile range 17-43) in England between 29 March and 23 May 2021 and whose positive specimen had undergone whole genome sequencing were linked to routine healthcare datasets on vaccination, emergency care attendance, hospital admission and mortality. Hospital attendance and admission outcomes were compared between cases with sequencing-confirmed Delta and Alpha variants. Stratified Cox regression was used to adjust for age, sex, ethnicity, deprivation, recent international travel, area of residence, calendar period and vaccination status. Findings: There were 960 hospital admissions (2.5%) and 1,946 hospital admissions or emergency care attendances (4.5%) within 14 days. The adjusted hazard ratio (HR) for Delta vs Alpha cases was 2.26 (95% CI 1.32-3.89) of hospital admission within 14 days, and 1.45 (95% CI 1.08-1.95) of emergency care attendance or hospital admission within 14 days. Most cases were unvaccinated (32,078/43,338, 74%). The HRs for vaccinated Delta vs Alpha cases were similar to the HRs for unvaccinated Delta vs Alpha cases, but the precision for the vaccinated subgroup was low. Interpretation: This large national study found a higher emergency care attendance or hospital admission risk for COVID-19 cases infected with the Delta compared with the Alpha variant. While rates of hospital care among vaccinated individuals were low overall, results suggest that outbreaks of the Delta variant in unvaccinated populations may lead to a greater burden on healthcare services than the Alpha variant. Funding: Medical Research Council and MRC UKRI/DHSC NIHR.