Extracting data from graphs: A case-study on animal research with implications for meta-analyses

A meta-analysis of the placebo response in vitiligo: Causes and consequences for the interpretation of clinical trials

The current understanding of the placebo response in vitiligo is limited. Nonetheless, it is difficult to compare the outcomes of vitiligo trials if the repigmentation rates in placebo patients vary significantly. We conducted a meta-analysis of the placebo response in vitiligo trials. Overall, repigmentation rates in patients receiving placebo were 22%, ranging substantially from 0 to 60%. Repigmentation (>25%) was still relatively common for placebo (9.35%), but fell to 5% when >50% improvement was analyzed. Higher frequencies of placebo responses correlated with more repigmentation in the intervention groups. Facial vitiligo and sunlight exposure was linked to higher placebo responses. Roughly estimating the amount of improvement using quartiles (0-25, 25%-50%, 50%-75%, 75%-100% repigmentation) resulted in higher placebo rates compared to other assessment methods. In clinical studies with older patients, the ratio of placebo reactions to treatment responses was higher. This is likely because clinical trials with older patients reported less repigmentation after treatment than studies with younger patients. The percentual difference in affected body surface area during the study period ranged from 6.2% worsening to 17.6% improvement in the placebo groups. This high variability in placebo responses illustrates the need for standardized outcome measures and more head-to-head trials in vitiligo.

A Systematic Review of the Effect of Cystic Fibrosis Treatments on the Nasal Potential Difference Test in Animals and Humans

To address unmet treatment needs in cystic fibrosis (CF), preclinical and clinical studies are warranted. Because it directly reflects the function of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR), the nasal potential difference test (nPD) can not only be used as a reliable diagnostic test for CF but also to assess efficacy of experimental treatments. We performed a full comprehensive systematic review of the effect of CF treatments on the nPD compared to control conditions tested in separate groups of animal and human subjects. Our review followed a preregistered protocol. We included 34 references: 20 describing mouse studies, 12 describing human studies, and 2 describing both. We provide a comprehensive list of these studies, which assessed the effects of antibiotics, bone marrow transplant, CFTR protein, CFTR RNA, directly and indirectly CFTR-targeting drugs, non-viral and viral gene transfer, and other treatments. Our results support the nPD representing a reliable method for testing treatment effects in both animal models and human patients, as well as for diagnosing CF. However, we also observed the need for improved reporting to ensure reproducibility of the experiments and quantitative comparability of the results within and between species (e.g., with meta-analyses). Currently, data gaps warrant further primary studies.

Effect estimates can be accurately calculated with data digitally extracted from interrupted time series graphs

Interrupted time series (ITS) studies are frequently used to examine the impact of population-level interventions or exposures. Systematic reviews with meta-analyses including ITS designs may inform public health and policy decision-making. Re-analysis of ITS may be required for inclusion in meta-analysis. While publications of ITS rarely provide raw data for re-analysis, graphs are often included, from which time series data can be digitally extracted. However, the accuracy of effect estimates calculated from data digitally extracted from ITS graphs is currently unknown. Forty-three ITS with available datasets and time series graphs were included. Time series data from each graph was extracted by four researchers using digital data extraction software. Data extraction errors were analysed. Segmented linear regression models were fitted to the extracted and provided datasets, from which estimates of immediate level and slope change (and associated statistics) were calculated and compared across the datasets. Although there were some data extraction errors of time points, primarily due to complications in the original graphs, they did not translate into important differences in estimates of interruption effects (and associated statistics). Using digital data extraction to obtain data from ITS graphs should be considered in reviews including ITS. Including these studies in meta-analyses, even with slight inaccuracy, is likely to outweigh the loss of information from non-inclusion.

Microbial dysbiosis in oral squamous cell carcinoma: A systematic review and meta-analysis

Objective

The aim of this study was to summarize previously published data and assess the alterations in the composition of the oral microbiome in OSCC using a systematic review and meta-analysis.

Design

Electronic databases were systematically searched for studies on the oral microbiome in OSCC published before December 2021. Qualitative assessments of compositional variations at the phylum level were performed. The meta-analysis on abundance changes of bacteria genera was performed via a random-effects model.

Results

A total of 18 studies involving 1056 participants were included. They consisted of two categories of studies: 1) case-control studies (n = 9); 2) nine studies that compared the oral microbiome between cancerous tissues and paired paracancerous tissues. At the phylum level, enrichment of Fusobacteria but depletion in Actinobacteria and Firmicutes in the oral microbiome was demonstrated in both categories of studies. At the genus level, Fusobacterium showed an increased abundance in OSCC patients (SMD = 0.65, 95% CI: 0.43-0.87, Z = 5.809, P = 0.000) and in cancerous tissues (SMD = 0.54, 95% CI: 0.36-0.72, Z = 5.785, P = 0.000). The abundance of Streptococcus was decreased in OSCC (SMD = -0.46, 95% CI: -0.88-0.04, Z = -2.146, P = 0.032) and in cancerous tissues (SMD = -0.45, 95% CI: -0.78-0.13, Z = -2.726, P = 0.006).

Conclusions

Disturbances in the interactions between enriched Fusobacterium and depleted Streptococcus may participate in or prompt the occurrence and development of OSCC and could be potential biomarkers for detection of OSCC.

A meta-analysis of chemokines in vitiligo: Recruiting immune cells towards melanocytes

Chemokine research offers insightful information on the pathogenesis of cutaneous immune disorders, such as vitiligo. Compared to cytokines, the higher detectable levels of chemokines display promising potential as future disease biomarkers. Nonetheless, some published study results are contradictory, which can be attributed to patient characteristics and methodological differences. In this study, a meta-analysis was performed to compare chemokine expression in blood and skin samples from vitiligo patients versus healthy controls. Furthermore, the relationship between chemokine expression and disease activity was evaluated. Chemokine levels were investigated in 15 articles in the circulation and in 9 articles in vitiligo skin. Overall, some clear trends were observed. CXCR3 signaling by CXCL10 and CXCL9 has been confirmed by several reports, although CXCL10 showed more robust findings in blood samples. In this meta-analysis, CCL5, CXCL8, CXCL12, and CXCL16 levels were also significantly elevated. This indicates a complex immune pathway activation in vitiligo that overall supports a Th1-dominant response. Chemokines linked to the Th2 and Th17 pathways were less prevalent. Despite these findings, study protocols that examine a broader range of chemokines are encouraged, because current research is mostly focused on a small number of chemokines that were differentially expressed in previous studies.

Neurological and psychiatric presentations associated with human monkeypox virus infection: A systematic review and meta-analysis

Background

Neuropsychiatric presentations of monkeypox (MPX) infection have not been well characterised, despite evidence of nervous system involvement associated with the related smallpox infection.

Methods

In this pre-registered (PROSPERO ID 336649) systematic review and meta-analysis, we searched MEDLINE, EMBASE, PsycINFO, AMED and the preprint server MedRxiv up to 31/05/2022. Any study design of humans infected with MPX that reported a neurological or psychiatric presentation was included. For eligible symptoms, we calculated a pooled prevalence using an inverse variance approach and corresponding 95% confidence intervals. The degree of variability that could be explained by between-study heterogeneity was assessed using the I 2 statistic. Risk of bias was assessed with the Newcastle Ottawa Scale and the Joanna Briggs Institute quality assessment tool.

Findings

From 1705 unique studies, we extracted data on 19 eligible studies (1512 participants, 1031 with confirmed infection using CDC criteria or PCR testing) most of which were cohort studies and case series with no control groups. Study quality was generally moderate. Three clinical features were eligible for meta-analysis: seizure 2.7% (95% CI 0.7-10.2%, I2 0%), confusion 2.4% (95% CI 1.1-5.2%, I2 0%) and encephalitis 2.0% (95% 0.5-8.2%, I2 55.8%). Other frequently reported symptoms included myalgia, headache and fatigue, where heterogeneity was too high for estimation of pooled prevalences, possibly as a result of differences in viral clades and study methodology.

Interpretation

There is preliminary evidence for a range of neuropsychiatric presentations including severe neurological complications (encephalitis and seizure) and nonspecific neurological features (confusion, headache and myalgia). There is less evidence regarding the psychiatric presentations or sequelae of MPX. This may warrant surveillance within the current MPX outbreak, with prospective longitudinal studies evaluating the mid- to long-term sequelae of the virus. Robust methods to evaluate the potential causality of MPX with these clinical features are required. More evidence is necessary to explain heterogeneity in prevalence estimates.

Funding

UKRI/MRC (MR/V03605X/1), MRC-CSF (MR/V007181/1), MRC/AMED (MR/T028750/1) and the Wellcome Trust (102186/B/13/Z) and (102186/B/13/Z) and UCLH BRC.

Effects of Progesterone on Preclinical Animal Models of Traumatic Brain Injury: Systematic Review and Meta-analysis

Since the publication of two phase III clinical trials not supporting the use of progesterone in patients with traumatic brain injury (TBI), several possible explanations have been postulated, including limitations in the analysis of results from preclinical evidence. Therefore, to address this question, a systematic review and meta-analysis was performed to evaluate the effects of progesterone as a neuroprotective agent in preclinical animal models of TBI. A total of 48 studies were included for review: 29 evaluated brain edema, 21 evaluated lesion size, and 0 studies reported the survival rate. In the meta-analysis, it was found that progesterone reduced brain edema (effect size - 1.73 [- 2.02, - 1.44], p < 0.0001) and lesion volume (effect size - 0.40 [- 0.65, - 0.14], p = 0.002). Lack of details in the studies hindered the assessment of risk of bias (through the SYRCLE tool). A funnel plot asymmetry was detected, suggesting a possible publication bias. In conclusion, preclinical studies show that progesterone has an anti-edema effect in animal models of TBI, decreasing lesion volume or increasing remaining tissue. However, more studies are needed using assessing methods with lower risk of histological artifacts.

Tumour burden and antigen-specific T cell magnitude represent major parameters for clinical response to cancer vaccine and TCR-engineered T cell therapy

BACKGROUND

Cancer vaccines and T-cell receptor (TCR) engineered T cells (Tg-T cell) represent two different therapeutic strategies that can target the same tumour epitopes. The first approach requires the induction of a specific immune response in patients, while the second relies on the efficacy of adoptively transferred T cells. Because the ratio of antigen-specific T cells to tumour cells engaged by these strategies may influence the clinical outcome, we evaluated the efficacy of these two therapeutic approaches in solid tumours according to the tumour burden.

METHODS

We performed a meta-analysis restricted to the therapeutic vaccine and Tg-T cell trials, presenting annotated individual clinical data. We adapted a previously published mathematical model for tumour immune dynamics to estimate the clinical impact of the number of specific T cells in regard to the tumour burden.

RESULTS

A focused analysis of Tg-T cell studies revealed that clinical responses were mostly observed with the highest doses of infused T cells, suggesting that exceeding a threshold of effector T cells may be required for clinical efficacy. In silico modelling of cancer vaccine and Tg-T cell therapies starting at different tumour burdens showed that therapeutic vaccines control low or moderate tumour burdens, whereas increasing the amount of infused Tg-T cells succeeds in controlling high tumour masses.

CONCLUSION

We propose that therapeutic vaccines should be considered in the context of low or moderate tumour burden, whereas Tg-T cell strategies may be more adapted for the treatment of advanced metastatic diseases.

Biomarkers that correlate with active pulmonary tuberculosis treatment response: a systematic review and meta-analysis

Current WHO recommendations for monitoring treatment response in adult pulmonary tuberculosis (TB) are sputum smear microscopy and/or culture conversion at the end of the intensive phase of treatment. These methods either have suboptimal accuracy or a long turnaround time. There is a need to identify alternative biomarkers to monitor TB treatment response. We conducted a systematic review of active pulmonary TB treatment monitoring biomarkers. We screened 9,739 articles published between 1 January 2008 and 31 December 2020, of which 77 met the inclusion criteria. When studies quantitatively reported biomarker levels, we meta-analyzed the average fold change in biomarkers from pretreatment to week 8 of treatment. We also performed a meta-analysis pooling the fold change since the previous time point collected. A total of 81 biomarkers were identified from 77 studies. Overall, these studies exhibited extensive heterogeneity with regard to TB treatment monitoring study design and data reporting. Among the biomarkers identified, C-reactive protein (CRP), interleukin-6 (IL-6), interferon gamma-induced protein 10 (IP-10), and tumor necrosis factor alpha (TNF-α) had sufficient data to analyze fold changes. All four biomarker levels decreased during the first 8 weeks of treatment relative to baseline and relative to previous time points collected. Based on limited data available, CRP, IL-6, IP-10, and TNF-α have been identified as biomarkers that should be further explored in the context of TB treatment monitoring. The extensive heterogeneity in TB treatment monitoring study design and reporting is a major barrier to evaluating the performance of novel biomarkers and tools for this use case. Guidance for designing and reporting treatment monitoring studies is urgently needed.

Extracting data from graphs: A case-study on animal research with implications for meta-analyses

Systematic reviews with meta-analyses are powerful tools that can answer research questions based on data from published studies. Ideally, all relevant data is directly available in the text or tables, but often it is only presented in graphs. In those cases, the data can be extracted from graphs, but this potentially introduces errors. Here, we investigate to what extent the extracted outcome and error values differ from the original data and if these differences could affect the results of a meta-analysis. Six extractors extracted 36 outcome values and corresponding errors from 22 articles. Differences between extractors were compared using overall concordance correlation coefficients (OCCC), differences between the original and extracted data were compared using concordance correlation coefficients (CCC). To test the possible influence on meta-analyses, random-effects meta-analyses on mean difference comparing original and extracted data were performed. The OCCCs and CCCs were high for both outcome values and errors, CCCs were >0.99 for the outcome and >0.92 for errors. The meta-analyses showed that the overall effect on outcome was very small (median: 0.025, interquartile range: 0.016-0.046). Therefore, data extraction from graphs is a good method to harvest data if it is not provided in the text or tables, and the original authors cannot provide the data.