Imbalance p values for baseline covariates in randomized controlled trials: a last resort for the use of p values? A pro and contra debate

Unravelling metabolite-microbiome interactions in inflammatory bowel disease through AI and interaction-based modelling

Inflammatory Bowel Diseases (IBDs) are chronic inflammatory disorders of the gastrointestinal tract and colon affecting approximately 7 million individuals worldwide. The knowledge of specific pathology and aetiological mechanisms leading to IBD is limited, however a reduced immune system, antibiotic use and reserved diet may initiate symptoms. Dysbiosis of the gut microbiome, and consequently a varied composition of the metabolome, has been extensively linked to these risk factors and IBD. Metagenomic sequencing and liquid-chromatography mass spectrometry (LC-MS) of N = 220 fecal samples by Fransoza et al., provided abundance data on microbial genera and metabolites for use in this study. Identification of differentially abundant microbes and metabolites was performed using a Wilcoxon test, followed by feature selection of random forest (RF), gradient-boosting (XGBoost) and least absolute shrinkage operator (LASSO) models. The performance of these features was then validated using RF models on the Human Microbiome Project 2 (HMP2) dataset and a microbial community (MICOM) model was utilised to predict and interpret the interactions between key microbes and metabolites. The Flavronifractor genus and microbes of the families Lachnospiraceae and Oscillospiraceae were found differential by all models. Metabolic pathways commonly influenced by such microbes in IBD were CoA biosynthesis, bile acid metabolism and amino acid production and degradation. This study highlights distinct interactive microbiome and metabolome profiles within IBD and the highly potential pathways causing disease pathology. It therefore paves way for future investigation into new therapeutic targets and non-invasive diagnostic tools for IBD.

The relationship between mindfulness and empathy with the oxytocinergic system in persons with schizophrenia spectrum disorders - A proof-of-concept randomized controlled trial (OXYGEN)

Background

The present study explored the feasibility and acceptability as well as the impact of mindfulness-based group therapy (MBGT) on oxytocin levels (OXT) and clinical parameters in outpatients with schizophrenia spectrum disorders (SSD).

Methods

In a randomized-controlled design, outpatients with SSD (N = 48) were assigned to either MBGT in addition to German university-level treatment as usual (MBGT+TAU; n = 25) or TAU (n = 23). At baseline and at four-week post-intervention, clinical parameters and OXT levels were determined.

Results

Results indicate high feasibility and acceptance with a 95.7% adherence- and 94% retention- rate of MBGT in SSD. While no significant changes in empathy were observed, MBGT+TAU demonstrated a significant reduction in positive symptoms (Positive and Negative Syndrom Scale) compared to TAU at post-intervention. OXT levels were significantly increased in MBGT+TAU at post-intervention, suggesting a potential link between mindfulness and the oxytocinergic system in SSD. Additionally, improvements in various clinical parameters were indicated.

Conclusion

The study contributes to the growing evidence supporting feasibility, acceptability, and positive effects of MBGT in outpatients with SSD, emphasizing the need for further research to solidify these findings. Overall, this work sheds first evidence on the intersection of mindfulness, oxytocin, and clinical outcomes in SSD.

Bias in published randomized trials that compare collagenase injection with percutaneous needle fasciotomy in the treatment of Dupuytren disease: a systematic review

Purpose

Controversy exists regarding the comparative efficacy of collagenase injection and percutaneous needle fasciotomy in the treatment of Dupuytren contracture. The randomized controlled trials (RCTs) that have compared the two treatment methods have reported results mostly implying similar treatment efficacy, durability, and complications. We aimed to review these RCTs regarding methodical quality and risk of bias.

Methods

We searched PubMed and Cochrane Library databases up to May 2023. All RCTs comparing collagenase injection with needle fasciotomy were included. Eligible articles were reviewed by two researchers, of whom one was blinded to each article's title, authors, year of publication, journal, and source of the studies. To assess methodical quality, we used the modified Jadad scale yielding a score of 0 (lowest quality) to 5 (highest quality). We assessed risk of bias with the Cochrane risk-of-bias tool (RoB 2).

Results

Five studies were eligible, comprising 204 patients treated with collagenase injection and 209 patients treated with needle fasciotomy. The modified Jadad score ranged from 1 to 2 points in the five studies, and the overall risk of bias was high in all studies. Pretrial protocols could be retrieved for only two studies, revealing important discrepancies with the published articles.

Conclusion

The published RCTs that have compared collagenase injection with needle fasciotomy in the treatment of Dupuytren contracture demonstrate a high risk of bias.

Evidence and risk indicators of non-random sampling in clinical trials in implant dentistry: A systematic appraisal

Aim

Analysis of distribution of p‐values of continuous differences between test and controls after randomization provides evidence of unintentional error, non‐random sampling, or data fabrication in randomized controlled trials (RCTs). We assessed evidence of highly unusual distributions of baseline characteristics of subjects enrolled in clinical trials in implant dentistry.

Materials and methods

RCTs published between 2005 and 2020 were systematically searched in Pubmed, Embase, and Cochrane databases. Baseline patient data were extracted from full text articles by two independent assessors. The hypothesis of non‐random sampling was tested by comparing the expected and the observed distribution of the p‐values of differences between test and controls after randomization.

Results

One‐thousand five‐hundred and thirty‐eight unique RCTs were identified, of which 409 (26.6%) did not report baseline characteristics of the population, and 671 (43.6%) reported data in forms other than mean and standard deviation and could not be used to assess their random sampling. Four‐hundred and fifty‐eight trials with 1449 baseline variables in the form of mean and standard deviation were assessed. The study observed an over‐representation of very small p‐values [<.001, 1.38%, 95% confidence interval (CI) 0.85–2.12 compared to the expected 0.10%, 95% CI 0.00–0.26]. No evidence of over‐representation of larger p‐values was observed. Unusual distributions were present in 2.38% of RCTs and more frequent in non‐registered trials, in studies supported by non‐industry funding, and in multi‐centre RCTs.

Conclusions

The inability to assess random sampling due to insufficient reporting in 26.6% of trials requires attention. In trials reporting suitable baseline data, unusual distributions were uncommon, and no evidence of data fabrication was detected, but there was evidence of non‐random sampling. Continued efforts are necessary to ensure high integrity and trust in the evidence base of the field.

Effect of a Community Health Worker-Delivered Parental Education and Counseling Intervention on Anemia Cure Rates in Rural Indian Children: A Pragmatic Cluster Randomized Clinical Trial

IMPORTANCE

Iron deficiency anemia, the largest cause of anemia worldwide, adversely affects cognitive development in children. Moreover, the imperceptible childhood anemia prevalence reduction in response to anemia control measures is associated with tremendous social and economic cost.

OBJECTIVE

To evaluate the effects of community-based parental education/counseling when combined with usual treatment on children's anemia cure rate.

DESIGN, SETTING, AND PARTICIPANTS

A pragmatic cluster randomized clinical trial in children aged 12 to 59 months from 55 villages from the rural Chamrajnagar district in southern India was conducted between November 2014 and July 2015; 6-month follow-up ended in January 2016. Villages were randomly assigned to either usual treatment (n = 27) or to the intervention (n = 28). Among 1144 participating children, 534 were diagnosed as having anemia (hemoglobin levels <11 g/dL and >7.9 g/dL; to convert to grams per liter, multiply by 10) and constituted the study sample in this analysis. Data were analyzed between July 2016 and September 2017.

INTERVENTIONS

Iron and folic acid (IFA), 20 mg/d, 5 times daily per week, for 5 months (usual treatment) or health worker-delivered education/counseling combined with usual treatment (intervention).

MAIN OUTCOMES AND MEASURES

The primary outcome was anemia cure rate defined as hemoglobin level at or greater than 11 g/dL during follow-up.

RESULTS

Of the children included in the study, the mean age was 30 months, with a slightly higher ratio of boys to girls. Of 534 children with anemia (intervention n = 303; usual treatment n = 231), 517 were reassessed after 6 months (intervention n = 298; usual treatment n = 219) while 17 were lost to follow-up (intervention n = 5 and usual treatment n = 12). Anemia cure rate was higher in children in the intervention group compared with children receiving usual treatment (55.7% [n = 166 of 298] vs 41.4% [n = 90 of 219]). The risk ratio derived through multilevel logistic regression was 1.37 (95% CI, 1.04-1.70); the model-estimated risk difference was 15.1% (95% CI, 3.9-26.3). Intervention-group children demonstrated larger mean hemoglobin increments (difference, intervention vs control: 0.25 g/dL; 95% CI, 0.07-0.44 g/dL) and improved IFA adherence (61.7%; 95% CI, 56.2-67.3 vs 48.4%; 95% CI, 41.7-55.1 consumed >75% of tablets provided). Adverse events were mild (intervention: 26.8%; 95% CI, 21.8-31.9 vs usual treatment: 21%; 95% CI, 15.6-26.4). To cure 1 child with anemia, 7 mothers needed to be counseled (number needed to treat: 7; 95% CI, 4-26).

CONCLUSIONS AND RELEVANCE

Parental education and counseling by a community health worker achieved perceivable gains in curing childhood anemia. Policy makers should consider this approach to enhance population level anemia control.

TRIAL REGISTRATION

ISRCTN identifier: ISRCTN68413407.

A Pilot Randomized Controlled Trial of a Web-Based Growth Mindset Intervention to Enhance the Effectiveness of a Smartphone App for Smoking Cessation

BACKGROUND

Although smartphone apps have shown promise for smoking cessation, there is a need to enhance their low engagement rates. This study evaluated the application of the growth mindset theory, which has demonstrated the potential to improve persistence in behavior change in other domains, as a means to improve engagement and cessation.

OBJECTIVE

This study aimed to explore the feasibility, utility, and efficacy of a Web-based growth mindset intervention for addiction when used alongside a smoking cessation app.

METHODS

Daily smokers (N=398) were all recruited on the Web and randomly assigned to receive either a cessation app alone or the app plus a Web-delivered growth mindset intervention. The primary outcome was engagement, that is, the number of log-ins to the smoking cessation app. The secondary outcome was 30-day point prevalence abstinence at 2-month follow-up collected through a Web-based survey.

RESULTS

The 2-month outcome data retention rate was 91.5% (364/398). In addition, 77.9% (310/398) of the participants in the experimental arm viewed at least 1 page of their growth mindset intervention, and 21.1% (84/398) of the group viewed all the growth mindset intervention. The intention-to-treat analysis did not show statistically significant differences between the experimental and comparison arms on log-ins to the app (19.46 vs 21.61; P=.38). The experimental arm had cessation rates, which trended higher than the comparison arm (17% vs 13%; P=.10). The modified intent-to-treat analysis, including only participants who used their assigned intervention at least once (n=115 in experimental group and n=151 in the control group), showed that the experimental arm had a similar number of log-ins (32.31 vs 28.48; P=.55) but significantly higher cessation rates (21% vs 13%; P=.03) than the comparison arm.

CONCLUSIONS

A growth mindset intervention for addiction did not increase engagement rates, although it may increase cessation rates when used alongside a smartphone app for smoking cessation. Future research is required to refine the intervention and assess efficacy with long-term follow-up to evaluate the efficacy of the mindset intervention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03174730; https://clinicaltrials.gov/ct2/show/NCT03174730.

Evidence that nonsignificant results are sometimes preferred: Reverse P-hacking or selective reporting?

There is increased concern about poor scientific practices arising from an excessive focus on P-values. Two particularly worrisome practices are selective reporting of significant results and 'P-hacking'. The latter is the manipulation of data collection, usage, or analyses to obtain statistically significant outcomes. Here, we introduce the novel, to our knowledge, concepts of selective reporting of nonsignificant results and 'reverse P-hacking' whereby researchers ensure that tests produce a nonsignificant result. We test whether these practices occur in experiments in which researchers randomly assign subjects to treatment and control groups to minimise differences in confounding variables that might affect the focal outcome. By chance alone, 5% of tests for a group difference in confounding variables should yield a significant result (P < 0.05). If researchers less often report significant findings and/or reverse P-hack to avoid significant outcomes that undermine the ethos that experimental and control groups only differ with respect to actively manipulated variables, we expect significant results from tests for group differences to be under-represented in the literature. We surveyed the behavioural ecology literature and found significantly more nonsignificant P-values reported for tests of group differences in potentially confounding variables than the expected 95% (P = 0.005; N = 250 studies). This novel, to our knowledge, publication bias could result from selective reporting of nonsignificant results and/or from reverse P-hacking. We encourage others to test for a bias toward publishing nonsignificant results in the equivalent context in their own research discipline.