Problems caused by heterogeneity in meta-analysis: a case study of acupuncture trials

Neuroprotective Effect and Possible Mechanisms of Berberine in Diabetes-Related Cognitive Impairment: A Systematic Review and Meta-Analysis of Animal Studies

Berberine, the main bioactive component of Coptis chinensis Franch., is widely used in the treatment of diabetes. Previous studies have reported that berberine supplementation may play a multitarget therapeutic role in diabetes-related cognitive impairment (DCI). This systematic review and meta-analysis evaluated the effect and possible mechanisms of berberine in animal models of DCI. Relevant studies were searched through PubMed, Web of Science, Embase, and three Chinese databases (CNKI, Wanfang, and VIP) until March 2022. Twenty studies involving 442 animals were included, and SYRCLE’s risk of bias tool was used to assess methodological quality. The statistical analysis was performed using STATA 15.0 to calculate the weighted standard mean difference (SMD) with a 95% confidence interval (CI). The fasting blood glucose (FBG) and Morris water maze test (MWM) were the main outcomes to be analyzed. The overall results showed that berberine could significantly improve FBG, escape latency, the times of crossing the platform, the time spent in the target quadrant, serum insulin, 2hBG of oral glucose tolerance test (OGTT), amyloid β (Aβ), acetylcholinesterase (AChE), oxidative stress, and inflammation levels. The present meta-analysis demonstrated that berberine could not only lower blood glucose levels but also improve learning and memory in DCI animal models, which might involve regulating glucose and lipid metabolism, improving insulin resistance, anti-oxidation, anti-neuroinflammation, inhibiting endoplasmic reticulum (ER) stress; and improving the cholinergic system. However, additional attention should be paid to these outcomes due to the significant heterogeneity.

Oral health, academic performance, and school absenteeism in children and adolescents: A systematic review and meta-analysis

BACKGROUND

The authors conducted a systematic review and meta-analysis to provide a summary estimate of the association between oral health and academic performance.

TYPES OF STUDIES REVIEWED

The authors conducted a systematic search of PubMed, Embase, and Google Scholar for studies on oral health, school absence, and academic achievement published in English from January 1945 through December 2017. Exposures included subjectively or objectively measured caries, oral pain, and periodontitis. Outcomes included school absence and school achievement.

RESULTS

The authors screened a total of 2,041 studies, from which they extracted data from 14 studies of 139,989 children (12 cross-sectional studies, 1 case-control study, and 1 longitudinal study). Five studies had school absence as the primary outcome, and 7 studies had student achievement as the primary outcome. Three studies included both outcomes. The authors found no studies for periodontitis. The average modified Newcastle-Ottawa Scale score was 3.93. The authors rated 10 studies as having a low risk of bias and 4 as having a high risk of bias. Qualitative synthesis suggested that poor oral health may have negative effects on student absenteeism and achievement, but study quality was highly variable. Results from meta-analyses indicated that poor oral health was significantly associated with increased odds of poor academic performance (pooled odds ratio, 1.52; 95% confidence interval, 1.20 to 1.83) and absenteeism (pooled odds ratio, 1.43; 95% confidence interval, 1.24 to 1.63).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Increased focus on the broader implications of improvements in oral health for children, such as educational or socioemotional development, is of further interest to practicing dentists owing to the greater connection between oral health and general health. The authors of this study found that caries or tooth pain had a negative association with academic achievement and school absenteeism. However, study quality was limited by inconsistent exposure and outcome definitions and a predominance of cross-sectional designs. Thus, causal conclusions are not supported.

Manual Acupuncture for Myofascial Pain Syndrome: A Systematic Review and Meta-Analysis

Objective

To assess the efficacy of manual acupuncture (MA) in the treatment of myofascial pain syndrome (MPS).

Methods

We searched for randomised controlled trials (RCTs) comparing MA versus sham/placebo or no intervention in patients with MPS in the following databases from inception to January 2016: PubMed; Cochrane Library; Embase; Web of Science; and China Biology Medicine. Two reviewers independently screened the literature extracted data and assessed the quality of the included studies according to the risk of bias tool recommended by the Cochrane Handbook (V.5.1.0). Then, a meta-analysis was performed using RevMan 5.3 software.

Results

Ten RCTs were combined in a meta-analysis of MA versus sham, which showed a favourable effect of MA on pain intensity after stimulation of myofascial trigger points (MTrPs; standardised mean difference (SMD) −0.90, 95% CI −1.48 to −0.32; p=0.002) but not traditional acupuncture points (p>0.05). Benefit was seen both after a single treatment (SMD −1.05, 95% CI −1.84 to −0.27; p=0.009) and course of eight sessions (weighted mean difference (WMD) −1.96, 95% CI −2.72 to −1.20; p<0.001). We also found a significant increase in pressure pain threshold following MA stimulation of MTrPs (WMD 1.00, 95% CI 0.32 to 1.67; p=0.004). Two of the included studies reported mild adverse events (soreness/haemorrhage) secondary to MA.

Conclusions

Through stimulation of MTrPs, MA might be efficacious in terms of pain relief and reduction of muscle irritability in MPS patients. Additional well-designed/reported studies are required to determine the optimal number of sessions for the treatment of MPS.

A systematic review on the development of asthma and allergic diseases in relation to international immigration: the leading role of the environment confirmed

BACKGROUND

The prevalence of asthma and allergic diseases is rising worldwide. Evidence on potential causal pathways of asthma and allergies is growing, but findings have been contradictory, particularly on the interplay between allergic diseases and understudied social determinants of health like migration status. This review aimed at providing evidence for the association between migration status and asthma and allergies, and to explore the mechanisms between migration status and the development of asthma and allergies.

METHODS AND FINDINGS

Systematic review on asthma and allergies and immigration status in accordance with the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The pooled odds ratio (OR) of the prevalence of asthma in immigrants compared to the host population was 0.60 (95% CI 0.45-0.84), and the pooled OR for allergies was 1.01 (95% CI 0.62-1.69). The pooled OR for the prevalence of asthma in first generation versus second generation immigrants was 0.37 (95% CI 0.25-0.58). Comparisons between populations in their countries of origin and those that emigrated vary depending on their level of development; more developed countries show higher rates of asthma and allergies.

CONCLUSIONS

Our findings suggest a strong influence of the environment on the development of asthma and allergic diseases throughout the life course. The prevalence of asthma is generally higher in second generation than first generation immigrants. With length of residence in the host country the prevalence of asthma and allergic diseases increases steadily. These findings are consistent across study populations, host countries, and children as well as adults. Differences have been found to be significant when tested in a linear model, as well as when comparing between early and later age of migration, and between shorter and longer time of residence.