Background There are debates in acupuncture related systematic reviews and meta-analyses on whether searching Chinese databases to get more Chinese-language studies may increase the risk of bias and overestimate the effect size, and whether the treatment effects of acupuncture differ between Chinese and non-Chinese populations.Methods In this meta-epidemiological study, we searched the Cochrane library from its inception until December 2021, and identified systematic reviews and meta-analyses with acupuncture as one of the interventions. Paired reviewers independently screened the reviews and extracted the information. We repeated the meta-analysis of the selected outcomes to separately pool the results of Chinese- and non-Chinese-language acupuncture studies and presented the pooled estimates as odds ratios (OR) with 95% confidence interval (CI). We calculated the Ratio of ORs (ROR) by dividing the OR of the Chinese-language trials by the OR of the non-Chinese-language trials, and the ROR by dividing the OR of trials addressing Chinese population by the OR of trials addressing non-Chinese population. We explored whether the impact of a high risk of bias on the effect size differed between studies published in Chinese- and in non-Chinese-language, and whether the treatment effects of acupuncture differed between Chinese and non-Chinese population.Results We identified 84 Cochrane acupuncture reviews involving 33 Cochrane groups, of which 31 reviews (37%) searched Chinese databases. Searching versus not searching Chinese databases significantly increased the contribution of Chinese-language literature both to the total number of included trials (54% vs. 15%) and the sample size (40% vs. 15%). When compared with non-Chinese-language trials, Chinese-language trials were associated with a larger effect size (pooled ROR 0.51, 95% CI 0.29 to 0.91). We also observed a higher risk of bias in Chinese-language trials in blinding of participants and personnel (97% vs. 51%) and blinding of outcome assessment (93% vs. 47%). The higher risk of bias was associated with a larger effect estimate in both Chinese-language (allocation concealment: high/unclear risk vs. low risk, ROR 0.43, 95% CI 0.21 to 0.87) and non-Chinese-language studies (blinding of participants and personnel: high/unclear risk vs. low risk, ROR 0.41, 95% CI 0.23 to 0.74). However, we found no evidence that the higher risk of bias would increase the effect size of acupuncture in Chinese-language studies more often than in non-Chinese-language studies (the confidence intervals of all ROR in the high-risk group included 1, Table 3). We further found acupuncture appeared to be more effective in Chinese than in non-Chinese population (Table 4).Conclusions The findings of this study suggest the higher risk of bias may lead to an overestimation of the treatment effects of acupuncture but would not increase the treatment effects in Chinese-language studies more often than in other language studies. The difference in treatment effects of acupuncture was probably associated with differences in population characteristics.

We conducted the present bibliometric analysis to explore menopausal hormone therapy (MHT)-related research trends between 2000 and 2021. The Web of Science database was systematically searched from 2000 to 2021 to retrieve MHT-related publications. Visualization mapping and keyword cluster graphs were utilized to illustrate the research topics and hotpots. We included 11,616 MHT-related publications for this bibliometric analysis. The results showed that (1) MHT-related research had a very slow increase in the past 22 years, and the trend fluctuated. Sum of times cited and average citations per item had the same trend: a sharp decline from 2002 to 2003, and a rapid increase from 2003 to 2006, reaching the peak in 2006, then following a downward trend. The average H-index was 57, peaking in 2001; (2) the USA, the League of European Research Universities, and Dr. JoAann Manson from Harvard University contributed the most; (3) Menopause: The Journal of The North American Menopause Society had the most significant number of MHT-related publications; (4) the research hotpots primarily focused on MHT for treating menopausal symptoms and the impact of MHT on women's health. According to previous studies, MHT was the most effective treatment for managing vasomotor symptoms of menopause, but results from the clinical trials and observational studies regarding MHT adverse events remain inconsistent. Mechanisms are fundamental when clinical studies give conflicting results. Therefore, future studies should focus on adverse events and their mechanisms.