Assessing the risk of bias (RoB) in included studies is one of the key methodological aspects of systematic reviews. Cochrane systematic reviews appraise RoB of randomised controlled trials (RCTs) with the Cochrane RoB tool. Detailed instructions for using the Cochrane RoB tool are provided in the Cochrane Handbook for Systematic Reviews of Interventions (The Cochrane Handbook). The purpose of this study was to analyse whether Cochrane authors use adequate judgments about the RoB for random sequence generation of RCTs included in Cochrane reviews. We extracted authors’ judgments (high, low or unclear RoB) and supports for judgments (comments accompanying judgments which explain the rationale for a judgment) for random sequence generation of included RCTs from RoB tables of Cochrane reviews using automated data scraping. We categorised all supporting comments, analysed the number and type of various supporting comments and assessed adequacy of RoB judgment for randomisation in line with recommendations from the Cochrane Handbook. We analysed 10,103 RCTs that were included in 704 Cochrane reviews. For 5,706 RCTs, randomisation was not described, but for the remaining RCTs, it was indicated that randomisation was performed using computer/software/internet (N = 2,850), random number table (N = 883), mechanical method (N = 359) or it was incomplete/inappropriate (N = 305). Overall, 1,220/10,103 trials (12%) did not have a RoB judgment in line with Cochrane Handbook guidance about randomisation. The highest proportion of misjudgements was found for trials with high RoB (28%), followed by those with low (20%) or unclear (3%). Therefore, one in eight judgments for the analysed domain in Cochrane reviews was not in line with Cochrane Handbook, and one in four if the judgment was "high risk". Authors of Cochrane reviews often make judgments about the RoB related to random sequence generation that are not in line with instructions given in the Cochrane Handbook, which compromises the reliability of the systematic reviews. Our results can help authors of both Cochrane and non-Cochrane reviews which use Cochrane RoB tool to avoid making common mistakes when assessing RoB in included trials.

Background: Bias in randomized controlled trials (RCTs) can lead to underestimation or overestimation of the true effects of interventions. Surgical RCTs may suffer from the risk of bias (RoB) that is avoidable in trials of other interventions, and vice versa. We aimed to compare the adequacy of RoB assessments in surgical versus non-surgical RCTs included in Cochrane reviews and to assess the most common differences in those RoB assessments. Due to specificities of surgical trials, i.e. difficulties associated with blinding of surgical interventions, we hypothesized that assessments of surgical trials may be more adequate, compared to RCTs of non-surgical interventions. Methods: This was a methodological study, analyzing methods of published Cochrane systematic reviews. Data were extracted from RoB tables in Cochrane reviews (judgments and accompanying explanatory comment) for the following four RoB domains used in the 2011 Cochrane RoB tool: randomization, allocation concealment, blinding of participants and personnel, and blinding of outcome assessors. We defined adequate assessments as those that were in line with instructions from the Cochrane Handbook for Systematic Reviews of Interventions. The prevalence of adequate assessments was compared in surgical versus non-surgical trials. The most common differences in both groups of reviews were presented. Results: In 729 analyzed Cochrane reviews, there were 10,537 included trials. The prevalence of adequate RoB judgments made by Cochrane authors ranged from 87.9, 95%CI (87.3 to 88.6%) for randomization to 70.7, 95%CI (69.8 to 71.5%) for blinding of participants and personnel. For all analyzed RoB domains, the prevalence of adequate RoB domains was higher in surgical trials than in non-surgical trials. For two RoB domains assessing blinding, this difference between surgical and non-surgical trials was statistically significant (P < 0.001), while the difference was not significant for the RoB domain regarding randomization (P = 0.124) and allocation concealment (P = 0.039, β < 0.8). Conclusions: RoB judgments were more in line with instructions from the Cochrane Handbook when Cochrane reviews assessed surgical trials, compared to those that analyzed non-surgical interventions. However, further steps are warranted to scrutinize RoB assessment in trials of both surgical and non-surgical interventions.

Background: Initially, the Cochrane risk of bias (RoB) tool had a domain for “blinding of participants, personnel and outcome assessors”. In the 2011 tool, the assessment of blinding was split into two domains: blinding of participants and personnel (performance bias) and blinding of outcome assessors (detection bias). The aims of this study were twofold; first, to analyze the frequency of usage of the joint blinding domain (a single domain for performance and detection bias), and second, to assess the proportion of adequate assessments made in the joint versus single RoB domains for blinding by comparing whether authors’ RoB judgments were supported by explanatory comments in line with the Cochrane Handbook recommendations. Methods: We extracted information about the assessment of blinding from RoB tables (judgment, comment, and whether it was specified which outcome type; e.g., objective, subjective) of 729 Cochrane reviews published in 2015-2016. In the Cochrane RoB tool, judgment (low, unclear or high risk) needs to be accompanied by a transparent comment, in which authors provide a summary justifying RoB judgment, to ensure transparency in how these judgments were reached. We reassessed RoB based on the supporting comments reported in Cochrane RoB tables, in line with instructions from the Cochrane Handbook. Then, we compared our new assessments to judgments made by Cochrane authors. We compared the frequency of adequate judgments in reviews with two separate domains for blinding versus those with a joint domain for blinding. Results: The total number of assessments for performance bias was 6918, with 8656 for detection bias and 3169 for the joint domain. The frequency of adequate assessments was 74% for performance bias, 78% for detection bias, and 59% for the joint domain. The lowest frequency of adequate assessments was found when Cochrane authors judged low risk – 47% in performance bias, 62% in detection bias, and 31% in the joint domain. The joint domain and detection bias domain had a similar proportion of specified outcome types (17% and 18%, respectively). Conclusions: Splitting joint RoB assessment about blinding into two domains was justified because the frequency of adequate judgments was higher in separate domains. Specification of outcome types in RoB domains should be further scrutinized.

Background and Objectives: Perforated peptic ulcers are a common surgical emergency and rank among the leading causes of acute peritonitis worldwide. Previous studies have suggested a seasonal pattern in the occurrence of symptomatic perforated peptic ulcers. With the advancement of modern medicine, including the widespread use of proton pump inhibitors, and the effects of climate change, this study aimed to assess potential seasonal variations in the incidence of peptic ulcer perforation in our region. Methods: This retrospective analysis included 104 adult patients (mean age: 61.5 ± 14.7 years) who underwent surgical treatment for peptic ulcer perforation between January 2021 and April 2024. Patients were analyzed by gender, age, risk factors (smoking and alcohol consumption), the location of the perforation (gastric or duodenal), and discharge outcome (survived or deceased). Additionally, cases were categorized by the month and season of the ulcer perforation. Results: Among the 104 patients (mean age 61.5 ± 14.7 years), 68 (65.4%) were male. Gastric and duodenal perforations were nearly equally observed (51% vs. 49%). A statistically significant difference in overall perforation rates by gender was observed (p = 0.009), though not between ulcer sites (p = 0.628 and p = 0.739). The highest number of perforations occurred in July (n = 12), while the lowest occurred in November (n = 4); however, no significant variation was found by month (p = 0.916) or season (p = 0.891), despite a predominance in spring. Comorbidities were present in 60% of patients. Smoking (33.6%) and alcohol use (22.1%) were common. Alcohol abuse was noted in 22.1% of patients and was significantly associated with both gastric (p < 0.001) and duodenal (p < 0.001) perforations, though not with the overall incidence (p = 0.284). Smoking, reported in 33.6% of patients, showed no significant association with the perforation site or overall incidence (p = 0.946). The combination of smoking and alcohol use favored gastric perforations, but without statistical significance (p = 0.157). Conclusions: Alcohol consumption appeared to increase the risk of ulcer perforation, while smoking did not demonstrate a statistically significant association. Although spring exhibited the highest observed incidence of peptic ulcer perforation, seasonal variation did not show a statistically significant difference overall.