Systematic Review of the Empirical Evidence of Study Publication Bias and Outcome Reporting Bias

BACKGROUND: The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias has received less attention. METHODOLOGY/PRINCIPAL FINDINGS: We review and summarise the evidence from a series of cohort studies that have assessed study publication bias and outcome reporting bias in randomised controlled trials. Sixteen studies were eligible of which only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Eleven of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40-62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies. CONCLUSIONS: Recent work provides direct empirical evidence for the existence of study publication bias and outcome reporting bias. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials

Condições de saúde bucal e diabetes mellitus na população nipo-brasileira de Bauru-SP Relation between oral health conditions and diabetes mellitus in a japanese population from Bauru-SP-Brazil

Este estudo transversal foi delineado para estimar a prevalência de diabetes mellitus, intolerância à glicose e condições de saúde bucal na população de origem japonesa, na faixa de 40 a 79 anos de idade, residente no município de Bauru-Brasil. Todos os indivíduos da primeira geração (isseis) e uma amostra casualizada de um terço da segunda geração (niseis) foram submetidos a entrevista domiciliar, totalizando 530 indivíduos. O exame clínico e teste oral de tolerância à glicose, e exame das condições de saúde bucal, foram realizados no Hospital de Reabilitação de Anomalias Crânio-Faciais - USP. Os dados foram processados através do programa Epi-Info, sendo que 22,9% apresentaram ocorrência de diabetes mellitus (grupo I), 15,1% tolerância à glicose diminuída (grupo II) e 61,9% foram considerados normoglicêmicos (grupo III). O percentual de indivíduos desdentados totais foi de 45,9% para a amostra e valores de 58,4%, 46,7% e 41,2% foram verificados para os grupos I, II e III, respectivamente. Entre os indivíduos edêntulos, nenhum apresentava necessidade de confecção de prótese total, em contraposição aos dados encontrados para a população brasileira em levantamento realizado pelo Ministério da Saúde (1986), cuja necessidade era da ordem de 8,3% na faixa etária de 35 a 59 anos. Pôde-se concluir que o edentulismo apresenta associação significante com a ocorrência de diabetes mellitus, porém não com a intolerância à glicose.<br>The aim of this cross-sectional study was to determine the oral health condition in a Japanese population aged 40 to 79, in Bauru, Brazil as well as its association with the occurrence of diabetes mellitus and impaired glucose tolerance. It involved 530 subjects, from both sexes. All persons of first generation (Issei) and a random sample of one third of second generation (Nisei) were submitted to a home interview. A clinical examination, oral glucose tolerance test, and examination of oral health conditions took place at the Hospital of Rehabilitation of Craniofacial Anomaly - USP. The data were processed by Epi-Info program and 22.9% of the individuals presented diabetes mellitus (group I), 15.1% impaired glucose tolerance (group II), and 61.9% were considered normoglycemics (group III). The percentage of edentulous subjects was 45.9% for the total sample, and values of 58.4%, 46.7%, and 41.2% were observed for groups I, II, and III, respectively. Among the edentulous subjects, no one showed necessity of making a total prothesis. These data indicate that tooth loss showed significant association with the occurrence of diabetes mellitus, but there was no significant association with glucose intolerance

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally

Critical care admission following elective surgery was not associated with survival benefit: prospective analysis of data from 27 countries

This was an investigator initiated study funded by Nestle Health Sciences through an unrestricted research grant, and by a National Institute for Health Research (UK) Professorship held by RP. The study was sponsored by Queen Mary University of London

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine