Does big data require a methodological change in medical research?

BACKGROUND: Use of big data is becoming increasingly popular in medical research. Since big data-based projects differ notably from classical research studies, both in terms of scope and quality, a debate is apt as to whether big data require new approaches to scientific reasoning different from those established in statistics and philosophy of science. MAIN TEXT: The progressing digitalization of our societies generates vast amounts of data that also become available for medical research. Here, the big promise of big data is to facilitate major improvements in the treatment, diagnosis and prevention of diseases. An ongoing examination of the idiosyncrasies of big data is therefore essential to ensure that the field stays congruent with the principles of evidence-based medicine. We discuss the inherent challenges and opportunities of big data in medicine from a methodological point of view, particularly highlighting the relative importance of causality and correlation in commercial and medical research settings. We make a strong case for upholding the distinction between exploratory data analysis facilitating hypothesis generation and confirmatory approaches involving hypothesis validation. An independent verification of research results will be ever more important in the context of big data, where data quality is often hampered by a lack of standardization and structuring. CONCLUSIONS: We argue that it would be both unnecessary and dangerous to discard long-established principles of data generation, analysis and interpretation in the age of big data. While many medical research areas may reasonably benefit from big data analyses, they should nevertheless be complemented by carefully designed (prospective) studies.

Effect of specialist palliative care services on quality of life in adults with advanced incurable illness in hospital, hospice, or community settings: systematic review and meta-analysis.

Objective To assess the effect of specialist palliative care on quality of life and additional outcomes relevant to patients in those with advanced illness.Design Systematic review with meta-analysis.Data sources Medline, Embase, Cochrane Central Register of Controlled Trials, PsycINFO, and trial registers searched up to July 2016.Eligibility criteria for selecting studies Randomised controlled trials with adult inpatients or outpatients treated in hospital, hospice, or community settings with any advanced illness. Minimum requirements for specialist palliative care included the multiprofessional team approach. Two reviewers independently screened and extracted data, assessed the risk of bias (Cochrane risk of bias tool), and evaluated the quality of evidence (GRADE tool).Data synthesis Primary outcome was quality of life with Hedges' g as standardised mean difference (SMD) and random effects model in meta-analysis. In addition, the pooled SMDs of the analyses of quality of life were re-expressed on the global health/QoL scale (item 29 and 30, respectively) of the European Organization for Research and Treatment of Cancer QLQ-C30 (0-100, high values=good quality of life, minimal clinically important difference 8.1).Results Of 3967 publications, 12 were included (10 randomised controlled trials with 2454 patients randomised, of whom 72% (n=1766) had cancer). In no trial was integration of specialist palliative care triggered according to patients' needs as identified by screening. Overall, there was a small effect in favour of specialist palliative care (SMD 0.16, 95% confidence interval 0.01 to 0.31; QLQ-C30 global health/QoL 4.1, 0.3 to 8.2; n=1218, six trials). Sensitivity analysis showed an SMD of 0.57 (-0.02 to 1.15; global health/QoL 14.6, -0.5 to 29.4; n=1385, seven trials). The effect was marginally larger for patients with cancer (0.20, 0.01 to 0.38; global health/QoL 5.1, 0.3 to 9.7; n=828, five trials) and especially for those who received specialist palliative care early (0.33, 0.05 to 0.61, global health/QoL 8.5, 1.3 to 15.6; n=388, two trials). The results for pain and other secondary outcomes were inconclusive. Some methodological problems (such as lack of blinding) reduced the strength of the evidence.Conclusions Specialist palliative care was associated with a small effect on QoL and might have most pronounced effects for patients with cancer who received such care early. It could be most effective if it is provided early and if it identifies though screening those patients with unmet needs.Systematic review registration PROSPERO CRD42015020674.

Roles and Responsibilities in the Provision of Accredited Continuing Medical Education/Continuing Professional Development.

The Cologne Consensus Conference 2015 has focused on "Providers in accredited CME[continuing medical education]/CPD [continuing professional development]". As an outcome of the CCC 2015, the authors of this paper, who were part of the faculty, propose a contemporary definition of the roles and responsibilities of stakeholders involved in the different stages of planning, delivery and evaluation of CME/CPD.

Pharmacological interventions for pruritus in adult palliative care patients.

BACKGROUND: This is an update of the original Cochrane review published in 2013 (Issue 6). Pruritus occurs in patients with disparate underlying diseases and is caused by different pathologic mechanisms. In palliative care patients, pruritus is not the most prevalent but is one of the most puzzling symptoms. It can cause considerable discomfort and affects patients' quality of life. OBJECTIVES: To assess the effects of different pharmacological treatments for preventing or treating pruritus in adult palliative care patients. SEARCH METHODS: For this update, we searched CENTRAL (the Cochrane Library), and MEDLINE (OVID) up to 9 June 2016 and Embase (OVID) up to 7 June 2016. In addition, we searched trial registries and checked the reference lists of all relevant studies, key textbooks, reviews and websites, and we contacted investigators and specialists in pruritus and palliative care regarding unpublished data. SELECTION CRITERIA: We included randomised controlled trials (RCTs) assessing the effects of different pharmacological treatments, compared with a placebo, no treatment, or an alternative treatment, for preventing or treating pruritus in palliative care patients. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed the identified titles and abstracts, performed data extraction and assessed the risk of bias and methodological quality. We summarised the results descriptively and quantitatively (meta-analyses) according to the different pharmacological interventions and the diseases associated with pruritus. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created 10 'Summary of findings' tables. MAIN RESULTS: In total, we included 50 studies and 1916 participants in the review. We added 10 studies with 627 participants for this update. Altogether, we included 39 different treatments for pruritus in four different patient groups.The overall risk of bias profile was heterogeneous and ranged from high to low risk. However, 48 studies (96%) had a high risk of bias due to low sample size (i.e. fewer than 50 participants per treatment arm). Using GRADE criteria, we downgraded our judgement on the quality of evidence to moderate in seven and to low in three comparisons for our primary outcome (pruritus), mainly due to imprecision and risk of bias.In palliative care participants with pruritus of different nature, the treatment with the drug paroxetine, a selective serotonin reuptake inhibitor, reduced pruritus by 0.78 points (numerical analogue scale from 0 to 10; 95% confidence interval (CI) -1.19 to -0.37; one RCT, N = 48, quality of evidence: moderate) compared to placebo.For participants suffering from uraemic pruritus (UP), gabapentin was more effective than placebo (visual analogue scale (VAS): 0 to 10), mean difference (MD) -5.91, 95% CI -6.87 to -4.96; two RCTs, N = 118, quality of evidence: moderate). The κ-opioid receptor agonist nalfurafine showed amelioration of UP (VAS 0 to 10, MD -0.95, 95% CI -1.32 to -0.58; three RCTs, N = 422, quality of evidence: moderate) and only few adverse events. Moreover, cromolyn sodium relieved UP participants from pruritus by 2.94 points on the VAS (0 to 10) (95% CI -4.04 to -1.83; two RCTs, N = 100, quality of evidence: moderate) compared to placebo.In participants with cholestatic pruritus (CP), data favoured rifampin (VAS: 0 to 100, MD -24.64, 95% CI -31.08 to -18.21; two RCTs, N = 42, quality of evidence: low) and flumecinol (RR > 1 favours treatment group; RR 1.89, 95% CI 1.05 to 3.39; two RCTs, N = 69, quality of evidence: low) and showed a low incidence of adverse events in comparison with placebo. The opioid antagonist naltrexone reduced pruritus for participants with CP (VAS: 0 to 10, MD -2.26, 95% CI -3.19 to -1.33; two RCTs, N = 52, quality of evidence: moderate) compared to placebo. However, effects in participants with UP were inconclusive (percentage difference -12.30%, 95% CI -25.82% to 1.22%, one RCT, N = 32). Furthermore, large doses of opioid antagonists (e.g. naltrexone) could be inappropriate in palliative care patients because of the risk of reducing analgesia.For participants with HIV-associated pruritus, it is uncertain whether drug treatment with hydroxyzine hydrochloride, pentoxifylline, triamcinolone or indomethacin reduces pruritus because the evidence was of very low quality (e.g. small sample size, lack of blinding). AUTHORS' CONCLUSIONS: Different interventions tended to be effective for CP and UP. However, therapies for patients with malignancies are still lacking. Due to the small sample sizes in most meta-analyses and the heterogeneous methodological quality of the included trials, the results should be interpreted cautiously in terms of generalisability.

Methods for detecting, quantifying, and adjusting for dissemination bias in meta-analysis are described.

OBJECTIVE: To systematically review methodological articles which focus on nonpublication of studies and to describe methods of detecting and/or quantifying and/or adjusting for dissemination in meta-analyses. To evaluate whether the methods have been applied to an empirical data set for which one can be reasonably confident that all studies conducted have been included. STUDY DESIGN AND SETTING: We systematically searched Medline, the Cochrane Library, and Web of Science, for methodological articles that describe at least one method of detecting and/or quantifying and/or adjusting for dissemination bias in meta-analyses. RESULTS: The literature search retrieved 2,224 records, of which we finally included 150 full-text articles. A great variety of methods to detect, quantify, or adjust for dissemination bias were described. Methods included graphical methods mainly based on funnel plot approaches, statistical methods, such as regression tests, selection models, sensitivity analyses, and a great number of more recent statistical approaches. Only few methods have been validated in empirical evaluations using unpublished studies obtained from regulators (Food and Drug Administration, European Medicines Agency). CONCLUSION: We present an overview of existing methods to detect, quantify, or adjust for dissemination bias. It remains difficult to advise which method should be used as they are all limited and their validity has rarely been assessed. Therefore, a thorough literature search remains crucial in systematic reviews, and further steps to increase the availability of all research results need to be taken.

[Is the age of causality over?]. / Ist das Zeitalter der Kausalität vorbei?

For the assessment of diagnostic and therapeutic interventions a sound scientific base has been developed during the last twenty years. Under the headline of Evidence-based Medicine nowadays a comprehensive set of tools is offered which can be used to assess the benefit and the risk of medical interventions. The overarching rule which evolved for the grading of evidence from studies is to maximize the protection against bias. Despite this coherent approach, there is still controversy that is regularly mainly sparked by the dominant position of randomized controlled trials. Observational studies and registries are deemed to be more relevant because they provide results that are produced under "everyday conditions". These controversial discussions often show a lack of orientation, as they do without the explicit naming of scientific criteria for the evaluation and to a large extent rely on common sense. That the latter may not be a good guide for assessments in the medical field is known from numerous studies. For unbiased assessments the rigorous use of basic scientific principles is the only way. To express doubt and question these principles requires a scientific basis itself. The alternative is to move away from the established scientific foundation. The path to a "new" scientific paradigm is currently dominated by a discussion under the buzzword Big Data. Defined by the three V's of Variety, Velocity and Volume, a potential of the unlimited analysis of data is envisioned, for which there is currently no validation and whose logical foundations are extremely doubtful. The demand must be reaffirmed that instead of promises strict validation criteria be followed for the evaluation of all interventions in medicine, particularly in view of these developments.

Pylorus-preserving pancreaticoduodenectomy (pp Whipple) versus pancreaticoduodenectomy (classic Whipple) for surgical treatment of periampullary and pancreatic carcinoma.

BACKGROUND: Pancreatic cancer is the fourth-leading cause of cancer death for both, men and women. The standard treatment for resectable tumours consists of a classic Whipple (CW) operation or a pylorus-preserving pancreaticoduodenectomy (PPW). It is unclear which of these procedures is more favourable in terms of survival, postoperative mortality, complications, and quality of life. OBJECTIVES: The objective of this systematic review was to compare the effectiveness of CW and PPW techniques for surgical treatment of cancer of the pancreatic head and the periampullary region. SEARCH METHODS: We conducted searches on 28 March 2006, 11 January 2011, 9 January 2014, and 18 August 2015 to identify all randomised controlled trials (RCTs), while applying no language restrictions. We searched the following electronic databases on 18 August 2015: the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Database of Systematic Reviews (CDSR) and the Database of Abstracts of Reviews of Effects (DARE) from the Cochrane Library (2015, Issue 8); MEDLINE (1946 to August 2015); and EMBASE (1980 to August 2015). We also searched abstracts from Digestive Disease Week and United European Gastroenterology Week (1995 to 2010); we did not update this part of the search for the 2014 and 2015 updates because the prior searches did not contribute any additional information. We identified two additional trials through the updated search in 2015. SELECTION CRITERIA: RCTs comparing CW versus PPW including participants with periampullary or pancreatic carcinoma. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data from the included trials. We used a random-effects model for pooling data. We compared binary outcomes using odds ratios (ORs), pooled continuous outcomes using mean differences (MDs), and used hazard ratios (HRs) for meta-analysis of survival. Two review authors independently evaluated the methodological quality and risk of bias of included trials according to the standards of The Cochrane Collaboration. MAIN RESULTS: We included eight RCTs with a total of 512 participants. Our critical appraisal revealed vast heterogeneity with respect to methodological quality and outcome parameters. Postoperative mortality (OR 0.64, 95% confidence interval (CI) 0.26 to 1.54; P = 0.32), overall survival (HR 0.84, 95% CI 0.61 to 1.16; P = 0.29), and morbidity showed no significant differences, except of delayed gastric emptying, which significantly favoured CW (OR 3.03, 95% CI 1.05 to 8.70; P = 0.04). Furthermore, we noted that operating time (MD -45.22 minutes, 95% CI -74.67 to -15.78; P = 0.003), intraoperative blood loss (MD -0.32 L, 95% CI -0.62 to -0.03; P = 0.03), and red blood cell transfusion (MD -0.47 units, 95% CI -0.86 to -0.07; P = 0.02) were significantly reduced in the PPW group. All significant results were associated with low-quality evidence based on GRADE (Grades of Recommendation, Assessment, Development and Evaluation) criteria. AUTHORS' CONCLUSIONS: Current evidence suggests no relevant differences in mortality, morbidity, and survival between the two operations. However, some perioperative outcome measures significantly favour the PPW procedure. Given obvious clinical and methodological heterogeneity, future high-quality RCTs of complex surgical interventions based on well-defined outcome parameters are required.

Bias in dissemination of clinical research findings: structured OPEN framework of what, who and why, based on literature review and expert consensus.

OBJECTIVE: The aim of this study is to review highly cited articles that focus on non-publication of studies, and to develop a consistent and comprehensive approach to defining (non-) dissemination of research findings. SETTING: We performed a scoping review of definitions of the term 'publication bias' in highly cited publications. PARTICIPANTS: Ideas and experiences of a core group of authors were collected in a draft document, which was complemented by the findings from our literature search. INTERVENTIONS: The draft document including findings from the literature search was circulated to an international group of experts and revised until no additional ideas emerged and consensus was reached. PRIMARY OUTCOMES: We propose a new approach to the comprehensive conceptualisation of (non-) dissemination of research. SECONDARY OUTCOMES: Our 'What, Who and Why?' approach includes issues that need to be considered when disseminating research findings (What?), the different players who should assume responsibility during the various stages of conducting a clinical trial and disseminating clinical trial documents (Who?), and motivations that might lead the various players to disseminate findings selectively, thereby introducing bias in the dissemination process (Why?). CONCLUSIONS: Our comprehensive framework of (non-) dissemination of research findings, based on the results of a scoping literature search and expert consensus will facilitate the development of future policies and guidelines regarding the multifaceted issue of selective publication, historically referred to as 'publication bias'.

A European multi-language initiative to make the general population aware of independent clinical research: the European Communication on Research Awareness Need project.

BACKGROUND: The ECRAN (European Communication on Research Awareness Needs) project was initiated in 2012, with support from the European Commission, to improve public knowledge about the importance of independent, multinational, clinical trials in Europe. METHODS: Participants in the ECRAN consortium included clinicians and methodologists directly involved in clinical trials; researchers working in partnership with the public and patients; representatives of patients; and experts in science communication. We searched for, and evaluated, relevant existing materials and developed additional materials and tools, making them freely available under a Creative Commons licence. RESULTS: The principal communication materials developed were: 1. A website ( http://ecranproject.eu ) in six languages, including a Media centre section to help journalists to disseminate information about the ECRAN project 2. An animated film about clinical trials, dubbed in the 23 official languages of the European Community, and an interactive tutorial 3. An inventory of resources, available in 23 languages, searchable by topic, author, and media type 4. Two educational games for young people, developed in six languages 5. Testing Treatments interactive in a dozen languages, including five official European Community languages 6. An interactive tutorial slide presentation testing viewers' knowledge about clinical trials CONCLUSIONS: Over a 2-year project, our multidisciplinary and multinational consortium was able to produce, and make freely available in many languages, new materials to promote public knowledge about the importance of independent and international clinical trials. Sustained funding for the ECRAN information platform could help to promote successful recruitment to independent clinical trials supported through the European Clinical Research Infrastructure Network.

[Up for Discussion: Using study registries for Oncology: StudyBox and the German Clinical Trials Register (DRKS)]. / Zur Diskussion: Studienregister für die Onkologie nutzen--StudyBox und Deutsches Register Klinischer Studien.

Study registries serve various purposes. Primarily, they provide as complete an overview as possible on planned, ongoing and completed studies and are thus intended to contribute to transparency in research. As such, they are an instrument for identifying and reducing publication bias. Study registries can also help doctors and patients to identify suitable studies for them. The National Cancer Plan (NCP) calls for ensuring an efficient oncological treatment, which requires the knowledge derived from trials. Study registries can play an important role in their identification. This paper describes the purpose that study registries fulfil in oncology as well as their health policy rationale. It then discusses two registries relevant for oncology, i. e. StudyBox and the German Clinical Trials Register (DRKS), against the backdrop of the National Cancer Plan and introduces the cooperation of the two registries.

Specialist palliative care services for adults with advanced, incurable illness in hospital, hospice, or community settings--protocol for a systematic review.

BACKGROUND: Specialist palliative care (SPC) interventions aim to relieve and prevent suffering in the physical, psychological, social, and spiritual domain. Therefore, SPC is carried out by a multi-professional team with different occupations (e.g., physician, nurse, psychologist, and social worker). Remaining skepticism concerning the need for SPC may be based on the scarcity of high-quality evaluations about the external evidence for SPC. Therefore, we will conduct a systematic review according to Cochrane standards to examine the effects of SPC for adults with advanced illness. METHODS/DESIGN: The comprehensive systematic literature search will include randomized controlled trials (RCTs) and cluster RCTs. We will search the databases MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and PsycINFO. Patients must be adults suffering from life-limiting diseases. Proxy and caregiver outcomes will not be assessed in order to ensure a clear and well-defined research question for this review. Interventions may be in an in- or outpatient setting, e.g., consulting service, palliative care ward, and palliative outpatient clinic. In line with the multi-dimensional scope of palliative care, the primary outcome is quality of life (QoL). Key secondary outcomes are patients' symptom burden, place of death and survival, and health economic aspects. Subgroup analysis will assess results according to cancer type, age, early vs not early SPC, site of care, and setting. Analysis will be performed with the current RevMan software. We will use the Cochrane Collaboration risk of bias assessment tool. The quality of evidence will be judged according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. DISCUSSION: The available evidence will be summarized and discussed to provide a basis for decision-making among health care professionals and policy makers. For SPC, we believe that multi-professional care is of utmost importance. Therefore, single-profession interventions such as physician consultations will not be included. Based on the multi-dimensional scope of palliative care, we chose QoL as the primary outcome, despite an expected heterogeneity among the QoL outcomes. We consider unidimensional endpoints such as "pain" for the physical domain to be inadequate for capturing the true scope of (S)PC (i.e., QoL) as defined by the World Health Organization. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42015020674.

Evidence-informed recommendations to reduce dissemination bias in clinical research: conclusions from the OPEN (Overcome failure to Publish nEgative fiNdings) project based on an international consensus meeting.

BACKGROUND: Dissemination bias in clinical research severely impedes informed decision-making not only for healthcare professionals and patients, but also for funders, research ethics committees, regulatory bodies and other stakeholder groups that make health-related decisions. Decisions based on incomplete and biased evidence cannot only harm people, but may also have huge financial implications by wasting resources on ineffective or harmful diagnostic and therapeutic measures, and unnecessary research. Owing to involvement of multiple stakeholders, it remains easy for any single group to assign responsibility for resolving the problem to others. OBJECTIVE: To develop evidence-informed general and targeted recommendations addressing the various stakeholders involved in knowledge generation and dissemination to help overcome the problem of dissemination bias on the basis of previously collated evidence. METHODS: Based on findings from systematic reviews, document analyses and surveys, we developed general and targeted draft recommendations. During a 2-day workshop in summer 2013, these draft recommendations were discussed with external experts and key stakeholders, and refined following a rigorous and transparent methodological approach. RESULTS: Four general, overarching recommendations applicable to all or most stakeholder groups were formulated, addressing (1) awareness raising, (2) implementation of targeted recommendations, (3) trial registration and results posting, and (4) systematic approaches to evidence synthesis. These general recommendations are complemented and specified by 47 targeted recommendations tailored towards funding agencies, pharmaceutical and device companies, research institutions, researchers (systematic reviewers and trialists), research ethics committees, trial registries, journal editors and publishers, regulatory agencies, benefit (health technology) assessment institutions and legislators. CONCLUSIONS: Despite various recent examples of dissemination bias and several initiatives to reduce it, the problem of dissemination bias has not been resolved. Tailored recommendations based on a comprehensive approach will hopefully help increase transparency in biomedical research by overcoming the failure to disseminate negative findings.

Cell-assisted lipotransfer.

BACKGROUND: Because of their easy accessibility and versatile biological properties, mesenchymal stem cells taken from fatty tissue (adipose-derived stem cells, ADSC) are attractive for various potential clinical uses. For example, ADSC can be added to fatty tissue before transplantation in the hope of improving the outcome of autologous lipotransfer: the modified procedure is called cell-assisted lipotransfer. The clinical use and commercial promotion of this novel stem-cell treatment (and others) are spreading rapidly, even though there is not yet any clear clinical evidence for its safety and efficacy. METHODS: In cooperation with the German Cochrane Center, we systematically searched the literature according to the PRISMA criteria. Eight major medical databases were searched. The retrieved publications were examined by two independent reviewers and assessed using objective criteria. RESULTS: After screening of the 3161 retrieved publications by title, abstract, and (where appropriate) full text, 78 were still considered relevant. 13 of these were reports of clinical studies; only 3 of the 13 met criteria for grade II or III evidence. The studies that were analyzed involved a total of 286 cell-assisted lipotransfer procedures with a longest follow-up time of 42 months. Oncological safety was not demonstrated. CONCLUSION: The studies published to date have not shown that cell-assisted lipotransfer is generally superior to conventional autologous lipotransfer. They dealt with safety aspects inappropriately or not at all. The case of cell-assisted lipotransfer illustrates the indispensability of high-quality clinical evidence before the introduction of novel stem-cell-based treatments.

Erratum: The National Institutes of Health and guidance for reporting preclinical research.

This is an Erratum to BMC Medicine 2015, 13:34, highlighting a corrected references list. Please see related article: http://www.biomedcentral.com/1741-7015/13/34.

The National Institutes of Health and guidance for reporting preclinical research.

The quality of reporting clinical and preclinical research is not optimal. Reporting guidelines can help make reports of research more complete and transparent, thus increasing their value and making them more useful to all readers. Getting reporting guidelines into practice is complex and expensive, and involves several stakeholders, including prospective authors, peer reviewers, journal editors, guideline developers, and implementation scientists. Working together will help ensure their maximum uptake and penetration. We are all responsible for helping to ensure that all research is reported so completely that it is of value to everybody. Please see related article: http://dx.doi.org/10.1186/s12916-015-0266-y.

Non-steroidal antiandrogen monotherapy compared with luteinizing hormone-releasing hormone agonists or surgical castration monotherapy for advanced prostate cancer: a Cochrane systematic review.

To assess the effects of non-steroidal antiandrogen monotherapy compared with luteinizing hormone-releasing hormone agonists or surgical castration monotherapy for treating advanced hormone-sensitive stages of prostate cancer. We searched the Cochrane Prostatic Diseases and Urologic Cancers Group Specialized Register (PROSTATE), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Web of Science with Conference Proceedings, three trial registries and abstracts from three major conferences to 23 December 2013, together with reference lists, and contacted selected experts in the field and manufacturers. We included randomized controlled trials comparing non-steroidal antiandrogen monotherapy with medical or surgical castration monotherapy for men in advanced hormone-sensitive stages of prostate cancer. Two review authors independently examined full-text reports, identified relevant studies, assessed the eligibility of studies for inclusion, extracted data and assessed risk of bias as well as quality of evidence according to the GRADE working group guidelines. We used Review Manager 5.2 for data synthesis and the fixed-effect model as primary analysis (when heterogeneity was low with I(2) < 50%); we used a random-effects model when confronted with substantial or considerable heterogeneity (when I(2) ≥50%). A total of 11 studies involving 3060 randomly assigned participants were included in the present review. Use of non-steroidal antiandrogens resulted in lower overall survival times (hazard ratio [HR] 1.24, 95% confidence interval [CI] 1.05-1.48, six studies, 2712 participants) and greater clinical progression (1 year: risk ratio [RR] 1.25, 95% CI 1.08-1.45, five studies, 2067 participants; 70 weeks: RR 1.26, 95% CI 1.08-1.45, six studies, 2373 participants; 2 years: RR 1.14, 95% CI 1.04-1.25, three studies, 1336 participants), as well as treatment failure (1 year: RR 1.19, 95% CI 1.02-1.38, four studies, 1539 participants; 70 weeks: RR 1.27, 95% CI 1.05-1.52, five studies, 1845 participants; 2 years: RR 1.14, 95% CI 1.05-1.24, two studies, 808 participants), compared with medical or surgical castration. The quality of evidence for overall survival, clinical progression and treatment failure was rated as moderate according to GRADE. Use of non-steroidal antiandrogens increased the risk for treatment discontinuation as a result of adverse events (RR 1.82, 95% CI 1.13-2.94, eight studies, 1559 participants), including events such as breast pain (RR 22.97, 95% CI 14.79- 35.67, eight studies, 2670 participants) and gynaecomastia (RR 8.43, 95% CI 3.19-22.28, nine studies, 2774 participants) The risk of other adverse events, such as hot flushes (RR 0.23, 95% CI 0.19-0.27, nine studies, 2774 participants) was decreased when non-steroidal antiandrogens were used. The quality of evidence for breast pain, gynaecomastia and hot flushes was rated as moderate according to GRADE. The effects of non-steroidal antiandrogens on cancer-specific survival and biochemical progression remained unclear. Non-steroidal antiandrogen monotherapy compared with medical or surgical castration monotherapy for advanced prostate cancer is less effective in terms of overall survival, clinical progression, treatment failure and treatment discontinuation resulting from adverse events. Evidence quality was rated as moderate according to GRADE; therefore, further research is likely to have an important impact on results for patients with advanced but non-metastatic prostate cancer treated with non-steroidal antiandrogen monotherapy.