Quality of reporting for randomised clinical trials published in Latin American and Spanish journals: A protocol for a systematic survey of three clinical specialities.

INTRODUCTION: Quality of reporting refers to how published articles communicate how the research was done and what was found. Gaps and imprecisions of reporting hamper the assessment of the methodological quality and internal and external validity. The CONsolidated Standards of Reporting Trials (CONSORT) are a set of evidence-based recommendations of the minimum elements to be included in the reporting of randomised controlled trials (RCTs) to ensure a complete and transparent account of what was done, how it was done and what was found. Few studies have been conducted on the impact of CONSORT on RCTs published in Latin American and Spanish journals. We aim to assess the reporting quality of RCTs of three clinical specialities published in Spanish and Latin American journals, as well as to assess changes over time and associations of quality with journal and country indicators. METHODS AND ANALYSIS: We will conduct a systematic survey of all RCTs published in Spanish-language journals in three clinical fields (dentistry, neurology and geriatrics) from 1990 to 2018. We will include RCTs from previous work that has identified all RCTs on these medical fields published in Spain and Latin America. We will update this work via handsearching of relevant journals. Assessment of quality of reporting will be conducted independently and in duplicate using the CONSORT 2010 Statement. We will also extract journal and country indicators. We will conduct descriptive statistics and secondary analyses considering the year, country, and journal of publication, among others. ETHICS AND DISSEMINATION: The Universidad de Santiago de Chile's ethics committee approved the protocol. We will disseminate the results of this work in peer-reviewed scientific journals and conference proceedings. We expect to raise awareness among researchers, journal editors and funders on the importance of training in reporting guidelines and using them from the inception of RCT protocols.

Measure of clinical improvement in children and adolescents with psychiatric disorders: an evaluation of multiple perspectives with HoNOSCA. / Valoración de la mejoría clínica en niños y adolescentes con trastornos psiquiátricos: una evaluación de múltiples perspectivas con HoNOSCA.

INTRODUCTION: Routine outcome assessment is helpful to inform decision-making, resource allocation, and health policy design. Routine outcome assessment in the hospital setting for children and adolescents with psychiatric disorders remains limited. The clinical instrument HoNOSCA (Health of the Nation Outcome Scales for Children and Adolescents), which has recently become available in Spanish and Catalan, allows outcome assessment in this population from the perspective of patients, their parents or legal guardians, and clinicians. HoNOSCA measures 13 areas of health and psychosocial functioning. OBJECTIVES: The aim of this study was to assess mental health outcomes in psychiatric day hospital pediatric patients from three perspectives (patient, par-ent/legal guardian, clinician), using the Spanish and Catalan versions of HoNOSCA. METHODS: We recruited patients up to 18 years old with any psychiatric disorder at the day unit of the Salut Mental Parc Taulí Hospital Universitari (Sabadell, Catalonia, Spain). We obtained admission and discharge HoNOSCA scores for the patients, their parents or legal guardians, and their clinicians. RESULTS: We recruited 99 patients over the study period (January 2015 to December 2017), 11 of which were lost to follow-up. Among the remaining 88, we found significant improvement in HoNOSCA scores from admission to discharge. Agreement between the HoNOSCA scores for the three different groups of evaluators (patients, parents/legal guardians, and clinicians) was weak at admission but better at discharge. In general, evaluations from patients and their parents or legal guardians had lower HoNOSCA scores (indicating a better mental health status) at admis-sion compared to those from clinicians. At discharge, however, the scores were more homogenous across the three groups of stakeholders. CONCLUSIONS: Use of HoNOSCA allows for routine evaluation of mental health outcomes in the psychiatric day hospital setting from the perspective of pa-tients, their parents or legal guardians, and clinicians.

INTRODUCCIÓN: La evaluación rutinaria de variables de resultado ayuda en la toma de decisiones, la asignación de recursos y el diseño de políticas en salud. La evaluación rutinaria de variables de resultado en el entorno hospitalario para niños y adolescentes con trastornos psiquiátricos sigue siendo limitada. La Health of the Nation Outcome Scales for Children and Adolescents, HoNOSCA, que recientemente se ha traducido al español y al catalán, permite la evaluación de resultados en esta población desde la perspectiva de pacientes, padres o tutores legales y clínicos. Este instrumento mide 13 áreas de salud y funcionamiento psicosocial. OBJETIVOS: Evaluar variables de resultado en salud mental entre pacientes jóvenes de hospital de día de psiquiatría desde estas tres perspectivas usando Health of the Nation Outcome Scales for Children and Adolescents. MÉTODOS: Reclutamos pacientes pediátricos (18 años o menos) con cualquier trastorno psiquiátrico en el hospital de día de la unidad de psiquiatría y psicología juvenil del Hospital Salut Mental Parc Taulí (Sabadell, Cataluña, España). Obtuvimos puntuaciones de Health of the Nation Outcome Scales for Children and Adolescents desde la perspectiva de pacientes, sus padres o tutores legales y clínicos, al ingreso y al alta. RESULTADOS: Reclutamos 99 pacientes entre enero de 2015 y diciembre de 2017; once se perdieron durante el seguimiento. Entre los 88 restantes, encontramos una mejora significativa en las puntuaciones de Health of the Nation Outcome Scales for Children and Adolescents desde el ingreso hasta el alta. El acuerdo en las puntuaciones de esta escala entre los diferentes evaluadores fue débil al inicio, pero mejor al alta. En general, los pacientes y los padres o tutores legales reportaron puntuaciones más bajas de Health of the Nation Outcome Scales for Children and Adolescents (mejor estado de salud) al ingreso en comparación con los profesionales de la salud. Al alta, las puntuaciones fueron homogéneas desde las tres perspectivas. CONCLUSIONES: La Health of the Nation Outcome Scales for Children and Adolescents permite la evaluación rutinaria de variables de resultado en salud mental en el entorno de hospital de día de psiquiatría desde la perspectiva de los pacientes, sus padres o tutores legales y los profesionales de la salud.

Valoración de la mejoría clínica en niños y adolescentes con trastornos psiquiátricos: una evaluación de múltiples perspectivas con HoNOSCA / Measure of clinical improvement in children and adolescents with psychiatric disorders: an evaluation of multiple perspectives with HoNOSCA

INTRODUCCIÓN La evaluación rutinaria de variables de resultado ayuda en la toma de decisiones, la asignación de recursos y el diseño de políticas en salud. La evaluación rutinaria de variables de resultado en el entorno hospitalario para niños y adolescentes con trastornos psiquiátricos sigue siendo limitada. La Health of the Nation Outcome Scales for Children and Adolescents, HoNOSCA, que recientemente se ha traducido al español y al catalán, permite la evaluación de resultados en esta población desde la perspectiva de pacientes, padres o tutores legales y clínicos. Este instrumento mide 13 áreas de salud y funcionamiento psicosocial. OBJETIVOS Evaluar variables de resultado en salud mental entre pacientes jóvenes de hospital de día de psiquiatría desde estas tres perspectivas usando Health of the Nation Outcome Scales for Children and Adolescents. MÉTODOS Reclutamos pacientes pediátricos (18 años o menos) con cualquier trastorno psiquiátrico en el hospital de día de la unidad de psiquiatría y psicología juvenil del Hospital Salut Mental Parc Taulí (Sabadell, Cataluña, España). Obtuvimos puntuaciones de Health of the Nation Outcome Scales for Children and Adolescents desde la perspectiva de pacientes, sus padres o tutores legales y clínicos, al ingreso y al alta. RESULTADOS Reclutamos 99 pacientes entre enero de 2015 y diciembre de 2017; once se perdieron durante el seguimiento. Entre los 88 restantes, encontramos una mejora significativa en las puntuaciones de Health of the Nation Outcome Scales for Children and Adolescents desde el ingreso hasta el alta. El acuerdo en las puntuaciones de esta escala entre los diferentes evaluadores fue débil al inicio, pero mejor al alta. En general, los pacientes y los padres o tutores legales reportaron puntuaciones más bajas de Health of the Nation Outcome Scales for Children and Adolescents (mejor estado de salud) al ingreso en comparación con los profesionales de la salud. Al alta, las puntuaciones fueron homogéneas desde las tres perspectivas. CONCLUSIONES La Health of the Nation Outcome Scales for Children and Adolescents permite la evaluación rutinaria de variables de resultado en salud mental en el entorno de hospital de día de psiquiatría desde la perspectiva de los pacientes, sus padres o tutores legales y los profesionales de la salud.

INTRODUCTION Routine outcome assessment is helpful to inform decision-making, resource allocation, and health policy design. Routine outcome assessment in the hospital setting for children and adolescents with psychiatric disorders remains limited. The clinical instrument HoNOSCA (Health of the Nation Outcome Scales for Children and Adolescents), which has recently become available in Spanish and Catalan, allows outcome assessment in this population from the perspective of patients, their parents or legal guardians, and clinicians. HoNOSCA measures 13 areas of health and psychosocial functioning. OBJECTIVES The aim of this study was to assess mental health outcomes in psychiatric day hospital pediatric patients from three perspectives (patient, par-ent/legal guardian, clinician), using the Spanish and Catalan versions of HoNOSCA. METHODS We recruited patients up to 18 years old with any psychiatric disorder at the day unit of the Salut Mental Parc Taulí Hospital Universitari (Sabadell, Catalonia, Spain). We obtained admission and discharge HoNOSCA scores for the patients, their parents or legal guardians, and their clinicians. RESULTS We recruited 99 patients over the study period (January 2015 to December 2017), 11 of which were lost to follow-up. Among the remaining 88, we found significant improvement in HoNOSCA scores from admission to discharge. Agreement between the HoNOSCA scores for the three different groups of evaluators (patients, parents/legal guardians, and clinicians) was weak at admission but better at discharge. In general, evaluations from patients and their parents or legal guardians had lower HoNOSCA scores (indicating a better mental health status) at admis-sion compared to those from clinicians. At discharge, however, the scores were more homogenous across the three groups of stakeholders. CONCLUSIONS Use of HoNOSCA allows for routine evaluation of mental health outcomes in the psychiatric day hospital setting from the perspective of pa-tients, their parents or legal guardians, and clinicians.

Quality assessment of controlled clinical trials published in Orthopaedics and Traumatology journals in Spanish: An observational study through handsearching and evidence mapping.

Few Orthopaedics and Traumatology journals from Latin America and Spain are indexed in major databases; controlled clinical trials published in these journals cannot be exhaustively retrieved using electronic literature searches. We aimed to identify, describe and assess the quality of controlled clinical trials published in Orthopaedics and Traumatology journals from Latin America and Spain through handsearching and evidence mapping methods. We identified controlled clinical trials published in eligible Orthopaedics/Traumatology journals in Spanish until July 2017 by handsearching. Data were extracted for controlled clinical trials main characteristics and the Cochrane risk of bias tool was used to assess the controlled clinical trials methodological quality. In addition, we mapped the main findings of these trials. As a result, we assessed 5631 references in 29 eligible journals of which 57 were controlled clinical trials (1.0%). Controlled clinical trials were published between 1995 and 2017 at a rate of 2.5 per year. Journals from Spain and Mexico published around 63% of the controlled clinical trials identified. The median sample size of patients enrolled was 60 (range = 30-300 participants). About conditions assessed, 38.5% of controlled clinical trials assessed issues related to knee conditions, 15.7% about hip and 10.5% about trauma or spine. The risk of bias domains most affected was selective reporting bias and random sequence generation. In addition, only two and seven trials had low risk of bias in all items related to participant/personnel and outcome assessment blindings, respectively. More than 40% of studies did not report differences on benefits/harms between the interventions assessed. As a conclusion, the number of controlled clinical trials published in Orthopaedics/Traumatology journals from Latin America and Spain is low. These controlled clinical trials had important methodological shortcomings and were judged as unclear or high risk of bias. These trials are now available in CENTRAL for their potential inclusion in systematic reviews and other documents of synthesis.

Identification and description of controlled clinical trials published in Spanish Ophthalmology Journals.

PURPOSE: Properly conducted controlled clinical trials (CCTs) provide the highest level of evidence for optimising decision-making in healthcare. Electronic search strategies do not exhaustively retrieve them, because of issues related to indexing, exclusion of journals in languages other than English, among others. A handsearch approach is therefore warranted. We aimed to identify all CCTs published in Ophthalmology journals in Spain, to describe their main features, and to submit them to the Cochrane Register of CCTs (CENTRAL). METHODS: After identifying all Spanish Ophthalmology Journals, we conducted a systematic handsearch following Cochrane guidelines. When appropriate, results were compared against electronic searches. A descriptive analysis was completed, including risk of bias assessment. RESULTS: We identified 18 eligible journals; 10 074 original articles, editorials, letters to the editor, abstracts and conference proceedings were assessed via handsearching for inclusion. Of these, 136 were subject to title and abstract screening, after which 102 were classified as CCTs. We identified three articles via electronic searches that had not been detected via handsearch, for a total of 105 CCTs. Among these, the most investigated pathologies were cataracts (32/105; 30.5%) and glaucoma (23/105 21.9%). Regarding risk of bias, 104/105 (99.0%) were deemed as "high risk of bias", mainly due to flaws in sequence generation and allocation concealment. 15/105 (14.3%) mentioned conflicts of interest, half of which had something to declare. No CCT reported adherence to CONSORT. CONCLUSION: Spanish Ophthalmology journals publish a low number of CCTs, with limited methodological quality. Handsearching was more sensitive than the electronic searching. Abbreviations CCT: Controlled clinical trial.

Interventions for infantile haemangiomas of the skin.

BACKGROUND: Infantile haemangiomas (previously known as strawberry birthmarks) are soft, raised swellings of the skin that occur in 3% to 10% of infants. These benign vascular tumours are usually uncomplicated and tend to regress spontaneously. However, when haemangiomas occur in high-risk areas, such as near the eyes, throat, or nose, impairing their function, or when complications develop, intervention may be necessary. This is an update of a Cochrane Review first published in 2011. OBJECTIVES: To assess the effects of interventions for the management of infantile haemangiomas in children. SEARCH METHODS: We updated our searches of the following databases to February 2017: the Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, AMED, LILACS, and CINAHL. We also searched five trials registries and checked the reference lists of included studies for further references to relevant trials. SELECTION CRITERIA: Randomised controlled trials (RCTs) of all types of interventions, versus placebo, active monitoring, or other interventions, in any child with single or multiple infantile haemangiomas (IHs) located on the skin. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. The primary outcome measures were clearance, a subjective measure of improvement, and adverse events. Secondary outcomes were other measures of resolution; proportion of parents or children who consider there is still a problem; aesthetic appearance; and requirement for surgical correction. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. MAIN RESULTS: We included 28 RCTs, with a total of 1728 participants, assessing 12 different interventions, including lasers, beta blockers (e.g. propranolol, timolol maleate), radiation therapy, and steroids. Comparators included placebo, an active monitoring approach, sham radiation, and interventions given alone or in combination.Studies were conducted in a number of countries, including China, Egypt, France, and Australia. Participant age ranged from 12 weeks to 13.4 years. Most studies (23/28) included a majority of females and different types of IHs. Duration of follow-up ranged from 7 days to 72 months.We considered most of the trials as at low risk of random sequence generation, attrition bias, and selective reporting bias. Domains such as allocation concealment and blinding were not clearly reported in general. We downgraded evidence for issues related to risk of bias and imprecision.We report results for the three most important comparisons, which we chose on the basis of current use. Outcome measurement of these comparisons was at 24 weeks' follow-up.Oral propranolol versus placeboCompared with placebo, oral propranolol 3 mg/kg/day probably improves clinician-assessed clearance (risk ratio (RR) 16.61, 95% confidence interval (CI) 4.22 to 65.34; 1 study; 156 children; moderate-quality evidence) and probably leads to a clinician-assessed reduction in mean haemangioma volume of 45.9% (95% CI 11.60 to 80.20; 1 study; 40 children; moderate-quality evidence). We found no evidence of a difference in terms of short- or long-term serious adverse events (RR 1.05, 95% CI 0.33 to 3.39; 3 studies; 509 children; low-quality evidence), nor in terms of bronchospasm, hypoglycaemia, or serious cardiovascular adverse events. The results relating to clearance and resolution for this comparison were based on one industry-sponsored study.Topical timolol maleate versus placeboThe chance of reduction of redness, as a measure of clinician-assessed resolution, may be improved with topical timolol maleate 0.5% gel applied twice daily when compared with placebo (RR 8.11, 95% CI 1.09 to 60.09; 1 study; 41 children;low-quality evidence). Regarding short- or long-term serious cardiovascular events, we found no instances of bradycardia (slower than normal heart rate) or hypotension in either group (1 study; 41 children; low-quality evidence). No other safety data were assessed, and clearance was not measured.Oral propranolol versus topical timolol maleateWhen topical timolol maleate (0.5% eye drops applied twice daily) was compared with oral propranolol (via a tablet taken once per day, at a 1.0 mg/kg dose), there was no evidence of a difference in haemangioma size (as a measure of resolution) when measured by the proportion of patients with a clinician-assessed reduction of 50% or greater (RR 1.13, 95% CI 0.64 to 1.97; 1 study; 26 participants; low-quality evidence). Although there were more short- or long-term general adverse effects (such as severe diarrhoea, lethargy, and loss of appetite) in the oral propranolol group, there was no evidence of a difference between groups (RR 7.00, 95% CI 0.40 to 123.35; 1 study; 26 participants; very low-quality evidence). This comparison did not measure clearance.None of our key comparisons evaluated, at any follow-up, a subjective measure of improvement assessed by the parent or child; proportion of parents or children who consider there is still a problem; or physician-, child-, or parent-assessed aesthetic appearance. AUTHORS' CONCLUSIONS: We found there to be a limited evidence base for the treatment of infantile haemangiomas: a large number of interventions and outcomes have not been assessed in RCTs.Our key results indicate that in the management of IH in children, oral propranolol and topical timolol maleate are more beneficial than placebo in terms of clearance or other measures of resolution, or both, without an increase in harms. We found no evidence of a difference between oral propranolol and topical timolol maleate with regard to reducing haemangioma size, but we are uncertain if there is a difference in safety. Oral propranolol is currently the standard treatment for this condition, and our review has not found evidence to challenge this. However, these results are based on moderate- to very low-quality evidence.The included studies were limited by small sample sizes and risk of bias in some domains. Future trials should blind personnel and participants; describe trials thoroughly in publications; and recruit a sufficient number of children to deduce meaningful results. Future trials should assess patient-reported outcomes, as well as objective outcomes of benefit, and should report adverse events comprehensively. Propranolol and timolol maleate require further assessment in RCTs of all types of IH, including those considered problematic, as do other lesser-used interventions and new interventions. All treatments should be compared against propranolol and timolol maleate, as beta blockers are approved as standard care.

Identification and description of controlled clinical trials in Spanish language dental journals.

BACKGROUND: To identify controlled clinical trials (CCTs) published in Spanish and in Latin American dental journals, and provide access to this body of evidence in a single source. METHODS: Handsearching, following Cochrane Collaboration guidelines, of CCTs published in Spanish dental journals from Spain and Latin America. For each eligible trial, we collected the dental specialty, the interventions evaluated, whether and how randomisation was achieved, and the corresponding bibliographic reference. RESULTS: We handsearched 107 journals published in Spain and Latin America in Spanish. Over 17 051 articles, 244 (1.43%) were CCTs. These studies focused mainly on periodontics (70, 29.0%) and oral and maxillofacial surgery (66, 27.0%), assessing mostly pharmacological interventions (112, 46.0%). One hundred fifty-three studies (62.7%) used a random allocation of participants to study arms. CONCLUSIONS: A significant number of dental journals published in Spain and Latin America in Spanish language present original research relevant to inform clinical practice. These journals are not indexed in the major electronic databases. PRACTICAL IMPLICATIONS: References to the identified CCTs are now available in CENTRAL, the Cochrane Collaboration repository for these studies. We call for adherence to the CONSORT statement in dentistry to improve reporting of CCTs in journals published in Spanish language.

Identification and description of controlled clinical trials published in Spanish Gynaecology and Obstetrics journals and risk of bias assessment of trials on assisted reproductive techniques.

OBJECTIVES: To identify and describe controlled clinical trials (CCTs) published in Spanish Gynaecology and Obstetrics journals. In addition, to assess the quality of the CCTs on Assisted Reproduction Techniques (ART) identified in this project. STUDY DESIGN: In order to identify eligible CCTs, all Spanish Gynaecology and Obstetrics journals were handsearched. Handsearching was conducted following the guidelines provided by the Cochrane Collaboration, which state that each journal article must be carefully reviewed, including original articles and other types of studies, letters to the editor, abstracts, and conference presentations. The results of the handsearching process were compared with an electronic search conducted in MEDLINE (PubMed). A descriptive analysis of the main characteristics of the identified CCTs was performed, as well as a methodological assessment of CCTs on ART. RESULTS: Sixteen Gynaecology and Obstetrics journals were identified, four of which have been indexed in MEDLINE at some point, although not currently. The journal with the most CCTs was "Progresos de Obstetricia y Ginecología". A total of 235 CCTs were published in these journals, of which 29 were on ART. Most CCTs (216, 91.9%) were carried out in a hospital setting; 201 (89.4%) were unicentric. Obstetrics was the most studied subspecialty (46.4%). Among CCTs on ART, the risk of bias was predominantly high. CONCLUSIONS: The number of CCTs published in Spanish Gynaecology and Obstetrics journals is limited. CCTs on ART present deficiencies in the report of results and low methodological quality. It is advised that authors and journals adhere to the CONSORT statement and to the Cochrane Collaboration recommendations to reduce risk of bias when designing and disseminating research projects.

Active body surface warming systems for preventing complications caused by inadvertent perioperative hypothermia in adults.

BACKGROUND: Inadvertent perioperative hypothermia is a phenomenon that can occur as a result of the suppression of the central mechanisms of temperature regulation due to anaesthesia, and of prolonged exposure of large surfaces of skin to cold temperatures in operating rooms. Inadvertent perioperative hypothermia has been associated with clinical complications such as surgical site infection and wound-healing delay, increased bleeding or cardiovascular events. One of the most frequently used techniques to prevent inadvertent perioperative hypothermia is active body surface warming systems (ABSW), which generate heat mechanically (heating of air, water or gels) that is transferred to the patient via skin contact. OBJECTIVES: To assess the effectiveness of pre- or intraoperative active body surface warming systems (ABSW), or both, to prevent perioperative complications from unintended hypothermia during surgery in adults. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 9, 2015); MEDLINE (PubMed) (1964 to October 2015), EMBASE (Ovid) (1980 to October 2015), and CINAHL (Ovid) (1982 to October 2015). SELECTION CRITERIA: We included randomized controlled trials (RCTs) that compared an ABSW system aimed at maintaining normothermia perioperatively against a control or against any other ABSW system. Eligible studies also had to include relevant clinical outcomes other than measuring temperature alone. DATA COLLECTION AND ANALYSIS: Several authors, by pairs, screened references and determined eligibility, extracted data, and assessed risks of bias. We resolved disagreements by discussion and consensus, with the collaboration of a third author. MAIN RESULTS: We included 67 trials with 5438 participants that comprised 79 comparisons. Forty-five RCTs compared ABSW versus control, whereas 18 compared two different types of ABSW, and 10 compared two different techniques to administer the same type of ABSW. Forced-air warming (FAW) was by far the most studied intervention.Trials varied widely regarding whether the interventions were applied alone or in combination with other active (based on a different mechanism of heat transfer) and/or passive methods of maintaining normothermia. The type of participants and surgical interventions, as well as anaesthesia management, co-interventions and the timing of outcome measurement, also varied widely. The risk of bias of included studies was largely unclear due to limitations in the reports. Most studies were open-label, due to the nature of the intervention and the fact that temperature was usually the principal outcome. Nevertheless, given that outcome measurement could have been conducted in a blinded manner, we rated the risk of detection and performance bias as high.The comparison of ABSW versus control showed a reduction in the rate of surgical site infection (risk ratio (RR) 0.36, 95% confidence interval (CI) 0.20 to 0.66; 3 RCTs, 589 participants, low-quality evidence). Only one study at low risk of bias observed a beneficial effect with forced-air warming on major cardiovascular complications (RR 0.22, 95% CI 0.05 to 1.00; 1 RCT with 12 events, 300 participants, low-quality evidence) in people at high cardiovascular risk. We found no beneficial effect for mortality. ABSW also reduced blood loss during surgery but the magnitude of this effect seems to be irrelevant (MD -46.17 mL, 95% CI -82.74 to -9.59; I² = 78%; 20 studies, 1372 participants). The same conclusion applies to total fluids infused during surgery (MD -144.49 mL, 95% CI -221.57 to -67.40; I² = 73%; 24 studies, 1491 participants). These effects did not translate into a significant reduction in the number of participants being transfused or the average amount of blood transfused. ABSW was associated with a reduction in shivering (RR 0.39, 95% CI 0.28 to 0.54; 29 studies, 1922 participants) and in thermal comfort (standardized mean difference (SMD) 0.76, 95% CI 0.29 to 1.24; I² = 77%, 4 trials, 364 participants).For the comparison between different types of ABSW system or modes of administration of a particular type of ABSW, we found no evidence for the superiority of any system in terms of clinical outcomes, except for extending systemic warming to the preoperative period in participants undergoing major abdominal surgery (one study at low risk of bias).There were limited data on adverse effects (the most relevant being thermal burns). While some trials included a narrative report mentioning that no adverse effects were observed, the majority made no reference to it. Nothing so far suggests that ABSW involves a significant risk to patients. AUTHORS' CONCLUSIONS: Forced-air warming seems to have a beneficial effect in terms of a lower rate of surgical site infection and complications, at least in those undergoing abdominal surgery, compared to not applying any active warming system. It also has a beneficial effect on major cardiovascular complications in people with substantial cardiovascular disease, although the evidence is limited to one study. It also improves patient's comfort, although we found high heterogeneity among trials. While the effect on blood loss is statistically significant, this difference does not translate to a significant reduction in transfusions. Again, we noted high heterogeneity among trials for this outcome. The clinical relevance of blood loss reduction is therefore questionable. The evidence for other types of ABSW is scant, although there is some evidence of a beneficial effect in the same direction on chills/shivering with electric or resistive-based heating systems. Some evidence suggests that extending systemic warming to the preoperative period could be more beneficial than limiting it only to during surgery. Nothing suggests that ABSW systems pose a significant risk to patients.The difficulty in observing a clinically-relevant beneficial effect with ABSW in outcomes other than temperature may be explained by the fact that many studies applied concomitant procedures that are routinely in place as co-interventions to prevent hypothermia, whether passive or active warming systems based in other physiological mechanisms (e.g. irrigation fluid or gas warming), as well as a stricter control of temperature in the context of the study compared with usual practice. These may have had a beneficial effect on the participants in the control group, leading to an underestimation of the net benefit of ABSW.