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PURPOSE: A history of fractures involving the distal radius, proximal humerus, spine, and hip may be associated with the incidence of subsequent hip fractures in older people. However, a comprehensive summary of this association using a rigorous methodology is lacking. Our objective was to systematically review the literature and examine the association between four major osteoporotic fractures and subsequent hip fractures in individuals aged ≥ 50 years. METHODS: We searched MEDLINE, Embase, CENTRAL, ICTRP, and ClinicalTrials.gov on February 15, 2023. The search included cohort or case-control studies investigating the association between these four types of osteoporotic fractures and subsequent hip fractures. We pooled the hazard ratios (HRs) with 95% confidence intervals (CI) using the random-effects model. We used the Quality In Prognosis Studies tool to assess the risk of bias in the included studies, and the grading of recommendations assessment, development, and evaluation approach to determine the certainty of evidence. RESULTS: The selection process identified 48 studies for qualitative synthesis and 23 studies (2,239,217 participants) for meta-analysis. The overall methodological quality had a low risk of bias in 65% of the included studies. The association between a history of major osteoporotic fractures and subsequent hip fracture varied, with a high certainty of evidence for a history of proximal humerus and hip fractures (HR 2.02, 95% CI 1.75-2.33 and 2.86, 95% CI 1.92-4.25, respectively), moderate certainty for distal radius fractures (HR 1.66, 95% CI 1.53-1.81), and low certainty for spine fractures (HR 1.53, 95% CI 1.38-1.69). CONCLUSIONS: In conclusion, a history of major osteoporotic fractures, particularly distal radius, proximal humerus, and hip fractures, is associated with subsequent hip fractures in older adults. Further research is needed to verify the association between a history of spine fracture and subsequent hip fractures. PROTOCOL REGISTRATION: Open Science Framework ( https://osf.io/7fjuc ).
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Fracturas de Cadera , Fracturas Osteoporóticas , Humanos , Fracturas de Cadera/epidemiología , Fracturas Osteoporóticas/epidemiología , Anciano , Incidencia , Factores de RiesgoRESUMEN
Meta-analyses examining dichotomous outcomes often include single-zero studies, where no events occur in intervention or control groups. These pose challenges, and several methods have been proposed to address them. A fixed continuity correction method has been shown to bias estimates, but it is frequently used because sometimes software (e.g., RevMan software in Cochrane reviews) uses it as a default. We aimed to empirically compare results using the continuity correction with those using alternative models that do not require correction. To this aim, we reanalyzed the original data from 885 meta-analyses in Cochrane reviews using the following methods: (i) Mantel-Haenszel model with a fixed continuity correction, (ii) random effects inverse variance model with a fixed continuity correction, (iii) Peto method (the three models available in RevMan), (iv) random effects inverse variance model with the treatment arm continuity correction, (v) Mantel-Haenszel model without correction, (vi) logistic regression, and (vii) a Bayesian random effects model with binominal likelihood. For each meta-analysis we calculated ratios of odds ratios between all methods, to assess how the choice of method may impact results. Ratios of odds ratios <0.8 or <1.25 were seen in ~30% of the existing meta-analyses when comparing results between Mantel-Haenszel model with a fixed continuity correction and either Mantel-Haenszel model without correction or logistic regression. We concluded that injudicious use of the fixed continuity correction in existing Cochrane reviews may have substantially influenced effect estimates in some cases. Future updates of RevMan should incorporate less biased statistical methods.
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Providing standardized, high-quality rehabilitation for critically ill patients is a crucial issue. In 2017, the Japanese Society of Intensive Care Medicine (JSICM) promulgated the "Evidence-Based Expert Consensus for Early Rehabilitation in the Intensive Care Unit" to advocate for the early initiation of rehabilitations in Japanese intensive care settings. Building upon this seminal work, JSICM has recently conducted a rigorous systematic review utilizing the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. This endeavor resulted in the formulation of Clinical Practice Guidelines (CPGs), designed to elucidate best practices in early ICU rehabilitation. The primary objective of this guideline is to augment clinical understanding and thereby facilitate evidence-based decision-making, ultimately contributing to the enhancement of patient outcomes in critical care settings. No previous CPGs in the world has focused specifically on rehabilitation of critically ill patients, using the GRADE approach. Multidisciplinary collaboration is extremely important in rehabilitation. Thus, the CPGs were developed by 73 members of a Guideline Development Group consisting of a working group, a systematic review group, and an academic guideline promotion group, with the Committee for the Clinical Practice Guidelines of Early Mobilization and Rehabilitation in Intensive Care of the JSICM at its core. Many members contributed to the development of the guideline, including physicians and healthcare professionals with multiple and diverse specialties, as well as a person who had been patients in ICU. Based on discussions among the group members, eight important clinical areas of focus for this CPG were identified. Fourteen important clinical questions (CQs) were then developed for each area. The public was invited to comment twice, and the answers to the CQs were presented in the form of 10 GRADE recommendations and commentary on the four background questions. In addition, information for each CQ has been created as a visual clinical flow to ensure that the positioning of each CQ can be easily understood. We hope that the CPGs will be a useful tool in the rehabilitation of critically ill patients for multiple professions.
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There are currently no abstract classifiers, which can be used for new diagnostic test accuracy (DTA) systematic reviews to select primary DTA study abstracts from database searches. Our goal was to develop machine-learning-based abstract classifiers for new DTA systematic reviews through an open competition. We prepared a dataset of abstracts obtained through database searches from 11 reviews in different clinical areas. As the reference standard, we used the abstract lists that required manual full-text review. We randomly splitted the datasets into a train set, a public test set, and a private test set. Competition participants used the training set to develop classifiers and validated their classifiers using the public test set. The classifiers were refined based on the performance of the public test set. They could submit as many times as they wanted during the competition. Finally, we used the private test set to rank the submitted classifiers. To reduce false exclusions, we used the Fbeta measure with a beta set to seven for evaluating classifiers. After the competition, we conducted the external validation using a dataset from a cardiology DTA review. We received 13,774 submissions from 1429 teams or persons over 4 months. The top-honored classifier achieved a Fbeta score of 0.4036 and a recall of 0.2352 in the external validation. In conclusion, we were unable to develop an abstract classifier with sufficient recall for immediate application to new DTA systematic reviews. Further studies are needed to update and validate classifiers with datasets from other clinical areas.
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Pruebas Diagnósticas de Rutina , Aprendizaje Automático , Humanos , Bases de Datos FactualesRESUMEN
OBJECTIVES: Researchers have identified cases in which newspaper stories have exaggerated the results of medical studies reported in original articles. Moreover, the exaggeration sometimes begins with journal articles. We examined what proportion of the studies quoted in newspaper stories were confirmed. METHODS: We identified newspaper stories from 2000 that mentioned the effectiveness of certain treatments or preventions based on original studies from 40 main medical journals. We searched for subsequent studies until June 2022 with the same topic and stronger research design than each original study. The results of the original studies were verified by comparison with those of subsequent studies. RESULTS: We identified 164 original articles from 1298 newspaper stories and randomly selected 100 of them. Four studies were not found to be effective in terms of the primary outcome, and 18 had no subsequent studies. Of the remaining studies, the proportion of confirmed studies was 68.6% (95% CI 58.1% to 77.5%). Among the 59 confirmed studies, 13 of 16 studies were considered to have been replicated in terms of effect size. However, the results of the remaining 43 studies were not comparable. DISCUSSION: In the dichotomous judgement of effectiveness, about two-thirds of the results were nominally confirmed by subsequent studies. However, for most confirmed results, it was impossible to determine whether the effect sizes were stable. CONCLUSIONS: Newspaper readers should be aware that some claims made by high-quality newspapers based on high-profile journal articles may be overturned by subsequent studies within the next 20 years.
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Concienciación , Humanos , Estudios de Seguimiento , Estudios EpidemiológicosRESUMEN
Psychological dysfunction is one of the considerable health-related outcomes among critically-ill patients and their informal caregivers. Follow-up of intensive care unit (ICU) survivors has been conducted in a variety of different ways, with different timing after discharge, targets of interest (physical, psychological, social) and measures used. Of diverse ICU follow-up, the effects of follow-ups which focused on psychological interventions are unknown. Our research question was whether follow-up with patients and their informal caregivers after ICU discharge improved mental health compared to usual care. We published a protocol for this systematic review and meta-analysis in https://www.protocols.io/ (https://dx.doi.org/10.17504/protocols.io.bvjwn4pe). We searched PubMed, Cochrane Library, EMBASE, CINAHL and PsycInfo from their inception to May 2022. We included randomized controlled trials for follow-ups after ICU discharge and focused on psychological intervention for critically ill adult patients and their informal caregivers. We synthesized primary outcomes, including depression, post-traumatic stress disorder (PTSD), and adverse events using the random-effects method. We used the Grading of Recommendations Assessment, Development and Evaluation approach to rate the certainty of evidence. From the 10,471 records, we identified 13 studies (n = 3, 366) focusing on patients and four (n = 538) focusing on informal caregivers. ICU follow-up for patients resulted in little to no difference in the prevalence of depression (RR 0.89, 95% CI [0.59-1.34]; low-certainty evidence) and PTSD (RR 0.84, 95% CI [0.55-1.30]; low-certainty evidence) among patients; however, it increased the prevalence of depression (RR 1.58 95% CI [1.01-2.46]; very low-certainty evidence), PTSD (RR 1.36, 95% CI [0.91-2.03]; very low-certainty evidence) among informal caregivers. The evidence for the effect of ICU follow-up on adverse events among patients was insufficient. Eligible studies for informal caregivers did not define any adverse event. The effect of follow-ups after ICU discharge that focused on psychological intervention should be uncertain.
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Líquidos Corporales , Cuidadores , Humanos , Adulto , Intervención Psicosocial , Estudios de Seguimiento , Unidades de Cuidados IntensivosRESUMEN
BACKGROUND: The shock index (heart rate divided by systolic blood pressure) of trauma patients upon emergency department arrival predicts blood loss and death. However, some patients with normal shock indices (0.4 < shock index <0.9) upon emergency department arrival also have poor prognoses. This study aimed to determine whether abnormal prehospital shock indices in trauma patients with normal shock indices upon emergency department arrival were predictors of a high risk of mortality. METHODS: We conducted a retrospective cohort study of emergency department-admitted trauma patients from 2004 to 2017. The study included 89,495 consecutive trauma patients aged ≥16 years, with Abbreviated Injury Scale score of ≥3, who were transported to the emergency department directly from the field and had a normal shock index upon emergency department arrival. According to the prehospital shock index scores, the patients were categorized into low shock index (≤ 0.4), normal shock index, and high shock index (≥0.9) groups. Odds ratios and 95% confidence intervals were calculated using logistic regression analysis. RESULTS: The 89,495 patients had a median age of 64 (interquartile range: 43-79) years, and 55,484 (62.0%) of the patients were male. There were 1350 (1.5%) 24-h deaths in total; 176/4263 (4.1%), 1017/78,901 (1.3%), and 157/6331 (2.5%) patients were in the low, normal, and high prehospital shock index groups, respectively. The adjusted odds ratios for 24-h mortality compared with the normal shock index group were 1.63 (95% confidence interval: 1.34-1.99) in the low shock index group and 1.62 (95% confidence interval: 1.31-1.99) in the high shock index group. CONCLUSION: Trauma patients with abnormal prehospital shock indices but normal shock indices upon emergency department arrival are at a higher risk of 24-h mortality. Identifying these indices could improve triage and targeted care for patients.
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Servicios Médicos de Urgencia , Choque , Heridas y Lesiones , Humanos , Masculino , Adulto , Persona de Mediana Edad , Anciano , Femenino , Estudios Retrospectivos , Servicio de Urgencia en Hospital , Triaje , Presión Sanguínea/fisiología , Heridas y Lesiones/complicaciones , Puntaje de Gravedad del TraumatismoRESUMEN
OBJECTIVES: Our objectives were to examine the magnitude of the proportion attributable to contextual effects (PCE), which shows what proportion of the treatment arm response can be achieved by the placebo arm across various interventions, and to examine PCE variability by outcome type and condition. DESIGN: We conducted a meta-epidemiological study. SETTING: We searched the Cochrane Database of Systematic Reviews with the keyword 'placebo' in titles, abstracts and keywords on 1 January 2020. PARTICIPANTS: We included reviews that showed statistically significant beneficial effects of the intervention over placebo for the first primary outcome. MAIN OUTCOME MEASURES: We performed a random-effects meta-analysis to calculate PCEs based on the pooled result of each included review, grouped by outcome type and condition. The PCE quantifies how much of the observed treatment response can be achieved by the contextual effects. PUBLIC AND PATIENT INVOLVEMENT STATEMENT: No patient or member of the public was involved in conducting this research. RESULTS: We included 328 out of 3175 Cochrane systematic reviews. The results of meta-analyses showed that PCEs varied greatly depending on outcome type (I2=98%) or condition (I2=98%), but mostly lie between 0.40 and 0.95. Overall, the PCEs were 0.65 (95% CI 0.59 to 0.72) on average. Subjective outcomes were 0.50 (95% CI 0.41 to 0.59), which was significantly smaller than those of semiobjective (PCE 0.78; 95% CI 0.72 to 0.85) or objective outcomes (PCE 0.94; 95% CI 0.91 to 0.97). CONCLUSIONS: The results suggest that much of the observed benefit is not just due to the specific effect of the interventions. The specific effects of interventions may be larger for subjective outcomes than for objective or semiobjective outcomes. However, PCEs were exceptionally variable. When we evaluate the magnitude of PCEs, we should consider each PCE individually, for each condition, intervention and outcome in its context, to assess the importance of an intervention for each specific clinical setting.
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Revisiones Sistemáticas como Asunto , Humanos , Estudios EpidemiológicosRESUMEN
OBJECTIVE: The purpose of this systematic review with meta-analysis was to examine the effectiveness of exercise with behavior change techniques (BCTs) on core outcome sets in people with knee osteoarthritis. LITERATURE SURVEY: We searched randomized controlled trials (RCTs) in eight databases (MEDLINE, Embase, CENTRAL, CINAHL, PsycINFO, PEDro, ICTRP, and ClinicalTrials.gov) up to November 4, 2021. METHODOLOGY: Eligible participants were people with knee osteoarthritis. The intervention was exercise with BCTs. Primary outcomes included physical function, quality of life (QOL) 6 to 12 months after intervention, and adverse events. Secondary outcomes were knee pain, exercise adherence, mobility, and self-efficacy 3 months or more after intervention. The bias risk was assessed using the Risk of Bias 2 tool. The random-effects model was used for the meta-analysis. SYNTHESIS: We found 16 individual BCTs, and 37.7% of trials used a single BCT. For meta-analysis, we included 21 RCTs (n = 1623). Most outcomes had a very low certainty of evidence, and the risk of bias was the consistent reason for downgrading evidence levels. The standardized mean difference (SMD) with 95% confidence interval (95% CI) was 0.00 (-0.24, 0.24) in physical function, 0.33 (-0.51, 1.17) in exercise adherence, and 0.04 (-0.39, 0.47) in self-efficacy. The risk ratio (95% CI) of adverse events was 3.6 (0.79, 16.45). QOL was not pooled due to insufficient data (very low certainty of evidence). In contrast, the SMD (95% CI) for knee pain reduction and mobility improvement was -0.33 (-0.53, -0.13) and 0.21 (-0.05, 0.47) with moderate and low certainty of evidence, respectively. CONCLUSION: The evidence is inconclusive regarding the effectiveness of BCTs with exercises on core outcome sets. Further research should explore the effectiveness of BCTs with valid design. PROTOCOL REGISTRATION: PROSPERO (CRD42020212904).
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Osteoartritis de la Rodilla , Humanos , Osteoartritis de la Rodilla/terapia , Ejercicio Físico , Terapia por Ejercicio/métodos , Terapia Conductista , DolorRESUMEN
OBJECTIVE: We aimed to compare the methodological quality of physical therapy-related trials published in open access with that of trials published in subscription-based journals, adjusting for subdiscipline, intervention type, endorsement of the Consolidated Standards of Reporting Trials, impact factor, and publication language. DESIGN: In this meta-epidemiological study, we searched the Physiotherapy Evidence Database on May 8, 2021, to include any physical therapy-related trials published from January 1, 2020. We extracted variables such as Consolidated Standards of Reporting Trials endorsement, the Physiotherapy Evidence Database score, and publication type. We compared the Physiotherapy Evidence Database score between the publication types using a multivariable generalized estimating equation by adjusting for covariates. RESULTS: A total of 2743 trials were included, with a mean total Physiotherapy Evidence Database score (standard deviation) of 5.8 (±1.5). Trials from open access journals had a lower total Physiotherapy Evidence Database score than those from subscription-based journals (5.5 ± 1.5 vs. 5.9 ± 1.5, mean difference = -0.4; 95% confidence interval = 0.3-0.5). Generalized estimating equation revealed that open access publication was significantly associated with the total Physiotherapy Evidence Database score (mean difference = -0.42; P < 0.001). CONCLUSIONS: In the recent physical therapy-related trials, open access publications demonstrated lower methodological quality than subscription-based publications, although with a small difference.
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Acceso a la Información , Medicina , Humanos , Estudios Transversales , Modalidades de Fisioterapia , Estudios EpidemiológicosRESUMEN
Objective: The Japan Coma Scale (JCS) is widely used in clinical practice to evaluate levels of consciousness in Japan. There have been several studies on the usefulness of JCS in adults. However, its usefulness in evaluating children has not been reported. Therefore, this study aimed to assess the usefulness of the JCS for the prediction of mortality in children. Methods: This is a multicenter cohort study which used data from a national trauma registry (Japan Trauma Data Bank). This study included patients under 16 years of age who were treated between 2004 and 2015.The primary outcome measure was in-hospital mortality. Two models were used to examine each item of the Glasgow Coma Scale (GCS) and the JCS. Model A included the discrete levels of each index. In model B, data regarding age, sex, vital signs on arrival to hospital, the Injury Severity Score, and blunt trauma were added to each index. The effectivity of the JCS score was then evaluated using the area under the curve (AUC) for discrimination, a calibration plot, and the Hosmer-Lemeshow test for calibration. Results: A total of 9045 patients were identified. The AUCs of the GCS and JCS were 0.929 (95% confidence interval (CI) 0.904 to 0.954) and 0.930 (95% CI 0.906 to 0.954) in model A and 0.975 (95% CI 0.963 to 0.987) and 0.974 (95% CI 0.963 to 0.985) in model B, respectively. The results of the Hosmer-Lemeshow test were 0.00 (p=1.00) and 0.00 (p=1.00) in model A and 4.14 (p=0.84) and 8.55 (p=0.38) in model B for the GCS and JCS, respectively. Conclusions: We demonstrated that the JCS is as valid as the GCS for predicting mortality. The findings of this study indicate that the JCS is a useful and relevant tool for pediatric trauma care and future research.
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The cytocompatibility and osteoconductivity of the Zr-14Nb-5Ta-1Mo alloy were investigated using a mouse osteoblastic cell line (MC3T3-E1) to promote the application of this newly developed alloy in dental/medical treatment. The initial cell-attached morphology was visualized by fluorescent staining, and cells cultured on the Zr alloy showed similar cell adhesion behavior to cells cultured on titanium (Ti). In our 5-day proliferation investigation, similar cell numbers were obtained with both Zr alloy and Ti. These results indicate that the cytocompatibility of Zr alloy is similar to that of Ti. In addition, the similar results in the evaluation of alkaline phosphatase (ALP) activity and staining of deposited calcium using alizarin red S with both Zr alloy and Ti indicated that the osteoconductivity of the Zr alloy is similar to that of Ti. Our results prove the good cytocompatibility and osteoconductivity of the Zr-14Nb-5Ta-1Mo alloy, enabling its promotion for use in dental/medical applications.
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Aleaciones , Circonio , Adhesión Celular , Osteoblastos , Titanio/farmacología , Circonio/farmacologíaRESUMEN
The manganese (Mn) ion has recently been probed as a potential candidate element for the surface chemistry modification of titanium (Ti) implants in order to develop a more osteogenic surface with the expectation of taking advantage of its strong binding affinity to the integrins on bone-forming cells. However, the exact mechanism of how Mn enhances osteogenesis when introduced into the surface of Ti implants is not clearly understood. This study investigated the corrosion resistance and potential osteogenic capacity of a Mn-incorporated Ti surface as determined by electrochemical measurement and examining the behaviors of human mesenchymal stem cells (MSCs) in a clinically available sandblasted/acid-etched (SLA) oral implant surface intended for future biomedical applications. The surface that resulted from wet chemical treatment exhibited the formation of a Mn-containing nanostructured TiO2 anatase thin film in the SLA implant and improved corrosion resistance. The Mn-incorporated SLA surface displayed sustained Mn ion release and enhanced osteogenesis-related MSC function, which enhanced early cellular events such as spreading, focal adhesion, and mRNA expression of critical adhesion-related genes and promoted full human MSC differentiation into mature osteoblasts. Our findings indicate that surface Mn modification by wet chemical treatment is an effective approach to produce a Ti implant surface with increased osteogenic capacity through the promotion of the osteogenic differentiation of MSCs. The improved corrosion resistance of the resultant surface is yet another important benefit of being able to provide favorable osseointegration interface stability with an increased barrier effect.
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Células Madre Mesenquimatosas , Osteogénesis , Diferenciación Celular , Humanos , Iones/metabolismo , Manganeso/metabolismo , Células Madre Mesenquimatosas/metabolismo , Oseointegración , Propiedades de Superficie , Titanio/farmacologíaRESUMEN
OBJECTIVES: This study aims to describe the distribution of anchor-based minimal important change (MIC) estimates in standard deviation (SD) units and examine if the robustness of such estimates depends on the specific SD used or on the methodological credibility of the anchor-based estimates. DESIGN AND SETTING: We included all anchor-based MIC estimates from studies published in MEDLINE and relevant literature databases upto October 2018. Each MIC was converted to SD units using baseline, endpoint, and change from baseline SDs. We performed a descriptive analysis of MICs in SD units and checked how the distribution would change if MICs with low methodological credibility were excluded from the analysis. RESULTS: We included 1,009 MIC estimates from 182 studies. The medians and interquartile ranges of MICs in SD units were 0.43 (0.25 to 0.69), 0.42 (0.22 to 0.70), and 0.51 (0.28 to 0.78) for baseline, endpoint, and change SD units, respectively. Some MICs were extremely large or small. The distribution did not change significantly after excluding MICs estimated by less credible methods. CONCLUSIONS: The size of the universally applicable MIC in SD units could not be determined. Anchor-based MICs in SD units were widely distributed, with more than half in the range of 0.2 to 0.8.
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OBJECTIVES: To assess the proportion of the recent Cochrane reviews that included outcomes in their literature search strategy, how often they acknowledged these limitations, and how qualitatively different the results of outcomes included and not included in the search strategy were. DESIGN AND SETTING: We identified all the Cochrane reviews of the interventions published in 2020 that used a search strategy connecting outcome terms with "AND." Reviews were defined as acknowledging the limitations of searching for outcomes if they mentioned them in the discussion. We compared the characteristics of outcomes included and not included in the search strategy. RESULTS: Of the 523 Cochrane reviews published in 2020, 51 (9.8%) included outcomes in their search strategy. Only one review acknowledged it as a limitation. Forty-seven (92%) assessed outcomes not included in the search strategy. Outcomes included in the search strategies tended to include a larger number of studies and show their effects in favor of the intervention. CONCLUSIONS: Around ten percent of the recent Cochrane reviews included outcomes in their search, which may have resulted in more outcomes significantly in favor of the intervention. Reviewers should be more explicit in acknowledging the potential implications of searching for outcomes.
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BACKGROUND: The number of new noncommercial clinical studies conducted in Japan declined within the first year of the implementation of the Clinical Trials Act (CTA) on April 1, 2018. This study aimed to examine the impact of the CTA's enforcement on the number of new noncommercial clinical studies registered in the Japanese Clinical Trial Registry. METHODS: An interrupted time-series design was used in the analysis, which was conducted from April 2015 to March 2019. We collected data for studies registered in the Clinical Trial Registry, managed by the University Hospital Medical Information Network. RESULTS: In total, 35,811 studies were registered; of these, 16,455 fulfilled the eligibility criteria. The difference in the trend of monthly number of new studies after CTA enforcement decreased significantly by 15.0 (95% confidence interval [CI], -18.7 to -11.3), and the level decreased by 40.8 (95% CI, -68.2 to -13.3) studies from the pre-enforcement to the post-enforcement period. Multigroup analyses indicated that the act exerted a significant effect on the trend of new clinical studies, particularly those with smaller sample sizes, interventional study designs, and nonprofit funding sponsors. CONCLUSIONS: The number of Japanese noncommercial clinical studies declined significantly following implementation of the CTA. It is necessary to establish a system to promote clinical studies in Japan while ensuring transparency and safety.
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Investigación Biomédica , Humanos , Japón , Factores de TiempoRESUMEN
Ti-Zr alloys have been investigated as an alternative to commercially pure Ti (c.p.Ti). According to our previous studies on the mechanical properties of Ti-Zr alloys, a Zr proportion in the range of 30-50 mol% has competitive advantages over Ti-10Zr and c.p.Ti. The aim of this study is to evaluate the biological response to Ti-Zr alloys with different compositions and their surface characteristics. Alloy surfaces are modified by sandblasting and sulfuric acid etching. As a result, similar surface structures are observed for c.p.Ti, Ti-10Zr, and Ti-30Zr, whereas Ti-50Zr does not form a micro-rough structure by the same treatment process. No significant difference is found in the viability of cells on c.p.Ti, Ti-10Zr, and Ti-30Zr, whereas lower cell attachment levels are detected on Ti-50Zr. In summary, Ti-30Zr reliably forms a micro-rough structure, which provides one evidence for its application in a new dental implant material.