Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 135
Filter
1.
Rev. colomb. anestesiol ; 49(3): e702, July-Sept. 2021.
Article in English | LILACS, COLNAL | ID: biblio-1280188

ABSTRACT

The SES-Hospital Universitario de Caldas takes care of approximately 210 deliveries per month, with an overall cesarean section rate of 32 %, of which 72 % were conducted with, or had an epidural catheter, as an extension of the analgesia delivered during labor and were therefore excluded from the trial. This may address some of the concerns expressed by Sotelo 1 It is important to consider the observational character of the study discussed; in the discussion paragraph, mention is made of a potential selection bias, based on the convenience sampling and the non-randomized approach which are typical of the design used


el SES-Hospital Universitario de Caldas atiende aproximadamente 210 partos por mes, con una tasa global de cesáreas del 32%, de las cuales el 72% se realizaron con o tenían un catéter epidural, como una extensión de la analgesia administrada durante el trabajo de parto y por lo tanto, fueron excluidos del ensayo. Esto puede abordar algunas de las preocupaciones expresadas por Sotelo 1 Es importante considerar el carácter observacional del estudio discutido; En el párrafo de discusión, se menciona un posible sesgo de selección, basado en el muestreo de conveniencia y el enfoque no aleatorio que son típicos del diseño utilizado.


Subject(s)
Humans , Female , Pregnancy , Labor, Obstetric , Cesarean Section , Character , Selection Bias , Sampling Studies , Catheters , Analgesia
2.
Rev. colomb. anestesiol ; 49(3): e701, July-Sept. 2021.
Article in English | LILACS, COLNAL | ID: biblio-1280187

ABSTRACT

After reading the article entitled "Comparison of subarachnoid opioid mix for cesarean section" published by Isabel Osorio et al., in January 2020; I would like to make the following observations and comments. The number of patients studied (n =71) is surprising considering that the hospital where the research was conducted is a third-level institution and a referral center for high complexity obstetric care. During the duration of the trial (one year, from June 2028 through May 2019) most likely many patients underwent this type of surgical intervention. Is it then possible to consider a potential selection bias? Moreover, the group distribution is not clearly defined, and certainly it was not random: A (29), B (16), C (26)


Después de leer el artículo titulado "Comparación de mezcla de opioides subaracnoides para cesárea" publicado por Isabel Osorio et al., En enero de 2020; Me gustaría hacer las siguientes observaciones y comentarios. Sorprende el número de pacientes estudiadas ( n = 71) si se considera que el hospital donde se realizó la investigación es una institución de tercer nivel y un centro de referencia de atención obstétrica de alta complejidad. Durante la duración del ensayo (un año, desde junio de 2028 hasta mayo de 2019), lo más probable es que muchos pacientes se hayan sometido a este tipo de intervención quirúrgica. ¿Es posible entonces considerar un posible sesgo de selección? Además, la distribución de los grupos no está claramente definida, y ciertamente no fue aleatoria: A (29), B (16), C (26)


Subject(s)
Humans , Female , Pregnancy , Surgical Procedures, Operative , Cesarean Section , Analgesics, Opioid , Research , Selection Bias , Hospitals
4.
Int. j. odontostomatol. (Print) ; 14(4): 602-609, dic. 2020. tab, graf
Article in Spanish | LILACS | ID: biblio-1134546

ABSTRACT

RESUMEN: Comparar mediante una revisión sistemática los resultados clínicos de los procedimientos de cirugía plástica periodontal/periimplantar (CP) con injerto de tejido blando autógeno (ITB) obtenido del área lateral del paladar (ALP) versus del área de la tuberosidad (AT). Se realizó una búsqueda electrónica de ensayos clínicos en la base de datos Medline/Pubmed, Cochrane y las revistas de Periodoncia e Implantes de mayor impacto según la Web of Science, para hallar artículos publicados hasta abril del 2020. Se valoró el riesgo de sesgo de los artículos añadidos según el manual Cochrane Versión 5.1.0 para ensayos clínicos aleatorizados y la escala Newcastle-Ottawa para ensayos clínicos controlados. De una muestra inicial de 930 artículos, cuatro ensayos clínicos (tres aleatorizados) fueron incluidos en el presente estudio, donde se realizaron un total de 87 CP alrededor de piezas e implantes dentales, de las cuales 42 cirugías fueron realizadas con ITB del ALP y 45 cirugías con ITB del AT, se evaluó los resultados desde las 8 semanas hasta los 12 meses. No se hallaron diferencias estadísticamente significativas en los resultados clínicos entre ambos grupos, se mejoró el fenotipo gingival en la zona receptora para el grupo que obtuvo el ITB del AT y el nivel del dolor del sitio donador del AT fue menor en las dos primeras semanas que el sitio donante del ALP. Los estudios incluidos manifestaron un bajo riesgo de sesgo en promedio. Ambas áreas donantes de injerto de tejido blando proporcionan resultados clínicos similares, el injerto del área de la tuberosidad mejora el fenotipo gingival de la zona receptora y reduce el dolor post operatorio en las primeras semanas del sitio donador.


ABSTRACT: The objective of the study was to compare, through a systematic review, the clinical results of periodontal / peri-implant plastic surgery (CP) procedures with autogenous soft tissue graft (ITB) obtained from the lateral palate area (ALP) versus the tuberosity area (AT). We conducted an electronic search of clinical trials in the Medline/Pubmed, Cochrane database and the journals of Periodontics and Implants with the greatest impact according to the Web of Science, to find articles published until April 2020. The risk of bias of the articles added was assessed according to the Cochrane Manual Version 5.1.0 for randomized clinical trials and the Newcastle-Ottawa scale for controlled clinical trials. From the initial sample of 930 articles, four clinical trials were included (three randomized) in the present study, where a total of 87 PC were performed around dental pieces and implants, of which 42 surgeries were performed with ITB of the ALP and 45 surgeries with ITB of the AT, the results were evaluated from the 8 weeks to 12 months. No statistically significant differences were found in the clinical results between the two groups, the gingival phenotype in the receiving area was improved for the group that obtained the ITB of the AT and the level of pain at the donor site was lower in the first two weeks than the ALP donor site. The studies showed a lowrisk of bias on average. Both soft tissue graft donor areas provide similar clinical results, grafting the tuberosity area improves the gingival phenotype of the recipient area and reduces post-operative pain of the donor site in the first few weeks.


Subject(s)
Humans , Dental Implants/statistics & numerical data , Oral Surgical Procedures , Dental Implantation, Endosseous , Palate , Transplantation, Autologous , Selection Bias , Tissue Transplantation , Connective Tissue/transplantation , Gingival Recession
5.
Säo Paulo med. j ; 138(3): 184-189, May-June 2020. tab, graf
Article in English | LILACS, SES-SP | ID: biblio-1139690

ABSTRACT

ABSTRACT BACKGROUND: The authors of randomized controlled trials will usually claim that they have met the randomization process criterion. However, sequence generation schemes differ and some schemes that are claimed to be randomized are not genuinely randomized. Even less well understood, and often more difficult to ascertain, is whether the allocation was really concealed. OBJECTIVE: To detect the extent of control over selection bias, in a comparison between two Cochrane groups: oral health and otorhinolaryngology; and to describe the methods used to control for this bias. DESIGN AND SETTING: Cross-sectional study conducted in a public university in São Paulo, Brazil. METHODS: The risk of selection bias in 1,714 records indexed in Medline database up to 2018 was assessed, independent of language and access. Two dimensions implicated in the allocation were considered: generation of the allocation sequence; and allocation concealment. RESULTS: We included 420 randomized controlled trials and all of them were evaluated to detect selection bias. In the sample studied, only 28 properly controlled the selection bias. Lack of control over selection bias was present in 80% of the studies evaluated in both groups. CONCLUSION: The two groups were similar regarding control over selection bias. They are also similar to the methods used. The dimension of allocation concealment appears to be a limiting factor with regard to production of randomized controlled trials with low risk of selection bias. The quality of reporting in studies on oral health and otorhinolaryngology is suboptimal and needs to be improved, in line with other fields of healthcare.


Subject(s)
Humans , Otolaryngology , Oral Health , Brazil , Selection Bias , Cross-Sectional Studies
6.
Aval. psicol ; 19(1): 87-96, jan.-abr. 2020. tab, il
Article in English | LILACS, INDEXPSI | ID: biblio-1089026

ABSTRACT

The CART algorithm has been extensively applied in predictive studies, however, researchers argue that CART produces variable selection bias. This bias is reflected in the preference of CART in selecting predictors with large numbers of cutpoints. Considering this problem, this article compares the CART algorithm to an unbiased algorithm (CTREE), in relation to their predictive power. Both algorithms were applied to the 2011 National Exam of High School Education, which includes many categorical predictors with a large number of categories, which could produce a variable selection bias. A CTREE tree and a CART tree were generated, both with 16 leaves, from a predictive model with 53 predictors and the students' writing essay achievement as the outcome. The CART algorithm yielded a tree with a better outcome prediction. This result suggests that for large data sets, called big data, the CART algorithm might give better results than the CTREE algorithm.(AU)


O algoritmo CART tem sido aplicado de forma extensiva em estudos preditivos. Porém, pesquisadores argumentam que o CART apresenta sério viés seletivo. Esse viés aparece na preferência do CART pelos preditores com grande número de categorias. Este artigo considera esse problema e compara os algoritmos CART e CTREE, este considerado não enviesado, tomando como resultado seu poder preditivo. Os algoritmos foram aplicados no Exame Nacional do Ensino Médio de 2011, no qual estão incluídos vários preditores nominais e ordinais com muitas categorias, o que pode produzir um viés seletivo. Foram geradas uma árvore do CTREE e outra do CART, ambas com 16 folhas, provenientes de um modelo com 53 variáveis preditoras e a nota da redação, como desfecho. A árvore do algoritmo CART apresentou uma melhor predição. Para grandes bancos de dados, possivelmente o algoritmo CART é mais indicado do que o algoritmo CTREE.(AU)


El algoritmo CART es ampliamente utilizado en análisis predictivos. Sin embargo, los investigadores argumentan que el CART presenta un fuerte sesgo de selección. Este sesgo se refleja en el CART en la preferencia de seleccionar predictores con elevado número de categorías. Teniendo en cuenta este problema, el presente artículo compara el algoritmo CART y un algoritmo imparcial (CTREE) con relación a su poder predictivo. Ambos algoritmos se aplicaron en el Examen Nacional de la Enseñanza Secundaria de 2011, incluyendo predictores nominales y ordinales con diversas categorías, un escenario susceptible de producir el sesgo de selección de variables mencionado. Fueron generados un árbol CTREE y un árbol CART, ambos con 16 hojas, provenientes de un modelo predictivo con 53 variables y la nota del comentario de texto. El árbol del algoritmo CART presentó mejor predicción. Para grandes bases de datos el algoritmo CART puede proporcionar mejores resultados que el CTREE.(AU)


Subject(s)
Algorithms , Decision Trees , Education, Primary and Secondary , Educational Measurement , Selection Bias , Predictive Value of Tests
7.
Journal of Gastric Cancer ; : 393-407, 2019.
Article in English | WPRIM | ID: wpr-785962

ABSTRACT

PURPOSE: To identify the potential therapeutic role of postoperative radiotherapy (RT) in patients with locally advanced (stage II and stage III) gastric signet ring cell carcinoma (SRC).MATERIALS AND METHODS: Patients with locally advanced gastric SRC from the Surveillance, Epidemiology, and End Results program database between 2004 and 2012 were included in our study. Univariate and multivariate Cox proportional models were performed, and survival curves were generated to evaluate the prognostic effect of postoperative RT and surgery alone on SRC patients. Propensity score matching (PSM) was used to avoid selection bias among the study cohorts.RESULTS: We found that patients with postoperative RT had better probability of survival compared with those who did not receive RT (overall survival [OS], P<0.001; cancer-specific survival [CSS], P<0.001). After PSM, analysis of both overall and CSS showed that patients who underwent postoperative RT had better prognosis than those receiving surgery alone in the matched cohort (OS, P=0.00079; CSS, P=0.0036). Multivariate Cox proportional model indicated that postoperative RT had better effect on prognosis compared with surgery alone with respect to both overall (hazard ratio [HR], 0.716; 95% confidence interval [95% CI], 0.590–0.87; P=0.001) and CSS (HR, 0.713; 95% CI, 0.570–0.890; P=0.003).CONCLUSIONS: Postoperative RT had better prognosis compared with surgery alone for both overall and CSS for patients with locally advanced gastric SRC.


Subject(s)
Carcinoma, Signet Ring Cell , Cohort Studies , Humans , Nomograms , Prognosis , Propensity Score , Radiotherapy , SEER Program , Selection Bias , Stomach Neoplasms
8.
Journal of Gastric Cancer ; : 438-450, 2019.
Article in English | WPRIM | ID: wpr-785958

ABSTRACT

PURPOSE: Although linear-shaped gastroduodenostomy (LSGD) was reported to be a feasible and reliable method of Billroth I anastomosis in patients undergoing totally laparoscopic distal gastrectomy (TLDG), the feasibility of LSGD for patients undergoing totally robotic distal gastrectomy (TRDG) has not been determined. This study compared the feasibility of LSGD in patients undergoing TRDG and TLDG.MATERIALS AND METHODS: ALL C: onsecutive patients who underwent LSGD after distal gastrectomy for gastric cancer between January 2009 and December 2017 were analyzed retrospectively. Propensity score matching (PSM) analysis was performed to reduce the selection bias between TRDG and TLDG. Short-term outcomes, functional outcomes, learning curve, and risk factors for postoperative complications were analyzed.RESULTS: This analysis included 414 patients, of whom 275 underwent laparoscopy and 139 underwent robotic surgery. PSM analysis showed that operation time was significantly longer (163.5 vs. 132.1 minutes, P<0.001) and postoperative hospital stay significantly shorter (6.2 vs. 7.5 days, P<0.003) in patients who underwent TRDG than in patients who underwent TLDG. Operation time was the independent risk factor for LSGD after intracorporeal gastroduodenostomy. Cumulative sum analysis showed no definitive turning point in the TRDG learning curve. Long-term endoscopic findings revealed similar results in the two groups, but bile reflux at 5 years showed significantly better improvement in the TLDG group than in the TRDG group (P=0.016).CONCLUSIONS: LSGD is feasible in TRDG, with short-term and long-term outcomes comparable to that in TLDG. LSGD may be a good option for intracorporeal Billroth I anastomosis in patients undergoing TRDG.


Subject(s)
Bile Reflux , Gastrectomy , Gastroenterostomy , Humans , Laparoscopy , Learning Curve , Length of Stay , Methods , Postoperative Complications , Propensity Score , Retrospective Studies , Risk Factors , Robotic Surgical Procedures , Selection Bias , Stomach Neoplasms
9.
Article in English | WPRIM | ID: wpr-759536

ABSTRACT

Randomized controlled trial is widely accepted as the best design for evaluating the efficacy of a new treatment because of the advantages of randomization (random allocation). Randomization eliminates accidental bias, including selection bias, and provides a base for allowing the use of probability theory. Despite its importance, randomization has not been properly understood. This article introduces the different randomization methods with examples: simple randomization; block randomization; adaptive randomization, including minimization; and response-adaptive randomization. Ethics related to randomization are also discussed. The study is helpful in understanding the basic concepts of randomization and how to use R software.


Subject(s)
Bias , Ethics , Probability Theory , Random Allocation , Selection Bias
10.
Article in English | WPRIM | ID: wpr-763087

ABSTRACT

The goal of the present study was to test the reliability and validity of the Japanese version of the Quality of Life after Brain Injury (QOLIBRI) scale. Correlations between the QOLIBRI and Glasgow Coma Scale scores, anxiety, depression, general quality of life (QOL), and demographic characteristics were examined to assess scale validity. The structure of the QOLIBRI was investigated with exploratory and confirmatory factor analyses, as well as the Partial Credit Model. Test–retest reliability was assessed over a 2-week interval. Participants were 129 patients with traumatic brain injury (TBI) recruited from rehabilitation centers in Japan. The QOLIBRI showed good-to-excellent internal consistency (Cronbach's α: 0.82–0.96), test–retest reliability, and validity (r = 0.77–0.90). Factor analyses revealed a 6-factor structure. Compared to an international sample (IS), Japanese patients had lower QOLIBRI scores and lower satisfaction in several domains. There were positive correlations between the QOLIBRI scales and the Short Form 36 Health Survey (r = 0.22–0.41). The Japanese version of the QOLIBRI showed good-to-excellent psychometric properties. Differences between JS and IS may reflect sampling bias and cultural norms regarding self-evaluation. The QOLIBRI could be a useful tool for assessing health-related QOL in individuals with TBI.


Subject(s)
Anxiety , Asian Continental Ancestry Group , Brain Injuries , Brain , Depression , Diagnostic Self Evaluation , Glasgow Coma Scale , Health Surveys , Humans , Japan , Psychometrics , Quality of Life , Rehabilitation Centers , Reproducibility of Results , Selection Bias , Weights and Measures
11.
Annals of Coloproctology ; : 137-143, 2019.
Article in English | WPRIM | ID: wpr-762307

ABSTRACT

PURPOSE: The aim of this study was to assess oncological outcomes of postoperative radiotherapy plus chemotherapy (CRT) versus chemotherapy alone (CTx) in stage II or III upper rectal cancer patients who underwent curative surgery. METHODS: We retrospectively reviewed 263 consecutive patients with pathologic stage II or III upper rectal cancer who underwent primary curative resection with postoperative CRT or CTx from January 2008 to December 2014 at Chonnam National University Hwasun Hospital. Multivariate and propensity score matching analyses were used to reduce selection bias. RESULTS: Median follow-up was 48.1 months for the entire cohort and 53.5 months for the matched cohort. In subgroup analysis of the propensity score matched cohort, the 3-year local recurrence-free survival was 94.1% (95% confidence interval [CI], 87.8%–100%) in the CRT group and 90.1% (95% CI, 82.8%–97.9%) in the CTx group (P = 0.370). No significant difference in disease-free survival was observed according to treatment type. On multivariate analysis, circumferential resection margin involvement (hazard ratio [HR], 2.386; 95% CI, 1.190–7.599; P = 0.032), N stage (HR, 6.262; 95% CI, 1.843–21.278, P = 0.003), and T stage (HR, 5.896, 95% CI, 1.298–6.780, P = 0.021) were identified as independent risk factors for local recurrence of tumors of the upper rectum. CONCLUSION: Omission of radiotherapy in an adjuvant treatment setting may not jeopardize oncologic outcomes in stages II and III upper rectal cancer.


Subject(s)
Chemoradiotherapy , Cohort Studies , Disease-Free Survival , Drug Therapy , Follow-Up Studies , Humans , Multivariate Analysis , Propensity Score , Radiotherapy , Rectal Neoplasms , Rectum , Recurrence , Retrospective Studies , Risk Factors , Selection Bias
12.
Article in Korean | WPRIM | ID: wpr-762269

ABSTRACT

BACKGROUND: Maintenance of tracheal intubation is associated with use of sedatives, stress due to mechanical ventilation, or respiratory complications. The aim of this study is to compare the incidence of delirium between early and late extubation groups after liver transplantation (LT). METHODS: Medical records from 247 patients who received LT from January 2010 to July 2017 in a single university hospital were retrospectively reviewed. Patients were divided with 2 groups: Those who underwent early extubation after LT (E group, n = 52) and those who underwent extubation within few hours of intensive care unit (ICU) admission after surgery (C group, n = 195). The patients’ demographic data, perioperative managements and postoperative complications were collected. Early extubation was defined as performing extubation in the operating room after LT. A propensity score matching analysis was performed to reduce the effects of selection bias. RESULTS: Among them, 4/52 (7.69%) in E group and 30/195 (15.38%) in C group occurred postoperative delirium after LT, respectively (P = 0.180). After propensity score matching, there was no difference of the period of hospitalization in ICU (P = 0.961), time to discharge after surgery (P = 0.117) and incidence of delirium between groups (P = 1.000). CONCLUSIONS: Although this study is a retrospective study and limited by the small number of subjects, early extubation does not affect the incidence of delirium after LT. Therefore, further prospective studies on this were needed.


Subject(s)
Airway Extubation , Delirium , Hospitalization , Humans , Hypnotics and Sedatives , Incidence , Intensive Care Units , Intubation , Liver Transplantation , Liver , Medical Records , Operating Rooms , Postoperative Complications , Propensity Score , Prospective Studies , Respiration, Artificial , Retrospective Studies , Selection Bias
13.
Journal of Gastric Cancer ; : 264-273, 2018.
Article in English | WPRIM | ID: wpr-716708

ABSTRACT

PURPOSE: To investigate the current status of adjuvant chemotherapy (AC) regimens in Korea and the difference in efficacy of AC administered by surgical and medical oncologists in patients with stage II or III gastric cancers. MATERIALS AND METHODS: We performed a retrospective observational study among 1,049 patients who underwent curative resection and received AC for stage II and III gastric cancers between February 2012 and December 2013 at 29 tertiary referral university hospitals in Korea. To minimize the influence of potential confounders on selection bias, propensity score matching (PSM) was used based on binary logistic regression analysis. The 3-year disease-free survival (DFS) rates were compared between patients who received AC administered by medical oncologists or surgical oncologists. RESULTS: Between February 2012 and December 2013 in Korea, the most commonly prescribed AC by medical oncologists was tegafur/gimeracil/oteracil (S-1, 47.72%), followed by capecitabine with oxaliplatin (XELOX, 16.33%). After performing PSM, surgical oncologists (82.74%) completed AC as planned more often than medical oncologists (75.9%), with statistical significance (P=0.036). No difference in the 3-year DFS rates of stage II (P=0.567) or stage III (P=0.545) gastric cancer was found between the medical and surgical oncologist groups. CONCLUSIONS: S-1 monotherapy and XELOX are a main stay of AC, regardless of whether the prescribing physician is a medical or surgical oncologist. The better compliance with AC by surgical oncologists is a valid reason to advocate that surgical oncologists perform the treatment of AC for stage II or III gastric cancers.


Subject(s)
Capecitabine , Chemotherapy, Adjuvant , Compliance , Disease-Free Survival , Hospitals, University , Humans , Korea , Logistic Models , Observational Study , Propensity Score , Referral and Consultation , Retrospective Studies , Selection Bias , Stomach Neoplasms
14.
Psychiatry Investigation ; : 649-654, 2018.
Article in English | WPRIM | ID: wpr-714982

ABSTRACT

OBJECTIVE: We aimed to investigate the long-term effects of atomoxetine on growth in Korean children and adolescents with attention-deficit/hyperactivity disorder (ADHD). METHODS: The medical records of 82 subjects (mean age, 9.0±2.0 years; 64 boys) with ADHD treated with atomoxetine for at least 1 year at the Department of Psychiatry at Asan Medical Center were retrospectively reviewed. Height and weight data were prospectively obtained and retrospectively gathered and converted to age- and gender-corrected z scores using norms from Korean youths. Growth changes were analyzed using random coefficients models with changes in height or weight z scores as the dependent variables. RESULTS: Height z scores significantly decreased during the treatment period (β=-0.054, p=0.024). Height z scores decreased during the 1st year of treatment (β=-0.086, p=0.003), but did not change after the 1st year. Weight z scores did not change significantly during treatment (β=0.004, p=0.925). CONCLUSION: Our results suggest that long-term atomoxetine treatment may be associated with deficits in height growth in Korean youths, although this effect was minor and tended to be attenuated over the first year. Because of the limitations of this study such as retrospective design and selection bias, further prospective studies are needed.


Subject(s)
Adolescent , Atomoxetine Hydrochloride , Child , Humans , Medical Records , Prospective Studies , Retrospective Studies , Selection Bias
15.
Int. j. cardiovasc. sci. (Impr.) ; 30(3): f:251-l:261, mai.-jun. 2017. tab, graf
Article in Portuguese | LILACS | ID: biblio-836717

ABSTRACT

Fundamento: A hipóxia é uma condição fisiológica que pode influenciar a modulação autonômica cardíaca, qualpode ser avaliada pelas flutuações espontâneas da frequência cardíaca, chamada de variabilidade da frequência cardíaca (VFC). Estudos têm reportado reduções ou manutenção da VFC em situação de hipóxia apresentando efeitos controversos. Há uma lacuna no conhecimento em relação às modificações da VFC durante a hipóxia. Objetivo: Revisar sistematicamente estudos que investigaram os efeitos da hipóxia na VFC em adultos saudáveis e não aclimatados durante o repouso. Métodos: A presente revisão sistemática foi realizada a partir da diretriz PRISMA. Os termos utilizados para a busca nas bases MEDLINE, SCOPUS, LILACS e EUROPE PMC foram: "heart rate variability" OR "cardiac autonomic modulation" OR "cardiac autonomic regulation" AND (hypoxia OR altitude) NOT intermitente NOT sleep. Os registros foram filtrados por espécie, idade e idiomas. Resultados: Ao final da triagem e elegibilidade restaram 13 artigos para a síntese qualitativa. Discussão: Os estudos utilizam protocolos experimentais variados que envolvem diferença na pressão barométrica, no nível de oxigênio, no tempo de exposição à hipóxia e no controle da frequência respiratória. Possivelmente a influência desses fatores e também a variação interindividual à hipóxia podem justificar diferentes respostas na VFC. Conclusão: A partir dos estudos investigados, a hipóxia foi capaz de gerar uma queda na VFC, seja por retirada ou manutenção da modulação vagal, ou por predomínio simpático ou mesmo pela combinação dessas respostas em adultos saudáveis não aclimatados a hipóxia. Este efeito parece ser dependente do nível de altitude e da pressão barométrica


Background: Hypoxia is a physiological condition that may affect the cardiac autonomic modulation, which can be assessed by spontaneous fluctuations in heart rate, know as heart rate variability (HRV). Studies have reported reductions or maintenance of HRV in hypoxic situation presenting controversial effects. There is a knowledge gap in relation to changes in HRV during hypoxia. Objective: The aim of this study was to systematically review the effects of hypoxia on HRV in unacclimatized healthy adults at rest. Methods: This systematic review was performed according to PRISMA guidelines. Search terms used in MEDLINE, SCOPUS, LILACS and EUROPE PMC database were: "heart rate variability" OR "cardiac autonomic modulation" OR "cardiac autonomic regulation" AND NOT intermittent NOT sleep (hypoxia OR altitude). Records were filtered by species, age group and language. Results: At the end of the screening and eligibility, 13 manuscripts remained for qualitative synthesis. Discussion: The studies used different experimental protocols involving difference in barometric pressure, oxygen level, time of exposure to hypoxia and control of respiratory rate. Possibly the influence of these factors and also the interindividual variation to hypoxia may justify different responses in HRV. Conclusion: Based on the investigated studies, hypoxia has been capable of generating a decrease in HRV, either by reduction or maintenance of vagal modulation, or by sympathetic predominance or even the combination of these responses in healthy adults unacclimatized to hypoxia. This effect appears to be dependent on altitude level and barometric pressure


Subject(s)
Humans , Male , Female , Adult , Adult , Autonomic Nervous System , Heart Rate/physiology , Hypoxia/complications , Altitude , Atmospheric Pressure , Cardiovascular System , Review Literature as Topic , Selection Bias
16.
An. bras. dermatol ; 92(2): 177-183, Mar.-Apr. 2017. tab, graf
Article in English | LILACS | ID: biblio-838042

ABSTRACT

Abstract: Background: Atopic dermatitis is a prevalent health problem in the world. Allergic sensitization is an important risk factor, but the roles of other factors, inherent in tropic region, are unknown. Objective: A cohort study was designed in a tropical city to investigate molecular and environmental risk factors for eczema, considering as particular features perennial exposure to mites, poor living conditions and others tropical characteristics. Methods: 433 patients were included at baseline and biological samples were collected during 24 months of follow-up. Clinical information was collected using questionnaires (SCORAD, DLQI and a subjective scale) during each clinical assessment. Results: The prevalence of atopic eczema was 93%, with similar frequency between children and adults; parents history of eczema and polysensitization to mites, dogs, cats, cockroaches and birds, were risk factors for severe and persistent eczema and allergic comorbidities. Food sensitization was present in 16% of patients but food-induced allergies were scarce. Psychiatric, dental and ocular disorders were the most frequent non-allergic comorbidities. Study limitations: selection bias. Conclusion: We presented a tropical cohort of patients with eczema and we identified some risk factors for severe and persistent dermatitis. Some patterns of sensitization were associated with severe eczema and respiratory symptoms, and the natural history of "atopic march" is different to that described in some industrialized countries. The collection of biological samples will contribute to the understanding of the gene/environment interactions leading to allergy inception and evolution.


Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Child , Adolescent , Adult , Young Adult , Dermatitis, Atopic/epidemiology , Eczema/epidemiology , Tropical Climate , Severity of Illness Index , Selection Bias , Prevalence , Risk Factors , Cohort Studies , Sensitivity and Specificity , Colombia/epidemiology , Dermatitis, Atopic/diagnosis , Dermatitis, Atopic/genetics , Eczema/diagnosis , Eczema/genetics
17.
Evid. actual. práct. ambul ; 20(1): 22-25, 2017.
Article in Spanish | LILACS | ID: biblio-1140548

ABSTRACT

Un ensayo clínico aleatorizado por conglomerados se da cuando se aleatorizan grupos (clusters) de individuos a las distintas ramas. Puede ser la única o mejor opción de diseño ante determinadas circunstancias: si hay un claro agrupamiento (biológico o funcional) en donde algunos individuos de análisis son más parecidos entre sí que otros; si las intervenciones a evaluar se realizan a nivel del conglomerado; cuando hay riesgo de contaminación; o por practicidad, costos o conveniencia. Entre los problemas más importantes que conllevan se encuentran posibles sesgos (especialmente cuando el reclutamiento de los individuos se realiza luego de la aleatorización, o no existe ceguera), así como mayor complejidad en el diseño y análisis. Asimismo, si no se tienen en cuenta la agrupación de individuos por conglomerados para el cálculo del tamaño muestral o del análisis de los datos, se podrían obtener resultados incorrectos. Estos estudios deben explicitar, además de lo habitualmente reportado: por qué se decidió realizar un diseño por conglomerados; si los objetivos, intervenciones y puntos finales a evaluar apuntan a nivel del conglomerado, individual, o ambos; describir los criterios de inclusión a nivel del conglomerado e individual; mostrar cómo se hicieron el cálculo del tamaño muestral y los análisis considerando los conglomerados; aclarar si los pacientes, profesionales actuantes e investigadores estaban ciegos a las ramas de investigación; y discutir la generalizabilidad de los resultados, entre otros. Si bien tienen mayor complejidad, estos estudios son cada vez más frecuentes. Es un diseño muy útil si está bien desarrollado y es importante conocer sus particularidades. (AU)


We perform a cluster randomized controlled trial when we randomize groups (or clusters) of individuals (whether humans, cells, or clinics) to different study arms, and not simply individuals. It can be the only or best study design option in certain circum-stances: if there is a clear grouping, when some subjects of analysis are more similar among them than the rest; if interventions to be evaluated are made at cluster level; when there is risk of "contamination" or cross-over; or because of practicality, costs or convenience according to researchers judgment. Cluster trials are associated with important issues: risk of bias (especially when individuals recruitment is made after randomization, or if there was no blinding); and the need of more complex design and analysis. If we do not take clusters into account in the sample size estimation and data analysis, we could get misleading results.When reporting these studies, researchers should make explicit (in addition to standard reporting requirements): the rationale for a cluster design; if the objectives, interventions and endpoints are for clusters, individuals or both; the inclusion criteria for clusters and individuals; how they did sample size estimations and data analysis considering cluster design; if patients, health care profes-sionals and researchers were blind; and if results can be generalized. Even though cluster randomized controlled trials are more complex, these studies are increasingly common. It is a very useful design, if correctly done. And it is important to understand its main characteristics. (AU)


Subject(s)
Humans , Randomized Controlled Trials as Topic/methods , Cluster Sampling , Cluster Analysis , Randomized Controlled Trials as Topic/classification , Randomized Controlled Trials as Topic/ethics , Selection Bias , Epidemiologic Study Characteristics
18.
Article in Korean | WPRIM | ID: wpr-194231

ABSTRACT

OBJECTIVES: The purpose of this study was to investigate the gender-related difference in the relationship between smoking status and periodontal diseases using data from the 2014 National Health and Nutrition Survey. METHODS: A total of 4,332 subjects were included in the study. Propensity score matching (PSM) was used to control selection bias, and factors affecting the smoking status were used as covariates in PSM. The chi-squared and t tests were used for bivariate analysis. Multiple logistic regression analysis was used to adjust for covariates (age, education level, household income, monthly drinking, stress, excises, dental visits, frequency of daily tooth brushing, and dental product usage). RESULTS: After adjusting for all covariates, the smoking status was associated with periodontal diseases. Among the male smoking group showed a 2.1-times higher probability of periodontal diseases than the non-smoking group (OR=2.1, 95% CI: 1.66-2.68). Among the female smoking group showed a 2.3-times higher probability of periodontal disease than the non-smoking group (OR=2.3, 95% CI: 1.12-4.89). CONCLUSIONS: Smoking was significantly associated with periodontitis in Korean male and even female although prevalence of smoking in women was very low. This result could suggest that smoking cessation program should be educated for men and women as well in order to prevent from periodontitis in Korea.


Subject(s)
Drinking , Education , Family Characteristics , Female , Humans , Korea , Logistic Models , Male , Nutrition Surveys , Periodontal Diseases , Periodontitis , Prevalence , Propensity Score , Selection Bias , Smoke , Smoking Cessation , Smoking , Tooth
19.
Article in Korean | WPRIM | ID: wpr-129943

ABSTRACT

Random allocation is commonly used in medical researches, and has become an essential part of designing clinical trials. It produces comparable groups with regard to known or unknown prognostic factors, and prevents the selection bias which occurs due to the arbitrary assignment of subjects to groups. It also provides the background for statistical testing. Depending on the change in allocation probability, random allocation is divided into two categories: fixed allocation randomization and dynamic allocation randomization. In this paper, the author briefly introduces both the theory and practice of randomization. The definition, necessity, principal, significance, and classification of randomization are also explained. Advantages and disadvantages of each randomization technique are further discussed. Dynamic allocation randomization (Adaptive randomization), which is as yet unfamiliar with the anesthesiologist, is also introduced. Lastly, the methods and procedures for random sequence generation using Microsoft Excel is provided.


Subject(s)
Classification , Random Allocation , Research Design , Selection Bias
20.
Article in Korean | WPRIM | ID: wpr-129929

ABSTRACT

Random allocation is commonly used in medical researches, and has become an essential part of designing clinical trials. It produces comparable groups with regard to known or unknown prognostic factors, and prevents the selection bias which occurs due to the arbitrary assignment of subjects to groups. It also provides the background for statistical testing. Depending on the change in allocation probability, random allocation is divided into two categories: fixed allocation randomization and dynamic allocation randomization. In this paper, the author briefly introduces both the theory and practice of randomization. The definition, necessity, principal, significance, and classification of randomization are also explained. Advantages and disadvantages of each randomization technique are further discussed. Dynamic allocation randomization (Adaptive randomization), which is as yet unfamiliar with the anesthesiologist, is also introduced. Lastly, the methods and procedures for random sequence generation using Microsoft Excel is provided.


Subject(s)
Classification , Random Allocation , Research Design , Selection Bias
SELECTION OF CITATIONS
SEARCH DETAIL