scholarly journals Influence of Indications on Perinatal Outcomes After Radio frequency Ablation in Complicated Monochorionic Pregnancies: A Retrospective Cohort Study

2020 ◽  
Author(s):  
Hongmei Wang ◽  
Qian Zhou ◽  
Xietong Wang ◽  
Jia Song ◽  
Pengzheng Chen ◽  
...  
Keyword(s):  
Cohort Study ◽  
Survival Rate ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Abdominal Wall Defect ◽  
Perinatal Outcomes ◽  
Neurological Injury ◽  
Categorical Variables ◽  
Continuous Variables ◽  
Arterial Perfusion

Abstract Background:Radiofrequency ablation (RFA) is recommended to prevent potential neurological injury or intrauterine foetal death (IUFD) of the co-twin(s) in complicated monochorionic (MC) pregnancies. However, the impacts of various indications on the pregnancy outcome following RFA remain unclear. This study aimed to determine how the indications influence the perinatal outcomes in complicated MC pregnancies undergoing radiofrequency ablation.Methods:This was a retrospective cohort study performed in a single centre. All consecutive MC pregnancies treated with RFA between July 2011 and July 2019 were included. The adverse perinatal outcomes and the survival rate were analysed based on various indications. The continuous variables with and without normal distribution were compared between the groups using Student’s t-test and Mann–Whitney U test, respectively, and for categorical variables, Chi-square and Fisher’s exact tests were used. P < 0.05 indicated a significant difference.Results:We performed 272 RFA procedures in 268 complicated MC pregnancies, including 60 selective intrauterine growth restriction (sIUGR), 64 twin–twin transfusion syndrome (TTTS), 12 twin reversed arterial perfusion sequence (TRAPs), 66 foetal anomaly and 66 elective foetal reduction (EFR) cases. The overall survival rate of the co-twin was 201/272 (73.9%). The overall technical successful rate was determined at 201/263 (76.7%). The IUFD rate in the co-twin was 20/272 (7.4%). The TTTS group had recorded the lowest survival rate (37/64, 57. 8%), and the survival rate significantly correlated with Quintero stages (P = 0.029). Moreover, the sIUGR III subgroup had a lower survival rate compared with sIUGR II (55.6%, versus 84.3%). The subgroup of foetal anomaly of gastroschisis or exomphalos had the highest IUFD rate (4/10, 40%), followed by sIUGR III (2/9, 22.2%) and dichorionic triamniotic (DCTA) subgroup (8/46, 17.9%). In EFR group, eight IUFD cases were all coming from the DCTA subgroup and received RFA before 17 weeks.Conclusions:The perinatal outcome of RFA was correlated with the indications, with the lowest survival rate in TTTS IV and the highest IUFD incidence in abdominal wall defect followed by sIUGR III. Elective RFA after 17 weeks may prevent IUFD in DCTA pregnancies.

scholarly journals Influence of Indications on Perinatal Outcomes After Radio frequency Ablation in Complicated Monochorionic Pregnancies: A Retrospective Cohort Study

2020 ◽  
Author(s):  
Hongmei Wang ◽  
Qian Zhou ◽  
Xietong Wang ◽  
Jia Song ◽  
Pengzheng Chen ◽  
...  
Keyword(s):  
Cohort Study ◽  
Survival Rate ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Abdominal Wall Defect ◽  
Perinatal Outcomes ◽  
Neurological Injury ◽  
Categorical Variables ◽  
Continuous Variables ◽  
Arterial Perfusion

Abstract Background:Radiofrequency ablation (RFA) is recommended to prevent potential neurological injury or intrauterine foetal death (IUFD) of the co-twin(s) in complicated monochorionic (MC) pregnancies. However, the impacts of various indications on the pregnancy outcome following RFA remain unclear. This study aimed to determine how the indications influence the perinatal outcomes in complicated MC pregnancies undergoing radiofrequency ablation.Methods:This was a retrospective cohort study performed in a single centre. All consecutive MC pregnancies treated with RFA between July 2011 and July 2019 were included. The adverse perinatal outcomes and the survival rate were analysed based on various indications. The continuous variables with and without normal distribution were compared between the groups using Student’s t-test and Mann–Whitney U test, respectively, and for categorical variables, Chi-square and Fisher’s exact tests were used. P < 0.05 indicated a significant difference.Results:We performed 272 RFA procedures in 268 complicated MC pregnancies, including 60 selective intrauterine growth restriction (sIUGR), 64 twin–twin transfusion syndrome (TTTS), 12 twin reversed arterial perfusion sequence (TRAPs), 66 foetal anomaly and 66 elective foetal reduction (EFR) cases. The overall survival rate of the co-twin was 201/272 (73.9%). The overall technical successful rate was determined at 201/263 (76.7%). The IUFD rate in the co-twin was 20/272 (7.4%). The TTTS group had recorded the lowest survival rate (37/64, 57. 8%), and the survival rate significantly correlated with Quintero stages (P = 0.029). Moreover, the sIUGR III subgroup had a lower survival rate compared with sIUGR II (55.6%, versus 84.3%). The subgroup of foetal anomaly of gastroschisis or exomphalos had the highest IUFD rate (4/10, 40%), followed by sIUGR III (2/9, 22.2%) and dichorionic triamniotic (DCTA) subgroup (8/46, 17.9%). In EFR group, eight IUFD cases were all coming from the DCTA subgroup and received RFA before 17 weeks.Conclusions:The perinatal outcome of RFA was correlated with the indications, with the lowest survival rate in TTTS IV and the highest IUFD incidence in abdominal wall defect followed by sIUGR III. Elective RFA after 17 weeks may prevent IUFD in DCTA pregnancies.

scholarly journals Influence of Indications on Perinatal Outcomes After Radio Frequency Ablation in Complicated Monochorionic Pregnancies: A Retrospective Cohort Study

2020 ◽  
Author(s):  
Hongmei Wang ◽  
Qian Zhou ◽  
Xietong Wang ◽  
Jia Song ◽  
Pengzheng Chen ◽  
...  
Keyword(s):  
Cohort Study ◽  
Survival Rate ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Abdominal Wall Defect ◽  
Perinatal Outcomes ◽  
Neurological Injury ◽  
Categorical Variables ◽  
Foetal Death ◽  
Arterial Perfusion

Abstract Background:Radiofrequency ablation (RFA) is recommended to prevent potential neurological injury or intrauterine foetal death (IUFD) of the co-twin(s) in complicated monochorionic (MC) pregnancies. However, the impacts of various indications on the pregnancy outcome following RFA remain undefined clearly. This study aimed to determine how the indications influence the perinatal outcomes in complicated MC pregnancies undergoing radiofrequency ablation.Methods:This was a retrospective cohort study performed in a single centre. All consecutive women treated with RFA between July 2011 and July 2019 were included. The adverse perinatal outcomes and the survival rate were analysed based on various indications. The continuous variables with and without normal distribution were compared between the groups using Student’s t-test and Mann–Whitney U test, respectively, and for categorical variables, Chi-square and Fisher’s exact tests were used. P < 0.05 indicated a significant difference.Results:We performed 272 RFA procedures in 268 complicated MC pregnancies, including 60 selective intrauterine growth restriction (sIUGR), 64 twin–twin transfusion syndrome (TTTS), 12 twin reversed arterial perfusion sequence (TRAPs), 66 foetal anomaly and 66 elective foetal reduction (EFR) cases. The overall survival rate of the co-twin was 201/272 (73.9%). The overall technical successful rate was determined at 201/263 (76.7%). The intrauterine foetal death (IUFD) rate in the co-twin was 20/272 (7.4%). The TTTS group had recorded the lowest survival rate (37/64, 57. 8%), and the survival rate significantly correlated with Quintero stages (P = 0.029). Moreover, the sIUGR III subgroup had a lower survival rate compared with sIUGR II (55.6%, versus 84.3%). The subgroup of foetal anomaly of gastroschisis or exomphalos had the highest IUFD rate (4/10, 40%), followed by sIUGR III (2/9, 22.2%) and dichorionic triamniotic (DCTA) subgroup (8/46, 17.9%). In EFR group, eight IUFD cases were all coming from the DCTA subgroup and received RFA before 17 weeks.Conclusions:The perinatal outcome of RFA was correlated with the indications, with the lowest survival rate in TTTS IV and the highest IUFD incidence in abdominal wall defect followed by sIUGR III. Elective RFA after 17 weeks may prevent IUFD in DCTA pregnancies.

scholarly journals Influence of Indications on Perinatal Outcomes After Radio frequency Ablation in Complicated Monochorionic Pregnancies: A Retrospective Cohort Study

2021 ◽  
Author(s):  
Hongmei Wang ◽  
Qian Zhou ◽  
Xietong Wang ◽  
Jia Song ◽  
Pengzheng Chen ◽  
...  
Keyword(s):  
Cohort Study ◽  
Radiofrequency Ablation ◽  
Survival Rate ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Perinatal Outcomes ◽  
Neurological Injury ◽  
Categorical Variables ◽  
Arterial Perfusion ◽  
Significant Difference

Abstract Background: Radiofrequency ablation (RFA) is recommended to prevent potential neurological injury or intrauterine foetal death (IUFD) of the co-twin(s) in complicated monochorionic (MC) pregnancies. However, the impacts of various indications on the pregnancy outcome following RFA remain unclear. This study aimed to determine how the indications influence the perinatal outcomes in complicated MC pregnancies undergoing radiofrequency ablation.Methods: This was a retrospective cohort study performed in a single centre. All consecutive MC pregnancies treated with RFA between July 2011 and July 2019 were included. The adverse perinatal outcomes and the survival rate were analysed based on various indications. The continuous variables with and without normal distribution were compared between the groups using Student’s t-test and Mann–Whitney U test, respectively, and for categorical variables, Chi-square and Fisher’s exact tests were used. P < 0.05 indicated a significant difference.Results: We performed 272 RFA procedures in 268 complicated MC pregnancies, including 60 selective intrauterine growth restriction (sIUGR), 64 twin–twin transfusion syndrome (TTTS), 12 twin reversed arterial perfusion sequence (TRAPs), 66 foetal anomaly and 66 elective foetal reduction (EFR) cases. The overall survival rate of the co-twin was 201/272 (73.9%). The overall technical successful rate was determined at 201/263 (76.7%). The IUFD rate in the co-twin was 20/272 (7.4%). The TTTS group had recorded the lowest survival rate (37/64, 57. 8%), and the survival rate significantly correlated with Quintero stages (P = 0.029). Moreover, the sIUGR III subgroup had a lower survival rate compared with sIUGR II (55.6%, versus 84.3%). The subgroup of foetal anomaly of gastroschisis or exomphalos had the highest IUFD rate (4/10, 40%), followed by sIUGR III (2/9, 22.2%) and dichorionic triamniotic (DCTA) subgroup (8/46, 17.9%). In EFR group, eight IUFD cases were all coming from the DCTA subgroup and received RFA before 17 weeks.Conclusions: The perinatal outcome of RFA was correlated with the indications, with the lowest survival rate in TTTS IV and the highest IUFD incidence in abdominal wall defect followed by sIUGR III. Elective RFA after 17 weeks may prevent IUFD in DCTA pregnancies.

scholarly journals Influence of indications on perinatal outcomes after radio frequency ablation in complicated monochorionic pregnancies: a retrospective cohort study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hongmei Wang ◽  
Qian Zhou ◽  
Xietong Wang ◽  
Jia Song ◽  
Pengzheng Chen ◽  
...  
Keyword(s):  
Cohort Study ◽  
Radiofrequency Ablation ◽  
Survival Rate ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Perinatal Outcomes ◽  
Neurological Injury ◽  
Categorical Variables ◽  
Arterial Perfusion ◽  
Significant Difference

Abstract Background Radiofrequency ablation (RFA) is recommended to prevent potential neurological injury or intrauterine foetal death (IUFD) of the co-twin(s) in complicated monochorionic (MC) pregnancies. However, the impacts of various indications on the pregnancy outcome following RFA remain unclear. This study aimed to determine how the indications influence the perinatal outcomes in complicated MC pregnancies undergoing radiofrequency ablation. Methods This was a retrospective cohort study performed in a single centre. All consecutive MC pregnancies treated with RFA between July 2011 and July 2019 were included. The adverse perinatal outcomes and the survival rate were analysed based on various indications. The continuous variables with and without normal distribution were compared between the groups using Student’s t-test and Mann–Whitney U test, respectively, and for categorical variables, Chi-square and Fisher’s exact tests were used. P < 0.05 indicated a significant difference. Results We performed 272 RFA procedures in 268 complicated MC pregnancies, including 60 selective intrauterine growth restriction (sIUGR), 64 twin–twin transfusion syndrome (TTTS), 12 twin reversed arterial perfusion sequence (TRAPs), 66 foetal anomaly and 66 elective foetal reduction (EFR) cases. The overall survival rate of the co-twin was 201/272 (73.9%). The overall technical successful rate was determined at 201/263 (76.7%). The IUFD rate in the co-twin was 20/272 (7.4%). The TTTS group had recorded the lowest survival rate (37/64, 57. 8%), and the survival rate was significantly correlated with Quintero stages (P = 0.029). Moreover, the sIUGR III subgroup had a lower survival rate compared with sIUGR II (55.6%, versus 84.3%). The subgroup of foetal anomaly of gastroschisis or exomphalos had the highest IUFD rate (4/10, 40%), followed by sIUGR III (2/9, 22.2%) and dichorionic triamniotic (DCTA) subgroup (8/46, 17.9%). In EFR group, eight IUFD cases were all coming from the DCTA subgroup and received RFA before 17 weeks. Conclusions The perinatal outcome of RFA was correlated with the indications, with the lowest survival rate in TTTS IV and the highest IUFD incidence in abdominal wall defect followed by sIUGR III. Elective RFA after 17 weeks may prevent IUFD in DCTA pregnancies.

scholarly journals LO43: First Nations emergency care visits in Alberta: Descriptive results of a retrospective cohort study

CJEM ◽  
2020 ◽  
Vol 22 (S1) ◽  
pp. S22-S22
Author(s):  
P. McLane ◽  
C. Barnabe ◽  
B. Holroyd ◽  
A. Colquhoun ◽  
L. Bill ◽  
...  
Keyword(s):  
Cohort Study ◽  
First Nations ◽  
Emergency Care ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Categorical Variables ◽  
Continuous Variables ◽  
Data Set ◽  
Care Visit ◽  
The Impact

Introduction: Emergency care serves as an important health resource for First Nations (FN) persons. Previous reporting shows that FN persons visit emergency departments at almost double the rate of non-FN persons. Working collaboratively with FN partners, academic researchers and health authority staff, the objective of this study is to investigate FN emergency care patient visit statistics in Alberta over a five year period. Methods: Through a population-based retrospective cohort study for the period from April 1, 2012 to March 31, 2017, patient demographics and emergency care visit characteristics for status FN patients in Alberta were analyzed and compared to non-FN statistics. Frequencies and percentages (%) describe patients and visits by categorical variables (e.g., Canadian Triage Acuity Scale (CTAS)). Means and standard deviations (medians and interquartile ranges (IQR)) describe continuous variables (e.g., distances) as appropriate for the data distribution. These descriptions are repeated for the FN and non-FN populations, separately. Results: The data set contains 11,686,288 emergency facility visits by 3,024,491 unique persons. FN people make up 4.8% of unique patients and 9.4% of emergency care visits. FN persons live further from emergency facilities than their non-FN counterparts (FN median 6 km, IQR 1-24; vs. non-FN median 4 km, IQR 2-8). FN visits arrive more often by ground ambulance (15.3% vs. 10%). FN visits are more commonly triaged as less acute (59% CTAS levels 4 and 5, compared to non-FN 50.4%). More FN visits end in leaving without completing treatment (6.7% vs. 3.6%). FN visits are more often in the evening – 4:01pm to 12:00am (43.6% vs. 38.1%). Conclusion: In a collaborative validation session, FN Elders and health directors contextualized emergency care presentation in evenings and receiving less acute triage scores as related to difficulties accessing primary care. They explained presentation in evenings, arrival by ambulance, and leaving without completing treatment in terms of issues accessing transport to and from emergency facilities. Many factors interact to determine FN patients’ emergency care visit characteristics and outcomes. Further research needs to separate the impact of FN identity from factors such as reasons for visiting emergency facilities, distance traveled to care, and the size of facility where care is provided.

scholarly journals Influenza Vaccine Effectiveness in Preventing Severe Outcomes in Patients Hospitalized with Laboratory-Confirmed Influenza during the 2017–2018 Season. A Retrospective Cohort Study in Catalonia (Spain)

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1465
Author(s):  
Lesly Acosta ◽  
Nuria Soldevila ◽  
Nuria Torner ◽  
Ana Martínez ◽  
Xavier Ayneto ◽  
...  
Keyword(s):  
Cohort Study ◽  
Influenza Vaccine ◽  
Influenza Vaccination ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Vaccine Effectiveness ◽  
Public Hospitals ◽  
Categorical Variables ◽  
Type B ◽  
Icu Admission

Seasonal influenza is a common cause of hospital admission, especially in older people and those with comorbidities. The objective of this study was to determine influenza vaccine effectiveness (VE) in preventing intensive care admissions and shortening the length of stay (LOS) in hospitalized laboratory-confirmed influenza cases (HLCI) in Catalonia (Spain). A retrospective cohort study was carried out during the 2017–2018 season in HLCI aged ≥18 years from 14 public hospitals. Differences in means and proportions were assessed using a t-test or a chi-square test as necessary and the differences were quantified using standardized effect measures: Cohen’s d for quantitative and Cohen’s w for categorical variables. Adjusted influenza vaccine effectiveness in preventing severity was estimated by multivariate logistic regression where the adjusted VE = (1 − adjusted odds ratio) · 100%; adjustment was also made using the propensity score. We analyzed 1414 HLCI aged ≥18 years; 465 (33%) were vaccinated, of whom 437 (94%) were aged ≥60 years, 269 (57.8%) were male and 295 (63.4%) were positive for influenza type B. ICU admission was required in 214 (15.1%) cases. There were 141/1118 (12.6%) ICU admissions in patients aged ≥60 years and 73/296 (24.7%) in those aged <60 years (p < 0.001). The mean LOS and ICU LOS did not differ significantly between vaccinated and unvaccinated patients. There were 52/465 (11.2%) ICU admissions in vaccinated cases vs. 162/949 (17.1%) in unvaccinated cases. Patients admitted to the ICU had a longer hospital LOS (mean: 22.4 [SD 20.3] days) than those who were not (mean: 11.1 [SD 14.4] days); p < 0.001. Overall, vaccination was associated with a lower risk of ICU admission. Taking virus types A and B together, the estimated adjusted VE in preventing ICU admission was 31% (95% CI 1–52; p = 0.04). When stratified by viral type, the aVE was 40% for type A (95% CI -11–68; p = 0.09) and 25% for type B (95% CI -18–52; p = 0.21). Annual influenza vaccination may prevent ICU admission in cases of HLCI. A non-significantly shorter mean hospital stay was observed in vaccinated cases. Our results support the need to increase vaccination uptake and public perception of the benefits of influenza vaccination in groups at a higher risk of hospitalization and severe outcomes.

scholarly journals Comparison of adverse perinatal outcomes between Asians and Caucasians: a population-based retrospective cohort study in Ontario

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Na Zeng ◽  
Erica Erwin ◽  
Wendy Wen ◽  
Daniel J. Corsi ◽  
Shi Wu Wen ◽  
...  
Keyword(s):  
Cohort Study ◽  
Birth Weight ◽  
Preterm Birth ◽  
Cesarean Section ◽  
Gestational Age ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Perinatal Outcomes ◽  
Population Based ◽  
Adverse Perinatal Outcomes

Abstract Background Racial disparities in adverse perinatal outcomes have been studied in other countries, but little has been done for the Canadian population. In this study, we sought to examine the disparities in adverse perinatal outcomes between Asians and Caucasians in Ontario, Canada. Methods We conducted a population-based retrospective cohort study that included all Asian and Caucasian women who attended a prenatal screening and resulted in a singleton birth in an Ontario hospital (April 1st, 2015-March 31st, 2017). Generalized estimating equation models were used to estimate the independent adjusted relative risks and adjusted risk difference of adverse perinatal outcomes for Asians compared with Caucasians. Results Among 237,293 eligible women, 31% were Asian and 69% were Caucasian. Asians were at an increased risk of gestational diabetes mellitus, placental previa, early preterm birth (< 32 weeks), preterm birth, emergency cesarean section, 3rd and 4th degree perineal tears, low birth weight (< 2500 g, < 1500 g), small-for-gestational-age (<10th percentile, <3rd percentile), neonatal intensive care unit admission, and hyperbilirubinemia requiring treatment, but had lower risks of preeclampsia, macrosomia (birth weight > 4000 g), large-for-gestational-age neonates, 5-min Apgar score < 7, and arterial cord pH ≤7.1, as compared with Caucasians. No difference in risk of elective cesarean section was observed between Asians and Caucasians. Conclusion There are significant differences in several adverse perinatal outcomes between Asians and Caucasians. These differences should be taken into consideration for clinical practices due to the large Asian population in Canada.

Re: Perinatal outcomes after open fetal surgery for myelomeningocele repair: a retrospective cohort study

2018 ◽  
Vol 126 (1) ◽  
pp. 131-132 ◽  
Author(s):  
Antonio Fernandes Moron ◽  
Mauricio Mendes Barbosa ◽  
Herbene José Figuinha Milani ◽  
Stephanno Gomes Sarmento ◽  
Eduardo Felix Martins Santana ◽  
...  
Keyword(s):  
Cohort Study ◽  
Retrospective Cohort Study ◽  
Retrospective Cohort ◽  
Fetal Surgery ◽  
Perinatal Outcomes ◽  
Myelomeningocele Repair

scholarly journals Continuous Blood Purification on Influenza-associated Neurological Disease in Children: A Retrospective Cohort Study

2021 ◽  
Author(s):  
Jingwen Ni ◽  
Kenan Fang ◽  
Zhe Zhao ◽  
Zhiyuan Wang ◽  
Qian Huang ◽  
...  
Keyword(s):  
Cohort Study ◽  
Intensive Care ◽  
Retrospective Cohort Study ◽  
Neurological Disease ◽  
Retrospective Cohort ◽  
Neurological Complications ◽  
Inflammatory Factors ◽  
Continuous Variables ◽  
Exact Test ◽  
Significant Difference

Abstract Background: Due to lack of proven therapies，we evaluated the effect of CBP on Influenza-Associated Neurological Disease in children.Methods: A single-center, retrospective, cohort study was conducted in Luoyang, Henan province China from January 2018 to January 2020. The children with Influenza-associated neurological disease (<18 years old) were enrolled into this study. The children with CBP indications and the parents’ consent received CBP, and the others were treated with maximal intensive care due to failure of parents consent. The outcomes were compared between CBP group and non-CBP group.Categorical variables were presented as percentage and compared by Chi-square test or Fisher’s exact test. Continuous variables were expressed as median (interquartile ranges) and compared with non-parametric independent sample test. Statistical analyses were finished by SPSS (version 26.0) and p < 0.05 (2 tailed) was considered statistically significant.Results: 30 influenza children with Influenza-associated neurological disease were enrolled in this study. 18 received CBP and other 12 were treated with maximal intensive care. There were no differences between CBP and non-CBP children in age, sex, body weight, type of influenza virus, neurological complications, Glasgow score, PIM-2 score and PCIS at admission (p > 0.05). The inflammatory factors (CRP, PCT and IL-6) of 30 cases were tested at admission and after 3 days of admission. In CBP group, the level of IL-6 decreased significantly at 3-day of admission (p = 0.003), the level of CRP and PCT also decreased, but there was no significant difference (p > 0.05). In the non-CBP group, there were no significant difference on level of CRP, PCT and IL-6 between at admission and 3-day of admission (p > 0.05). The 28-day mortality in the CBP group was significantly lower compared to non-CBP group (11.11% vs 50%, p = 0.034).Conclusions: CBP could Reduce inflammatory factors and may reduce 28-day mortality and improve neurologic function of influenza children.Trial registration: http://www.chictr.org.cn/index.aspx (ChiCTR2000031754).

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