Low awareness of the transitivity assumption in complex networks of interventions: a systematic survey from 721 network meta-analyses.

BACKGROUND: The transitivity assumption is the cornerstone of network meta-analysis (NMA). Violating transitivity compromises the credibility of the indirect estimates and, by extent, the estimated treatment effects of the comparisons in the network. The present study offers comprehensive empirical evidence on the completeness of reporting and evaluating transitivity in systematic reviews with multiple interventions. METHODS: We screened the datasets of two previous empirical studies, resulting in 361 systematic reviews with NMA published between January 2011 and April 2015. We updated our evidence base with an additional 360 systematic reviews with NMA published between 2016 and 2021, employing a pragmatic approach. We devised assessment criteria for reporting and evaluating transitivity using relevant methodological literature and compared their reporting frequency before and after the PRISMA-NMA statement. RESULTS: Systematic reviews published after PRISMA-NMA were more likely to provide a protocol (odds ratio (OR): 3.94, 95% CI: 2.79-5.64), pre-plan the transitivity evaluation (OR: 3.01, 95% CI: 1.54-6.23), and report the evaluation and results (OR: 2.10, 95% CI: 1.55-2.86) than those before PRISMA-NMA. However, systematic reviews after PRISMA-NMA were less likely to define transitivity (OR: 0.57, 95% CI: 0.42-0.79) and discuss the implications of transitivity (OR: 0.48, 95% CI: 0.27-0.85) than those published before PRISMA-NMA. Most systematic reviews evaluated transitivity statistically than conceptually (40% versus 12% before PRISMA-NMA, and 54% versus 11% after PRISMA-NMA), with consistency evaluation being the most preferred (34% before versus 47% after PRISMA-NMA). One in five reviews inferred the plausibility of the transitivity (22% before versus 18% after PRISMA-NMA), followed by 11% of reviews that found it difficult to judge transitivity due to insufficient data. In justifying their conclusions, reviews considered mostly the comparability of the trials (24% before versus 30% after PRISMA-NMA), followed by the consistency evaluation (23% before versus 16% after PRISMA-NMA). CONCLUSIONS: Overall, there has been a slight improvement in reporting and evaluating transitivity since releasing PRISMA-NMA, particularly in items related to the systematic review report. Nevertheless, there has been limited attention to pre-planning the transitivity evaluation and low awareness of the conceptual evaluation methods that align with the nature of the assumption.

Type of delivery and gestational age is not affected by pregnant Latin-American women engaging in vigorous exercise. A secondary analysis of data from a controlled randomized trial / El tipo de parto y la edad gestacional no se afectan por el ejercicio aeróbico vigoroso en mujeres gestantes latinas. Análisis secundario de un ensayo clínico

ABSTRACT Objective There is controversy concerning whether exercise during pregnancy may increase preterm delivery risk and type of delivery. The effect of pregnant Latin-American women engaging in vigorous exercise during the second and third trimester was examined regarding type of delivery and gestational age. Materials and Methods This was a secondary analysis of data from a controlled randomized trial for determining the influence of physical exercise on pregnant women's endothelial function. The study included 35 nulliparous women, gestational week 16-20 attending prenatal care at three tertiary hospitals in Colombia, who were randomly assigned to one of two groups. The experimental group engaged in aerobic exercise involving 55 % - 75 % maximum heart rate for 60 min, three times a week for 12 weeks. The control group engaged in their usual physical activity. Maternal weight, height, weight gain, blood pressure and type of delivery were recorded; gender, abdominal and head circumference (cm), weight (g), height (cm), vitality (Apgar score at 1 and 5 min) and gestational age at the time of delivery (in weeks, days) were recorded for the newborn. Results There was no difference in type of delivery by the end of the 12-week program (p>0.05), nor regarding newborn anthropometric variables, Apgar score, or maternal variables concerning weight, height, relative weight gain, blood pressure or weeks of gestation (p>0.05). Conclusion The potential public health benefits of vigorous exercise were enormous. This study support ed existing guidelines indicating that Latin-American women may begin or maintain an on-going exercise program during pregnancy. Trial registration: NCT00741312.

Objetivo Existe controversia acerca del efecto del ejercicio físico vigoroso (EFV) durante el embarazo por sus posibles consecuencias en el tipo de parto y la edad gestacional. El objetivo de este estudio fue evaluar el efecto del EFV durante el segundo y tercer trimestre, en mujeres gestantes latinas sobre el tipo de parto y la edad gestacional. Materiales y Métodos Se trata de un análisis secundario de un ensayo clínico controlado en 35 gestantes, asignadas al azar en dos grupos. Grupo experimental (n=18): EFV entre el 55 % y 75 % de la FC max, por 60 min, 3 veces por sem. Por 12 sem. Grupo Control (n=17): actividad física cotidiana y control prenatal habitual. Se registraron en las maternas: peso, talla, ganancia de peso, presión arterial y tipo de parto. En el recién nacido se registró: género, perímetro cefálico y abdominal (cm), peso (g), talla (cm), semanas de gestación, vitalidad (score Apgar al 1 y 5 min), y semanas de gestación. Resultados No se encontraron diferencias estadísticamente significativas respecto al tipo de parto (p>0,05). Tampoco en las variables antropométricas del recién nacido, ni en las variables maternas: peso, talla, ganancia de peso, presión arterial o semanas de gestación (p>0,05). Conclusión Los beneficios potenciales en salud pública del efecto EFV durante la gestación son importantes y este estudio favorece que mujeres latinas puedan comenzar o mantener un programa de ejercicios durante el embarazo. Trial registration: NCT00741312.

Type of delivery and gestational age is not affected by pregnant Latin-American women engaging in vigorous exercise: a secondary analysis of data from a controlled randomized trial.

OBJECTIVE: There is controversy concerning whether exercise during pregnancy may increase preterm delivery risk and type of delivery. The effect of pregnant Latin-American women engaging in vigorous exercise during the second and third trimester was examined regarding type of delivery and gestational age. MATERIALS AND METHODS: This was a secondary analysis of data from a controlled randomized trial for determining the influence of physical exercise on pregnant women's endothelial function. The study included 35 nulliparous women, gestational week 16-20 attending prenatal care at three tertiary hospitals in Colombia, who were randomly assigned to one of two groups. The experimental group engaged in aerobic exercise involving 55 % - 75 % maximum heart rate for 60 min, three times a week for 12 weeks. The control group engaged in their usual physical activity. Maternal weight, height, weight gain, blood pressure and type of delivery were recorded; gender, abdominal and head circumference (cm), weight (g), height (cm), vitality (Apgar score at 1 and 5 min) and gestational age at the time of delivery (in weeks, days) were recorded for the newborn. RESULTS: There was no difference in type of delivery by the end of the 12-week program (p > 0.05), nor regarding newborn anthropometric variables, Apgar score, or maternal variables concerning weight, height, relative weight gain, blood pressure or weeks of gestation (p>0.05). CONCLUSION: The potential public health benefits of vigorous exercise were enormous. This study supported existing guidelines indicating that Latin-American women may begin or maintain an on-going exercise program during pregnancy. TRIAL REGISTRATION: NCT00741312.