There is life beyond the statistical significance.

This article challenges the "tyranny of P-value" and promote more valuable and applicable interpretations of the results of research on health care delivery. We provide here solid arguments to retire statistical significance as the unique way to interpret results, after presenting the current state of the debate inside the scientific community. Instead, we promote reporting the much more informative confidence intervals and eventually adding exact P-values. We also provide some clues to integrate statistical and clinical significance by referring to minimal important differences and integrating the effect size of an intervention and the certainty of evidence ideally using the GRADE approach. We have argued against interpreting or reporting results as statistically significant or statistically non-significant. We recommend showing important clinical benefits with their confidence intervals in cases of point estimates compatible with results benefits and even important harms. It seems fair to report the point estimate and the more likely values along with a very clear statement of the implications of extremes of the intervals. We recommend drawing conclusions, considering the multiple factors besides P-values such as certainty of the evidence for each outcome, net benefit, economic considerations and values and preferences. We use several examples and figures to illustrate different scenarios and further suggest a wording to standardize the reporting. Several statistical measures have a role in the scientific communication of studies, but it is time to understand that there is life beyond the statistical significance. There is a great opportunity for improvement towards a more complete interpretation and to a more standardized reporting.

Distribution of postpartum blood loss: modeling, estimation and application to clinical trials.

BACKGROUND: The loss of large amounts of blood postpartum can lead to severe maternal morbidity and mortality. Understanding the nature of postpartum blood loss distribution is critical for the development of efficient analysis techniques when comparing treatments to prevent this event. When blood loss is measured, resulting in a continuous volume measure, often this variable is categorized in classes, and reduced to an indicator of volume greater than a cutoff point. This reduction of volume to classes entails a substantial loss of information. As a consequence, very large trials are needed to assess clinically important differences between treatments to prevent postpartum haemorrhage. METHODS: The authors explore the nature of postpartum blood loss distribution, assuming that the physical properties of blood loss lead to a lognormal distribution. Data from four clinical trials and one observational study are used to confirm this empirically. Estimates of probabilities of postpartum haemorrhage events 'blood loss greater than a cutoff point' and relative risks are obtained from the fitted lognormal distributions. Confidence intervals for relative risk are obtained by bootstrap techniques. RESULTS: A variant of the lognormal distribution, the three-parameter lognormal distribution, showed an excellent fit to postpartum blood loss data of the four trials and the observational study. A measurement quality assessment showed that problems of digit preference and lower limit of detection were well handled by the lognormal fit. The analysis of postpartum haemorrhage events based on a lognormal distribution improved the efficiency of the estimates. Sample size calculation for a hypothetical future trial showed that the application of this procedure permits a reduction of sample size for treatment comparison. CONCLUSION: A variant of the lognormal distribution fitted very well postpartum blood loss data from different geographical areas, suggesting that the lognormal distribution might fit postpartum blood loss universally. An approach of analysis of postpartum haemorrhage events based on the lognormal distribution improves efficiency of estimates of probabilities and relative risk, and permits a reduction of sample size for treatment comparison. TRIAL REGISTRATION: This paper reports secondary analyses for trials registered at Australian New Zealand Clinical Trials Registry (ACTRN 12608000434392 and ACTRN12614000870651); and at clinicaltrials.gov (NCT00781066).

Prevention of postpartum haemorrhage: a distributional approach for analysis.

BACKGROUND: There is empirical evidence that measured postpartum blood loss has a lognormal distribution. This feature can be used to analyze events of the type 'blood loss greater than a certain cutoff point' using a lognormal approach, which takes into account all the quantitative observations, as opposed to dichotomizing the variable blood loss volume into two categories. This lognormal approach uses all the information contained in the data and is expected to provide more efficient estimates of proportions and relative risk when comparing treatments to prevent postpartum haemorrhage. As a consequence, sample size can be reduced in clinical trials, while keeping the statistical precision requirements. METHODS: The authors illustrate how a lognormal approach can be used in this situation, using data from a clinical trial and the event 'blood loss greater than 1000 mL'. RESULTS: Estimates of the proportions of this event for each treatment, and relative risks obtained with this method are presented and compared with the standard estimates obtained by dichotomizing measured blood loss volume. An example of how the blood loss distributions of two treatments can be compared is also presented. Different scenarios of the sample size needed to compare two treatments or interventions are presented to illustrate how with the lognormal approach the size of a clinical trial can be reduced. CONCLUSIONS: A distributional approach for postpartum blood loss using the lognormal distribution fitted to the data results in more precise estimates of risks of events and relative risks, compared to the use of binomial proportions of events. It also results in reduced required sample size for clinical trials. TRIAL REGISTRATION: This paper reports a secondary analysis for a trial that was registered at clinicaltrials.gov ( NCT00781066 ).

The World Health Organization fetal growth charts: concept, findings, interpretation, and application.

Ultrasound biometry is an important clinical tool for the identification, monitoring, and management of fetal growth restriction and development of macrosomia. This is even truer in populations in which perinatal morbidity and mortality rates are high, which is a reason that much effort is put onto making the technique available everywhere, including low-income societies. Until recently, however, commonly used reference ranges were based on single populations largely from industrialized countries. Thus, the World Health Organization prioritized the establishment of fetal growth charts for international use. New fetal growth charts for common fetal measurements and estimated fetal weight were based on a longitudinal study of 1387 low-risk pregnant women from 10 countries (Argentina, Brazil, Democratic Republic of Congo, Denmark, Egypt, France, Germany, India, Norway, and Thailand) that provided 8203 sets of ultrasound measurements. The participants were characterized by median age 28 years, 58% nulliparous, normal body mass index, with no socioeconomic or nutritional constraints (median caloric intake, 1840 calories/day), and had the ability to attend the ultrasound sessions, thus essentially representing urban populations. Median gestational age at birth was 39 weeks, and birthweight was 3300 g, both with significant differences among countries. Quantile regression was used to establish the fetal growth charts, which also made it possible to demonstrate a number of features of fetal growth that previously were not well appreciated or unknown: (1) There was an asymmetric distribution of estimated fetal weight in the population. During early second trimester, the distribution was wider among fetuses <50th percentile compared with those above. The pattern was reversed in the third trimester, with a notably wider variation >50th percentile. (2) Although fetal sex, maternal factors (height, weight, age, and parity), and country had significant influence on fetal weight (1-4.5% each), their effect was graded across the percentiles. For example, the positive effect of maternal height on fetal weight was strongest on the lowest percentiles and smallest on the highest percentiles for estimated fetal weight. (3) When adjustment was made for maternal covariates, there was still a significant effect of country as covariate that indicated that ethnic, cultural, and geographic variation play a role. (4) Variation between populations was not restricted to fetal size because there were also differences in growth trajectories. (5) The wide physiologic ranges, as illustrated by the 5th-95th percentile for estimated fetal weight being 2205-3538 g at 37 weeks gestation, signify that human fetal growth under optimized maternal conditions is not uniform. Rather, it has a remarkable variation that largely is unexplained by commonly known factors. We suggest this variation could be part of our common biologic strategy that makes human evolution extremely successful. The World Health Organization fetal growth charts are intended to be used internationally based on low-risk pregnancies from populations in Africa, Asia, Europe, and South America. We consider it prudent to test and monitor whether the growth charts' performance meets the local needs, because refinements are possible by a change in cut-offs or customization for fetal sex, maternal factors, and populations. In the same line, the study finding of variations emphasizes the need for carefully adjusted growth charts that reflect optimal local growth when public health issues are addressed.

Reporting of noninferiority and equivalence randomized trials: extension of the CONSORT 2010 statement.

The CONSORT (Consolidated Standards of Reporting Trials) Statement, which includes a checklist and a flow diagram, is a guideline developed to help authors improve the reporting of the findings from randomized controlled trials. It was updated most recently in 2010. Its primary focus is on individually randomized trials with 2 parallel groups that assess the possible superiority of one treatment compared with another. The CONSORT Statement has been extended to other trial designs such as cluster randomization, and recommendations for noninferiority and equivalence trials were made in 2006. In this article, we present an updated extension of the CONSORT checklist for reporting noninferiority and equivalence trials, based on the 2010 version of the CONSORT Statement and the 2008 CONSORT Statement for the reporting of abstracts, and provide illustrative examples and explanations for those items that differ from the main 2010 CONSORT checklist. The intent is to improve reporting of noninferiority and equivalence trials, enabling readers to assess the reliability of their results and conclusions.

Effect on pregnancy rates of the delay in the administration of levonorgestrel for emergency contraception: a combined analysis of four WHO trials.

BACKGROUND: Levonorgestrel is an effective method for emergency contraception (EC) and is used worldwide. Consistent with its mechanism of action in delaying ovulation, the earlier it is administered within 72 h of an unprotected act of intercourse, the more effective it is. There is uncertainty, however, about its effectiveness after 72 h. This analysis explores the effect of 24-h intervals of delay in levonorgestrel administration on pregnancy rates when used until 120 h of an unprotected act of intercourse. STUDY DESIGN: Data were analyzed from 6794 women participating in four World Health Organization randomized trials and receiving 1.5 mg of levonorgestrel for EC in a single dose or split into two doses 12 h apart, within 48, 72 or 120 h of an act of unprotected intercourse. The pregnancy rates among women in successive days after an unprotected act of intercourse and odds ratios of pregnancy were calculated using logistic regression with the first day as the reference. RESULTS: For the four trials combined, odds ratios for pregnancy in the second, third and fourth day with respect to the first day were not significantly different from 1 at the 5% level of significance. On the fifth day, the odds ratio of pregnancy compared to the first day was almost 6. CONCLUSIONS: Levonorgestrel for EC should be administered as soon as possible after unprotected intercourse. Delaying levonorgestrel administration until the fifth day after unprotected intercourse increases the risk of pregnancy over five times compared with administration within 24 h. It is uncertain whether levonorgestrel administration on the fifth day still offers some protection against unwanted pregnancy.

Magnesium sulfate is not used for pre-eclampsia and eclampsia in Mexico and Thailand as much as it should be.

OBJECTIVE: In the past ten years effective treatments for pre-eclampsia and eclampsia have been evaluated and identified following large trials and systematic reviews. We investigated the extent of those effective interventions implementation. METHODS: Descriptive analysis of data collected as part of a cluster randomized trial. The trial was assigned the International Standardised Randomized Controlled Trial Number ISRCTN 14055385. Hospitals with more than 1000 deliveries per year not directly associated with an academic institution in Mexico City municipal area in Mexico (n = 22) and the north-east region of Thailand (n = 18) were included. All women delivering at the participating hospitals at two time periods in 2000 and 2002 contributed data on practice rates. The use of magnesium sulfate for pre-eclampsia and eclampsia were the outcomes. FINDINGS: Eight out of 22 hospitals in Mexico (range 0.8% to 8.5%) and all 18 hospitals in Thailand (range 18.6% to 63.6%) used magnesium sulfate for women with pre-eclampsia. In Mexico, 11 of 22 hospitals used magnesium sulfate for eclampsia (range 9.1% to 60.0%). In Thailand, all 17 hospitals having eclampsia cases used magnesium sulfate (range 25% to 100%). CONCLUSION: Despite compelling evidence, magnesium sulfate use is below desired levels. Clinical practices should be audited and implementation of this effective intervention should be taken up as a priority where universal implementation is not in place.

Effectiveness and acceptability of vitamin E and low-dose aspirin, alone or in combination, on Norplant-induced prolonged bleeding.

A study (ISRCTN 77665712) was undertaken to test the effectiveness and the acceptability of vitamin E and low-dose aspirin, alone or in combination, as treatment for prolonged vaginal bleeding induced by Norplant. A total of 486 Norplant users who were requesting treatment for bleeding lasting longer than 7 days were enrolled in five centers: Beijing, China; Jakarta, Indonesia; Santiago, Chile; Santo Domingo, Dominican Republic; and Tunis, Tunisia. They were randomized to one of four different 10-day oral treatments: 200 mg vitamin E daily, 80 mg aspirin daily, both or a placebo. Treatment packs were designed to ensure blinding of both the subjects and the clinical staff. Neither vitamin E nor low-dose aspirin nor their combination was found to have any effect on reducing the length of the bleeding episode for which treatment was taken or on the vaginal bleeding patterns these women experienced during the year of follow-up.

Cluster randomized trial of an active, multifaceted information dissemination intervention based on The WHO Reproductive health library to change obstetric practices: methods and design issues [ISRCTN14055385].

BACKGROUND: Effective strategies for implementing best practices in low and middle income countries are needed. RHL is an annually updated electronic publication containing Cochrane systematic reviews, commentaries and practical recommendations on how to implement evidence-based practices. We are conducting a trial to evaluate the improvement in obstetric practices using an active dissemination strategy to promote uptake of recommendations in The WHO Reproductive Health Library (RHL). METHODS: A cluster randomized trial to improve obstetric practices in 40 hospitals in Mexico and Thailand is conducted. The trial uses a stratified random allocation based on country, size and type of hospitals. The core intervention consists of three interactive workshops delivered over a period of six months. The main outcome measures are changes in clinical practices that are recommended in RHL measured approximately a year after the first workshop. RESULTS: The design and implementation of a complex intervention using a cluster randomized trial design are presented. CONCLUSION: Designing the intervention, choosing outcome variables and implementing the protocol in two diverse settings has been a time-consuming and challenging process. We hope that sharing this experience will help others planning similar projects and improve our ability to implement change.

Are women and providers satisfied with antenatal care? Views on a standard and a simplified, evidence-based model of care in four developing countries.

BACKGROUND: This study assessed women and providers' satisfaction with a new evidence-based antenatal care (ANC) model within the WHO randomized trial conducted in four developing countries. The WHO study was a randomized controlled trial that compared a new ANC model with the standard type offered in each country. The new model of ANC emphasized actions known to be effective in improving maternal or neonatal health, excluded other interventions that have not proved to be beneficial, and improved the information component, especially alerting pregnant women to potential health problems and instructing them on appropriate responses. These activities were distributed within four antenatal care visits for women that did not need any further assessment. METHODS: Satisfaction was measured through a standardized questionnaire administered to a random sample of 1,600 pregnant women and another to all antenatal care providers. RESULTS: Most women in both arms expressed satisfaction with ANC. More women in the intervention arm were satisfied with information on labor, delivery, family planning, pregnancy complications and emergency procedures. More providers in the experimental clinics were worried about visit spacing, but more satisfied with the time spent and information provided. CONCLUSIONS: Women and providers accepted the new ANC model generally. The safety of fewer visits for women without complications with longer spacing would have to be reinforced, if such a model is to be introduced into routine practice.