Duration of third stage labour and postpartum blood loss: a secondary analysis of the WHO CHAMPION trial data

Background

Obstetric haemorrhage continues to be a leading cause of maternal mortality, contributing to more than a quarter of the 2,443,000 maternal deaths reported between 2003 and 2009. During this period, about 70% of the haemorrhagic deaths occurred postpartum. In addition to other identifiable risk factors for greater postpartum blood loss, the duration of the third stage of labour (TSL) seems to be important, as literature shows that a longer TSL can be associated with more blood loss. To better describe the association between the duration of TSL and postpartum blood loss in women receiving active management of third stage of labour (AMTSL), this secondary analysis of the WHO CHAMPION trial data has been conducted.

Methods

This was a secondary analysis of the WHO CHAMPION trial conducted in twenty-three sites in ten countries. We studied the association between the TSL duration and blood loss in the sub cohort of women from the CHAMPION trial (all of whom received AMTSL), with TSL upto 60 min and no interventions for postpartum haemorrhage. We used a general linear model to fit blood loss as a function of TSL duration on the log scale, arm and center, using a normal distribution and the log link function. We showed this association separately for oxytocin and for Heat stable (HS) carbetocin.

Results

For the 10,040 women analysed, blood loss rose steeply with third stage duration in the first 10 min, but more slowly after 10 min. This trend was observed for both Oxytocin and HS carbetocin and the difference in the trends for both drugs was not statistically significant (p-value = 0.2070).

Conclusions

There was a positive association between postpartum blood loss and TSL duration with either uterotonic. Blood loss rose steeply with TSL duration until 10 min, and more slowly after 10 min.

Study registration The main trial was registered with Australian New Zealand Clinical Trials Registry ACTRN12614000870651 and Clinical Trial Registry of India CTRI/2016/05/006969

The duration of the third stage of labour (TSL) seems to be an important risk factor for greater postpartum blood loss, as literature shows that a longer TSL can be associated with more blood loss. Active management of third stage of labour (AMTSL), included in the WHO guidelines for prevention of postpartum haemorrhage (PPH), is effective in reducing both the amount of postpartum blood loss and the duration of the third stage. To better describe the association between duration of TSL and postpartum blood loss in women receiving AMTSL, we conducted this secondary analysis of WHO CHAMPION trial data.

To assess the association between the duration of third stage of labour and postpartum blood loss, a subcohort of the CHAMPION modified ITT population was selected by excluding women with missing blood loss or missing TSL duration or TSL duration more than 60 min and women with interventions. Thus, the subcohort consisted of 10,040 women.

In women with vaginal birth and not receiving interventions for treating atonic PPH or other sources of bleeding, and with TSL duration up to 60 min, there was a positive association between duration of the TSL and postpartum blood loss. The blood loss rose steeply with duration in women with TSL of 10 min or less, while in women with longer TSL duration the slope was less steep.

There was no evidence of a difference between oxytocin and HS carbetocin in the pattern of association of duration of the TSL and blood loss.

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 ).

Susceptibility of Argentinean Biomphalaria tenagophila and Biomphalaria straminea to infection by Schistosoma mansoni and the possibility of geographic expansion of mansoni schistosomiasis

INTRODUCTION

Human migration and the presence of natural vectors (mollusks) of Schistosoma mansoni are the primary causes of the expansion of mansoni schistosomiasis into southern areas of South America. Water conditions are favorable for the expansion of this disease because of the extensive hydrographic network, which includes the basins of the Paraná and Uruguay rivers and favors mollusk reproduction. These rivers also aid agriculture and tourism in the area. Despite these favorable conditions, natural infection by S. mansoni has not yet been reported in Argentina, Uruguay, or Paraguay.

METHODS

Two species of planorbid from Argentina, Biomphalaria straminea and B. tenagophila, were exposed to the miracidia of five Brazilian strains of S. mansoni.

RESULTS

Biomphalaria tenagophila (Atalaya, Buenos Aires province) was infected with the SJS strain (infection rate 3.3%), confirming the experimental susceptibility of this Argentinian species. Biomphalaria straminea (Rio Santa Lucía, Corrientes province) was susceptible to two Brazilian strains: SJS (infection rate 6.7%) and Sergipe (infection rate 6.7%).

CONCLUSIONS

These results demonstrate that species from Argentina have the potential to be natural hosts of S. mansoni and that the appearance of foci of mansoni schistosomiasis in Argentina is possible.

Dental plaque removal efficacy of three toothbrushes with different designs: A comparative analysis

PURPOSE

This study aimed to compare dental plaque removal efficacy of three manual toothbrushes.

MATERIALS AND METHODS

Three toothbrushes (Colgate Flexível - Colgate (T1), Oral B Advantage Control Grip - Oral B (T2), Comfort Clean - Johnson & Johnson - Reach (T3) were evaluated for dental plaque removal in 17 subjects. Dental plaque was scored before and after seven days' use of each toothbrush, employing an adaptation of Quigley-Hein Index modified by Turesky (Plaque Index). Assessments were performed at days 0, 7, 14, 21, 28, and 35. At the end of the trial each subject was asked which toothbrush was preferred.

RESULTS

Final dental plaque scores for toothbrush T3 were statistically different from toothbrushes T1 and T2, which in turn did not differ from each other. Subjects showed preference towards toothbrush T3.

CONCLUSION

Toothbrush T3 was more efficient in terms of dental plaque removal when compared with toothbrushes T2 and T1.

Behavior in Mus musculus of Schistosoma mansoni from mollusks treated with hydrocortisone

Twenty mice were exposed to cercariae from mollusks treated with hydrocortisone and another 20 mice received cercariae from non-treated mollusks. The behavior of the parasites from the two groups of mollusks was compared based on the ability of cercariae to penetrate mice, on the total number of worms recovered after eight weeks of infection, on the relationship between the number of penetrating cercariae and the number of recovered worms and on the number of eggs in the feces. Treating the mollusks with hydrocortisone did not alter the ability of cercariae to penetrate mice nor did it affect the total number of worms recovered. The number of female worms, the number of coupled worms and the number of eggs in the feces were greater in mice infected by cercariae from mollusks treated with hydrocortisone.

The influence of hydrocortisone on cellular defence mechanisms of Biomphalaria glabrata

Since the internal defense system of mollusks consists of cellular and humoral mechanisms, we examined the role of hydrocortisone in mollusks defense cells and the influence of this steroid on the development of Schistosoma mansoni in its intermediary host. Hydrocortisone had an immunosuppressive action in Biomphalaria glabrata, as reflected in the reduced number of defense cells and the altered cell physiology. Histopathological analysis showed that hydrocortisone facilitated the intramolluscan development of S. mansoni, by reducing the extent of the inflammatory response, seen as a greater number of viable sporocysts with no surrounding hemocytes.

[Influence of hydrocortisone on Schistosoma mansoni development in Biomphalaria glabrata]

The effect of hydrocortisone on the development of BH strain of S. mansoni in B. glabrata snails is evaluated. Snails in a randomly chosen group were submitted to hydrocortisone during four days. In the second day of hydrocortisone exposure, the snails were exposed, each, to ten S. mansoni miracidia. Another group, not treated with hydrocortisone, was exposed to miracidia and observed in the same manner. Various items of data were observed: the infection rate, survival time, prepatent period and total number of cercariae released. It was found that the snails in the group treated with hydrocortisone had a higher infection rate, shorter prepatent periods, produced more cercariae and also had longer survival times. This suggests that the hydrocortisone in snails induces a decrease in resistance to schistosome infection and facilitates the development of the trematode, while also reducing adverse infection effects, thereby leading to longer snail survival.

Aleitamento materno e a prática de desmame em duas comunidades rurais de Piracicaba - SP

O aleitamento materno e a prática de desmame foram estudados em 76 crianças de 3 a 24 meses de idade pertencentes a 69 famílias de comunidades rurais de Piracicaba, SP, por meio de entrevistas. Foram analisadas as medianas da duração do aleitamento materno exclusivo, predominante (incluindo somente água e chá) e misto, utilizando-se a tábua de vida. O teste Wilcoxon foi aplicado para verificar as variáveis socioeconômicas e demográficas associadas com o tempo de aleitamento. A mediana da duração de aleitamento materno exclusivo foi de 3 dias para Anhumas e 30 dias para Santa Olímpia. O aleitamento predominante e o aleitamento misto prolongaram-se por 90 e 180 dias em Anhumas e 120 e 165 dias em Santa Olímpia, respectivamente. Somente o sexo da criança apresentou associação com a duração do aleitamento materno. Iniciou-se o processo de desmame especialmente com água, chás, leite de vaca fluido e sucos açucarados.