Critical appraisal of international guidelines for the prevention and treatment of pregnancy-associated venous thromboembolism: a systematic review

Estimating the value of future research into thromboprophylaxis for women during pregnancy and after delivery: a value of information analysis

BACKGROUND

Risk assessment models (RAMs) are used to select women at increased risk of venous thromboembolism (VTE) during pregnancy and the puerperium for thromboprophylaxis.

OBJECTIVES

To estimate the value of potential future studies that would reduce the decision uncertainty associated with offering thromboprophylaxis according to available RAMs in the following groups: high-risk antepartum women (eg, prior VTE), unselected postpartum women, and postpartum women with risk factors (obesity or cesarean delivery).

METHODS

A decision-analytic model was developed to simulate clinical outcomes, lifetime costs, and quality-adjusted life-years for different thromboprophylaxis strategies, including thromboprophylaxis for all, thromboprophylaxis for none, and RAM-based thromboprophylaxis. The expected value of perfect information analysis was used to determine which factors are associated with high decision uncertainty. The value of future research studies was estimated using expected value of sample information analysis. Costs were assessed from a health and social services perspective.

RESULTS

The expected value of perfect information analysis identified high decision uncertainty for high-risk antepartum women (£21.8 million) and obese postpartum women (£13.4 million), which was largely attributable to uncertainty regarding the effectiveness of thromboprophylaxis in reducing VTE. A randomized controlled trial of thromboprophylaxis compared with none in obese postpartum women is likely to have substantial value (£2.8 million; 300 participants per arm). A trial in women with previous VTE would have higher value but would be less acceptable.

CONCLUSION

Future research should focus on estimating the effectiveness of thromboprophylaxis in obese postpartum women with additional risk factors who have not had a previous VTE.

Thromboprophylaxis during pregnancy and the puerperium: a systematic review and economic evaluation to estimate the value of future research

Background

Pharmacological prophylaxis to prevent venous thromboembolism is currently recommended for women assessed as being at high risk of venous thromboembolism during pregnancy or in the 6 weeks after delivery (the puerperium). The decision to provide thromboprophylaxis involves weighing the benefits, harms and costs, which vary according to the individual's venous thromboembolism risk. It is unclear whether the United Kingdom's current risk stratification approach could be improved by further research.

Objectives

To quantify the current decision uncertainty associated with selecting women who are pregnant or in the puerperium for thromboprophylaxis and to estimate the value of one or more potential future studies that would reduce that uncertainty, while being feasible and acceptable to patients and clinicians.

Methods

A decision-analytic model was developed which was informed by a systematic review of risk assessment models to predict venous thromboembolism in women who are pregnant or in the puerperium. Expected value of perfect information analysis was used to determine which factors are associated with high decision uncertainty and should be the target of future research. To find out whether future studies would be acceptable and feasible, we held workshops with women who have experienced a blood clot or have been offered blood-thinning drugs and surveyed healthcare professionals. Expected value of sample information analysis was used to estimate the value of potential future research studies.

Results

The systematic review included 17 studies, comprising 19 unique externally validated risk assessment models and 1 internally validated model. Estimates of sensitivity and specificity were highly variable ranging from 0% to 100% and 5% to 100%, respectively. Most studies had unclear or high risk of bias and applicability concerns. The decision analysis found that there is substantial decision uncertainty regarding the use of risk assessment models to select high-risk women for antepartum prophylaxis and obese postpartum women for postpartum prophylaxis. The main source of decision uncertainty was uncertainty around the effectiveness of thromboprophylaxis for preventing venous thromboembolism in women who are pregnant or in the puerperium. We found that a randomised controlled trial of thromboprophylaxis in obese postpartum women is likely to have substantial value and is more likely to be acceptable and feasible than a trial recruiting women who have had a previous venous thromboembolism. In unselected postpartum women and women following caesarean section, the poor performance of risk assessment models meant that offering prophylaxis based on these models had less favourable cost effectiveness with lower decision uncertainty.

Limitations

The performance of the risk assessment model for obese postpartum women has not been externally validated.

Conclusions

Future research should focus on estimating the efficacy of pharmacological thromboprophylaxis in pregnancy and the puerperium, and clinical trials would be more acceptable in women who have not had a previous venous thromboembolism.

Study registration

This study is registered as PROSPERO CRD42020221094.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR131021) and is published in full in Health Technology Assessment; Vol. 28, No. 9. See the NIHR Funding and Awards website for further award information.

Decision Analysis in SHared decision making for Thromboprophylaxis during Pregnancy (DASH-TOP): a sequential explanatory mixed-methods pilot study

OBJECTIVES

To gain insight into formal methods of integrating patient preferences and clinical evidence to inform treatment decisions, we explored patients' experience with a personalised decision analysis intervention, for prophylactic low-molecular-weight heparin (LMWH) in the antenatal period.

DESIGN

Mixed-methods explanatory sequential pilot study.

SETTING

Hospitals in Canada (n=1) and Spain (n=4 sites). Due to the COVID-19 pandemic, we conducted part of the study virtually.

PARTICIPANTS

15 individuals with a prior venous thromboembolism who were pregnant or planning pregnancy and had been referred for counselling regarding LMWH.

INTERVENTION

A shared decision-making intervention that included three components: (1) direct choice exercise; (2) preference elicitation exercises and (3) personalised decision analysis.

MAIN OUTCOME MEASURES

Participants completed a self-administered questionnaire to evaluate decision quality (decisional conflict, self-efficacy and satisfaction). Semistructured interviews were then conducted to explore their experience and perceptions of the decision-making process.

RESULTS

Participants in the study appreciated the opportunity to use an evidence-based decision support tool that considered their personal values and preferences and reported feeling more prepared for their consultation. However, there were mixed reactions to the standard gamble and personalised treatment recommendation. Some participants could not understand how to complete the standard gamble exercises, and others highlighted the need for more informative ways of presenting results of the decision analysis.

CONCLUSION

Our results highlight the challenges and opportunities for those who wish to incorporate decision analysis to support shared decision-making for clinical decisions.

Women's values and preferences on low-molecular-weight heparin and pregnancy: a mixed-methods systematic review

BACKGROUND

Venous thromboembolism (VTE) in pregnancy is an important cause of maternal morbidity and mortality. Low-molecular-weight heparin (LMWH) is the cornerstone of prophylaxis and treatment of thrombotic events during pregnancy. LMWH has fewer adverse effects than other anticoagulants, does not cross the placenta, and is safe for the fetus. However, the use of LMWH during pregnancy is sensitive to womens' underlying preferences. The objective of this review is to systematically assess women's values and preferences research evidence on this topic.

METHODS

We searched four electronic databases from inception to March 2022, and included studies examining values and preferences of using LMWH among pregnant women at risk of VTE. We followed a convergent integrated mixed-methods design to compare and contrast quantitative outcomes (utility and non-utility measures) and qualitative findings. We assessed the certainty of the values and preferences evidence with the GRADE approach for quantitative findings, and with GRADE-CERqual for qualitative evidence. Results were presented in a conjoint display.

RESULTS

We screened 3,393 references and identified seven eligible studies. The mixed methods analysis resulted in four themes. Datasets confirmed each other in that: 1) the majority of women consider that benefits of treatment outweigh the inconveniences of daily injections; and 2) main concerns around medication are safety and injections administration. Quantitative outcomes expanded on the qualitative findings in that: 3) participants who perceived a higher risk of VTE were more willing to take LMWH. Finally, we found a discrepancy between the datasets around: 4) the amount of information preferred to make the decision; however, qualitative data expanded to clarify that women prefer making informed decisions and receive support from their clinician in their decision-making process.

CONCLUSIONS

We are moderately confident that in the context of pregnancy, using LMWH is preferred by women given its net beneficial balance. Integrating data from different sources of evidence, and representing them in a jointly manner helps to identify patient's values and preferences. Our results may inform clinical practice guidelines and support shared decision-making process in the clinical encounter for the management of VTE in the context of pregnancy.

The Risk of Thrombosis Around Pregnancy: Where Do We Stand?

Pregnancy and puerperium increase the relative risk of venous thromboembolism (VTE) and the absolute risk remains low, around 1 per 1,000, with induced mortality of around 1 per 100,000. Analysis of large databases has helped specify the modes of presentation and risk factors (RF) whose impact is greater after than before childbirth, since VTE during pregnancy and post-partum obey different RFs. The evolution of the population concerned (mostly women over 35, obese, of multi-ethnicity undergoing medically assisted reproduction) affects the frequency of these RFs. Pulmonary embolism (PE) is over-represented after childbirth, but 30% of PE in pregnancy occurs without any RFs. Recommendations for prevention, mainly from expert groups, are heterogeneous and often discordant. Low molecular weight heparins (LMWH) are the mainstay of pharmacological thromboprophylaxis, in a field where randomized controlled studies are definitely lacking. VTE risk assessment in pregnancy must be systematic and repetitive. Risk assessment methods and scores are beginning to emerge to guide thromboprophylaxis and should be used more systematically. In the future, analyzing observational data from huge, nationwide registries and prospective cluster clinical trials may bring to light clinically relevant outcomes likely to feed comprehensive guidelines.

Missed opportunities for venous thromboembolism prophylaxis during pregnancy and the postpartum period: evidence from mainland China in 2019

BACKGROUND

Venous thromboembolism (VTE) has become one of the leading causes of maternal mortality. Thromboprophylaxis is recommended for the prevention of this condition; however, its use appears to be insufficient. Therefore, in this study, we aimed to identify the missed opportunities for VTE prophylaxis in hospitals that provide maternal healthcare in mainland China.

METHODS

In this cross-sectional survey-based study, we collected case data on pregnant and puerperal women with deep vein thrombosis and pulmonary thromboembolism from January 1st to December 31st, 2019. Demographics, obstetric information, VTE risk assessment scores, and prophylaxis-related information were recorded. Thromboprophylaxis included mobilization, mechanical methods, and treatment with anticoagulants.

RESULTS

Data corresponding to a total of 106 cases from 26 hospitals across China were collected, and 100 (94.3%) cases, 75 cases involving deep vein thrombosis and 25 cases involving pulmonary thromboembolism, were included in the final analysis. VTE occurred in 80% of the patients at the postpartum stage, while 20 patients developed the disease during the antenatal stage. Cesarean section, advanced maternal age, and obesity were the most common risk factors related to VTE during the postpartum stage, while a previous VTE-related history was a prominent risk factor among antenatal cases. Up to 75% of the patients had one or more missed opportunities for prophylaxis. The lack of the implementation of mechanical methods (60.8% vs. 24.5%, P < 0.001) and anticoagulant treatment (61.1% vs. 48.7%, P < 0.001) were more common in general hospitals compared to those of specialized hospitals. In women assessed as high-risk, anticoagulant treatment was lacking in 41 (54.7%) cases. More importantly, the lack of the implementation of mechanical methods was more common among women assessed as low-risk (56.0% vs. 38.7%, P < 0.001). Among the antenatal cases, the lack of treatment with anticoagulants (100.0% vs. 48.5%, P < 0.001) and implementation of mechanical methods (70.0% vs. 36.7%, P < 0.001) was highlighted. In addition, the lack of early mobilization was much more prominent among the PTE cases (10.5% vs. 37.5%, P < 0.001).

CONCLUSIONS

At least one prophylactic opportunity was missed in most of the enrolled Chinese women with VTE during the course of their maternal healthcare. Missed prophylactic opportunities varied with the type of hospitals, risk assessment, onset timing and disease type. Further efforts from patients, healthcare systems, and healthcare providers are needed for improving the implementation of preventative strategies.

Decision Analysis in SHared decision making for Thromboprophylaxis during Pregnancy (DASH-TOP): a sequential explanatory mixed methods pilot study protocol

INTRODUCTION

Decision analysis is a quantitative approach to decision making that could bridge the gap between decisions based solely on evidence and the unique values and preferences of individual patients, a feature especially important when existing evidence cannot support clear recommendations and there is a close balance between harms and benefits for the treatments options under consideration. Low molecular weight heparin (LMWH) for the prevention of venous thromboembolism (VTE) during pregnancy represents one such situation. The objective of this paper is to describe the rationale and methodology of a pilot study that will explore the application of decision analysis to a shared decision-making process involving prophylactic LMWH for pregnant women or those considering pregnancy who have experienced a VTE.

METHODS AND ANALYSIS

We will conduct an international, mixed methods, explanatory, sequential study, including quantitative data collection and analysis followed by qualitative data collection and analysis. In step I, we will ask women who are pregnant or considering pregnancy and have experienced VTE to participate in a shared decision-making intervention for prophylactic LMWH. The intervention consists of three components: a direct choice exercise, a values elicitation exercise and a personalised decision analysis. After administration of the intervention, we will ask women to make a treatment decision and measure decisional conflict, self-efficacy and satisfaction. In step II, which follows the analysis of quantitative data, we will use the results to inform the qualitative interview. Step III will be a qualitative descriptive study that explores participants' experiences and perceptions of the intervention. In step IV, we will integrate findings from the qualitative and quantitative analyses to obtain meta-inferences.

ETHICS AND DISSEMINATION

Site-specific ethics boards have approved the study. All participants will provide informed consent. The research team will take an integrated approach to knowledge translation.

Risk stratification for venous thrombosis in post-partum women in a tertiary care setup in south India

Background & objectives

The Royal College of Obstetricians and Gynaecologists (RCOG) guidelines for thromboprophylaxis among post-partum women are recommended across Asia. This study was aimed to find the proportion of post-partum women eligible for thromboprophylaxis based on the RCOG guidelines and how many actually received it in a tertiary care health facility in south India.

Methods

This cross-sectional study was carried out on 1652 consecutive women who delivered in the setup of tertiary care. Risk stratification for venous thrombosis was done as per the RCOG guidelines. The number of women who received thromboprophylaxis was also noted.

Results

Among the 1652 women studied, three [0.18%; 95% confidence interval (CI): 0.06-0.53] were in the high-risk, 598 (36.2%; 95% CI: 33.9-38.6) in the intermediate and 254 (15.4%; 95% CI: 13.7-17.2) in the low-risk category for thrombosis. All the three women in the high-risk and only two women in the intermediate-risk category actually received thromboprophylaxis with heparin.

Interpretation & conclusions

It was seen that the number of women needing prophylaxis in our setup, as per the RCOG guidelines, was as high as 601 (36.4%), but only five (0.8%) received it.

Clinical practice guidelines for recurrent miscarriage in high-income countries: a systematic review

Recurrent miscarriage affects 1-2% of women of reproductive age, depending on the definition used. A systematic review was conducted to identify, appraise and describe clinical practice guidelines (CPG) published since 2000 for the investigation, management, and/or follow-up of recurrent miscarriage within high-income countries. Six major databases, eight guideline repositories and the websites of 11 professional organizations were searched to identify potentially eligible studies. The quality of eligible CPG was assessed using the Appraisal of Guidelines for Research and Evaluation (AGREE II) Tool. A narrative synthesis was conducted to describe, compare and contrast the CPG and recommendations therein. Thirty-two CPG were included, from which 373 recommendations concerning first-trimester recurrent miscarriage were identified across four sub-categories: structure of care (42 recommendations, nine CPG), investigations (134 recommendations, 23 CPG), treatment (153 recommendations, 24 CPG), and counselling and supportive care (46 recommendations, nine CPG). Most CPG scored 'poor' on applicability (84%) and editorial independence (69%); and to a lesser extent stakeholder involvement (38%) and rigour of development (31%). Varying levels of consensus were found across CPG, with some conflicting recommendations. Greater efforts are required to improve the quality of evidence underpinning CPG, the rigour of their development and the inclusion of multi-disciplinary perspectives, including those with lived experience of recurrent miscarriage.

Maternal and perinatal outcomes of a venous thromboembolism high-risk cohort using a multidisciplinary treatment approach

OBJECTIVE

To evaluate the maternal and perinatal outcomes in a cohort of pregnant women at high risk of venous thromboembolism (VTE).

METHODS

Women at high risk of VTE were evaluated in a multidisciplinary program using a complete diagnostic workup, and specific prophylactic or therapeutic treatment.

RESULTS

Women were considered at high risk of VTE in 57% (85/148) because of prior (75) or current (10) thromboembolism, and in 27% (40/148) of the cases due to adverse obstetric history. Thrombophilia was diagnosed in 57% of the cases (85/148), either in patients with previous thromboembolism (48%, 41/85) or without a history of thrombosis (70%, 44/63). The most common thrombophilia was antiphospholipid syndrome in 34% (29/85) of the cases. Under respective prophylactic or therapeutic treatment, there were no VTE during pregnancy (0%, 0/148), whereas four events occurred during the puerperium (3%, 4/148). An adverse obstetric outcome was present in 5% (7/148) of all pregnancies, with four early spontaneous abortions (3%, 4/148) and three late miscarriages (2%, 3/148).

CONCLUSION

Pregnant women at high risk of VTE can be effectively managed using a risk-adapted treatment. Our results support prospective enrollment and a multidisciplinary assessment of VTE in high-risk pregnant women.

Quality appraisal of clinical guidelines for venous thromboembolism prophylaxis in patients undergoing hip and knee arthroplasty: a systematic review

INTRODUCTION

Venous thromboembolism (VTE) occurs in up to 40%-80% of patients after hip and knee arthroplasty. Clinical decision-making aided by guidelines is the most effective strategy to reduce the burden of VTE. However, the quality of guidelines is dependent on the strength of their evidence base. The objective of this article is to critically evaluate the quality of VTE prevention guidelines and the strength of their recommendations in VTE prophylaxis in patients undergoing hip and knee arthroplasty.

METHODS

Relevant literature up to 16 March 2020 was systematically searched. We searched databases such as Web of Science, PubMed, EMBASE, Cumulative Index of Nursing and Allied Health Literature, China National Knowledge Infrastructure and WanFang and nine guidelines repositories. The identified guidelines were appraised by two reviewers using the Appraisal of Guidelines for Research and Evaluation II and appraised the strength of their recommendations independently. Following quality assessment, a predesigned data collection form was used to extract the characteristics of the included guideline.

RESULTS

We finally included 15 guidelines. Ten of the included guidelines were rated as 'recommended' or 'recommended with modifications'. The standardised scores were relatively high in the domains of Clarity of Presentation, and Scope and Purpose. The lowest average standardised scores were observed in the domains of Applicability and Stakeholder Involvement. In reference to the domains of Rigour of Development and Editorial Independence, the standardised scores varied greatly between the guidelines. The agreement between the two appraisers is almost perfect (intraclass correlation coefficients higher than 0.80). A considerable proportion of the recommendations is based on low-quality or very-low-quality evidence or is even based on working group expert opinion.

CONCLUSIONS

In summary, the majority of the recommendations are based on low-quality evidence, and further confirmation is needed. Furthermore, guideline developers should pay more attention to methodological quality, especially in the Stakeholder Involvement domain and the Applicability domain.