Screening and prevention of venous thromboembolism in critically ill patients: a decision analysis and economic evaluation

Incidence and Risk Factors for Deep Venous Thrombosis and Its Impact on Outcome in Patients Admitted to Medical Critical Care

Objectives

This study evaluated the incidence and risk factors for deep venous thrombosis (DVT) while on thromboprophylaxis, in patients admitted to the medical intensive care unit (MICU), and to assess its impact on outcomes.

Methods

Consecutive patients admitted to the MICU underwent compression ultrasound of the jugular, axillary, femoral, and popliteal veins at admission, day 3 and 7 to screen for DVT. All patients were on pharmacological and/or mechanical thromboprophylaxis as per protocol. The primary outcome was the incidence of DVT (defined as occurrence on day 3 or 7). Secondary outcomes were death and duration of hospitalization. Risk factors for DVT were explored using bivariate and multivariable logistic regression analysis and expressed as risk ratio (RR) with 95% confidence intervals (CIs).

Results

The incidence of DVT was 17.2% (95% CI 12.0, 22.3) (n = 35/203); two-thirds were catheter associated (23/35). There was no difference in mortality between those with and without incident DVT (9/35 vs 40/168, p = 0.81). The mean (SD) duration of hospitalization was longer in the DVT group (20.1 (17) vs 12.9 (8.5) days, p = 0.007). Although day 3 INR (RR 2.1, 95% CI 0.9-5.3), age >40 years (2.1, 0.8-5.3), vasopressor use (1.0, 0.4-2.9) and SOFA score (0.9, 0.85-1.1) were associated with the development of DVT on bivariate analysis, only central venous catheters (15.97, 1.9-135.8) was independently associated with DVT on multivariable analysis.

Conclusions

Despite thromboprophylaxis, 17% of ICU patients develop DVT. The central venous catheter is the main risk factor. DVT is not associated with increased mortality in the setting of prophylaxis.

How to cite this article

Krishnamoorthy A, Hansdak SG, Peter JV, Pichamuthu K, Rajan SJ, Sudarsan TI, et al. Incidence and Risk Factors for Deep Venous Thrombosis and Its Impact on Outcome in Patients Admitted to Medical Critical Care. Indian J Crit Care Med 2024;28(6):607-613.

Development of a Risk Assessment Tool for Venous Thromboembolism among Hospitalized Patients in the ICU

BACKGROUND

ICU patients have a high incidence of VTE. The American College of Chest Physicians antithrombotic practice guidelines recommend assessing the risk of VTE in all ICU patients. Although several VTE risk assessment tools exist to evaluate the risk factors among hospitalized patients, there is no validated tool specifically for assessing the risk of VTE in ICU patients.

METHODS

A retrospective corhort study was conducted between June 2018 and October 2022. We obtained data from the electronic medical records of patients with a variety of diagnoses admitted to a mixed ICU. Multivariable logistic regression analysis was used to evaluate the independent risk factors of VTE. Receiver operating characteristic (ROC) curves were used to analyse the predictive accuracy of different tools.

RESULTS

A total of 566 patients were included, and VTE occurred in 89 patients (15.7%), 62.9% was asymptomatic VTE. A prediction model (the ICU-VTE prediction model) was derived from the independent risk factors identified using multivariate analysis. The ICU-VTE prediction model included eight independent risk factors: history of VTE (3 points), immobilization ≥4 days (3 points), multiple trauma (3 points), age ≥70 years (2 points), platelet count >250 × 103/μL (2 points), central venous catheterization (1 point), invasive mechanical ventilation (1 point), and respiratory failure or heart failure (1 point). Patients with a score of 0-4 points had a low (1.81%) risk of VTE. Patients were at intermediate risk, scoring 5-6 points, and the overall incidence of VTE in the intermediate-risk category was 17.1% (odds ratio [OR], 11.1; 95% confidence interval [CI], 4.2-29.4). Those with a score ≥7 points had a high (44.1%) risk of VTE (OR, 42.6; 95% CI, 16.4-110.3). The area under the curve (AUC) of the ICU-VTE prediction model was 0.838, and the differences in the AUCs were statistically significant between the ICU-VTE prediction model and the other three tools (ICU-VTE score, Z = 3.723, P < 0.001; Caprini risk assessment model, Z = 6.212, P < 0.001; Padua prediction score, Z = 7.120, P < 0.001).

CONCLUSIONS

We identified eight independent risk factors for acquired VTE among hospitalized patients in the ICU, deriving a new ICU-VTE risk assessment model. The model aims to predict asymptomatic VTE in ICU patients. The new model has higher predictive accuracy than the current tools. A prospective study is required for external validation of the tool and risk stratification in ICU patients.

Approach to Intensive Care Costing and Provision of Cost-effective Care

Intensive care unit (ICU) service is resource-intense, finite, and valuable. The outcome of critically ill patients has improved because of a better understanding of disease pathology, technological developments, and newer treatment modalities. These improvements have however come at a price, with ICUs contributing significantly to health budgets. Several costing tools are used to assess cost. Accurate assessment has been hampered by the lack of standardized methodology and the heterogeneity of ICUs. In a costing exercise, the level of disaggregation (micro-costing vs gross-costing) and the method of costing (top-down vs bottom-up) need to be considered. Intensive care unit costing also needs to be viewed from the perspective of stakeholders. While all stakeholders aim to provide quality health care, objectives may vary. For the public health care provider, the focus is on optimizing expenditure; for the private health care provider it is bottomline; for a patient, it is affordability; for an insurance service provider, it is minimizing payout; and for the regulator, it is ensuring quality standards and fair pricing. The field of health economics deals with the application of the principles of cost-minimization, cost-effectiveness, cost-utility, and cost-benefit to identify treatments that result in the best outcome at the lowest cost, without limiting resources to other competing interests. In the ICU setting, studies on the efficient use of available resources, and interventions that reduce cost and minimize avoidable cost, would not only translate to cost savings, lives saved, and quality-adjusted life years gained but also enable policymakers to better allocate health care resources.

HOW TO CITE THIS ARTICLE

Chacko B, Ramakrishnan N, Peter JV. Approach to Intensive Care Costing and Provision of Cost-effective Care. Indian J Crit Care Med 2023;27(12):876-887.

Point-of-care ultrasound in pre-bronchoscopy assessment of acute dyspnea: A case of concurrent massive pulmonary embolism and deep vein thrombosis

Point-of-care ultrasound (POCUS) leads to efficient real-time diagnosis in a wide range of medical specialties. We describe the use of cardiac, lung and lower limb POCUS to rapidly diagnose massive pulmonary embolism and deep vein thrombosis in a 64-year-old patient presenting with acute dyspnea prior to elective bronchoscopy. Left femoral vein thrombus and features of increased right heart pressure on POCUS led to the decision to administer fibrinolytic therapy, with subsequent CT pulmonary angiogram confirming bilateral PE. The use of POCUS allowed for rapid imaging and interpretation leading to a rapid diagnosis of PE, thus fast-tracking lifesaving anticoagulation, especially in an outpatient setting.

Efficacy of ultrasound assisted catheter-directed thrombolysis compared to catheter-directed thrombolysis in vitro

BACKGROUND

Catheter-directed thrombolysis (CDT) is an effective and safe endovascular method used in critical limb ischemia and many other thromboembolic events. Ultrasound-assisted catheter-directed thrombolysis (US-CDT) is an emerging technique considered to accelerate thrombolysis and therefore is supposed to improve outcome.

PURPOSE

To evaluate the efficacy of US-CDT in comparison to standard CDT in vitro.

MATERIAL AND METHODS

A total of 69 sets of human venous blood were evaluated, each comprising a tube just treated with CDT, a tube treated with US-CDT, and a control tube. All tubes were kept under physiological conditions. Except for the controls, in all tubes 5 mg of tissue-type plasminogen activator was administered over the predetermined treatment interval. Thrombus mass was weighted at the end of the lysis intervals at 6 h or 24 h, respectively.

RESULTS

CDT led to a mean thrombus reduction of 32% and ultrasound-assisted lysis led to a mean thrombus reduction of 41% (P < 0.001 for both). Thrombus reduction was significantly higher after US-CDT compared to CDT (P = 0.001). The better efficacy of US-CDT was mostly already apparent at early phases during thrombolysis and did further mildly increase over time (r = 0.24; P = 0.047).

CONCLUSION

In vitro US-CDT is significantly superior to standard CDT; this effect is apparent at an early timepoint of lysis and slightly further increases over time.

Venous Thromboembolism Prophylaxis in Critically Ill Adults: A Systematic Review and Network Meta-analysis

BACKGROUND

Critically ill adults are at increased risk of VTE, including DVT, and pulmonary embolism. Various agents exist for venous thromboprophylaxis in this population.

RESEARCH QUESTION

What is the comparative efficacy and safety of prophylaxis agents for prevention of VTE in critically ill adults?

STUDY DESIGN AND METHODS

Systematic review and network meta-analysis of randomized clinical trials (RCTs) evaluating efficacy of thromboprophylaxis agents among critically ill patients. We searched six databases (including PubMed, EMBASE, and Medline) from inception through January 2021 for RCTs of patients in the ICU receiving pharmacologic, mechanical, or combination therapy (pharmacologic agents and mechanical devices) for thromboprophylaxis. Two reviewers performed screening, full-text review, and extraction. We used the Grading of Recommendations Assessment, Development, and Evaluation to rate certainty of effect estimates.

RESULTS

We included 13 RCTs (9,619 patients). Compared with control treatment (a composite of no prophylaxis, placebo, or compression stockings only), low-molecular-weight heparin (LMWH) reduced the incidence of DVT (OR, 0.59 [95% credible interval [CrI], 0.33-0.90]; high certainty) and unfractionated heparin (UFH) may reduce the incidence of DVT (OR, 0.82 [95% CrI, 0.47-1.37]; low certainty). LMWH probably reduces DVT compared with UFH (OR, 0.72 [95% CrI, 0.46-0.98]; moderate certainty). Compressive devices may reduce risk of DVT compared with control treatments; however, this is based on low-certainty evidence (OR, 0.85 [95% CrI, 0.50-1.50]). Combination therapy showed unclear effect on DVT compared with either therapy alone (very low certainty).

INTERPRETATION

Among critically ill adults, compared with control treatment, LMWH reduces incidence of DVT, whereas UFH and mechanical compressive devices may reduce the risk of DVT. LMWH is probably more effective than UFH in reducing incidence of DVT and should be considered the primary pharmacologic agent for thromboprophylaxis. The efficacy and safety of combination pharmacologic therapy and mechanical compressive devices were unclear.

TRIAL REGISTRY

Open Science Framework; URL: https://osf.io/694aj.

How I Do It: Point-of-Care Ultrasound for Bedside Diagnosis of Lower Extremity DVT

The point-of-care ultrasound (POCUS) DVT examination can facilitate rapid bedside diagnosis and treatment of lower extremity DVT. Awaiting radiology-performed Doppler ultrasonography and interpretation by radiologists can lead to delays in lifesaving anticoagulation, and the POCUS DVT examination can provide timely diagnostic information in the patient with lower extremity symptoms. This article outlines accepted techniques for the POCUS DVT examination, discusses the historical context from which the current recommendations have evolved, and provides illustrations alongside ultrasound images of relevant venous anatomy to orient the clinician. Finally, common pitfalls and methods to avoid them are described.

Prediction of Symptomatic Venous Thromboembolism in Critically Ill Patients: The ICU-Venous Thromboembolism Score

OBJECTIVES

To identify risk factors and develop a prediction score for in-hospital symptomatic venous thromboembolism in critically ill patients.

DESIGN

Retrospective cohort study.

SETTING

Henry Ford Health System, a five-hospital system including 18 ICUs.

PATIENTS

We obtained data from the electronic medical record of all adult patients admitted to any ICU (total 264 beds) between January 2015 and March 2018.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Symptomatic venous thromboembolism was defined as deep vein thrombosis, pulmonary embolism, or both, diagnosed greater than 24 hours after ICU admission and confirmed by ultrasound, CT, or nuclear medicine imaging. A prediction score (the ICU-Venous Thromboembolism score) was derived from independent risk factors identified using multivariable logistic regression. Of 37,050 patients who met the eligibility criteria, 529 patients (1.4%) developed symptomatic venous thromboembolism. The ICU-Venous Thromboembolism score consists of six independent predictors: central venous catheterization (5 points), immobilization greater than or equal to 4 days (4 points), prior history of venous thromboembolism (4 points), mechanical ventilation (2 points), lowest hemoglobin during hospitalization greater than or equal to 9 g/dL (2 points), and platelet count at admission greater than 250,000/μL (1 point). Patients with a score of 0-8 (76% of the sample) had a low (0.3%) risk of venous thromboembolism; those with a score of 9-14 (22%) had an intermediate (3.6%) risk of venous thromboembolism (hazard ratio, 6.7; 95% CI, 5.3-8.4); and those with a score of 15-18 (2%) had a high (17.7%) risk of venous thromboembolism (hazard ratio, 28.1; 95% CI, 21.7-36.5). The overall C-statistic of the model was 0.87 (95% CI, 0.85-0.88).

CONCLUSIONS

Clinically diagnosed symptomatic venous thromboembolism occurred in 1.4% of this large population of ICU patients with high adherence to chemoprophylaxis. Central venous catheterization and immobilization are potentially modifiable risk factors for venous thromboembolism. The ICU-Venous Thromboembolism score can identify patients at increased risk for venous thromboembolism.

Health-Related Quality-of-Life and Cost Utility Analyses in Critical Care: A Systematic Review

OBJECTIVES

Cost utility analyses compare the costs and health outcome of interventions, with a denominator of quality-adjusted life year, a generic health utility measure combining both quality and quantity of life. Cost utility analyses are difficult to compare when methods are not standardized. It is unclear how cost utility analyses are measured/reported in critical care and what methodologic challenges cost utility analyses pose in this setting. This may lead to differences precluding cost utility analyses comparisons. Therefore, we performed a systematic review of cost utility analyses conducted in critical care. Our objectives were to understand: 1) methodologic characteristics, 2) how health-related quality-of-life was measured/reported, and 3) what costs were reported/measured.

DESIGN

Systematic review.

DATA SOURCES

We systematically searched for cost utility analyses in critical care in MEDLINE, Embase, American College of Physicians Journal Club, CENTRAL, Evidence-Based Medicine Reviews' selected subset of archived versions of UK National Health Service Economic Evaluation Database, Database of Abstracts of Reviews of Effects, and American Economic Association electronic databases from inception to April 30, 2020.

SETTING

Adult ICUs.

PATIENTS

Adult critically ill patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 8,926 citations, 80 cost utility analyse studies were eligible. The time horizon most commonly reported was lifetime (59%). For health utility reporting, health-related quality-of-life was infrequently measured (29% reported), with only 5% of studies reporting baseline health-related quality-of-life. Indirect utility measures (generic, preference-based health utility measurement tools) were reported in 85% of studies (majority Euro-quality-of-life-5 Domains, 52%). Methods of estimating health-related quality-of-life were seldom used when the patient was incapacitated: imputation (19%), assigning fixed utilities for incapacitation (19%), and surrogates reporting on behalf of incapacitated patients (5%). For cost utility reporting transparency, separate incremental costs and quality-adjusted life years were both reported in only 76% of studies. Disaggregated quality-adjusted life years (reporting separate health utility and life years) were described in only 34% of studies.

CONCLUSIONS

We identified deficiencies which warrant recommendations (standardized measurement/reporting of resource use/unit costs/health-related quality-of-life/methodological preferences) for improved design, conduct, and reporting of future cost utility analyses in critical care.

Critical Care Beds With Continuous Lateral Rotation Therapy to Prevent Ventilator-Associated Pneumonia and Hospital-Acquired Pressure Injury: A Cost-effectiveness Analysis

OBJECTIVES

Mechanical ventilation increases the risk of hospital-acquired conditions (HACs) such as ventilator-associated pneumonia (VAP) and pressure injury (PrI). Beds with continuous lateral rotation therapy (CLRT) are shown to reduce HAC incidence, but the value of switching to CLRT beds is presently unknown. We compared the cost-effectiveness of CLRT beds with standard care in intensive care units.

METHODS

A cost-effectiveness analysis from the healthcare sector and societal perspectives was conducted. A Markov model was constructed to predict health state transitions from time of ventilation through 28 days for the healthcare sector perspective and 1 year for the U.S. societal perspective. Value of information was calculated to determine whether parameter uncertainty warranted further research.

RESULTS

Our analysis suggested that CLRT beds dominate standard care from both perspectives. From the healthcare sector perspective, expected cost for CLRT was U.S. $47,165/patient compared with a higher cost of U.S. $49,258/patient for standard care. The expected effectiveness of CLRT is 0.0418 quality-adjusted life years/patient compared with 0.0416 quality-adjusted life years/patient for standard care. Continuous lateral rotation therapy dominated standard care in approximately 93% of Monte Carlo simulations from both perspectives. Value of information analysis suggests that additional research is potentially cost-effective.

CONCLUSIONS

Continuous lateral rotation therapy is highly cost-effective compared with standard care by preventing HACs that seriously harm patients in the intensive care unit.

Optimizing pharmacologic thromboprophylaxis use in pediatric orthopedic surgical patients through implementation of a perioperative venous thromboembolism risk screening tool

BACKGROUND

Although rare, venous thromboembolic events (VTE) are a significant challenge in pediatric orthopedic surgical patients (POSP). A VTE thromboprophylaxis screening tool was developed and implemented in POSPs at the IWK Health Centre since October 2016.

OBJECTIVES

This retrospective cohort study was designed to evaluate and assess the impact of the VTE thromboprophylaxis screening tool in terms of use of thromboprophylaxis in POSP.

METHODS

Using the tool, POSPs were screened and were categorized into risk groups. Patient groups were compared and spearman correlation analysis was performed to show the strength of association between risk factors and thromboprophylaxis. Retrospective screening of pre-algorithm patients who received thromboprophylaxis was done to further assess the screening tool.

RESULTS

After the implementation of the VTE thromboprophylaxis screening tool in POSPs, there was a 47.9% reduction in the use of thromboprophylaxis (P = 0.046) as compared with before. Neither VTE nor significant bleeding complications occurred before or after screening tool implementation. Compliance with the screening tool was excellent (100% of patients in the high-risk category received thromboprophylaxis). High-risk patients were more likely to have body mass index  > 30 (35.7%), limited/altered mobility (57.1%), and to be undergoing a complicated/repeat surgery (64.3%).

CONCLUSIONS

The present study demonstrates successful implementation of a VTE thromboprophylaxis screening tool that resulted in significant reduction in use of thromboprophylaxis in POSPs with no increase in VTE or change in bleeding complications.

Post-operative deep vein thrombosis in patients over sixty years of age diagnosed with closed distal femur fractures undergoing open reduction internal fixation

BACKGROUND AND PURPOSE

New-onset deep vein thrombosis (DVT) reportedly affects prognosis and surgical outcomes of elderly patients. However, its effect on distal femur fractures (DFFs) remains unclear. We aimed to address the epidemiological characteristics and the associated predictors for post-operative DVT in patients with closed DFFs over age 60 years old.

PATIENTS AND METHODS

We designed a prospective cohort trial at our hospital between October 2018 and June 2020 and recruited consecutive 140 patients over age 60 years diagnosed with closed DFFs. We examined location and prognosis of postoperative DVT and then conducted a three month follow-up. We used Duplex ultrasonography (DUS) to diagnose DVT in all patients and then classified the subjects into DVT and non-DVT groups. We further classified DVTs into proximal, distal, and mixed thromboses and then performed Whitney U test or t test, receiver operating characteristic (ROC) curve analysis, Chi-square test, and multiple logistic regression analysis to confirm the adjusted factors of post-operative DVT.

RESULTS

We found a 35% (n = 49) overall incidence of post-operative DVTs, which occurred 5.7 days following open reduction internal fixation (ORIF). Among patients with post-operative DVTs, 53.1% (n = 26) and 10.2% (n = 5) were distal and proximal thromboses, respectively. Additionally, peroneal veins were the most common DVT sites (71.4%, n = 35). Multivariate analysis revealed that venous thrombosis at admission (odds ratio [OR], 4.619; 95% confidence interval [CI]: 2.072-10.299; P = 0.000), operation duration over 195 minutes (OR, 3.289; 95% CI, 1.155-9.370; P = 0.026), intra-operative blood loss over 325 mL (OR, 2.538; 95% CI, 1.047-6.155; P = 0.039) were the three independent risk factors of post-operative DVT. Unified antithrombotic agents after diagnosis showed that 16.3% (n = 8) of DVTs were completely recanalized, 12.6 days after first diagnosis.

CONCLUSION

Our findings indicate a strong association between venous thrombosis at admission, the longer operation duration, and considerable intra-operative blood loss with high risk of post-operative DVTs in patients over age 60 years with closed DFFs. Preventive approaches for postoperative DVTs should seek to shorten operation duration and reduce intra-operative blood loss.

Prevalence of venous thromboembolism after lung surgery in China: a single-centre, prospective cohort study involving patients undergoing lung resections without perioperative venous thromboembolism prophylaxis†

OBJECTIVES

Venous thromboembolism (VTE) is a common postoperative complication. Previous studies have shown that the incidence of VTE after major thoracic surgery ranges from 2.3% to 15%. However, there have been no such data from China so far. To evaluate the incidence of postoperative VTE, we conducted a single-centre, prospective cohort study.

METHODS

Patients who underwent lung resections between July 2016 and March 2017 were enrolled in this study. None of the patients received any prophylaxis perioperatively. All patients were screened for deep venous thrombosis (DVT) using non-invasive duplex lower-extremity ultrasonography 30 days before surgery and within 30 days after surgery and before discharge. Chest tomography, pulmonary embolism protocol was carried out if patients had one of the following conditions: (i) typical symptoms of pulmonary embolism, (ii) high Caprini score (≥9 points) and (iii) newly diagnosed postoperative DVT.

RESULTS

Two hundred and sixty-two patients undergoing lung surgery were enrolled, including 115 benign and 147 malignant disease cases. The procedures included 84 sublobar lung resections, 161 lobectomies, 5 pneumonectomies and 12 mixed procedures. The overall postoperative incidence of VTE was 11.5% (30 of 262). Twenty-four patients were diagnosed with DVT (80.0%) and 6 with DVT + pulmonary embolism (20.0%). None of the patients diagnosed with VTE had obvious symptoms of VTE. The median time for VTE detection was 5 days postoperatively. The incidence of VTE was 7.0% in patients with benign lung diseases and 15.0% in those with malignant lung diseases (P < 0.05). Using the Caprini risk assessment model, 63 cases were scored as low risk, 179 as moderate risk and 20 as high risk, and each group had an incidence of postoperative VTE of 0%, 12.3% (22 of 179) and 40.0% (8 of 20), respectively (P < 0.05). In patients with lung cancer, 98% were moderate or high risk, and only 3 patients were scored in the low risk category. The incidence of VTE in patients at moderate risk and high risk was 12.0% and 36.8%, respectively, while it was 0 in low-risk patients.

CONCLUSIONS

The following conclusions were drawn: (i) the overall incidence of postoperative VTE after lung surgery without VTE prophylaxis is substantial; (ii) lower-extremity ultrasonography was helpful in detecting asymptomatic DVT in symptomatic or high-risk patients; and (iii) VTE prophylaxis should be considered as a mandatory part of perioperative care.

CLINICAL TRIAL REGISTRATION NUMBER

ChiCTR-EOC-17010577.

A preliminary study of intensivist-performed DVT ultrasound screening in trauma ICU patients (APSIT Study)

Background

Multiple screening Duplex ultrasound scans (DUS) are performed in trauma patients at high risk of deep vein thrombosis (DVT) in the intensive care unit (ICU). Intensive care physician performed compression ultrasound (IP-CUS) has shown promise as a diagnostic test for DVT in a non-trauma setting. Whether IP-CUS can be used as a screening test in trauma patients is unknown. Our study aimed to assess the agreement between IP-CUS and vascular sonographer performed DUS for proximal lower extremity deep vein thrombosis (PLEDVT) screening in high-risk trauma patients in ICU.

Methods

A prospective observational study was conducted at the ICU of Alfred Hospital, a major trauma center in Melbourne, Australia, between Feb and Nov 2015. All adult major trauma patients admitted with high risk for DVT were eligible for inclusion. IP-CUS was performed immediately before or after DUS for PLEDVT screening. The paired studies were repeated twice weekly until the DVT diagnosis, death or ICU discharge. Written informed consent from the patient, or person responsible, or procedural authorisation, was obtained. The individuals performing the scans were blinded to the others’ results. The agreement analysis was performed using Cohen’s Kappa statistics and intraclass correlation coefficient for repeated binary measurements.

Results

During the study period, 117 patients had 193 pairs of scans, and 45 (39%) patients had more than one pair of scans. The median age (IQR) was 47 (28–68) years with 77% males, mean (SD) injury severity score 27.5 (9.53), and a median (IQR) ICU length of stay 7 (3.2–11.6) days. There were 16 cases (13.6%) of PLEDVT with an incidence rate of 2.6 (1.6–4.2) cases per 100 patient-days in ICU. The overall agreement was 96.7% (95% CI 94.15–99.33). The Cohen’s Kappa between the IP-CUS and DUS was 0.77 (95% CI 0.59–0.95), and the intraclass correlation coefficient for repeated binary measures was 0.75 (95% CI 0.67–0.81).

Conclusions

There is a substantial agreement between IP-CUS and DUS for PLEDVT screening in trauma patients in ICU with high risk for DVT. Large multicentre studies are needed to confirm this finding.

Cost-Effectiveness Studies in the ICU: A Systematic Review

OBJECTIVES

Cost-effectiveness analyses are increasingly used to aid decisions about resource allocation in healthcare; this practice is slow to translate into critical care. We sought to identify and summarize original cost-effectiveness studies presenting cost per quality-adjusted life year, incremental cost-effectiveness ratios, or cost per life-year ratios for treatments used in ICUs.

DESIGN

We conducted a systematic search of the English-language literature for cost-effectiveness analyses published from 1993 to 2018 in critical care. Study quality was assessed using the Drummond checklist.

SETTING

Critical care units.

PATIENTS OR SUBJECTS

Critical care patients.

INTERVENTIONS

Identified studies with cost-effectiveness analyses.

MEASUREMENTS AND MAIN RESULTS

We identified 97 studies published through 2018 with 156 cost-effectiveness ratios. Reported incremental cost-effectiveness ratios ranged from -$119,635 (hypothetical cohort of patients requiring either intermittent or continuous renal replacement therapy) to $876,539 (data from an acute renal failure study in which continuous renal replacement therapy was the most expensive therapy). Many studies reported favorable cost-effectiveness profiles (i.e., below $50,000 per life year or quality-adjusted life year). However, several therapies have since been proven harmful. Over 2 decades, relatively few cost-effectiveness studies in critical care have been published (average 4.6 studies per year). There has been a more recent trend toward using hypothetical cohorts and modeling scenarios without proven clinical data (2014-2018: 19/33 [58%]).

CONCLUSIONS

Despite critical care being a significant healthcare cost burden there remains a paucity of studies in the literature evaluating its cost effectiveness.

Cost-Effectiveness of Betrixaban Compared with Enoxaparin for Venous Thromboembolism Prophylaxis in Nonsurgical Patients with Acute Medical Illness in the United States

BACKGROUND

Studies show that the risk of venous thromboembolism (VTE) continues post-discharge in nonsurgical patients with acute medical illness. Betrixaban is the first anticoagulant approved in the United States (US) for VTE prophylaxis extending beyond hospitalization.

OBJECTIVE

The aim was to establish whether betrixaban for VTE prophylaxis in nonsurgical patients with acute medical illness at risk of VTE in the US is cost-effective compared with enoxaparin.

METHODS

A cost-effectiveness analysis was conducted, estimating the cost per quality-adjusted life-year (QALY) gained with betrixaban (35-42 days) compared with enoxaparin (6-14 days) from a US payer perspective over a lifetime horizon. A decision tree (DT) estimated primary VTE events, thrombotic events, and treatment complications in the first 3 months based on data from the phase III Acute Medically Ill VTE Prevention with Extended Duration Betrixaban study. A Markov model estimated recurrent events and long-term complication risks from published literature. EuroQoL-5 Dimensions utility data and costs inflated to 2017 US dollars (US$) were from published literature. Results were discounted at 3.0% per annum. Deterministic and probabilistic sensitivity analyses explored uncertainty.

RESULTS

Betrixaban dominated enoxaparin, with savings of US$784 and increased QALYs of 0.017 per patient. In addition, betrixaban dominated enoxaparin across all sensitivity analyses, but was most sensitive to utilities and DT probabilities. Furthermore, probabilistic sensitivity analysis found that betrixaban was more cost-effective than enoxaparin at all willingness-to-pay thresholds.

CONCLUSION

Betrixaban can be considered cost-effective for nonsurgical patients with acute medical illness at risk of VTE, requiring longer VTE prophylaxis from hospitalization through post-discharge.

Risk assessment of venous thromboembolism and thromboprophylaxis in pregnant women hospitalized with cancer: Preliminary results from a risk score

OBJECTIVES

Hospitalized patients with cancer are at high risk of developing venous thromboembolism, and the risk increases with pregnancy. The aim of this study was to apply a thromboprophylaxis protocol with a venous thromboembolism risk score for hospitalized pregnant women with cancer and to evaluate the effects on maternal morbidity and mortality.

METHODS

A longitudinal and prospective study was conducted from December 2014 to July 2016. The venous thromboembolism risk score was modified from the guidelines of the Royal College of Obstetricians and Gynaecologists. Patients were classified as low (score <3) or high risk (score ≥3). The high-risk group received thromboprophylaxis with low-molecular-weight heparin, unless the patient had a contraindication for anticoagulation. One patient could have undergone more than one evaluation.

RESULTS

Fifty-two ratings were descriptively analyzed: 34 (65.4%) were classified as high risk, and 28/34 (82.3%) received low-molecular-weight heparin, 1 received unfractionated heparin, and 5 did not receive intervention. Most patients (23/52; 44.2%) had breast cancer. The main risk factors for venous thromboembolism in the high-risk group were chemotherapy (within 6 months; 22/34; 64.7%). No patient exhibited venous thromboembolism, adverse effects of anticoagulation or death up to three months after hospitalization.

CONCLUSIONS

Most pregnant women with cancer had a high risk for venous thromboembolism at the time of hospitalization. Breast cancer was the most prevalent cancer, and recent chemotherapy was the main risk factor for anticoagulation. The application of a thromboprophylaxis protocol and determination of a venous thromboembolism risk score for these patients was useful for the prevention of maternal morbidity and mortality due to venous thromboembolism.

Surveillance or no surveillance for deep venous thrombosis and outcomes of critically ill patients: A study protocol and statistical analysis plan

OBJECTIVE

Surveillance ultrasounds in critically ill patients detect many deep venous thrombi (DVTs) that would otherwise go unnoticed. However, the impact of surveillance for DVT on mortality among critically ill patients remains unclear.

DESIGN

We are conducting a multicenter, multinational randomized controlled trial that examines the effectiveness of adjunct intermittent pneumatic compression use with pharmacologic thromboprophylaxis compared to pharmacologic thromboprophylaxis alone on the incidence of proximal lower extremity DVT in critically ill patients (the PREVENT trial). Enrolled patients undergo twice weekly surveillance ultrasounds of the lower extremities as part of the study procedures. We plan to compare enrolled patients who have surveillance ultrasounds to patients who meet the eligibility criteria but are not enrolled (eligible non-enrolled patients) and only who will have ultrasounds performed at the clinical team's discretion. We hypothesize that twice-weekly ultrasound surveillance for DVT in critically ill patients who are receiving thromboprophylaxis will have more DVTs detected, and consequently, fewer pulmonary emboli and lower all-cause 90-day mortality.

DISCUSSION

We developed a detailed a priori plan to guide the analysis of the proposed study and enhance the validity of its results.

Factors Associated with Bleeding and Thrombosis in Children Receiving Extracorporeal Membrane Oxygenation

RATIONALE

Extracorporeal membrane oxygenation (ECMO) is used for respiratory and cardiac failure in children but is complicated by bleeding and thrombosis.

OBJECTIVES

(1) To measure the incidence of bleeding (blood loss requiring transfusion or intracranial hemorrhage) and thrombosis during ECMO support; (2) to identify factors associated with these complications; and (3) to determine the impact of these complications on patient outcome.

METHODS

This was a prospective, observational cohort study in pediatric, cardiac, and neonatal intensive care units in eight hospitals, carried out from December 2012 to September 2014.

MEASUREMENTS AND MAIN RESULTS

ECMO was used on 514 consecutive patients under age 19 years. Demographics, anticoagulation practices, severity of illness, circuitry components, bleeding, thrombotic events, and outcome were recorded. Survival was 54.9%. Bleeding occurred in 70.2%, including intracranial hemorrhage in 16%, and was independently associated with higher daily risk of mortality. Circuit component changes were required in 31.1%, and patient-related clots occurred in 12.8%. Laboratory sampling contributed to transfusion requirement in 56.6%, and was the sole reason for at least one transfusion in 42.2% of patients. Pump type was not associated with bleeding, thrombosis, hemolysis, or mortality. Hemolysis was predictive of subsequent thrombotic events. Neither hemolysis nor thrombotic events increased the risk of mortality.

CONCLUSIONS

The incidences of bleeding and thrombosis are high during ECMO support. Laboratory sampling is a major contributor to transfusion during ECMO. Strategies to reduce the daily risk of bleeding and thrombosis, and different thresholds for transfusion, may be appropriate subjects of future trials to improve outcomes of children requiring this supportive therapy.

Detailed assessment of benefits and risks of retrievable inferior vena cava filters on patients with complicated injuries: the da Vinci multicentre randomised controlled trial study protocol

INTRODUCTION

Retrievable inferior vena cava (IVC) filters have been increasingly used in patients with major trauma who have contraindications to anticoagulant prophylaxis as a primary prophylactic measure against venous thromboembolism (VTE). The benefits, risks and cost-effectiveness of such strategy are uncertain.

METHODS AND ANALYSIS

Patients with major trauma, defined by an estimated Injury Severity Score >15, who have contraindications to anticoagulant VTE prophylaxis within 72 hours of hospitalisation to the study centre will be eligible for this randomised multicentre controlled trial. After obtaining consent from patients, or the persons responsible for the patients, study patients are randomly allocated to either control or IVC filter, within 72 hours of trauma admission, in a 1:1 ratio by permuted blocks stratified by study centre. The primary outcomes are (1) the composite endpoint of (A) pulmonary embolism (PE) as demonstrated by CT pulmonary angiography, high probability ventilation/perfusion scan, transoesophageal echocardiography (by showing clots within pulmonary arterial trunk), pulmonary angiography or postmortem examination during the same hospitalisation or 90-day after trauma whichever is earlier and (B) hospital mortality; and (2) the total cost of treatment including the costs of an IVC filter, total number of CT and ultrasound scans required, length of intensive care unit and hospital stay, procedures and drugs required to treat PE or complications related to the IVC filters. The study started in June 2015 and the final enrolment target is 240 patients. No interim analysis is planned; incidence of fatal PE is used as safety stopping rule for the trial.

ETHICS AND DISSEMINATION

Ethics approval was obtained in all four participating centres in Australia. Results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ACTRN12614000963628; Pre-results.

Incidence and risk factors for preoperative deep venous thrombosis in 314 consecutive patients undergoing surgery for spinal metastasis

OBJECTIVE The authors of this study aimed to identify the incidence of and risk factors for preoperative deep venous thrombosis (DVT) in patients undergoing surgical treatment for spinal metastases. METHODS Univariate analysis of patient age, sex, ethnicity, laboratory values, comorbidities, preoperative ambulatory status, histopathological classification, spinal level, and surgical details was performed. Factors significantly associated with DVT univariately were entered into a multivariate logistic regression model. RESULTS The authors identified 314 patients, of whom 232 (73.9%) were screened preoperatively for a DVT. Of those screened, 22 (9.48%) were diagnosed with a DVT. The screened patients were older (median 62 vs 55 years, p = 0.0008), but otherwise similar in baseline characteristics. Nonambulatory status, previous history of DVT, lower partial thromboplastin time, and lower hemoglobin level were statistically significant and independent factors associated with positive results of screening for a DVT. Results of screening were positive in only 6.4% of ambulatory patients in contrast to 24.4% of nonambulatory patients, yielding an odds ratio of 4.73 (95% CI 1.88-11.90). All of the patients who had positive screening results underwent preoperative placement of an inferior vena cava filter. CONCLUSIONS Patients requiring surgery for spinal metastases represent a population with unique risks for venous thromboembolism. This study showed a 9.48% incidence of DVT in patients screened preoperatively. The highest rates of preoperative DVT were identified in nonambulatory patients, who were found to have a 4-fold increase in the likelihood of harboring a DVT. Understanding the preoperative thrombotic status may provide an opportunity for early intervention and risk stratification in this critically ill population.

The Saudi clinical practice guideline for the prophylaxis of venous thromboembolism in medical and critically ill patients

Venous thromboembolism (VTE) acquired during hospitalization is common, yet preventable by the proper implementation of thromboprophylaxis which remains to be underutilized worldwide. As a result of an initiative by the Saudi Ministry of Health to improve medical practices in the country, an expert panel led by the Saudi Association for Venous Thrombo Embolism (SAVTE; a subsidiary of the Saudi Thoracic Society) with the methodological guidance of the McMaster University Guideline working group, produced this clinical practice guideline to assist healthcare providers in VTE prevention. The expert part panel issued ten recommendations addressing 10 prioritized questions in the following areas: thromboprophylaxis in acutely ill medical patients (Recommendations 1-5), thromboprophylaxis in critically ill medical patients (Recommendations 6-9), and thromboprophylaxis in chronically ill patients (Recommendation 10). The corresponding recommendations were generated following the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach.

Comparison of Chemical and Mechanical Prophylaxis of Venous Thromboembolism in Nonsurgical Mechanically Ventilated Patients

Background. Thromboembolic events are major causes of morbidity, and prevention is important. We aimed to compare chemical prophylaxis (CP) and mechanical prophylaxis (MP) as methods of prevention in nonsurgical patients on mechanical ventilation. Methods. We performed a retrospective study of adult patients admitted to the Cooper University Hospital ICU between 2002 and 2010. Patients on one modality of prophylaxis throughout their stay were included. The CP group comprised 329 patients and the MP group 419 patients. The primary outcome was incidence of thromboembolic events. Results. Acuity measured by APACHE II score was comparable between the two groups (p = 0.215). Univariate analysis showed 1 DVT/no PEs in the CP group and 12 DVTs/1 PE in the MP group (p = 0.005). Overall mortality was 34.3% and 50.6%, respectively. ICU LOS was similar. Hospital LOS was shorter in the MP group. Multivariate analysis showed a significantly higher incidence of events in the MP prophylaxis group (odds ratio 9.9). After excluding patients admitted for bleeding in both groups, repeat analysis showed again increased events in the MP group (odds ratio 2.9) but this result did not reach statistical significance. Conclusion. Chemical methods for DVT/PE prophylaxis seem superior to mechanical prophylaxis in nonsurgical patients on mechanical ventilation and should be used when possible.

Venoarterial extracorporeal membrane oxygenation for patients in shock or cardiac arrest secondary to cardiotoxicant poisoning: a cost-effectiveness analysis

PURPOSE

Venoarterial extracorporeal membrane oxygenation represents an emerging and recommended option to treat life-threatening cardiotoxicant poisoning. The objective of this cost-effectiveness analysis was to estimate the incremental cost-effectiveness ratio of using venoarterial extracorporeal membrane oxygenation for adults in cardiotoxicant-induced shock or cardiac arrest compared with standard care.

MATERIALS AND METHODS

Adults in shock or in cardiac arrest secondary to cardiotoxicant poisoning were studied with a lifetime horizon and a societal perspective. Venoarterial extracorporeal membrane oxygenation cost effectiveness was calculated using a decision analysis tree, with the effect of the intervention and the probabilities used in the model taken from an observational study representing the highest level of evidence available. The costs (2013 Canadian dollars, where $1.00 Canadian = $0.9562 US dollars) were documented with interviews, reviews of official provincial documents, or published articles. A series of one-way sensitivity analyses and a probabilistic sensitivity analysis using Monte Carlo simulation were used to evaluate uncertainty in the decision model.

RESULTS

The cost per life year (LY) gained in the extracorporeal membrane oxygenation group was $145 931/18 LY compared with $88 450/10 LY in the non-extracorporeal membrane oxygenation group. The incremental cost-effectiveness ratio ($7185/LY but $34 311/LY using a more pessimistic approach) was mainly influenced by the probability of survival. The probabilistic sensitivity analysis identified variability in both cost and effectiveness.

CONCLUSION

Venoarterial extracorporeal membrane oxygenation may be cost effective in treating cardiotoxicant poisonings.

Economic evaluation of the prophylaxis for thromboembolism in critical care trial (E-PROTECT): study protocol for a randomized controlled trial

Background

Venous thromboembolism (VTE) is a common complication of critical illness with important clinical consequences. The Prophylaxis for ThromboEmbolism in Critical Care Trial (PROTECT) is a multicenter, blinded, randomized controlled trial comparing the effectiveness of the two most common pharmocoprevention strategies, unfractionated heparin (UFH) and low molecular weight heparin (LMWH) dalteparin, in medical-surgical patients in the intensive care unit (ICU). E-PROTECT is a prospective and concurrent economic evaluation of the PROTECT trial.

Methods/Design

The primary objective of E-PROTECT is to identify and quantify the total (direct and indirect, variable and fixed) costs associated with the management of critically ill patients participating in the PROTECT trial, and, to combine costs and outcome results to determine the incremental cost-effectiveness of LMWH versus UFH, from the acute healthcare system perspective, over a data-rich time horizon of ICU admission and hospital admission. We derive baseline characteristics and probabilities of in-ICU and in-hospital events from all enrolled patients. Total costs are derived from centers, proportional to the numbers of patients enrolled in each country. Direct costs include medication, physician and other personnel costs, diagnostic radiology and laboratory testing, operative and non-operative procedures, costs associated with bleeding, transfusions and treatment-related complications. Indirect costs include ICU and hospital ward overhead costs. Outcomes are the ratio of incremental costs per incremental effects of LMWH versus UFH during hospitalization; incremental cost to prevent a thrombosis at any site (primary outcome); incremental cost to prevent a pulmonary embolism, deep vein thrombosis, major bleeding event or episode of heparin-induced thrombocytopenia (secondary outcomes) and incremental cost per life-year gained (tertiary outcome). Pre-specified subgroups and sensitivity analyses will be performed and confidence intervals for the estimates of incremental cost-effectiveness will be obtained using bootstrapping.

Discussion

This economic evaluation employs a prospective costing methodology concurrent with a randomized controlled blinded clinical trial, with a pre-specified analytic plan, outcome measures, subgroup and sensitivity analyses. This economic evaluation has received only peer-reviewed funding and funders will not play a role in the generation, analysis or decision to submit the manuscripts for publication.

Trial registration

Clinicaltrials.gov Identifier: NCT00182143. Date of registration: 10 September 2005.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-502) contains supplementary material, which is available to authorized users.

PROF-ETEV study: prophylaxis of venous thromboembolic disease in critical care units in Spain

PURPOSE

Venous thromboembolic disease (VTE) in critically ill patients has a high incidence despite prophylactic measures. This fact could be related to an inappropriate use of these measures due to the absence of specific VTE risk scores. To assess the current situation in Spain, we have performed a cross-sectional study, analyzing if the prophylactic measures were appropriate to the patients' VTE risk.

METHODS

Through an electronic questionnaire, we carried out a single day point prevalence study on the VTE prophylactic measures used in several critical care units in Spain. We performed a risk stratification for VTE in three groups: low, moderate-high, and very high risk. The American College of Chest Physicians guidelines were used to determine if the patients were receiving the recommended prophylaxis.

RESULTS

A total of 777 patients were included; 62% medical, 30% surgical, and 7% major trauma patients. The median number of the risk factors for VTE was four. According to the proposed VTE risk score, only 2% of the patients were at low risk, whereas 83% were at very high risk. Sixty-three percent of patients received pharmacological prophylaxis, 12% mechanical prophylaxis, 6% combined prophylaxis, and 19% did not receive any prophylactic measure. According to criteria suggested by the guidelines, 23% of medical, 71% of surgical, and 70% of major trauma patients received an inappropriate prophylaxis.

CONCLUSIONS

Most critically ill patients are at high or very high risk of VTE, but there is a low rate of appropriate prophylaxis. The efforts to improve the identification of patients at risk, and the implementation of appropriate prevention protocols should be enhanced.

Prevalence of deep vein thrombosis in acutely admitted ambulatory non-surgical intensive care unit patients

Background

Data on prevalence rates of venous thromboembolism (VTE) in different patient populations are scarce. Most studies on this topic focus on older patients or patients with malignancies, immobilization or thrombophilia. Less is known about the VTE risk profile of non-surgical patients presenting with a variety of medical diseases of differing severity. Aim of the present study was to investigate VTE prevalence in a pospective cohort study of ambulatory medical intensive care unit patients within 24 h after acute admission.

Methods

Prospective cohort study of 102 consecutive patients after acute admission to medical intensive care unit. Ultrasound compression sonography, APACHE-II-Scoring and laboratory examination was performed within 24 hours after admission.Possible determinants of a high risk of VTE were examined. In all patients with a confirmed diagnosis of DVT or suspicion of PE thoracic computer tomography (CT) was performed.

Results

VTE was found in 7.8% out of 102 of patients, mean APACHE-II-Score was 14 (mortality risk of about 15%). Thrombus location was femoropopliteal in 5 patients, iliacal in 2 and peroneal in 1 patient. Five VTE patients had concomitant PE (62.5% of VTE, 4.9% of all patients). No predictors of prevalent VTE were identified from univariable regression analysis although relative risk was high in patients with a history of smoking (RR 3.40), immobility (RR 2.50), and elevated D-Dimer levels (RR 3.49).

Conclusions

Prevalent VTE and concomitant PE were frequent in acutely admitted ICU patients.

Implementation of vertical clinical pharmacist service on venous thromboembolism prophylaxis in hospitalized medical patients

Objective:

To describe the vertical clinical pharmacist service's interventions in prevention of venous thromboembolism.

Methods:

This prospective study was done at a private hospital. From January to May 2012, the clinical pharmacist evaluated medical patients without prophylaxis for thromboembolism. If the patient fulfilled criteria for thromboembolism and did not have contraindications, the clinical pharmacist suggested inclusion of pharmacologic agents and/or mechanical methods for venous thromboembolism prevention. In addition, the appropriate dose, route of administration, duplicity and replacement of the drug were suggested.

Results:

We evaluated 9,000 hospitalized medical patients and carried out 77 pharmaceutical interventions. A total of 71 cases (92.21%) adhered to treatment so that non-adherence occurred in 6 cases (7.79%). In 25 cases pharmacologic agents were included and in 20 cases mechanical prophylaxis. Dose adjustments, route, frequency, duplicity and replacement made up 32 cases.

Conclusion:

The vertical clinical pharmacist service included the prophylaxis for venous thromboembolism and promotion of appropriate use of medicines in the hospital.

The association between statin therapy during intensive care unit stay and the incidence of venous thromboembolism: a propensity score-adjusted analysis

Background

Studies have shown that statins have pleiotropic effects on inflammation and coagulation; which may affect the risk of developing venous thromboembolism (VTE). The objective of this study was to evaluate the association between statin therapy during intensive care unit (ICU) stay and the incidence of VTE in critically ill patients.

Methods

This was a post-hoc analysis of a prospective observational cohort study of patients admitted to the intensive care unit between July 2006 and January 2008 at a tertiary care medical center. The primary endpoint was the incidence of VTE during ICU stay up to 30 days. Secondary endpoint was overall 30-day hospital mortality. Propensity score was used to adjust for clinically and statistically relevant variables.

Results

Of the 798 patients included in the original study, 123 patients (15.4%) received statins during their ICU stay. Survival analysis for VTE risk showed that statin therapy was not associated with a reduction of VTE incidence (crude hazard ratio (HR) 0.66, 95% confidence interval (CI) 0.28-1.54, P = 0.33 and adjusted HR 0.63, 95% CI 0.25-1.57, P = 0.33). Furthermore, survival analysis for hospital mortality showed that statin therapy was not associated with a reduction in hospital mortality (crude HR 1.26, 95% CI 0.95-1.68, P = 0.10 and adjusted HR 0.98, 95% CI 0.72-1.36, P = 0.94).

Conclusion

Our study showed no statistically significant association between statin therapy and VTE risk in critically ill patients. This question needs to be further studied in randomized control trials.

Inclusion of compliance and persistence in economic models: past, present and future

Economic models are developed to provide decision makers with information related to the real-world effectiveness of therapeutics, screening and diagnostic regimens. Although compliance with these regimens often has a significant impact on real-world clinical outcomes and costs, compliance and persistence have historically been addressed in a relatively superficial fashion in economic models. In this review, we present a discussion of the current state of economic modelling as it relates to the consideration of compliance and persistence. We discuss the challenges associated with the inclusion of compliance and persistence in economic models and provide an in-depth review of recent modelling literature that considers compliance or persistence, including a brief summary of previous reviews on this topic and a survey of published models from 2005 to 2012. We review the recent literature in detail, providing a therapeutic-area-specific discussion of the approaches and conclusions drawn from the inclusion of compliance or persistence in economic models. In virtually all publications, variation of model parameters related to compliance and persistence was shown to have a significant impact on predictions of economic outcomes. Growing recognition of the importance of compliance and persistence in the context of economic evaluations has led to an increasing number of economic models that consider these factors, as well as the use of more sophisticated modelling techniques such as individual simulations that provide an avenue for more rigorous consideration of compliance and persistence than is possible with more traditional methods. However, we note areas of continuing concern cited by previous reviews, including inconsistent definitions, documentation and tenuous assumptions required to estimate the effect of compliance and persistence. Finally, we discuss potential means to surmount these challenges via more focused efforts to collect compliance and persistence data.