Behavioural digital biomarkers enable real-time monitoring of patient-reported outcomes: a substudy of the multicenter, prospective observational SafeHeart study.

INTRODUCTION: Patient-reported outcome measures (PROMs) serve multiple purposes, including shared decision-making and patient communication, treatment monitoring and health-technology assessment. Patient monitoring using PROMs is constrained by recall and non-response bias, respondent burden and missing data. We evaluated the potential of behavioural digital biomarkers obtained from a wearable accelerometer to achieve personalised predictions of PROMs. METHODS: Data from the multicenter, prospective SafeHeart study conducted at Amsterdam University Medical Center in the Netherlands and Copenhagen University Hospital, Rigshospitalet in Copenhagen, Denmark, was used. The study enrolled patients with an implantable cardioverter defibrillator (ICD) between May 2021 and September 2022 who then wore wearable devices with raw acceleration output to capture digital biomarkers reflecting physical behaviour. To collect PROMs, patients received the KCCQ and EQ5D-5 L questionnaire at two instances; baseline and after 6 months. Multivariable Tobit regression models were used to explore associations between digital biomarkers and PROMs, specifically whether digital biomarkers could enable PROM prediction. RESULTS: The study population consisted of 303 patients (mean age 62.9 ± 10.9 years, 81.2% male). Digital biomarkers showed significant correlations to patient-reported physical and social limitations, severity and frequency of symptoms and quality of life. Prospective validation of the Tobit models indicated moderate correlations between the observed and predicted scores for KCCQ (concordance correlation coefficient (CCC) = 0.49, mean difference: 1.07 points) and EQ5D-5 L (CCC = 0.38, mean difference 0.02 points). CONCLUSION: Wearable digital biomarkers correlate with PROMs, and may be leveraged for real-time prediction. These findings hold promise for monitoring of PROMs through wearable accelerometers.

Conventional-dose hormone therapy (HT) and tibolone, but not low-dose HT and raloxifene, increase markers of activated coagulation.

OBJECTIVES: Hormone therapy (HT) is associated with a modest, but significantly increased risk for arterial and venous thromboembolism. We have compared the effects of estrogen, tibolone, and raloxifene on relevant markers of coagulation activation and investigated whether there is a dose-response relationship of oral HT. METHODS: Randomized, open-label, comparative study of 202 healthy women who were assigned to receive treatment for 12 weeks with either low-dose hormone therapy containing 1 mg 17beta-estradiol + 0.5 mg norethisterone acetate (NETA) (n=50), conventional-dose HT containing 2 mg 17beta-estradiol and 1 mg NETA (n=50), 2.5 mg tibolone (n=51), or 60 mg raloxifene (n=51). RESULTS: The groups were comparable with regard to demographic characteristics and laboratory variables at baseline. D-dimer increased markedly in the conventional-dose HT group, but remained unchanged in the low-dose HT group. Tibolone was associated with a medium increase, whereas raloxifene was associated with a decrease in D-dimer levels. Changes in prothrombin fragment 1 + 2 showed a similar pattern for all four groups, whereas no significant differences in changes of thrombin-antithrombin complex were observed. CONCLUSIONS: Our data suggest that low-dose HT is associated with less activation of coagulation than conventional-dose HT. This finding may be of clinical importance since randomized clinical trials showing increased risk of thrombosis have utilized conventional-dose HT.

A novel anticoagulant activity assay of tissue factor pathway inhibitor I (TFPI).

Tissue factor (TF) pathway inhibitor I (TFPI) is the physiological inhibitor of TF-induced blood coagulation. Circulating blood contains full-length TFPI and TFPI truncated at the C-terminal end. Previous studies have shown that full-length TFPI exerts a stronger anticoagulant effect on diluted prothrombin time (DPT) than truncated TFPI, and it has been suggested that full-length TFPI is biologically more important in vivo. The objective of this study was to develop and validate an assay of TFPI anticoagulant activity. TFPI anticoagulant activity was assayed using a modified DPT assay. Plasmas were incubated in the absence and the presence of TFPI-blocking antibodies. Results were expressed as a ratio with the clotting time in the presence of anti-TFPI as the denominator. The ratio was normalized against a ratio obtained with a reference plasma. The assay was compared with assays of TFPI free antigen, total antigen, and bound TFPI, and TFPI chromogenic substrate activity. We performed all tests in 436 healthy individuals. The normalized TFPI anticoagulant ratio was strongly associated with TFPI free antigen (r = 0.73) but was weakly associated with TFPI chromogenic substrate activity (r = 0.46), TFPI total antigen (r = 0.48), and bound TFPI (r = 0.30). TFPI chromogenic substrate activity was strongly associated with TFPI total antigen (r = 0.73). We have developed a novel assay of TFPI anticoagulant activity in plasma, which may be considered a functional assay of full-length TFPI. Further studies are needed to establish the role of TFPI anticoagulant activity for thrombotic disorders.

JAB1/CSN5 interacts with the GAL4 DNA binding domain: a note of caution about two-hybrid interactions.

The Jun activation domain binding protein 1 (JAB1) was first identified as an interaction partner and coactivator of c-Jun. Subsequently, it was found to be a subunit of the COP9 signalosome (CSN) and termed CSN subunit 5 (CSN5). This complex regulates light-mediated development in plants and plays an essential role in a variety of organisms. A striking feature of JAB1/CSN5 is its reported interaction with a wide range of proteins and its modulation of their activity or stability. We applied the yeast two-hybrid system to screen for proteins interacting with the DNA-binding domain of the transcription factor c-Myb and found JAB1/CSN5 among the double-positive clones. To our surprise JAB1/CSN5 was shown to interact with the DNA-binding domain of GAL4 alone and had to be rejected as a false positive in the GAL4-based two-hybrid system. This finding emphasizes the necessity of particular caution when JAB1/CSN5 is found in two-hybrid screenings.

Low molecular weight heparin prevents activation of coagulation in a hypobaric environment.

It is commonly thought that people are at increased risk of venous thrombosis during air flights, but the magnitude of the risk is unknown. Suggested risk factors are hypobaric hypoxia, stasis, and dehydration. In a previous experimental study, we found immediate activation of coagulation as determined by the levels of prothrombin fragments 1 + 2 (F(1 + 2)) and thrombin-antithrombin complex (TAT) after rapid exposure to a hypobaric and hypoxic environment (76 kPa). The aim of the present study was to examine the ability of low molecular weight heparin (LMWH) to prevent such activation. Twelve healthy male volunteers were given 40 mg enoxaparin as a single subcutaneous injection 1 h prior to exposure from 96.3 to 76 kPa. We found no activation of coagulation as judged by F(1 + 2) or TAT. Anti-activated factor X activity levels and release of tissue factor pathway inhibitor was normal. We conclude that high prophylactic doses of a LMWH most probably prevent activation of coagulation in a hypobaric environment.

The effects of hormone replacement therapy (HRT) on hemostatic variables in women with previous venous thromboembolism--results from a randomized, double-blind, clinical trial.

In a recent randomized, double-blind, placebo-controlled trial of women with a history of venous thromboembolism (VTE), we found that hormone replacement therapy (HRT) was associated with an early excess risk of recurrent thrombosis. The aims of the present study were to characterize the effects of HRT on coagulation in these women to elucidate the mechanism(s) by which HRT increases the risk of thrombosis. The study comprised 140 women who were randomized to receive continuous treatment for 24 months with once daily 2 mg 17-beta-estradiol plus 1 mg norethisterone acetate (n = 71) or placebo (n = 69). HRT caused significant increases in prothrombin fragments 1+2, thrombin-antithrombin complex, and D-Dimer after 3 months, but these changes were less pronounced on prolonged treatment. The increases in markers of activated coagulation was higher in those women who subsequently developed recurrent thrombosis, but was similar in carriers and non-carriers of the factor V Leiden mutation. HRT had no effects on fibrinogen and factor VIII. Activated factor VII, but not factor VII antigen, decreased significantly on HRT as compared with placebo. The coagulation inhibitors antithrombin, protein C, and TFPI, but not protein S, all showed significant sustained decreases in the HRT group as compared with placebo. Antithrombin and protein C decreased by 8-12% on HRT, whereas TFPI activity decreased by 12-17% and TFPI free antigen by 29-30%. In multivariate analysis, only TFPI activity was a significant predictor for the increased activation of coagulation. We conclude that HRT was associated with early activation of coagulation, which corroborates the finding of an early risk of recurrent VTE. This activation may in part be explained by reduction in circulating anticoagulants.

Association between acute hypobaric hypoxia and activation of coagulation in human beings.

The risk of venous thrombosis is thought to be increased by flying. In a study of 20 healthy male volunteers who were suddenly exposed to a hypobaric environment similar to that encountered within aeroplane cabins, markers of activated coagulation transiently Increased by two-fold to eight-fold. We suggest that hypobaric hypoxia, with sedentariness and dehydration, may cause this increased risk of venous thrombosis.

Dose-dependent release of endogenous tissue factor pathway inhibitor by different low molecular weight heparins.

Tissue factor pathway inhibitor (TFPI) is released to circulating blood after intravenous and subcutaneous injections of heparins, and may thus contribute to the antithrombotic effect of heparins. A previous study suggested different abilities of various low molecular weight heparins (LMWH) to release endogenous TFPI, but the dose-response relationship was not determined. In the present study, the dose-response relationship for escalating doses of two LMWHs, dalteparin and enoxaparin, on the release of endogenous TFPI was investigated. Six healthy male participants were given 50, 100 and 200 U/kg dalteparin and 0.5, 1.0 and 2.0 mg/kg enoxaparin as a single subcutaneous injection. The study was a randomized, cross-over design with a 1-week wash-out period between each injection. Peak free TFPI antigen and TFPI activity were detected after only 1 h, whereas anti-activated factor X (anti-FXa) and anti-activated factor II (anti-FIIa) activities were detected after 2-6 h. Putative therapeutic equivalent doses of dalteparin and enoxaparin gave similar release of endogenous TFPI, but dissimilar effects on anti-FXa and anti-FIIa activities.

A new sensitive chromogenic substrate assay of tissue factor pathway inhibitor type 1.

The present assay is a modification of our previously published two-stage chromogenic substrate assay of tissue factor pathway inhibitor type-1 (TFPI) activity [1]. In the first stage, the reaction mixture was made with factor VIIa (FVIIa) molecules in excess of tissue factor (TF) binding sites and contained diluted plasma, recombinant FVIIa (10 nM), recombinant TF (1/400 vol/vol), bovine factor Xa (1,1 nM), I-2882(R) (100 microg/ml), and CaCl(2) (10 mM). The fibrin polymerisation inhibitor I-2882(R) was added to the reaction mixture to prevent formation of cross-linked fibrin. In the second stage, residual TF/FVIIa catalytic activity was measured by the addition of a substrate mixture that contained bovine factor X and a chromogenic substrate (S-2222(R)). Standard curves were constructed using serial dilutions (0-1%) of pooled normal plasma. The dose-response relationship for serial dilutions of plasma was linear. The intra-assay coefficient of variations (CVs) for pre- and postheparin plasma samples (i.e., normal and high TFPI levels) were 1.7% and 9.9%, respectively; the inter-assay CVs were 10.0% and 19. 7%, respectively. The effect of variation in antithrombin activity on the assay was approximately 5%. The present assay correlated fairly well with our previously published assay (r=0.82, n=100) and with a commercial TFPI activity assay (Actichrome(R) TFPI Activity Assay, American Diagnostica, Greenwich, CT, USA; r=0.90, n=100), as well as with an antigen assay for TFPI total antigen (Imubind(R), American Diagnostica; r=0,96, n=100). Altman and Bland plots revealed that our previous assay underestimated TFPI activity at high TFPI levels (i.e., postheparin TFPI samples) compared with the other methods.

The effects of hormone replacement therapy on hemostatic variables in women with angiographically verified coronary artery disease: results from the estrogen in women with atherosclerosis study.

Data on the effect of hormone replacement therapy on hemostasis are inconsistent, and there are few data in women with coronary artery disease. In a single-center, open, randomized study, 118 postmenopausal women with angiographically verified coronary artery disease were randomized to hormone replacement therapy, given as long-cycle transdermal 17-beta-estradiol (50 microg/24 hour) for 3 months with sequential medroxy-progesterone acetate for 14 days, or to a control group receiving no therapy. Hemostatic parameters were measured at baseline and after 3 and 12 months of therapy. The coagulation inhibitors antithrombin, protein C, and protein S, but not tissue factor pathway inhibitor, decreased significantly from baseline in the hormone replacement therapy group at both 3 and 12 months as compared with the control group. The absolute decreases within the hormone replacement therapy group were 3 to 10%. No significant differences between the two treatment groups were observed for the coagulation products prothrombin fragment 1+2 or thrombin-antithrombin complex or for D-dimer, although there were significant decreases in the levels within the hormone replacement therapy group. Levels of fibrinogen, activated factor VII, and factor VII antigen were not significantly influenced by hormone replacement therapy treatment. Similarly, nonsignificant changes were detected for the fibrinolytic parameters tissue plasminogen activator activity, tissue plasminogen activator antigen, and global fibrinolytic activity, but plasminogen activator inhibitor type 1 was significantly lower in the hormone replacement therapy group due to a questionable increase in the levels in the control group. In conclusion, treatment with transdermal estradiol combined with long-cycle progestins was associated with no net activation of coagulation despite reduced levels of coagulation inhibitors.

Partial depletion of tissue factor pathway inhibitor during subcutaneous administration of unfractionated heparin, but not with two low molecular weight heparins.

Tissue factor pathway inhibitor (TFPI) is released to circulating blood after intravenous (i.v.) and subcutaneous (s.c.) injections of heparins, and may thus contribute to the antithrombotic effect of heparins. We have recently shown that total TFPI activity, plasma free TFPI antigen, and heparin releasable TFPI were partially depleted during repeated and continuous i.v. infusion of unfractionated heparin (UFH), but not during s.c. treatment with a low molecular weight heparin (LMWH). The difference may be attributed to a different mode of action or the different mode of administration. In the present randomized cross-over study, s.c. administration of therapeutic doses of UFH was compared with s.c. administration of two LMWHs. 12 healthy male volunteers were treated for 3 d with UFH, 250 U/kg twice daily, dalteparin, 200 U/kg once daily, and enoxaparin, 1.5 mg/kg once daily. Six participants were also treated with UFH, 300 U/kg once daily. On day 5 a single dose of either drug was given. Peak levels of total TFPI activity and free TFPI antigen were detected 1 h after injection, whereas maximal prolongation of activated partial thromboplastin time (APTT) and peak levels of anti-factor Xa activity and anti-factor IIa activity were detected after 4 h. On UFH administered twice daily, free TFPI antigen decreased by 44% from baseline level before the first injection on day 1 to pre-injection level on day 5. On UFH administered once daily, basal free TFPI antigen decreased by 50%, 56% and 27% on day 2, 3 and 5 respectively, compared with day 1. Minimal depletion of TFPI was detected during treatment with LMWHs. The study demonstrates the different modes of action of LMWHs and UFH and may help to explain the superior antithrombotic efficacy of LMWHs.