Improved prediction of cardiac, limb and bleeding events in patients with coronary and peripheral arterial disease using machine learning models and artificial intelligence

Background

Coronary artery disease (CAD) and peripheral arterial disease (PAD) represent a significant burden in patients with cardiovascular disease (CVD). However, current antithrombotic therapies are inconsistently used because of clinical concerns about selecting patients with optimal benefit versus risk.

Purpose

We aimed to determine whether complex data engineering, multi-layered machine learning and artificial intelligence could be used to derive and test an improved risk stratification tool to support clinical decision making among CAD/PAD patients at risk of thrombotic events.

Methods

We conducted a retrospective cohort study using claims data from the US Optum Clinformatics dataset, derived from Jan 1, 2010 to Dec 31, 2018. Predictive modeling analytics, including multi-label logistic regression, cox-regression and machine learning techniques (Random Forests and Gradient Boosting Machines) were used to calculate individual patient risks for Major Adverse Cardiac Events (MACE), Major Adverse Limb Events (MALE) and Major Bleeding (MB) events for 1-year and 5-year predictions. To translate findings from black box models into interpretable results, explainable artificial intelligence (AI) techniques based on Shapley additive explanations (SHAP) were applied.

Results

The study cohort consisted of 1,842 million patients with a diagnosis of CAD (mean age: 71±11) and 1,557 million patients with a diagnosis of PAD (mean age: 74±10). 1,017 million patients had a diagnosis of both. Annual event rates for MACE, MALE and Major Bleeding events were 3.5%, 0.7% and 1.6%. 865 variables were extracted from the patient history, including demographics, diagnoses, procedures and prescriptions. For all outcomes, the gradient boosting machines outperformed all other statistical models, including risk scores like CHA2DS2VASc and REACH. The AUCs for the 1-year prediction were 0.75 for MACE, 0.88 for MALE and 0.76 for MB, respectively. For a standard risk score-based approach AUCs were 0.67 for both MACE and Major Bleeding, there was no risk score available for MALE. Linear regression models using all 865 variables showed slightly inferior results compared to the machine learning methods (AUCs: 0.74 for MACE, 0.84 for MALE and 0.75 for MB, respectively).

Conclusion

Our study showed that in a very heterogeneous patient population, machine learning techniques can outperform existing risk scores as well as linear models when assessing individual patient risks. Machine learning and artificial intelligence can be used to shape and evolve evidence generation for personalized healthcare and digital health solutions and support HCPs and payers in understanding most relevant prognostic factors that are associated with patient outcomes.

Figure 1

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Bayer AG

P4746Worsening of renal function in atrial fibrillation patients with stage 3 or 4 chronic kidney disease treated with warfarin or rivaroxaban - evidence from the real-world CALLIPER study in the US claims

Background

Anticoagulation therapy with vitamin K antagonists (e.g. warfarin) has recently been shown to contribute to the accelerated vascular calcification and worsening of renal function. Therefore, it is compelling to investigate the impact of different oral anticoagulants (OACs) on kidney function in non-valvular atrial fibrillation (NVAF) patients. Common co-morbidities in these patients are chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM), which might be presented at the OAC therapy initiation.

Purpose

The overall objective of the CALLIPER study was to evaluate the effectiveness and safety of the reduced dose rivaroxaban (15 mg once daily) as compared to warfarin in NVAF patients with renal dysfunction in real-world setting. In particular, we evaluated the risk of worsening of renal function in NVAF patients with CKD stage 3 and 4 at baseline (1 year prior to the cohort entry). Additionally, a sub-group analysis of patients with T2DM was performed. We defined worsening of renal function as progression to CKD stage 5, kidney failure or need for dialysis.

Methods

Individual level data of warfarin- and rivaroxaban-naïve NVAF patients from the MarketScan database for the years 2012 through 2017 were used. Patients with moderate-to-severe CKD (stage 3 and 4) were included in the study cohort and were followed until progression to CKD 5, kidney failure or dialysis, OAC discontinuation/switch, insurance disenrollment or end of data availability. A comparative analysis evaluating the hazard ratios (HRs) with the corresponding 95% confidence intervals (CIs) under warfarin or rivaroxaban treatment was performed using Cox regression. A stabilized inverse probability of treatment weighting was used to adjust for imbalances in baseline patient characteristics.

Results

We identified 5,906 warfarin- and 1,466 rivaroxaban-naïve patients with NVAF and CKD stage 3 and 4, of which 60% were male, median (25–75% range) age=79 (71- 84) years, CHADS2 score=2.67 (2.00- 3.50), CHA2DS2-VASc score=4.43 (3.40–5.62), modified HAS-BLED score=3.00 (2.40 - 3.65). T2DM was present in more than 50% of patients (Table), namely, in 3,160 warfarin- and 746 rivaroxaban-users. Hazard ratios and 95% CI for worsening of renal function were evaluated at 0.53 (0.35; 0.78) in the main cohort and 0.50 (0.30; 0.83) in the T2DM sub-group, meaning that rivaroxaban was associated with a significant 47% and 50% risk reduction of this outcome in NVAF patients with CKD stage 3 and 4 with and without T2DM, respectively.

Conclusion

The reduced dose of rivaroxaban has appeared to lower significantly the risk of worsening of renal function versus warfarin in NVAF patients with CKD stage 3 and 4 present at the OAC therapy initiation. The conclusion holds true for the patients with the co-morbid T2DM. This evidence was generated by the CALLIPER study using one of the largest US administrative claims database.

Acknowledgement/Funding

CI Coleman has received research grants from Bayer AG

P4749Renal function worsening in factor-xa inhibitors vs phenprocoumon in patients with non-valvular atrial fibrillation and renal disease - insights from the RELOADED study

Background

Data on the effectiveness and safety of Factor-Xa non-vitamin-K oral anticoagulants in patients with non-valvular atrial fibrillation (NVAF) and renal disease is scarce. Among others, our study aimed to investigate the risk of renal function worsening in new users of NOACs vs. phenprocoumon with renal disease.

Methods

We conducted a new user cohort study (one year washout period) in patients with NVAF overall and additionally with renal disease defined by either an extended list of ICD-10 codes (definition 1) or chronic kidney disease (CKD) stages 3 or 4 (definition 2). German claims data between January 1st, 2013 and June 30th, 2017 were utilized and a multiple Cox-regression was performed to calculate confounder-adjusted hazard ratios (HRs) for the risk of end stage renal disease (ESRD)/dialysis and acute kidney injury in new users of NOACs (rivaroxaban, apixaban and edoxaban) vs. new users of phenprocoumon.

Results

In the overall population 22,339 patients initiating rivaroxaban, 16,201 patients initiating apixaban, 2,828 patients initiating edoxaban and 23,552 patients initiating phenprocoumon were included. NOAC patients with renal disease (definition 1) initiating reduced doses comprised 2,121 initiators of rivaroxaban, 2,507 of apixaban and 292 of edoxaban. 7,289 patients of phenprocoumon were identified. Patients with CKD (definition 2) initiating reduced doses of Factor-Xa inhibitors comprised 1,216 initiators of rivaroxaban, 1,522 of apixaban, 166 of edoxaban and 3,513 of phenprocoumon. In the confounder-adjusted analysis, a beneficial effect for both, rivaroxaban and apixaban over phenprocoumon was seen for the risk of ESRD/dialysis for all populations (overall, renal definition 1 and renal definition 2). In addition, in the CKD population we found a statistically significant risk reduction related to acute kidney injury only for rivaroxaban initiators (44%). There was not sufficient data to conduct the analyses for edoxaban.

Figure 1

Conclusion

This is the first observational retrospective database study evaluating the effect of renal function worsening in Germany. Results indicate a beneficial effect for both, reduced doses of rivaroxaban and apixaban related to renal function worsening over time when compared to phenprocoumon. This effect was more pronounced for the risk reduction with rivaroxaban related to ESRD /dialysis and specifically also related to a significant risk reduction for AKI.

Acknowledgement/Funding

The study was funded by Bayer AG

P4795Comparative safety of factor-xa inhibitors vs phenprocoumon in patients with non-valvular atrial fibrillation and renal disease - insights from the RELOADED study

Background

Data on safety of Factor-Xa inhibitors and phenprocoumon in patients with non-valvular atrial fibrillation (NVAF) and renal disease is scarce. Among others, our study aimed to investigate the safety risks of fatal bleeding and intracranial haemorrhage (ICH) in new users of Factor-Xa inhibitors vs. phenprocoumon, the vitamin-K antagonist (VKA) of choice in Germany.

Methods

We conducted a new user cohort study (one year washout period) in patients with NVAF and renal disease. German claims data between January 1st, 2013 and June 30th, 2017 were utilized and a multiple Cox-regression was performed to calculate confounder-adjusted hazard ratios (HRs) for the risk of fatal bleeding and ICH in Factor-Xa inhibitors and phenprocoumon initiators. Additionally, a propensity score matching and an inverse probability of treatment weight analysis were performed as sensitivity analyses. Cases of fatal bleeding were defined as hospitalization with a primary hospital discharge diagnoses for bleeding with documented death as reason for hospital discharge or within 30 days after hospital discharge.

Results

The overall population comprised 23,552 phenprocoumon initiators, 22,338 rivaroxaban initiators and 16,201 apixaban initiators, where the number of patients with renal disease initiating these agents were 7,289 for phenprocoumon, 5,121 patients for rivaroxaban 15mg or 20mg and 4,750 patients for apixaban 2.5mg or 5mg, respectively. In the confounder-adjusted analysis, a beneficial effect for rivaroxaban and apixaban over phenprocoumon was observed for the risk of ICH and fatal bleeding (figure 1) for both the overall and renal disease population. Hazard ratios for rivaroxaban and the risk of ICH were calculated as 0.57 (0.43; 0.75) for the overall population and 0.62 (0.37; 1.01) for the renal disease population where hazard ratios for apixaban were calculated as 0.43 (0.31; 0.60) for the overall population and 0.41 (0.23; 0.74) for the renal disease population, respectively. There was not sufficient data to conduct the analyses for edoxaban.

Figure 1

Conclusion

This large retrospective database study conducted in Germany confirms the safety profile of rivaroxaban and apixaban over VKA in patients overall and specifically in patients with renal disease when assessing the risk of ICH and fatal bleeding. Our study adds evidence in a relevant subgroup of patients where anticoagulation is often challenging.

Acknowledgement/Funding

This study was funded by Bayer AG

P4781Comparative effcomparative effectiveness and safety of factor-xa inhibitors vs phenprocoumon in patients with non-valvular atrial fibrillation and malignant diseases, insights from the RELOADED study

Background

Data on safety and effectiveness of Factor-Xa inhibitors and phenprocoumon in patients with non-valvular atrial fibrillation (NVAF) and malignant diseases is scarce. Among others, our study aimed to investigate the safety and effectiveness in new users of Factor-Xa inhibitors vs. phenprocoumon, the vitamin-K antagonist (VKA) of choice in Germany.

Methods

We conducted a new user cohort study (one year washout period) in patients with NVAF and malignant diseases. German claims data between January 1st, 2013 and June 30th, 2017 were utilized and a multiple Cox-regression was performed to calculate confounder-adjusted hazard ratios (HRs) for the risk of ischemic stroke (IS)/systemic embolism (SE), intracranial haemorrhage (ICH) as well as renal function worsening, defined by end stage renal disease (ESRD) or dialysis and acute kidney injury (AKI) in Factor-Xa inhibitors and phenprocoumon initiators. Diagnoses of malignant diseases were assessed over the one-year baseline period.

Results

The population comprised 3,779 phenprocoumon initiators, 3,386 rivaroxaban initiators, 2,697 apixaban initiators and 434 edoxaban initiators. In the confounder-adjusted analysis, no difference related to the risk of IS/SE was found for rivaroxaban and edoxaban vs. phenprocoumon, where apixaban showed a numerically increased risk for stroke (figure 1). Point estimates related to the risk of ICH showed the expected beneficial effects for both, rivaroxaban and apixaban. A strong beneficial effect was observed for rivaroxaban when assessing the risk of renal function worsening. Hazard ratios related to the risk of ESRD/dialysis and AKI were 0.27 (0.10; 0.69) and 0.64 (0.38; 1.06), respectively. For apixaban, only the ESRD/dialysis showed a reduction in risk when compared to phenprocoumon, HR 0.42 (0.19; 0.94).

Conclusion

This retrospective database study conducted in Germany adds evidence on the effectiveness and safety profile of Factor-Xa inhibitors over VKA in patients with NVAF and malignant diseases, a critical subgroup of patients where anticoagulation is challenging. However, apixaban showed a numerically increased risk for IS/SE compared to phenprocoumon. Both, rivaroxaban and apixaban showed a risk reduction for renal function worsening within the study period of 63% and 48%, respectively compared to phenprocoumon. Only rivaroxaban showed a risk reduction of 36% for AKI.

Acknowledgement/Funding

The study was funded by Bayer AG

Histological, hormonal and biomolecular analysis of the pathogenesis of ovine Prolapsus vaginae ante partum

The objectives of the present study were to evaluate the hormonal profiles, histology of the vagina and biomolecular analysis of connective tissue of ewes with and without vaginal prolapse. Blood samples from the jugular vein and biopsies of the vaginal tissue were taken from five late term pregnant, unaffected animals, four sheep during parturition and six ewes suffering from vaginal prolapse ante partum. The blood samples were submitted for determining the concentration of the steroid hormones progesterone by automatic luminescence immunoassay and estradiol-17β by the sequence test. Investigations in the mRNA-expression including the estimation of the transcript levels of the α(2)-chain of collagen I, the collagenolytic metalloproteinase 1 (MMP 1), the tissue inhibitor of MMP 1 (TIMP 1) and the estrogen receptor α were carried out by using semiquantitative reverse transcription-PCR. Additionally, the histology of the vaginal wall of ewes with and without vaginal prolapse and animals intra partum was assessed. Because of a right-skewed distribution, data were logarithmised and described using the geometric mean (xg) and the dispersion factor (DF). The average progesterone concentration of affected ewes (xg = 19.35 ng/ml, DF 1.33) was above those of control animals ante (xg = 10.44 ng/ml, DF 1.58) and intra partum (xg = 9.24 ng/ml, DF 1.92). Compared to the pregnant control group (xg = 20.13 pg/ml, DF 1.49) the plasma levels of 17β-estradiol in animals suffering from ante partum vaginal prolapse (xg = 27.81 pg/ml, DF 1.56) appeared to be slightly increased, but the difference was without statistical significance. The analysis of mRNA expression revealed a difference in the ante partum collagen metabolism in affected sheep. In prolapsed tissue the α2-chain of collagen I showed a decreased expression level in relation to the control animals in late-term pregnancy (P < 0.01). The average mRNA synthesis of MMP 1 or TIMP 1 in affected ewes was higher or lower, respectively, than the synthesis in healthy, late-term pregnant sheep. Significant differences were not observed. The production of transcripts of the estrogen receptor α was significantly decreased within the group of affected sheep compared to the unaffected pregnant ewes. Histological assessment showed that oedema was only detected in the subepithelial zone of the vaginal wall of intra partum sheep. There was no evidence for an inflammation of the prolapsed vaginal tissue since infiltration of leucocytes was present in all samples equally. The thickest vaginal epithelium due to hyperplasia of the epithelial cells was observed in sheep suffering from ante partum vaginal prolapse (xg = 83.95 μm, DF 1.21). This difference was statistically significant between the ante (xg = 31.12 μm, DF 1.22) and intra partum groups (xg = 33.27 μm, DF 1.24). Peripheral concentrations of progesterone and estradiol-17β seem to have no influence on the occurrence of vaginal prolapse in ewes. Regarding histology of the vaginal wall in combination with the expression of local estrogen receptors, it was determined that there is neither a pronounced oedema nor an overexpression of the estrogen receptor α in affected animals, which means that no local estrogenic effect provokes the prolapse of vaginal tissue. The biomolecular analysis led to the new result, that ewes suffering from vaginal prolapse show alterations in the antepartal metabolism of vaginal connective tissue.

[Studies on the recovery of pharmaceutical drug substances from surfaces made of defined stainless-steel alloys]

Facilities for the manufacturing of pharmaceutical drug substances on the pilot-plant and the industrial scale as well as chemical reactors and vessels used for chemical work-up mainly consist of alloyed stainless steel. The influence of the alloy composition and the surface condition, i.e. of the roughness of the stainless-steel materials, on the adsorption of structurally diverse steroidal substances and, hence, on the quality of the products was studied. In general, stainless-steel alloys with smooth, not so rough surfaces are to be favored as reactor material. However, it was demonstrated in this study that, on account of the weak interaction between active substances and steel materials, mechanically polished materials of a medium roughness up to approx. 0.4 microm can be employed instead of the considerably more cost-intensive electrochemically polished stainless-steel surfaces. The type of surface finishing up to a defined roughness, then, has no influence on the quality of these pharmaceutical products. Substances that, because of their molecular structure, can function as "anions" in the presence of polar solvents, are adsorbed on very smooth surfaces prepared by electrochemical methods, forming an amorphous surface film. For substances with this structural characteristics, the lower-cost mechanically polished reactor materials of a medium roughness up to approx. 0.5 microm should be used exclusively.

Operationsergebnisse bei kongenitalem Brown-Syndrom

BACKGROUND

There are various surgical procedures for the treatment of congenital ("true") Brown's syndrome. We have evaluated the effects of a superior oblique tendon recession.

PATIENTS AND METHODS

In a retrospective study, we evaluated the files of 22 patients who received surgery for congenital Brown's syndrome in our department. A recession of the superior oblique tendon was performed, when there was a hypotropia in primary position with an abnormal head posture and a significant elevation deficit in adduction, and when these findings did not improve spontaneously. The squint angles (alternate prism and cover test), the monocular motility and the abnormal head posture at distance fixation were assessed. The measurements were performed 1 day before and 3 months after surgery. Thirteen patients were examined 2 - 10 years after surgery.

RESULTS

At the time of surgery, the patients were 4 - 17 years old (median 7 years), 13 were male, in 15 patients, the right eye was concerned. Eight patients had an additional esotropia, one patient was exotropic. The vertical deviation in straight gaze was 0 - 12 deg (median 7 deg). The elevation of the eye was restricted to - 10 deg (below horizontal) to 15 deg (median 0 deg) in adduction and to 10 - 35 deg (median 25 deg) in abduction. Sixteen patients had an abnormal head posture. The superior oblique tendon was recessed by 10 mm, in some patients with an additional loop (6x0 polyester). Nine patients received simultaneous surgery for their eso/exotropia. At the end of the operation, the elevation of the eye in adduction (forced duction test) was free. Three months postoperatively, the vertical deviation was 0 - 6 deg (median 1 deg). Twelve patients did not show any abnormal head posture. Inspite of free passive motility, the monocular elevation in adduction was only slightly improved to - 5 to 15 deg (median 5 deg). At the late control, the hypotropia (0 - 4 deg, median 0 deg) and the elevation in adduction (5 - 35 deg, median 15 deg) were significantly improved.

CONCLUSION

The recession of the superior oblique tendon is an effective and safe surgical procedure for congenital Brown's syndrome. The efficiency of the procedure is individually variable. Presumably, this variability was caused by the heterogenous etiology of Brown's syndrome rather than by surgical technique. The hypotropia and the abnormal head posture were reduced immediately after surgery, while the delayed improvement of active elevation in adduction often remained incomplete. Postoperative forced upgaze training may be beneficial.

Dissoziierte Naheinstellungstrias mit akkommodativem Konvergenzexzess

We report on an 8-year-old boy whose near reflex could be elicited exclusively when the left eye was fixing (LF) but not when the right eye was fixing (RF). With RE +1.25/-1.25/169 degrees and LE +1.0/-0.75/24 degrees, the visual acuity was 1.0 OU at 5 m and RE 0.5, LE 1.0 at 0.3 m improving to 1.0 OU by a near addition of 3.0 D. Stereopsis was 100 degrees (Titmus test). The prism and cover test revealed an esophoria of 4 degrees at 5 m. At 3 m there was an esophoria of 6 degrees (RF) and an esotropia of 28 degrees (LF), compensating to an esophoria of 3 degrees (RF/LF) with a near addition of 3.0 D. Accommodation and the pupillary near reaction (OU) were hardly elicitable during RF. During LF, retinoscopy revealed an accommodation of 8 D (OU) and the pupils constricted normally. Correction by bifocal glasses yielded orthotropia with random dot stereopsis at near.

Epilepsy surgery in children with focal cortical dysplasia (FCD): results of long-term seizure outcome

The purpose of this study was to assess the effect of epilepsy surgery on seizure outcome in children and adolescents under 18 years with intractable epilepsy due to focal cortical dysplasia. We analysed clinical data, such as age at seizure onset, epilepsy course, localisation of focus from presurgical evaluation, MRI, tissue pathology and seizure outcome in 68 patients 6 months to 9 years after epilepsy surgery. Seizure outcome was classified according to the Engel classification. Mean age at seizure onset was 7 months, ranging from the first days of life to 7 years. All patients had medically intractable epilepsy. Localisation of the lesion was predominantly extratemporal: posterior (uni- or multilobar) 43 %, frontal without central region 26 %, multilobar involving central area 19 % and temporal in 12 %. MRI signs typically seen in cortical dysplasia (FCD) such as localised blurring of gray-white matter junction was found in 68 %, dysgyria in 62 %, thickening of the cortical ribbon in 46 % and T2 signal elongation of the subcortical white matter in 40 % of the patients' MRI. Age at surgery ranged from 5 months to 16 years; 14 patients were under 2 years when operated on. In 34 patients (6 patients under 3 years) subdural grid electrode evaluation was performed prior to surgery. Pathology revealed focal cortical dysplasia without balloon cells (type I) in 60 %, FCD of the balloon cell subtype (type II) in 40 % of the specimens. Postoperative complications were subdural hygroma in 5 and an increased motor deficit in 2 patients. Up to two years after epilepsy surgery 50 % of the children were seizure free (Engel class I), 10 % Engel class II, 33 % Engel class III and 7 % unchanged (Engel class IV). Long-term seizure outcome (> 3 years post surgery) in 32 patients showed similar results (class I 50 %, class II 19 %, class III 28 %, class IV 3 %). Complete resection of the dysplastic lesion was significantly correlated with favorable seizure outcome, whereas seizure outcome was not significantly different in patients with mild (type I) or balloon cell (type II) FCD. Children operated after 6 years of age had no better outcome than children operated in infancy or at preschool age. Epilepsy surgery resulted in good (class I and II) seizure control in 60 % of children with intractable epilepsy due to focal cortical dysplasia.

Control of proven pulmonary and suspected CNS aspergillus infection with itraconazole in a patient with chronic granulomatous disease

An 11-year-old boy with chronic granulomatous disease caused by cytochrome b deficiency developed right upper lung lobe aspergillosis. Intracerebral lesions developed on maximum doses of flucytosine and amphotericin B. Treatment with 16 mg/kg oral itraconazole was followed by a dramatic clinical improvement and almost complete disappearance of the intracerebral lesions. Plasma itraconazole levels were between 40 and 3440 ng/ml depending on concomitant medication. Toxicity was restricted to transient elevation of alkaline phosphatase and gamma glutamyl transferase. We conclude that further trials with itraconazole are justified in high risk patients in whom conventional therapy has failed.