Avoiding infinite estimates of time-dependent effects in small-sample survival studies

Substrate Characterization and Outcomes of Ventricular Tachycardia Ablation in Amyloid Cardiomyopathy: A Multicenter Study

BACKGROUND

Sustained ventricular tachycardia (VT) in cardiac amyloidosis is uncommon, and the substrate and outcomes of catheter ablation are not defined.

METHODS

We included 22 consecutive patients (mean age, 68±10 years; male sex, 91%) with cardiac amyloidosis (ATTR [transthyretin], n=16; light chain, n=6) undergoing catheter ablation for VT/ventricular fibrillation (VF) between 2013 and 2023 in a retrospective, observational, international study. The primary efficacy outcome was recurrent VT/VF during follow-up, while the primary safety end point included major procedure-related adverse events.

RESULTS

The indication for ablation was drug-refractory VT in 17 patients (77%), and premature ventricular complex-initiated polymorphic VT/VF in 5 patients (23%). Catheter ablation was performed using endocardial (n=17.77%) or endo-epicardial approaches (n=5.23%). Complete endocardial electroanatomical voltage maps of the left and right ventricles were obtained in 17 (77%) and 10 (45%) patients, respectively. Each patient had evidence of low-voltage areas, most commonly involving the interventricular septum (n=16); late potentials were recorded in 16 patients (73%). A median of 1 (1-2) VT was inducible per patient; 12 of the 26 mappable VTs (46%) originated from the interventricular septum. Complete procedural success was achieved in 16 patients (73%), with 4 (18%) major procedure-related adverse events. After a median follow-up of 32 (14-42) months, sustained VT/VF recurrence was observed in 9 patients (41%); survival free from VT/VF recurrence was 56% (95% CI, 36%-86%) at 36-month follow-up, and most patients remained on antiarrhythmic drugs. A significant reduction in per patient implantable cardioverter defibrillator therapies was noted in the 6-month period after ablation (before: 6 [4-9] versus after: 0 [0-0]; P<0.001). In multivariable analysis, complete procedural success was associated with reduced risk of recurrent VT/VF (hazard ratio, 0.002; P=0.034).

CONCLUSIONS

Catheter ablation can achieve control of recurrent VT/VF in more than half of patients with cardiac amyloidosis, and the reduction in VT/VF burden post-ablation may be relevant for quality of life. Septal substrate and risk of procedure-related complications challenge successful management of patients with cardiac amyloidosis and VT/VF.

Risk for Suicidal Behavior After Psychiatric Hospitalization Among Sexual and Gender Minority Patients

Importance

The months following inpatient psychiatric hospitalization are a period of high risk for suicidal behavior. Sexual and gender minority (SGM) individuals have elevated risk for suicidal behavior, but no prior research has examined whether SGM inpatients have disproportionate risk for suicidal behavior following discharge from psychiatric hospitalization.

Objectives

To evaluate whether SGM patients have elevated risk for suicidal behavior following discharge from psychiatric hospitalization compared with heterosexual and cisgender patients and to examine whether differences in risk across groups were accounted for by demographic characteristics and clinical factors known to be associated with suicidal behavior.

Design, Setting, and Participants

This prospective cohort study was conducted from August 2017 to July 2021 among inpatients aged 18 to 30 years who were voluntarily enrolled during psychiatric hospitalization. The study was conducted at an inpatient psychiatric hospital, with prospective data collected via follow-up visits and electronic health records.

Main Outcomes and Measures

Onset and/or recurrence of suicidal behavior following discharge from psychiatric hospitalization, assessed at follow-up visits and through electronic health records.

Results

A total of 160 patients were included, with 56 sexual minority (SM) and 15 gender minority (GM) patients. The median (IQR) age of the patients was 23.5 (20.4-27.6) years, 77 (48%) reported male sex assigned at birth, and 114 (71%) identified their race as White. During the follow-up period, 33 suicidal behavior events occurred (among 21% of patients). SM (hazard ratio [HR], 2.02; 95% CI, CI, 1.02-4.00; log-rank P = .04) and GM (HR, 4.27; 95% CI, 1.75-10.40; log-rank P < .001) patients had significantly higher risk for suicidal behavior compared with their heterosexual and cisgender counterparts, respectively, in bivariable analyses. Risk between SM and heterosexual patients was not different after controlling for demographic characteristics and clinical factors associated with suicidal behavior. GM patients exhibited elevated risk during the 100 days following discharge even after controlling for demographic and clinical characteristics (HR, 3.80; 95% CI, 1.18-11.19; P = .03).

Conclusions and Relevance

Within this cohort study of psychiatric patients, SGM patients had higher risk for suicidal behavior than non-SGM patients following discharge. While SM patients' risk was accounted for by clinical characteristics, GM patients' risk for suicidal behavior was not accounted for by their acute psychiatric state on admission. Future studies with larger subsamples of GM individuals are needed, and inpatient clinicians must attend to the unique needs of SGM individuals to ensure they receive affirming services.

ViLoN-a multi-layer network approach to data integration demonstrated for patient stratification

With more and more data being collected, modern network representations exploit the complementary nature of different data sources as well as similarities across patients. We here introduce the Variation of information fused Layers of Networks algorithm (ViLoN), a novel network-based approach for the integration of multiple molecular profiles. As a key innovation, it directly incorporates prior functional knowledge (KEGG, GO). In the constructed network of patients, patients are represented by networks of pathways, comprising genes that are linked by common functions and joint regulation in the disease. Patient stratification remains a key challenge both in the clinic and for research on disease mechanisms and treatments. We thus validated ViLoN for patient stratification on multiple data type combinations (gene expression, methylation, copy number), showing substantial improvements and consistently competitive performance for all. Notably, the incorporation of prior functional knowledge was critical for good results in the smaller cohorts (rectum adenocarcinoma: 90, esophageal carcinoma: 180), where alternative methods failed.

Association Between Preexisting Elevated Left Ventricular Filling Pressure and Clinical Outcomes of Future Acute Myocardial Infarction

BACKGROUND

Because no data were available regarding the effect of preexisting left ventricular filling pressure (LVFP) on clinical outcomes in patients with acute myocardial infarction (AMI), we evaluated whether preexisting high LVFP can determine outcomes of subsequent AMI events.

METHODS AND RESULTS

Among 399,613 subjects who underwent echocardiography for various reason from August 2004 to June 2019, 231 had experienced subsequent AMI and were stratified according to preexisting LVFP: low LVFP (E/e' ≤14) and high LVFP (E/e' >14). The primary outcome was cardiac death at 30 days and 1 year after AMI. Overall, 19.5% had high LVFP prior to AMI events. Preexisting high LVFP was associated with an increased risk of cardiac death at 30 days (3.8% vs. 11.6%; adjusted hazard ratio (HR) 4.56, 95% confidence interval (CI) 1.20-17.24, P=0.026) and 1 year after AMI (7.9% vs. 35.9%; adjusted HR 4.14, 95% CI 1.79-9.57, P<0.001). Preexisting E/e' as a continuous value was significantly associated with 1-year risk of cardiac death (adjusted HR 1.08, 95% CI 1.02-1.15, P=0.007). Follow-up echocardiography showed that patients with high LVFP did not show improvement in systolic or diastolic function.

CONCLUSIONS

Preexisting high LVFP was associated with poor clinical course and 1-year cardiac death after subsequent AMI, as well as no improvement in systolic or diastolic function.

Dose-Response and Dose-Toxicity Relationships for Glass 90Y Radioembolization in Patients with Liver Metastases from Colorectal Cancer

Radioembolization based on personalized treatment planning requires established dose-response and dose-toxicity relationships. The aim of this study was to investigate dose-response and dose-toxicity relationships in patients with colorectal liver metastases (CRLMs) treated with glass 90Y-microspheres. Methods: All CRLM patients treated with glass 90Y-microspheres in our institution were retrospectively analyzed. The tumor-absorbed dose was calculated for each measurable metastasis (i.e.,18F-FDG-positive and more than a 5-cm3 tumor volume) on posttreatment 90Y PET. Metabolic tumor response was determined on 18F-FDG PET/CT by measuring the total lesion glycolysis at baseline and at 3 mo after treatment. The relationship between tumor-absorbed dose and metabolic response was determined on a per-lesion and per-patient basis using a linear mixed-effects regression model. Clinical toxicity and laboratory toxicity were correlated with healthy liver-absorbed dose. Results: Thirty-one patients were included. The median tumor-absorbed dose of 85 measurable metastases was 133 Gy (range, 20-1001 Gy). Per response category, this was 196 Gy for complete response (CR), 177 Gy for partial response (PR), 72 Gy for stable disease, and 95 Gy for progressive disease (PD). A significant dose-response relationship was found on a tumor level, with a significantly higher tumor-absorbed dose in metastases with CR (+94%) and PR (+74%) than in metastases with PD (P < 0.001). A similar relationship was found on a patient level, with PR having a higher tumor-absorbed dose than did PD (+58%, P = 0.044). A tumor-absorbed dose of more than 139 Gy predicted a 3-mo metabolic response with the greatest accuracy (89% specificity and 77% sensitivity), whereas a tumor-absorbed dose of more than 189 Gy predicted response with 97% specificity and 45% sensitivity. The median healthy liver-absorbed dose was 63 Gy (range, 24-113 Gy). Toxicity was limited mostly to grades 1 and 2, with 1 case of radioembolization-induced liver disease in a patient who received the highest healthy liver-absorbed dose. A positive trend was seen for most laboratory parameters in our dose-toxicity analysis. Conclusion: A significant relationship was observed between dose and response in CRLM patients treated with glass 90Y radioembolization.

Integrated coronary disease burden and patterns to discriminate vessels benefiting from percutaneous coronary intervention

OBJECTIVE

To evaluate the prognostic implications of atherosclerosis functional pattern on ischemia-causing vessels received percutaneous coronary intervention (PCI) or conservative treatment.

BACKGROUND

Quantitative flow ratio (QFR)-derived pullback pressure gradient (PPG) index is recently proposed to characterize atherosclerosis functional pattern, but its prognostic value remains unclear.

METHODS

QFR-derived PPG index was retrospectively calculated in patients from the PANDA III trial. Vessels with low or high PPG treated by PCI or not were compared for the risk of 2-year vessel-oriented composite outcome (VOCO), which was a composite of vessel-related ischemia-driven revascularization, vessel-related myocardial infarction, or cardiac death.

RESULTS

A total of 1444 vessels were included while 94 (6.5%) VOCOs occurred within 2 years. Among physiologically ischemic vessels (QFR ≤ 0.80) treated by PCI, those with low PPG acquired higher VOCO risk than those with high PPG (8.4% vs. 3.8%; adjusted hazard ratio [HR] 2.13, 95% confidence interval [CI] 1.18 to 3.86), and a similar VOCO risk (8.4% vs. 7.8%; adjusted HR 1.11, 95%CI 0.70-1.78) compared to those treated by conservatively. After multiple adjustment, PPG index was an independent predictor for VOCO (HR 1.30, 95% CI 1.05-1.62). The addition of PPG to the model of clinical risk factors substantially improved the predictions of VOCO (C-index 0.67 vs. 0.62, net reclassification index 0.42).

CONCLUSIONS

PCI treatment was associated with improved outcomes in vessels with high PPG, but not for those with low PPG, which acquired similar risk of VOCO compared to vessels treated conservatively. QFR-derived PPG might assist the treatment strategy selection in ischemia-causing vessels.

Use of an anti-reflux catheter to improve tumor targeting for holmium-166 radioembolization-a prospective, within-patient randomized study

PURPOSE

The objective of this study was to investigate whether the use of an anti-reflux catheter improves tumor targeting for colorectal cancer patients with unresectable, chemorefractory liver metastases (mCRC) treated with holmium-166 (¹⁶⁶Ho)-radioembolization.

MATERIALS AND METHODS

In this perspective, within-patient randomized study, left and right hepatic perfusion territories were randomized between infusion with a Surefire® anti-reflux catheter or a standard microcatheter. The primary outcome was the difference in tumor to non-tumor (T/N) activity distribution. Secondary outcomes included the difference in infusion efficiency, absorbed doses, predictive value of ¹⁶⁶Ho-scout, dose-response relation, and survival.

RESULTS

Twenty-one patients were treated in this study (the intended number of patients was 25). The median T/N activity concentration ratio with the use of the anti-reflux catheter was 3.2 (range 0.9-8.7) versus 3.6 (range 0.8-13.3) with a standard microcatheter. There was no difference in infusion efficiency (0.04% vs. 0.03% residual activity for the standard microcatheter and anti-reflux catheter, respectively) (95%CI - 0.05-0.03). No influence of the anti-reflux catheter on the dose-response rate was found. Median overall survival was 7.8 months (95%CI 6-13).

CONCLUSION

Using a Surefire® anti-reflux catheter did not result in a higher T/N activity concentration ratio in mCRC patients treated with ¹⁶⁶Ho-radioembolization, nor did it result in improved secondary outcomes measures.

TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT02208804.

Dose-Effect Relationships of 166Ho Radioembolization in Colorectal Cancer

Radioembolization is a treatment option for colorectal cancer (CRC) patients with inoperable, chemorefractory hepatic metastases. Personalized treatment requires established dose thresholds. Hence, the aim of this study was to explore the relationship between dose and effect (i.e., response and toxicity) in CRC patients treated with ¹⁶⁶Ho radioembolization. Methods: CRC patients treated in the HEPAR II and SIM studies were analyzed. Absorbed doses were estimated using the activity distribution on posttreatment ¹⁶⁶Ho SPECT/CT. Metabolic response was assessed using the change in total-lesion glycolysis on ¹⁸F-FDG PET/CT between baseline and 3-mo follow-up. Toxicity between treatment and 3 mo was evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE), version 5, and its relationship with parenchyma-absorbed dose was assessed using linear models. The relationship between tumor-absorbed dose and patient- and tumor-level response was analyzed using linear mixed models. Using a threshold of 100% sensitivity for response, the threshold for a minimal mean tumor-absorbed dose was determined and its impact on survival was assessed. Results: Forty patients were included. The median parenchyma-absorbed dose was 37 Gy (range, 12-55 Gy). New CTCAE grade 3 or higher clinical and laboratory toxicity was present in 8 and 7 patients, respectively. For any clinical toxicity (highest grade per patient), the mean difference in parenchymal dose (Gy) per step increase in CTCAE grade category was 5.75 (95% CI, 1.18-10.32). On a patient level, metabolic response was as follows: complete response, n = 1; partial response, n = 11; stable disease, n = 17; and progressive disease, n = 8. The mean tumor-absorbed dose was 84% higher in patients with complete or partial response than in patients with progressive disease (95% CI, 20%-180%). Survival for patients with a mean tumor-absorbed dose of more than 90 Gy was significantly better than for patients with a mean tumor-absorbed dose of less than 90 Gy (hazard ratio, 0.16; 95% CI, 0.06-0.511). Conclusion: A significant dose-response relationship in CRC patients treated with ¹⁶⁶Ho radioembolization was established, and a positive association between toxicity and parenchymal dose was found. For future patients, it is advocated to use a ¹⁶⁶Ho scout dose to select patients and yo personalize the administered activity, targeting a mean tumor-absorbed dose of more than 90 Gy and a parenchymal dose of less than 55 Gy.

Actigraphy-estimated sleep and 24-hour activity rhythms and the risk of dementia

Introduction

We investigated and compared associations of objective estimates of sleep and 24‐hour activity rhythms using actigraphy with risk of dementia.

Methods

We included 1322 non‐demented participants from the prospective, population‐based Rotterdam Study cohort with valid actigraphy data (mean age 66 ± 8 years, 53% women), and followed them for up to 11.2 years to determine incident dementia.

Results

During follow‐up, 60 individuals developed dementia, of which 49 had Alzheimer's disease (AD). Poor sleep as indicated by longer sleep latency, wake after sleep onset, and time in bed and lower sleep efficiency, as well as an earlier “lights out” time, were associated with increased risk of dementia, especially AD. We found no associations of 24‐hour activity rhythms with dementia risk.

Discussion

Poor sleep, but not 24‐hour activity rhythm disturbance, is associated with increased risk of dementia. Actigraphy‐estimated nighttime wakefulness may be further targeted in etiologic or risk prediction studies.

Prostate-specific membrane antigen (PSMA) expression in adenoid cystic carcinoma of the head and neck

BACKGROUND

Treatment options for advanced head and neck adenoid cystic carcinoma (AdCC) are limited. Prostate-Specific Membrane Antigen (PSMA), a transmembrane protein that is known for its use in diagnostics and targeted therapy in prostate cancer, is also expressed by AdCC. This study aimed to analyse PSMA expression in a large cohort of primary, recurrent and metastasized AdCC of the head and neck.

METHODS

One hundred ten consecutive patients with histologically confirmed AdCC in the period 1990-2017 were included. An analysis was made of clinical details, revised pathology and semiquantitative immunohistochemical expression of PSMA on tissue microarray and whole slides. Associations of PSMA expression with clinicopathological parameters were explored and survival was analysed by multivariate Cox-proportional Hazard analysis.

RESULTS

PSMA expression was present in 94% of the 110 primary tumours, with a median of 31% positive cells (IQR 15-60%). Primary tumours (n = 18) that recurred (n = 15) and/or had metastases (n = 10) demonstrated 40, 60 and 23% expression respectively. Expression was not independently related to increased pathological stage, tumour grade, and the occurrence of locoregional recurrence or metastasis. After dichotomization, only primary tumour PSMA expression ≤10% appeared to be associated with reduced 10-years recurrence-free survival (HR 3.0, 95% CI 1.1-8.5, p = .04).

CONCLUSIONS

PSMA is highly expressed in primary, recurrent and metastatic AdCC of the salivary and seromucous glands. PSMA expression has no value in predicting clinical behaviour of AdCC although low expression may indicate a reduced recurrence-free survival. This study provides supporting results to consider using PSMA as target for imaging and therapy when other diagnostic and palliative treatment options fail.

High CXCR4 expression in adenoid cystic carcinoma of the head and neck is associated with increased risk of locoregional recurrence

AIM

Treatment options for head and neck adenoid cystic carcinoma (AdCC) are limited in advanced disease. Chemokine receptor type 4 (CXCR4) is present in various tumour types, including AdCC. Upregulation is associated with tumour recurrence and metastasis. New CXCR4-specific diagnostic and therapeutic target agents have recently been available. This study aimed to analyse CXCR4 expression in a cohort of primary head and neck AdCC.

METHODS

After histopathological revision, tumour tissues of 73 consecutive patients with AdCC over 1990-2016 were sampled on a tissue microarray. Slides were immunohistochemically stained for CXCR4 and semiquantitatively scored. Associations between protein expression and cliniopathological parameters were tested. HRs were calculated using a Cox proportional hazard model.

RESULTS

Sixty-six tumours could be analysed. CXCR4 expression was present in 81% of the tumours with a median of 29% (IQR 1-70) positive cells. Expression was univariately correlated to perineural growth (Spearman ρ .26, p=0.04) and bone invasion (Spearman ρ .32, p=0.01), but not with tumour grade.CXCR4 expression in the primary tumour was significantly higher in tumours that recurred as compared with those that did not recur (median 60%, IQR 33-72 vs 12%, IQR 1-70, Kruskal-Wallis p=0.01). After dichotomisation, >25% of CXCR4 expressions proved an independent prognosticator for a reduced recurrence-free survival (RFS) (HR 7.2, 95% CI 1.5 to 72.4, p=0.04).

CONCLUSION

CXCR4 is expressed in the majority of primary AdCCs and independently correlated to worse RFS, suggesting CXCR4 as a target for imaging and therapy purposes in patients with advanced AdCC.

A six-gene leukemic stem cell score identifies high risk pediatric acute myeloid leukemia

Recently, mRNA-expression signature enriched in LSCs was used to create a 17-gene leukemic stem cell (LSC17) score predictive of prognosis in adult AML. By fitting a Cox-LASSO regression model to the clinical outcome and gene-expression levels of LSC enriched genes in 163 pediatric participants of the AML02 multi-center clinical trial (NCT00136084), we developed a 6-gene LSC score of prognostic value in pediatric AML (pLSC6). In the AML02 cohort, the 5-year event-free survival (EFS) of patients within low-pLSC6 group (n=97) was 78.3 (95% CI=70.5–86.9%) as compared to 34.5(95% CI=24.7–48.2 %) in patients within high-pLSC6 group (n=66 subjects), p<0.00001. pLSC6 remained significantly associated with EFS and overall survival (OS) after adjusting for induction 1-MRD status, risk-group, FLT3-status, WBC-count at diagnosis and age. pLSC6 formula developed in the AML02 cohort was validated in the pediatric AML-TARGET project data (n=205), confirming its prognostic value in both single-predictor and multiple-predictor Cox regression models. In both cohorts, pLSC6 predicted outcome of transplant patients, suggesting it as a useful criterion for transplant referrals. Our results suggest that pLSC6 score holds promise in redefining initial risk-stratification and identifying poor risk AML thereby providing guidance for developing novel treatment strategies.

Early outcome of a 31-gene expression profile test in 86 AJCC stage IB-II melanoma patients. A prospective multicentre cohort study

Background

The clinical and pathological features of primary melanoma are not sufficiently sensitive to accurately predict which patients are at a greater risk of relapse. Recently, a 31‐gene expression profile (DecisionDx‐Melanoma) test has shown promising results.

Objectives

To evaluate the early prognostic performance of a genetic signature in a multicentre prospectively evaluated cohort.

Methods

Inclusion of patients with AJCC stages IB and II conducted between April 2015 and December 2016. All patients were followed up prospectively to assess their risk of relapse. Prognostic performance of this test was evaluated individually and later combined with the AJCC staging system. Prognostic accuracy of disease‐free survival was determined using Kaplan–Meier curves and Cox regression analysis. Results of the gene expression profile test were designated as Class 1 (low risk) and Class 2 (high risk).

Results

Median follow‐up time was 26 months (IQR 22–30). The gene expression profile test was performed with 86 patients; seven had developed metastasis (8.1%) and all of them were in the Class 2 group, representing 21.2% of this group. Gene expression profile was an independent prognostic factor for relapse as indicated by multivariate Cox regression analysis, adjusted for AJCC stages and age.

Conclusions

This prospective multicentre cohort study, performed in a Spanish Caucasian cohort, shows that this 31‐gene expression profile test could correctly identify patients at early AJCC stages who are at greater risk of relapse. We believe that gene expression profile in combination with the AJCC staging system could well improve the detection of patients who need intensive surveillance and optimize follow‐up strategies.

Assessing covariate effects using Jeffreys-type prior in the Cox model in the presence of a monotone partial likelihood

In medical studies, the monotone partial likelihood is frequently encountered in the analysis of time-to-event data using the Cox model. For example, with a binary covariate, the subjects can be classified into two groups. If the event of interest does not occur (zero event) for all the subjects in one of the groups, the resulting partial likelihood is monotone and consequently, the covariate effects are difficult to estimate. In this article, we develop both Bayesian and frequentist approaches using a data-dependent Jeffreys-type prior to handle the monotone partial likelihood problem. We first carry out an in-depth examination of the conditions of the monotone partial likelihood and then characterize sufficient and necessary conditions for the propriety of the Jeffreys-type prior. We further study several theoretical properties of the Jeffreys-type prior for the Cox model. In addition, we propose two variations of the Jeffreys-type prior: the shifted Jeffreys-type prior and the Jeffreys-type prior based on the first risk set. An efficient Markov-chain Monte Carlo algorithm is developed to carry out posterior computation. We perform extensive simulations to examine the performance of parameter estimates and demonstrate the applicability of the proposed method by analyzing real data from the SEER prostate cancer study.

Identification of genetic modifiers of age-at-onset for familial Parkinson's disease

Parkinson's disease (PD) is the most common cause of neurodegenerative movement disorder and the second most common cause of dementia. Genes are thought to have a stronger effect on age-at-onset of PD than on risk, yet there has been a phenomenal success in identifying risk loci but not age-at-onset modifiers. We conducted a genome-wide study for age-at-onset. We analysed familial and non-familial PD separately, per prior evidence for strong genetic effect on age-at-onset in familial PD. GWAS was conducted in 431 unrelated PD individuals with at least one affected relative (familial PD) and 1544 non-familial PD from the NeuroGenetics Research Consortium (NGRC); an additional 737 familial PD and 2363 non-familial PD were used for replication. In familial PD, two signals were detected and replicated robustly: one mapped to LHFPL2 on 5q14.1 (PNGRC = 3E-8, PReplication = 2E-5, PNGRC + Replication = 1E-11), the second mapped to TPM1 on 15q22.2 (PNGRC = 8E-9, PReplication = 2E-4, PNGRC + Replication = 9E-11). The variants that were associated with accelerated onset had low frequencies (<0.02). The LHFPL2 variant was associated with earlier onset by 12.33 [95% CI: 6.2; 18.45] years in NGRC, 8.03 [2.95; 13.11] years in replication, and 9.79 [5.88; 13.70] years in the combined data. The TPM1 variant was associated with earlier onset by 15.30 [8.10; 22.49] years in NGRC, 9.29 [1.79; 16.79] years in replication, and 12.42 [7.23; 17.61] years in the combined data. Neither LHFPL2 nor TPM1 was associated with age-at-onset in non-familial PD. LHFPL2 (function unknown) is overexpressed in brain tumours. TPM1 encodes a highly conserved protein that regulates muscle contraction, and is a tumour-suppressor gene.

PSHREG: a SAS macro for proportional and nonproportional subdistribution hazards regression

We present a new SAS macro %pshreg that can be used to fit a proportional subdistribution hazards model for survival data subject to competing risks. Our macro first modifies the input data set appropriately and then applies SAS's standard Cox regression procedure, PROC PHREG, using weights and counting-process style of specifying survival times to the modified data set. The modified data set can also be used to estimate cumulative incidence curves for the event of interest. The application of PROC PHREG has several advantages, e.g., it directly enables the user to apply the Firth correction, which has been proposed as a solution to the problem of undefined (infinite) maximum likelihood estimates in Cox regression, frequently encountered in small sample analyses. Deviation from proportional subdistribution hazards can be detected by both inspecting Schoenfeld-type residuals and testing correlation of these residuals with time, or by including interactions of covariates with functions of time. We illustrate application of these extended methods for competing risk regression using our macro, which is freely available at: http://cemsiis.meduniwien.ac.at/en/kb/science-research/software/statistical-software/pshreg, by means of analysis of a real chronic kidney disease study. We discuss differences in features and capabilities of %pshreg and the recent (January 2014) SAS PROC PHREG implementation of proportional subdistribution hazards modelling.

Time-dependent Cox regression: serial measurement of the cardiovascular biomarker proadrenomedullin improves survival prediction in patients with lower respiratory tract infection

BACKGROUND

The aim of this study was to determine the prognostic utility of serial measurement of the cardiovascular biomarker midregion proadrenomedullin (MR-proADM) in patients admitted with lower respiratory tract infection. In a previous trial in dyspneic patients (BACH trial) we could show that serial measurement of MR-proADM proves useful for risk assessment and patient monitoring. Models designed to evaluate serial biomarker measurements usually fail to answer two fundamental questions necessary to judge their clinical relevance: whether serial measurements provide additional information on top of the first measurement, and, if yes, at which time point a re-evaluation may be clinically useful.

METHOD

We apply an adapted time-dependent Cox model to data from the ProHosp trial, a prospective trial, which was observational in regards to application of prognostic biomarkers, where blood draws for biomarker evaluation were collected at day of patient inclusion, days 3, 5 and 7. In this trial, the cardiovascular biomarker MR-proADM was evaluated for its ability to predict survival in comparison to clinical risk scores.

RESULTS

With the adapted time-dependent Cox model, we could demonstrate a significant added value of the follow up measurements on top of that obtained on admission. Despite a high correlation between serial measurements, the gain can be observed as early as 3 days after inclusion. We illustrate the added prognostic value and clinical relevance of re-evaluation via Kaplan-Meier plots.

CONCLUSION

We could demonstrate that the prognostic biomarker MR-proADM can potentially serve as a outcome monitoring marker in patients admitted with lower respiratory tract infections.

Essential polyunsaturated fatty acids, inflammation and mortality in dialysis patients

BACKGROUND

Polyunsaturated fatty acids (PUFA) are essential nutrients with anti-inflammatory and cardioprotective properties. We investigated the association of essential dietary PUFA intake, reflected by plasma fatty acid composition, with inflammation and mortality in dialysis patients.

METHODS

We recruited 222 Swedish dialysis subjects (39% women) with median age of 57 years and average 12 months of dialysis vintage. Plasma phospholipid PUFA were assessed by gas-liquid chromatography. Overall mortality was assessed after 18.4 (10th-90th percentiles: 2.3-60) months of follow-up.

RESULTS

Linoleic acid (LA), Mead acid (MA), α-linolenic acid (ALA) and long-chain n-3 PUFA (LC n-3; the sum of eicosapentaenoic, docosapentaenoic and docosahexaenoic acids) represented 19.7, 0.26, 0.26 and 7.64% of all fatty acids in plasma, respectively. This may reflect an adequate n-3 PUFA intake. LA was negatively (β = - 0.21, P = 0.004) but MA positively (β = 0.25, P < 0.001) associated with interleukin (IL)-6 in multivariate analyses. Neither ALA nor LC n-3 were independently associated with IL-6. During follow-up, 61 deaths and 115 kidney transplants occurred. Fully adjusted competing risk models showed that every percent increase in the proportion of plasma LA was associated with 12% reduction in mortality risk before transplantation (hazard ratio 0.88, 95% confidence interval 0.79-0.99). MA was directly associated with mortality. Neither ALA nor LC n-3 predicted outcome.

CONCLUSIONS

The proportion of plasma phospholipid LA is inversely associated with IL-6 and all-cause mortality in Swedish dialysis patients. We raise the hypothesis that dialysis patients could benefit from increased intake of vegetable oils, the primary source of LA in the Western-type diet.

Effect of circulating soluble receptor for advanced glycation end products (sRAGE) and the proinflammatory RAGE ligand (EN-RAGE, S100A12) on mortality in hemodialysis patients

BACKGROUND AND OBJECTIVES

The soluble receptor of advanced glycation end products (sRAGE) may exert anti-inflammatory protective roles on the vasculature. In contrast, the RAGE ligand S100A12 (also known as EN-RAGE) contributes to inflammation and the development of atherosclerosis in animal models. Whether alterations at this level contribute to the increased mortality observed in patients on dialysis is currently unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Prospective study including 184 prevalent hemodialysis patients and 50 healthy controls matched for age and gender. Plasma concentrations of S100A12 and sRAGE were studied in relation to risk profile and mortality after a median follow-up period of 41 months.

RESULTS

S100A12 and sRAGE levels were significantly elevated in hemodialysis patients compared with healthy controls. S100A12 had a strong positive correlation with C-reactive protein and IL-6, whereas sRAGE negatively associated with C-reactive protein. S100A12, but not sRAGE, was independently and positively associated with clinical cardiovascular disease (CVD). During follow-up, 85 (33 cardiovascular-related) deaths occurred. Whereas sRAGE did not predict mortality, S100A12 was associated with both all-cause (per log(10) ng/ml hazard ratio [HR] 1.93, 95% confidence interval [CI] 1.18 to 3.15) and CVD-related (HR 3.23, 95% CI 1.48 to 7.01) mortality, even after adjustment for age, sex, vintage, and comorbidities. Further adjustment for inflammation made the predictive value of S100A12 disappear for all-cause mortality, but still persisted in CVD-related mortality.

CONCLUSIONS

Circulating S100A12 and sRAGE are both elevated in hemodialysis patients. However, only S100A12 associates with mortality, partly explained by its links with inflammation.