Backward Variable Selection Method Research Articles

Dietary mineral intakes predict Coronavirus-disease 2019 (COVID-19) incidence and hospitalization in older adults

BackgroundThe aim of this study was to determine the association between dietary mineral intake and Coronavirus-disease 2019 (COVID-19) infection and its associated hospitalization.MethodsThis cohort study utilized the MASHAD study population, which comprised individuals aged 35–65. Upon recruitment in 2007, dietary intake was documented using a validated 65-item food frequency questionnaire (FFQ). Data on COVID-19 PCR test results was collected from all relevant medical centers in Mashhad between February 2020 and June 2022. The regression model included dietary minerals and employed the backward variable selection method, along with advanced data analysis techniques.ResultsThe final analysis involved 1957 participants, including 193 COVID-19-positive patients. The mean age was 49.71 and 50.28 years in the COVID-19-positive and negative groups, respectively (p = 0.12). Dietary intakes of magnesium, iron, and potassium were notably lower in COVID-19-positive patients (P < 0.05). Following adjustments for age and sex, dietary iron remained significantly associated with COVID-19 incidence (OR = 0.94, 95% CI: 0.90–0.98). Furthermore, a statistically significant relationship was observed between dietary zinc and hospitalization due to COVID-19 (OR = 0.69, 95% CI: 0.51–0.93). In dynamical system models, intakes of calcium, zinc, and iron below the cut-offs of 1138, 9.7, and 8.17 mg/day, respectively, were linked to an increased risk of COVID-19 incidence.ConclusionHigher dietary iron and zinc intake are associated with decreased risk of COVID-19 infection and hospitalization, respectively.

To Examine the Effects of Risk Factors Associated with Kidney Stones in Determining the Disease by Considering their Combinations

Aim: Kidney stone disease, which can affect people of all ages and whose incidence increases day by day, is becoming a public health problem due to treatment costs. This study aims to determine how factors related to kidney stones affect the diagnosis of the disease when taken together, rather than determining their relationship with the disease one by one. Materials and methods: An open-access dataset containing kidney stone status and associated factors was used in the study. Mann Whitney U test and independent sample t-test were used in data analysis. Logistic regression was performed with the backward variable selection method to determine the factors associated with kidney stones. ROC analysis was used to determine the power of the variables that were significant as a result of logistic regression analysis, individually and together, in discriminating kidney stones. Results: According to the results of logistic regression analysis, gravity, cond, and urea calc variables were found to be associated with kidney stones. With ROC analysis, it can be said that urea, calc, and gravity variables with AUC values above 0.60 can distinguish kidney stones. When the combinations of these variables are examined, the AUC values of the binary combinations are between 0.734 and 0.759, while the AUC value obtained for the triple combination is 0.831. Conclusion: According to the results obtained from the article, it can be said that while the factors associated with the disease and used in the diagnosis have little effect on the diagnosis of the disease alone based on the AUC values obtained from the ROC analysis, it can be said that considering them together increases the accuracy in diagnosis. Therefore, considering the factors thought to be associated with the disease together may be more appropriate in diagnosis and may give more accurate results.

Red Blood Cell Transfusion Independence Status Is an Independent Predictor of Survival: A Post Hoc Time-Dependent Analysis of the Phase 3 Simplify-1, Simplify-2, and Momentum Trials

Introduction: The management of anemia in myelofibrosis (MF), a chronic progressive myeloproliferative neoplasm, remains an ongoing medical need as it is present in approximately 30% of patients (pts) at diagnosis and &amp;gt;50% after 1 year, contributing to negative impacts such as fatigue, medical complications, and poor quality of life. Furthermore, anemia and resulting transfusion need are independent predictors of poor prognosis. Momelotinib (MMB) is a Janus kinase (JAK) 1/JAK2/activin A receptor type 1 (ACVR1) inhibitor that has demonstrated spleen, symptom, and anemia benefits, including increases in hemoglobin (Hb) and reduction or elimination of red blood cell (RBC) transfusion requirements in pts with MF. Data from the phase 3 SIMPLIFY-1 (S1), SIMPLIFY-2 (S2), and MOMENTUM studies have shown an association between transfusion independence at wk 24 and prolonged overall survival (OS) with MMB (Mesa R, et al. Leukemia. 2022; Verstovsek S, et al. ASH 2022. Poster 3028). Because these analyses did not adjust for additional prognostic factors or effect modifiers nor potential longitudinal changes in transfusion status over time, the impact of transfusion status on OS has not been fully characterized. Here, we describe an analysis investigating the prognostic influence of RBC transfusion status over time and other covariates on OS from the S1 (NCT01969838), S2 (NCT02101268), and MOMENTUM (NCT04173494) studies irrespective of the treatment received. Methods: These treatment-agnostic OS analyses incorporated data from 3 multicenter, international, randomized trials investigating MMB vs an active comparator. Analyses were performed in the safety populations of S1 (N=430; MMB vs ruxolitinib [RUX], JAK inhibitor [JAKi] naive), S2 (N=156; MMB vs best available therapy [88.5% RUX], JAKi experienced), and MOMENTUM (N=195; MMB vs danazol, JAKi experienced). In the current analysis, which accounts for evaluations of transfusion status every 4 wk, time-dependent covariates (RBC transfusion status, categorized as either transfusion independent [TI; absence of RBC transfusion and no Hb level &amp;lt;8 g/dL in the prior 12 wk] or non-TI [not satisfying the criteria for TI]) and fixed baseline covariates (age, sex, MF subtype, Eastern Cooperative Oncology Group [ECOG] status, JAK2 mutational profile, Total Symptom Score, International Prognostic Scoring System [IPSS] score for S1, Dynamic IPSS [DIPSS] score for S2 and MOMENTUM, platelet count, baseline spleen volume as assessed by central reading of magnetic resonance imaging/computed tomography scan) were evaluated to determine their prognostic impact. An extended Cox model was used to generate an overall hazard ratio (HR) using all available follow-up time for each study, and independent variables were retained if a backward variable selection method determined that they were significantly associated with OS. Results: Significant covariates associated with survival across the 3 trials are presented in the table, with RBC transfusion status as a consistent prognostic variable. In S1, age, platelet count, and baseline spleen volume were also significantly associated with OS, and in S2, significant covariates included age, baseline spleen volume, and DIPSS. In MOMENTUM, only RBC transfusion status was significantly associated with survival. When accounting for differences in prognostic factors and effect modifiers as well as changes in transfusion status over time, results from MOMENTUM demonstrate a strong and significant relationship between transfusion status and OS (HR, 5.18; 95% CI, 1.86-14.47; P=.0017), suggesting that non-TI pts have a higher risk of all-cause mortality of more than 5 times that of TI pts. Similar results with respect to the survival benefits of TI status were observed in both S1 (HR, 3.32; 95% CI, 2.31-4.78; P&amp;lt;.0001) and S2 (HR, 1.87; 95% CI, 1.07-3.29; P=.0287). Conclusions: These data demonstrate that when accounting for differences in known prognostic factors and effect modifiers as well as changes in RBC transfusion status over time, a consistent and statistically significant relationship was observed between transfusion status and OS across all 3 phase 3 MMB trials. Consistent with inclusion of transfusion status in DIPSS-plus risk assessment, these data validate TI status as a clinically relevant and meaningful endpoint that is prognostic for survival in JAKi-naive and JAKi-experienced disease settings.

Hemorrhage Risk after Stereotactic Radiosurgery for Patients with Unruptured Brain Arteriovenous Malformation: Significance of Vascular Compactness

<h3>Purpose/Objective(s)</h3> Our purpose was to investigate whether the morphology (i.e., compact/ diffuse) of brain arteriovenous malformations (bAVMs) correlates with the incidence of hemorrhagic events in patients with unruptured bAVMs after receiving non-invasive stereotactic radiosurgery (SRS). <h3>Materials/Methods</h3> This study retrospectively included 264 adult patients with unruptured bAVMs undergoing upfront SRS from multi-institutions. Two senior neurosurgeons confirmed the unruptured presentation. The follow-ups were performed in a 6-month interval. Hemorrhagic events were defined as bleeding signs on computed tomography (CT) or magnetic resonance images (MRI). The morphology of bAVMs was evaluated using fully automated segmentation, which calculated the proportion of vessel, brain tissue, and cerebrospinal fluid in bAVMs on T2-weighted MRI. Compactness index, defined as a ratio of vessel to brain tissue, was proposed and further dichotomized based on Youden indices to classify the bAVMs into compact or diffuse type. Cox proportional hazard model was used to identify the independent factors for the occurrence of post-SRS hemorrhage. <h3>Results</h3> The median follow-up duration was 62.1 months. Post-SRS hemorrhage occurred in 14 (5.3%) patients with 2 bAVMs bleeding twice, incurring an annual bleeding risk of 0.9%. Multivariable analysis with stepwise backward variable selection method revealed that bAVM morphology (compact versus diffuse), bAVM volume and prescribed margin dose were significant predictors for post-GKRS hemorrhage. The incidence density of post-GKRS hemorrhage in the compact and diffuse bAVMs were 4.9 and 11.8 (hemorrhagic events/ 1000 person-years (P-Ys)). Among the diffuse bAVMs (n=153), the post-GKRS hemorrhage rate was lower for smaller bAVM volume, <15ml versus 15-30ml versus >30ml (2.2 versus 13.5 versus 26.3 hemorrhagic events/ 1000 P-Ys; p=0.044) and for bAVMs receiving margin dose >16.6 Gy versus <16.6 Gy (5.2 versus 25.8 hemorrhagic events/ 1000 P-Ys; p=0.004). For the compact bAVMs (n=111), the post-GKRS hemorrhage rate was not significantly different between the dose and volume groups. <h3>Conclusion</h3> Compact and smaller bAVMs, with higher prescribed margin dose harbor lower risks of post-SRS hemorrhage. Among the diffuse bAVMs, post-GKRS hemorrhage risk varied with bAVM volume and margin dose. The finding could help guide GKRS treatment decision-making for the unruptured bAVMs.

Estimation of euphotic zone depth in shallow inland water using inherent optical properties and multispectral remote sensing imagery

Euphotic zone depth (Zeu) is a key indicator of underwater light environment that regulates different biogeochemical and physical processes in aquatic ecosystem. Remote sensing approaches offer a unique opportunity to frequently monitor Zeu, although its estimation from diffuse attenuation coefficient (Kd) requires depth profiles of the down-welling irradiance (Ed). Measuring Ed values at different water depths (i.e., Ed profiling) in shallow waterbodies is a challenging task with the available profiling equipment. In this study, Kd values were estimated from measured absorption coefficient (a) data at multiple locations in the Chilika lagoon, which is a shallow waterbody located in the eastern coast of India and is a prestigious Ramsar site. Specifically, remote sensing reflectance (Rrs), a values (wavelength: 400–715 nm at 4 nm interval), Secchi disc depth (ZSD), suspended particulate matter (SPM) and chlorophyll-a (Chl-a) contents were measured during Oct. 07–08, 2018 and Feb. 02–08, 2019 in the Chilika lagoon. Atmospherically corrected Sentinel 2A/2B (S2A/S2B) MSI- Rrs data (level 2A) were then used to develop algorithms for mapping Zeu for the entire lagoon. Modeling results showed that Rrs values at band 4 (665 nm) or band 5 (704 nm) extracted from the S2A/S2B MSI data may be used to estimate Kd of photosynthetically active radiation (PAR) (observed range: 1.29 m−1 to 10.74 m−1) with the root-mean-squared error (RMSE) as low as 0.81 m−1. However, uncertainties associated with atmospheric correction of S2A/S2B MSI-single band Rrs values are high when compared with in situ Rrs. Thus, a multivariate modeling approach was adopted with Rrs- band ratio and band difference variables selected by stepwise, forward, and backward variable selection method with p < 0.05. Modeling results showed that the band differences between band 2 and band 4 and band 3 and band 5 may be used to estimate Kd(PAR) with improved mean absolute percentage difference (MAPD) while ensuring low uncertainty associated with atmospheric correction. Spatio-temporal dynamics from S2A/S2B MSI for 85 different dates during Jan. 2017 to June 2021 provided seasonal patterns for Zeu in the Chilika lagoon.

Correlates of common concerns in older cancer survivors of leukemia and lymphoma: Results from the WHI-LILAC study.

e24031 Background: Older survivors of leukemia and lymphoma often experience long-term and late effects of chemotherapy, worsened by aging-related conditions such as functional and cognitive impairment, which may be inadequately addressed. In this study, we described common concerns in older survivors of leukemia and lymphoma, and assessed demographic and clinical factors associated with these concerns. Methods: We utilized data from the WHI LILAC study that recruited post-menopausal women aged 50 and 79 years. Participants who were diagnosed with leukemia and lymphoma after enrollment in WHI and answered at least half of the questions on current concerns in LILAC were included (n = 420). Participants were asked about 14 areas of current concerns common in cancer survivorship and to rate each from 0 (no concern) to 2 (major concern), with total score ranging 0-28. Linear regression was used to assess demographic and clinical factors associated with the concern score, and logistic regression for factors associated with the three most common concerns, with backward variable selection methods. Results: Mean age at assessment was 81 years (range 69-99) and 73% had non-Hodgkin lymphomas. Median time since diagnosis was 8.8 years (range 2.5-20.8 years). Seventy-two percent reported any concern; median concern score among these survivors was 3.5 (Q1-Q3, 2-5) (Table). Factors significantly correlated with the concern score were sadness, pain, loneliness, worse quality of life (QoL), lower physical functioning, more comorbidities, and greater prior symptom count (all p &lt; 0.05). Significant factors correlated with common concerns were: 1) Fatigue/sleep: leukemia diagnosis, greater prior symptom count, feeling sad or depressed, reported distress, lower physical functioning; 2) Physical functioning/activity: public health insurance, older age, greater prior symptom count, reported pain, worse QoL, higher BMI; 3) Memory/concentration: prior chemotherapy or radiation, loneliness, worse QoL, greater prior symptom count (all p &lt; 0.05). Conclusions: Almost three-quarter of survivors of leukemia and lymphoma reported at least one concern, with common concerns being fatigue/sleep, physical functioning/activity, and memory/concentration. A multicomponent intervention is needed to address these common concerns in older cancer survivors.[Table: see text]

The association of acute--to--chronic glycemic ratio with no-reflow in patients with ST--segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

No‑reflow (NR) is a strong and independent predictor of poor cardiovascular outcomes among patients with ST‑segment elevation myocardial infarction (STEMI). The aim of the study was to investigate the association of the acute‑to‑chronic (A/C) glycemic ratio with no‑reflow (NR) in STEMI patients following primary percutaneous coronary intervention (PCI). This retrospective study included 905 patients with STEMI. The A/C glycemic ratio was determined as admission blood glucose (ABG) divided by the estimated average glucose (eAG). We evaluated 2 primary models (full model and reduced model). The primary outcome was the presence of NR. The incidence of NR was 22.7% (206 cases) in the present study. We divided the study population into 3 tertiles (T1, T2, and T3) based on the ABG/eAG ratio. There was a stepwise increase of the frequency of NR from the T1 to T3 group (36 patients [12%] vs 70 patients [23%] vs 100 patients [33%]; respectively [P <0.001, for each group comparison]). In a full model, the ABG/eAG ratio (OR, 2.274; 95% CI, 1.587-3.26; P <0.001) was associated with NR. After the performance of a step-down backward variable selection method, the thrombus grade, the ABG/eAG ratio, the infarct‑related artery diameter, and age remained in the reduced model. The ABG/eAG ratio (contributing 25.3% of the explainable outcome in the model) was one of the strong predictors of NR in the reduced model. To our knowledge, this might be the first study showing a significant relationship between the ABG/eAG ratios with NR in patients with STEMI after primary PCI.

The association of acute-to-chronic glycemic ratio with no-reflow in ST elevation myocardial infarction patients undergoing primary percutaneous coronary intervention

Abstract Introduction In the present study, we investigate the association of acute-to-chronic (A/C) glycemic ratio with no-reflow (NR) development in ST elevation myocardial infarction (STEMI) patients following primary percutaneous coronary intervention (PCI). Material and methods This retrospective study included 905 consecutive STEMI patients who were treated with primary PCI. The A/C glycemic ratio was determined as admission blood glucose (ABG) divided by the estimated average glucose (eAG). We evaluated two primary models (full model and reduced model).The primary outcome was the presence of NR. Results The incidence of NR was 22.7% (206 cases) in the present study. We divided the study population into three tertiles (T1, T2, and T3) based on the ABG/eAG ratio. There was a stepwise increase of the frequency of NR development from the T1 to T3 group (36 patients [12%] vs. 70 patients [23%] vs. 100 patients [33%]; respectively [p &amp;lt;0.001, for each group comparison]). In a full model, the ABG/eAG ratio (OR; 2.274, 95% CI; 1.587–3.26, p&amp;lt;0.001) was associated with NR. After the performance of a step-down backward variable selection method, the thrombus grade, the ABG/eAG ratio, the infarct-related artery diameter, and age remained in the reduced model. The ABG/eAG ratio (contributing 25.3% of the explainable outcome in the model) was one of the strong predictors of NR in the reduced model. Conclusion To the best of our knowledge, this might be the first study showing a significant relationship between the ABG/eAG ratios with NR in STEMI patients after primary PCI. Figure 1 Funding Acknowledgement Type of funding source: None

Risk Factors for Adverse Events in Patients with Chronic Constipation Following Lubiprostone Administration

Introduction: Lubiprostone is an effective treatment of chronic constipation (CC). However, as with other stimulant or osmotic laxatives, adverse events (AEs) can make it difficult to continue treatment. This article investigates AE risk factors associated with lubiprostone. Methods: We retrospectively analyzed all 1,338 Japanese patients with CC treated at our hospital from October 2013 to July 2017. All patients were diagnosed with constipation as defined by the Roma III criteria. Enrolled patients received lubiprostone orally (24 or 48 μg daily), after which we investigated the incidence of AEs. The causative factors for diarrhea and nausea, the most common AEs, were examined by the backward logistic regression model. Results: Two hundred eight (15.5%) experienced at least 1 AE. No serious AEs were associated with the study drug. The AEs reported by >1% of patients overall were diarrhea (6.1%) and nausea (4.2%). We performed a multivariate logistic regression using a backward variable selection method to investigate AE risk factors. Factors associated with higher incidence of diarrhea were patient age of 65 years or more (odds ratio: [95% confidence interval]; p value) (2.09: [1.05–4.16]; 0.035). Factors associated with greater likelihood of nausea included female gender (1.99: [1.10–3.61]; 0.023), and the chief complaint was a patient complaining of abdominal pain and fullness (2.07: [1.01–4.22]; 0.046). Conclusions: Understanding AE risk factors can help avoid unnecessary AEs and promote more effective treatment.

The Annual Direct and Indirect Health Care Costs for Patients with Chronic Pruritus and their Determining Factors

The Annual Direct and Indirect Health Care Costs for Patients with Chronic Pruritus and their Determining Factors

Normalization of Spinal Cord Displacement With the Straight Leg Raise and Resolution of Sciatica in Patients With Lumbar Intervertebral Disc Herniation: A 1.5-year Follow-up Study.

A controlled radiologic follow-up study. The aim of this study was to ascertain whether changes in cord excursion with straight leg raise test (SLR) at 1.5-year follow-up time accompany changes in clinical symptoms. Lumbar intervertebral disc herniation (LIDH) is known to be a key cause of sciatica. Previously, we found that a significant limitation of neural displacement (66.6%) was evident with the SLR on the symptomatic side of patients with subacute single level posterolateral LIDH. Fourteen patients with significant sciatic symptoms due to a subacute single-level posterolateral LIDH were reassessed clinically and radiologically at 1.5 years follow-up with a 1.5T MRI scanner. Displacement of the conus medullaris during the unilateral and bilateral SLR was quantified reliably with a randomized procedure and compared between SLRs and to data from baseline. Multivariate regression models and backward variable selection method were employed to identify variables more strongly associated with a decrease in low back pain (LBP) and radicular symptoms. Compared with previously presented baseline values, the data showed a significant increase in neural sliding in all the quantified maneuvers (P ≤ 0.01), and particularly of 2.52 mm (P ≤ 0.001) with the symptomatic SLR.Increase in neural sliding correlated significantly with decrease of both radicular symptoms (Pearson = -0.719, P ≤ 0.001) and LBP (Pearson = -0.693, P ≤ 0.001). Multivariate regression models and backward variable selection method confirmed the improvement of neural sliding effects (P ≤ 0.004) as the main variable being associated with improvement of self-reported clinical symptoms. To our knowledge, these are the first noninvasive data to objectively support the association between increase in magnitude of neural adaptive movement and resolution of both radicular and LBP symptoms in in vivo and structurally intact human subjects. 2.

Developing a prediction model for disease-free survival from upper urinary tract urothelial carcinoma in the Korean population.

BackgroundIn this study, we aimed to propose a validated prediction model for disease‐free survival (DFS) after radical nephroureterectomy (RNU) in a Korean population with upper urinary tract urothelial carcinoma (UTUC).MethodsWe performed a retrospective review of 1561 cases of UTUC who underwent either open RNU (ONU, n = 906) or laparoscopic RNU (LNU, n = 615) from five tertiary Korean institutions between January 2000 and December 2012. Data were used to develop a prediction model using the Cox proportional hazards model. Prognostic factors were selected using the backward variable selection method. The prediction model performance was investigated using Harrell's concordance index (C‐index) and Hosmer‐Lemeshow type 2 statistics. Internal validation was performed using a bootstrap approach, and the National Cancer Center data set (n = 128) was used for external validation.ResultsA best‐fitting prediction model with seven significant factors was developed. The C‐index and two Hosmer‐Lemeshow type statistics of the prediction model were 0.785 (95% CI, 0.755‐0.815), 4.810 (P = 0.8506), and 5.285 (P = 0.8088). The optimism‐corrected estimate through the internal validation was 0.774 (95% CI, 0.744‐0.804) and the optimism‐corrected calibration curve was close to the ideal line with mean absolute error = 0.012. In external validation, the discrimination was 0.657 (95% CI, 0.560‐0.755) and the two calibration statistics were 0.790 (P = 0.9397) and 3.103 (P = 0.5408), respectively.ConclusionA validated prediction model based on a large Korean RNU cohort was developed with acceptable performance to estimate DFS in patients with UTUC.

A weighted bootstrap approach to logistic regression modelling in identifying risk behaviours associated with sexual activity

ABSTRACTThe latest population estimates released by Statistics South Africa indicate that 25.03% of all deaths in 2017 in South Africa were AIDS-related. Along with these results, it is also reported that 7.06% of the population were living with HIV, with the HIV-prevalence among youth (aged 15–24) at 4.64% for 2017 (STATSSA. (2018). Retrieved from Statistics South Africa: http://www.statssa.gov.za/publications/P0302/P03022017.pdf). The data used in the study contained information related to the risk-taking behaviours associated with the sexual activity of entering first-year students at the University of the Western Cape. In this study, a logistic regression modelling procedure was carried out on those students that were determined to be sexually active, therefore, in the modelling procedure significant risk behaviours of sexually active first-year students could be identified. Of the 14 variables included in the modelling procedure, six were found to be significantly associated with sexually active students. The significant variables included; the age and race of the student, whether the student had ever taken an HIV test, the importance of religion in influencing the sexual behaviour of the student, whether the student consumed alcohol and lastly whether the student smoked. This study further investigated the impact of introducing sample weighting, bootstrap sampling as well as variable selection methods into the logistic regression modelling procedure. It is shown that incorporating these techniques into the modelling procedure produces logistic regression models that are more accurate and have an increased predictive capability. The bootstrapping procedure is shown to produce logistic regression models that are more accurate than those produced without a bootstrap procedure. A comparison between 200, 500 and 1000 bootstrap samples is also incorporated into the modelling procedure with the models produced from 200 bootstrap samples shown to be just as accurate those produced from 500 or 1000 bootstrap samples. Of the five variable selection methods used, it is shown that the Newton–Raphson and Fisher methods are unreliable in producing logistic regression models. The forward, backward and stepwise variable selection methods are shown to produce very similar results.

Development and validation of a predictive risk factor model for epidural re-siting in women undergoing labour epidural analgesia: a retrospective cohort study

BackgroundEpidural catheter re-siting in parturients receiving labour epidural analgesia is distressing to the parturient and places them at increased complications from a repeat procedure. The aim of this study was to develop and validate a clinical risk factor model to predict the incidence of epidural catheter re-siting in labour analgesia.MethodsThe data from parturients that received labour epidural analgesia in our centre during 2014–2015 was used to develop a predictive model for epidural catheter re-siting during labour analgesia. Multivariate logistic regression analysis was used to identify factors that were predictive of epidural catheter re-siting. The forward, backward and stepwise variable selection methods were applied to build a predictive model, which was internally validated. The final multivariate model was externally validated with the data collected from 10,170 parturients during 2012–2013 in our centre.ResultsNinety-three (0.88%) parturients in 2014–2015 required re-siting of their epidural catheter. The training data set included 7439 paturients in 2014–2015. A higher incidence of breakthrough pain (OR = 4.42), increasing age (OR = 1.07), an increased pain score post-epidural catheter insertion (OR = 1.35) and problems such as inability to obtain cerebrospinal fluid in combined spinal epidural technique (OR = 2.06) and venous puncture (OR = 1.70) were found to be significantly predictive of epidural catheter re-siting, while spontaneous onset of labour (OR = 0.31) was found to be protective. The predictive model was validated internally on a further 3189 paturients from the data of 2014–2015 and externally on 10,170 paturients from the data of 2012–2013. Predictive accuracy of the model based on C-statistic were 0.89 (0.86, 0.93) and 0.92 (0.88, 0.97) for training and internal validation data respectively. Similarly, predictive accuracy in terms of C-statistic was 0.89 (0.86, 0.92) based on 2012–2013 data.ConclusionOur predictive model of epidural re-siting in parturients receiving labour epidural analgesia could provide timely identification of high-risk paturients required epidural re-siting.

Retracted: The prognosis analysis of epidermal growth factor receptor tyrosine kinase inhibitor targeted treatment combined with chemotherapy in smokers with nonsmall cell lung cancer.

Administering epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) tyrosine kinase inhibitor (TKI) combined with chemotherapy in patients with non-small cell lung cancer (NSCLC) is a common treatment strategy. However, the prognostic factors for the EGFR-TKI combined with chemotherapy in smokers with NSCLC are still uncertain. In this retrospective study, we enrolled patients with stage IV NSCLC diagnosed between June 2011 and March 2015 at two university-affiliated hospitals in China. Basic characteristics including age, sex, smoking status, performance status, EGFR mutation status, tumor response, and progression-free survival were recorded. A total of 72 patients with stage IV NSCLC with susceptible EGFR gene mutations who had been treated with EGFR-TKI combined with chemotherapy were enrolled. Survival analysis using the Kaplan-Meier method and log-rank test showed a significant difference when classifying the patients according to age and sex (P = 0.0179). When stratifying the patients by sex, a significant difference was found between males and females (1.87 vs 4.87 months; P = 0.0081). A reduced multivariate model developed using the backward variable selection method showed that advanced age remained an independent poor prognostic factor for NSCLC patients, and that sex and advanced age remained independent poor prognostic factors for NSCLC patients (hazard ratio = 3.386, 95% confidence interval: 1.015-11.298, P = 0.0473). This study is the first to demonstrate that female elderly patients have a poorer prognosis if they have received EGFR-TKI combined with chemotherapy. Further large-scale studies are urgently needed to elucidate the mechanism.

Friday, September 28, 2018 1:00 PM–2:30 PM abstracts: a new look at imaging: 208. Normalization of spinal cord displacement with the straight leg raise with resolution of sciatica in patients with lumbar intervertebral disc herniation: a 1.5-year follow-up study

BACKGROUND CONTEXT Lumbar intervertebral disc herniation (LIDH) is known to be a key cause of sciatica. Previously we found a significant limitation of neural displacement (66.6%) with the straight leg raise test (SLR) on the symptomatic side of patients with sub-acute single level posterolateral LIDH. PURPOSE To ascertain if changes incord excursion with SLR at 1.5-year follow-up time accompany changes in clinicalsymptoms. STUDY DESIGN/SETTING Controlled radiological study. PATIENT SAMPLE Follow-up study on 15 patients with significant sciatic symptoms due to a single level posterolateral LIDH. OUTCOME MEASURES Conus medullaris displacement was quantified reliably with a randomized procedure during the unilateral and bilateral SLR and results compared both between maneuvers and with baseline data. LIDH was examined with 1.5T Magnetic Resonance Imaging (MRI) scannerusing different scanning sequences for planning and for measurement purposes, while low back pain (LBP) and radicular symptoms were assessed during clinical examination with visual analogic scales. METHODS The patients were re-assessed clinically and radiologically with a 1.5T MRI scanner at 1.5-year follow-up. Displacement of the conus medullaris with the unilateral and bilateral SLR was quantified with a randomized procedure and compared between SLRs and to data from baseline. Multivariate regression models and backward variable selection method were employed to identify variables associated with the patients’ symptoms. RESULTS Conus medullaris caudal displacement in response to SLRs increased significantly in all the tested subjects. Compared to baseline values, the data showed a large increase in neural sliding with the symptomatic SLR (323.4%, 2.52mm, p≤.001), 37.1% with asymptomatic SLR (0.82mm, p=.0058) and 48.2% with bilateral SLR (1.64mm, p≤.001). Increase in neural sliding correlated significantly with the resolution of radicular symptoms in the ipsilateral limb (Pearson=−0.719, p≤.001) and low back pain (LBP) (Pearson=−0.693, p≤.001). Backward variable selection method indicated improvement of neural sliding (p=.004) and degrees of hip flexion with symptomatic SLR (p=.025) as the main variables being associated with improvement of radicular pain. Reduction of LBP showed to be associated with improvement of neural sliding (p=.006). Overall, there was an average increase in neural sliding of 230.7% (symptomatic, asymptomatic and bilateral SLRs) in association with decrease of symptoms during the follow-up period. This improvement of neural sliding was found to be associated with 74.7% decrease in self-reported LBP symptoms on visual analog scale (VAS), as well as 76.0% decrease in self-reported radicular symptoms on VAS. CONCLUSIONS This study shows a significant association between the improvement of neural adaptive movement with the SLR and resolution of both radicular and LBP symptoms in patients with posterolateral LIDH during 1.5-year follow-up time. To our knowledge, these are the first noninvasive data to objectively support the association between magnitude of neural adaptive movement and improvement of clinical symptoms in in-vivo and structurally intact human subjects. The data also gives new and valuable insights into our understanding of the mechanisms of the SLR test.

PD61-11 PERCUTANEOUS ABLATION OF LOCALIZED RENAL TUMORS: FEASIBILITY STUDY, EVOLUTION AND OPERATIVE COMPLICATIONS.

You have accessJournal of UrologyKidney Cancer: Localized: Ablative Therapy1 Apr 2018PD61-11 PERCUTANEOUS ABLATION OF LOCALIZED RENAL TUMORS: FEASIBILITY STUDY, EVOLUTION AND OPERATIVE COMPLICATIONS. Marco Arap, Carlos Henrique Segall Jr, Livia Neto, Mark Neumaier, and Marcos Menezes Marco ArapMarco Arap More articles by this author , Carlos Henrique Segall JrCarlos Henrique Segall Jr More articles by this author , Livia NetoLivia Neto More articles by this author , Mark NeumaierMark Neumaier More articles by this author , and Marcos MenezesMarcos Menezes More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.2835AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Percutaneous thermal ablation (Cryoablation and Radiofrequency) is the main alternative to the treatment of localized renal tumors in relation to conventional surgical treatment. This technology was implemented in 2008 at the Sírio-Libanês Hospital. Our goal is to demonstrate the feasibility, outcome, complications and their respective treatments. In addition, we evaluated whether patients profile, characteristics of the lesions or the method used in the treatment were associated with the length of stay at hospital, duration of procedure or operative complications. METHODS Retrospective cohort study with patients treated between 2008 and 2010, where categorical and quantitative variables were described as standard. Multivariate analysis was performed through multiple Poisson regression, multiple linear regression and multiple logistic regression, using Stepwise and Backward variable selection methods. The level of statistical significance adopted in all analyzes was 5% with confidence interval of 95%. The program used was IBM SPSS Statistics, version 21. RESULTS We selected 38 patients with 41 treated lesions. Age ranged from 37.70 to 83.20 years (mean of 61.91 years). Body Mass Index (BMI) ranged from 20.90 to 33.70 kg / m2 (mean of 26.87 kg / m2). ASA index ranged from 1 to 3 (median of 2). There were 24 (58.5%) lesions on the right side and 17 (41.5%) on the left side. Of these, 3 (7.3%) were superficial, 38 (92.7%) were intraparenchymal, 14 (34.5%) were polar and 27 (65.5%) were central. Tumor size ranged from 1 to 4.7 cm, with mean of 2.27 cm. We found 18 (43.9%) patients submitted to cryoablation (CA) and 23 (56.1%) submitted to radiofrequency (RFA). We observed the presence of acute complications in 8 (19.5%) procedures, all classified as Clavien I. Later, 2 (4.9%) of them evolved to stenosis of the collecting pathway, which led to organ loss. The procedure time varied from 45 to 285 minutes (mean of 117.6 minutes) and the hospitalization period was of 1 to 2 days (mean of 1.27 days). Considering the aforementioned factors, multivariate analysis verified that only the CA method and tumor size interfered in the outcomes of our interest. Cryoablation increased the procedure time by 75 minutes in relation to RFA and, on average, the largest tumors reduced the procedure time by 4 minutes. CONCLUSIONS The treatment of renal tumors with ablative therapies proved to be feasible, with low rates of morbidity and complications. It was also evidenced that different factors, such as BMI, ASA, patient profile or lesion characteristics, did not have any impact on the outcomes evaluated (length of stay at hospital, time of procedure or operative complications). © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e1156 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Marco Arap More articles by this author Carlos Henrique Segall Jr More articles by this author Livia Neto More articles by this author Mark Neumaier More articles by this author Marcos Menezes More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

An improved partial least-squares regression method for Raman spectroscopy

It is known that the performance of partial least-squares (PLS) regression analysis can be improved using the backward variable selection method (BVSPLS). In this paper, we further improve the BVSPLS based on a novel selection mechanism. The proposed method is based on sorting the weighted regression coefficients, and then the importance of each variable of the sorted list is evaluated using root mean square errors of prediction (RMSEP) criterion in each iteration step. Our Improved BVSPLS (IBVSPLS) method has been applied to leukemia and heparin data sets and led to an improvement in limit of detection of Raman biosensing ranged from 10% to 43% compared to PLS. Our IBVSPLS was also compared to the jack-knifing (simpler) and Genetic Algorithm (more complex) methods. Our method was consistently better than the jack-knifing method and showed either a similar or a better performance compared to the genetic algorithm.

Synthesis, anticonvulsant activity and QSAR studies of some new pyrazolyl pyridines

Twenty-one new 3,5-bipyridinyl-1H-pyrazole derivatives (pyrazolyl pyridines) have been synthesized and evaluated for their anticonvulsant activity in animal models of epilepsy. The pyrazolyl pyridines, 7–27, were obtained through a general one-pot synthesis, from ketones and acid chlorides via formation of 1,3-diketones in situ carried out in hydrocarbon solvent and LiHMDS base. The profile of anticonvulsant activity of final compounds was established in the maximal electroshock (MES) and subcutaneous pentylenetetrazole (sc PTZ) tests, after intraperitoneal injection in rats and mice, respectively, at doses of 30, 100, and 300 mg/kg. An observation was carried out at two different time intervals—0.5 and 4 h. Phenytoin was used as a standard antiepileptic against MES convulsions and valproic acid against sc PTZ convulsions. Furthermore, in addition to the primary anticonvulsant screening, the acute neurological toxicity was determined in mice by the rotarod test and in rats by positional sense test. The compounds showed anticonvulsant activity exclusively against MES convulsions. The compounds were found especially active in 100 mg/kg dose at both the time points, i.e., 0.5 and 4 h, depending upon the lipophilicity of molecules as indicated by statistically significant reduction in the time spent in tonic extension phase (p < 0.001). Further, the newly synthesized compounds were subjected to two-dimensional quantitative structure–activity relationship (2D QSAR) analysis through multiple linear regression, principal component regression, and partial least square regression analysis, and three-dimensional quantitative structure–activity relationship (3D QSAR) analysis by k-nearest neighbor molecular field analysis in conjunction with stepwise forward–backward, genetic algorithm, and simulated annealing variable selection methods using the software VLife MDS. The structure–activity relationship (SAR) as well as quantitative structure–activity relationship (QSAR) studies for anticonvulsant activity confirmed the crucial role of 3,5-bipyridinyl-1H-pyrazole core fragment for anticonvulsant activity.

Poorer prognosis in Taiwanese female ever smokers with stage IV lung adenocarcinoma who were readministered a tyrosine kinase inhibitor.

BackgroundReadministering a second epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) in patients with lung adenocarcinoma with acquired resistance to an initial EGFR TKI is a common treatment strategy. However, the prognostic factors for the second EGFR TKI are still uncertain.Patients and methodsIn this retrospective study, we enrolled patients with stage IV lung adenocarcinoma diagnosed between June 2009 and October 2013 at two university-affiliated hospitals in Taiwan. Basic characteristics including age, sex, smoking status, performance status, EGFR mutation status, tumor response, and progression-free survival (PFS) of the second EGFR TKI (PFS2) were recorded.ResultsA total of 72 patients with stage IV adenocarcinoma with susceptible EGFR gene mutations who had been treated with a second EGFR TKI were enrolled. Survival analysis using the Kaplan–Meier method and log-rank test showed a significant difference in PFS2 when classifying the patients according to smoking history and sex (P=0.0179). When stratifying the patients by sex, a significant difference was found in PFS2 between ever smokers and never smokers in the female (1.87 vs 4.87 months, P=0.0081) but not in the male (2.83 vs 2.9 months, P=0.9605) patients. A reduced multivariate model developed using the backward variable selection method showed that only ever smoking remained an independent poor prognostic factor for PFS2, and that sex and ever smoking remained independent poor prognostic factors for PFS2 in the female patients (hazard ratio [HR] =3.386, 95% confidence interval [CI]: 1.015–11.298, P=0.0473).ConclusionThis study is the first to demonstrate that female ever smokers have a poorer PFS if they have acquired resistance to an initial EGFR TKI and receive a second EGFR TKI. Further large-scale studies are urgently needed to elucidate the mechanism.